diff --git a/config/scripts/journal-replay-retention-benchmark.mjs b/config/scripts/journal-replay-retention-benchmark.mjs
index ed347670277..ecbc2353849 100644
--- a/config/scripts/journal-replay-retention-benchmark.mjs
+++ b/config/scripts/journal-replay-retention-benchmark.mjs
@@ -27,8 +27,10 @@ const identity = {
   workspaceId: 'fixture',
   hostId: 'local',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread' }
+  providerHandle: { transport: 'codex-app-server', agent: 'codex', nativeId: 'thread' }
 }
+// The baseline predates the neutral handle and takes its journal identity in the typed form.
+const baselineIdentity = { ...identity, providerHandle: { kind: 'codex', threadId: 'thread' } }
 const fixture = await mkdtemp(join(tmpdir(), 'orca-journal-replay-bench-'))
 // Released in `finally`, newest first: an open SQLite handle blocks the fixture's removal on Windows.
 const releases = []
@@ -75,7 +77,10 @@ async function openArm(arm) {
   let journal
   let database
   if (arm === 'baseline') {
-    journal = await implementation.openAgentSessionJournal({ identity, journalDir: stateDirectory })
+    journal = await implementation.openAgentSessionJournal({
+      identity: baselineIdentity,
+      journalDir: stateDirectory
+    })
   } else {
     database = implementation.JournalHostDatabase.open(stateDirectory)
     releases.push(() => database.close())
diff --git a/src/main/ai-vault/structured-session-ownership.test.ts b/src/main/ai-vault/structured-session-ownership.test.ts
index b7104e50a0c..d363e47627f 100644
--- a/src/main/ai-vault/structured-session-ownership.test.ts
+++ b/src/main/ai-vault/structured-session-ownership.test.ts
@@ -11,6 +11,10 @@ import {
   assertLegacyAiVaultResumeCommandAllowed,
   projectStructuredAiVaultSessions
 } from './structured-session-ownership'
+import {
+  claudeProviderHandle,
+  codexProviderHandle
+} from '../../shared/agent-session-provider-handle-encoding'
 
 const PROVIDER_SESSION = '019fd532-7c11-7a90-b6de-4e1a2c3d5f60'
 
@@ -93,6 +97,7 @@ function installOwnership(overrides: Partial<StructuredProviderSessionOwnership>
     ...overrides
   }
   const record = agentSessionRecordFixture(ownership.lease)
+  // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: the ownership read touches only `deps.store.listRecords`; the rest of the host is never reached.
   setStructuredAgentSessionHost({
     deps: {
       store: {
@@ -105,7 +110,10 @@ function installOwnership(overrides: Partial<StructuredProviderSessionOwnership>
             providerHandleChain: [
               {
                 ...record.providerHandleChain[0]!,
-                handle: { provider: ownership.provider, threadId: ownership.providerSessionId }
+                handle:
+                  ownership.provider === 'claude'
+                    ? claudeProviderHandle(ownership.providerSessionId, null)
+                    : codexProviderHandle(ownership.providerSessionId)
               }
             ],
             lease: { ...ownership.lease, sessionId: ownership.sessionId }
diff --git a/src/main/claude/claude-api-retry-idle-sweep.test.ts b/src/main/claude/claude-api-retry-idle-sweep.test.ts
index dcbd00776fd..695acefbb6f 100644
--- a/src/main/claude/claude-api-retry-idle-sweep.test.ts
+++ b/src/main/claude/claude-api-retry-idle-sweep.test.ts
@@ -19,6 +19,7 @@ import {
 import { createClaudeJournalTranslator } from './claude-structured-journal-translation'
 import { openTestJournalHostDatabase } from '../native-chat/agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const SWEEP_MS = 5
 const RETRY_GAP_MS = 10 * 60_000
@@ -63,7 +64,7 @@ beforeEach(async () => {
         acquisitionGeneration: 'generation-1',
         link: {
           linkId: `link-${fence}`,
-          handle: { provider: 'codex', threadId: THREAD },
+          handle: codexProviderHandle(THREAD),
           origin: 'created',
           mintedAtFence: fence,
           observedAt: NOW
diff --git a/src/main/claude/claude-api-retry-row.test.ts b/src/main/claude/claude-api-retry-row.test.ts
index 843fbb281d3..f2933b8a702 100644
--- a/src/main/claude/claude-api-retry-row.test.ts
+++ b/src/main/claude/claude-api-retry-row.test.ts
@@ -13,13 +13,14 @@ import { unhandledProviderFrameJournalItem } from '../native-chat/agent-session-
 import { createClaudeJournalTranslator } from './claude-structured-journal-translation'
 import { openTestJournalHostDatabase } from '../native-chat/agent-session-journal/journal-host-database-test-support'
 import { testEventSinkLogging } from '../native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'workspace-1',
   hostId: 'host-1',
   agent: 'claude',
-  providerHandle: { kind: 'claude', sessionId: 'provider-1', leafUuid: 'leaf-1' }
+  providerHandle: claudeProviderHandle('provider-1', 'leaf-1')
 }
 
 /** A frame as Claude Code sends it while it retries a refused request. */
diff --git a/src/main/claude/claude-context-usage-restart.test.ts b/src/main/claude/claude-context-usage-restart.test.ts
index be2c1569ead..33ce088cca0 100644
--- a/src/main/claude/claude-context-usage-restart.test.ts
+++ b/src/main/claude/claude-context-usage-restart.test.ts
@@ -11,6 +11,7 @@ import { readAgentJournalTurn } from '../../shared/agent-session-turn-record'
 import { bindClaudeContextUsageCapture } from './claude-context-usage'
 import { createClaudeJournalTranslator } from './claude-structured-journal-translation'
 import { testEventSinkLogging } from '../native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const journals = createTrackedJournalOpener()
 let root: string
@@ -104,7 +105,7 @@ async function openJournal(): Promise<AgentSessionJournal> {
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'claude',
-      providerHandle: { kind: 'claude', sessionId: 'claude-session', leafUuid: null }
+      providerHandle: claudeProviderHandle('claude-session', null)
     },
     now: () => 9_000,
     stateDirectory: join(root, 'orca-session')
diff --git a/src/main/claude/claude-context-usage-unloaded-turn.test.ts b/src/main/claude/claude-context-usage-unloaded-turn.test.ts
index d98ef7583df..5473719ce11 100644
--- a/src/main/claude/claude-context-usage-unloaded-turn.test.ts
+++ b/src/main/claude/claude-context-usage-unloaded-turn.test.ts
@@ -28,6 +28,7 @@ import {
 } from './claude-context-usage-test-support'
 import { createClaudeJournalTranslator } from './claude-structured-journal-translation'
 import { testEventSinkLogging } from '../native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'orca-session'
 const journals = createTrackedJournalOpener()
@@ -49,7 +50,7 @@ async function openJournal(): Promise<AgentSessionJournal> {
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'claude',
-      providerHandle: { kind: 'claude', sessionId: 'claude-session', leafUuid: null }
+      providerHandle: claudeProviderHandle('claude-session', null)
     },
     now: () => 9_000,
     stateDirectory: join(root, SESSION)
diff --git a/src/main/claude/claude-informational-row.test.ts b/src/main/claude/claude-informational-row.test.ts
index e41b71e1a2c..b40d16b633b 100644
--- a/src/main/claude/claude-informational-row.test.ts
+++ b/src/main/claude/claude-informational-row.test.ts
@@ -8,13 +8,14 @@ import { createDeferredStructuredAgentSessionEventSink } from '../native-chat/ag
 import { createClaudeJournalTranslator } from './claude-structured-journal-translation'
 import { openTestJournalHostDatabase } from '../native-chat/agent-session-journal/journal-host-database-test-support'
 import { testEventSinkLogging } from '../native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'workspace-1',
   hostId: 'host-1',
   agent: 'claude',
-  providerHandle: { kind: 'claude', sessionId: 'provider-1', leafUuid: 'leaf-1' }
+  providerHandle: claudeProviderHandle('provider-1', 'leaf-1')
 }
 
 /** A frame as Claude Code 2.1.280 sends it: a transcript note at a render level. */
diff --git a/src/main/claude/claude-stream-json-connection.test.ts b/src/main/claude/claude-stream-json-connection.test.ts
index 082ed4c12ce..bd79a4a2c9d 100644
--- a/src/main/claude/claude-stream-json-connection.test.ts
+++ b/src/main/claude/claude-stream-json-connection.test.ts
@@ -22,6 +22,7 @@ import type { ClaudeSession } from './claude-structured-session-state'
 import { CLAUDE_STRUCTURED_BASE_OPTIONS } from './claude-structured-launch-resolution'
 import { openTestJournalHostDatabase } from '../native-chat/agent-session-journal/journal-host-database-test-support'
 import { testEventSinkLogging } from '../native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 // These drive the real SDK against the scripted fake CLI, so every assertion is
 // about the environment, argv and frames a real child actually saw.
@@ -380,7 +381,7 @@ describe('Claude stream-json connection', () => {
         workspaceId: 'workspace-1',
         hostId: 'host-1',
         agent: 'claude',
-        providerHandle: { kind: 'claude', sessionId: SESSION_ID, leafUuid: 'leaf-1' }
+        providerHandle: claudeProviderHandle(SESSION_ID, 'leaf-1')
       },
       database: openTestJournalHostDatabase(join(scenario.cwd, 'journal')),
       now: () => 1_700_000_000_000,
diff --git a/src/main/claude/claude-structured-acquisition-launch.ts b/src/main/claude/claude-structured-acquisition-launch.ts
index b3764b16d99..4de526c7c4d 100644
--- a/src/main/claude/claude-structured-acquisition-launch.ts
+++ b/src/main/claude/claude-structured-acquisition-launch.ts
@@ -1,3 +1,4 @@
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 import {
   AgentSessionAcquisitionExitUnprovenError,
   AgentSessionPreSpawnError,
@@ -72,11 +73,10 @@ export async function resolveClaudeAcquisitionLaunch(args: {
     const launchIdentity = resumeSession
       ? {
           ...input.identity,
-          providerHandle: {
-            kind: 'claude' as const,
-            sessionId: resumeSession.providerSessionId,
-            leafUuid: resumeSession.turnEndLeafUuid
-          }
+          providerHandle: claudeProviderHandle(
+            resumeSession.providerSessionId,
+            resumeSession.turnEndLeafUuid
+          )
         }
       : input.identity
     const launch = await deps
diff --git a/src/main/claude/claude-structured-auth-parity.test.ts b/src/main/claude/claude-structured-auth-parity.test.ts
index 002240e4dd7..aa535a12a32 100644
--- a/src/main/claude/claude-structured-auth-parity.test.ts
+++ b/src/main/claude/claude-structured-auth-parity.test.ts
@@ -15,6 +15,7 @@ import {
   fakeClaude,
   identityFor
 } from './claude-structured-session-test-support'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const SESSION_ID = 'orca-session-auth'
 const IDENTITY = { sessionId: SESSION_ID } as Parameters<
@@ -60,11 +61,10 @@ function realResolverAdapter(
   claude: ReturnType<typeof fakeClaude>,
   authSwitchSettleTimeoutMs: number
 ): ClaudeStructuredSessionAdapter {
+  // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: the resolver reads only the chain head's handle from this partial record.
   const resumable = {
     ...record(),
-    providerHandleChain: [
-      { handle: { provider: 'claude', sessionId: PROVIDER_SESSION_ID, leafUuid: null } }
-    ]
+    providerHandleChain: [{ handle: claudeProviderHandle(PROVIDER_SESSION_ID, null) }]
   } as unknown as AgentSessionRecord
   return new ClaudeStructuredSessionAdapter({
     resolveLaunch: createClaudeStructuredLaunchResolver({
diff --git a/src/main/claude/claude-structured-history-window.test.ts b/src/main/claude/claude-structured-history-window.test.ts
index 851831b86f1..e5ed29561cb 100644
--- a/src/main/claude/claude-structured-history-window.test.ts
+++ b/src/main/claude/claude-structured-history-window.test.ts
@@ -13,6 +13,7 @@ import {
   claudeProviderHistoryWindowFromJsonl,
   resolveClaudeProviderHistoryWindow
 } from './claude-structured-history-window'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const PROVIDER_SESSION = 'provider-1'
 const ORCA_SESSION = 'session-1'
@@ -82,7 +83,7 @@ describe('claudeProviderHistoryWindowFromJsonl', () => {
         workspaceId: 'workspace-1',
         hostId: 'host-1',
         agent: 'claude',
-        providerHandle: { kind: 'claude', sessionId: PROVIDER_SESSION, leafUuid: 'anchor' }
+        providerHandle: claudeProviderHandle(PROVIDER_SESSION, 'anchor')
       },
       accountHomePath: accountHome,
       hasLiveSession: false
diff --git a/src/main/claude/claude-structured-history-window.ts b/src/main/claude/claude-structured-history-window.ts
index 00ae8692025..fc5c661a690 100644
--- a/src/main/claude/claude-structured-history-window.ts
+++ b/src/main/claude/claude-structured-history-window.ts
@@ -16,6 +16,11 @@
 
 import { join } from 'node:path'
 import type { AgentSessionJournalIdentity } from '../../shared/agent-session-journal-types'
+import {
+  CLAUDE_STRUCTURED_HANDLE_NAMESPACE,
+  claudeProviderHandleLeafUuid,
+  isAgentSessionProviderHandleInNamespace
+} from '../../shared/agent-session-provider-handle-encoding'
 import { resolveSessionFilePath } from '../native-chat/session-file-resolver'
 import type {
   ProviderHistoryItem,
@@ -242,10 +247,13 @@ export async function resolveClaudeProviderHistoryWindow(input: {
   hasLiveSession: boolean
 }): Promise<ProviderHistoryWindow | null> {
   const handle = input.identity.providerHandle
-  if (handle.kind !== 'claude') {
+  if (
+    !handle ||
+    !isAgentSessionProviderHandleInNamespace(handle, CLAUDE_STRUCTURED_HANDLE_NAMESPACE)
+  ) {
     return null
   }
-  const transcriptPath = await resolveSessionFilePath('claude', handle.sessionId, {
+  const transcriptPath = await resolveSessionFilePath('claude', handle.nativeId, {
     claudeProjectsDir: join(input.accountHomePath, 'projects')
   })
   if (!transcriptPath) {
@@ -253,8 +261,8 @@ export async function resolveClaudeProviderHistoryWindow(input: {
   }
   return readClaudeProviderHistoryWindow({
     transcriptPath,
-    providerSessionId: handle.sessionId,
-    previousLeafUuid: handle.leafUuid,
+    providerSessionId: handle.nativeId,
+    previousLeafUuid: claudeProviderHandleLeafUuid(handle),
     sessionId: input.identity.sessionId,
     turnInFlight: input.hasLiveSession
   })
diff --git a/src/main/claude/claude-structured-journal-translation.test.ts b/src/main/claude/claude-structured-journal-translation.test.ts
index 0cf7b30368a..4aa02ed525c 100644
--- a/src/main/claude/claude-structured-journal-translation.test.ts
+++ b/src/main/claude/claude-structured-journal-translation.test.ts
@@ -24,6 +24,7 @@ import { readAgentJournalTurn } from '../../shared/agent-session-turn-record'
 import { createClaudeJournalTranslator } from './claude-structured-journal-translation'
 import { openTestJournalHostDatabase } from '../native-chat/agent-session-journal/journal-host-database-test-support'
 import { testEventSinkLogging } from '../native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 function sinkState() {
   const items: { identity: AgentJournalItemIdentity; body: AgentJournalItemBody }[] = []
@@ -180,7 +181,7 @@ const JOURNAL_IDENTITY: AgentSessionJournalIdentity = {
   workspaceId: 'workspace-1',
   hostId: 'host-1',
   agent: 'claude',
-  providerHandle: { kind: 'claude', sessionId: 'claude-session', leafUuid: 'leaf-1' }
+  providerHandle: claudeProviderHandle('claude-session', 'leaf-1')
 }
 
 let journalRoot = ''
diff --git a/src/main/claude/claude-structured-launch-resolution.test.ts b/src/main/claude/claude-structured-launch-resolution.test.ts
index 66fed64c323..9db732d3430 100644
--- a/src/main/claude/claude-structured-launch-resolution.test.ts
+++ b/src/main/claude/claude-structured-launch-resolution.test.ts
@@ -16,6 +16,7 @@ import {
   createClaudeStructuredLaunchResolver
 } from './claude-structured-launch-resolution'
 import { claudeStructuredPermissionModeForSettings } from './claude-structured-permission-mode'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const SESSION_ID = 'orca-session-1'
 const IDENTITY = { sessionId: SESSION_ID } as Parameters<
@@ -41,7 +42,7 @@ function record(overrides: Partial<AgentSessionRecord> = {}): AgentSessionRecord
 function identityAt(leafUuid: string | null): typeof IDENTITY {
   return {
     ...IDENTITY,
-    providerHandle: { kind: 'claude', sessionId: 'provider-current', leafUuid }
+    providerHandle: claudeProviderHandle('provider-current', leafUuid)
   }
 }
 
@@ -100,8 +101,9 @@ const WSL_ONLY_NORMALIZED: ClaudeManagedAccountGateSettings = {
 }
 
 const RESUMABLE = record({
+  // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: the resolver reads only each link's handle, so the link's other fields stay unset.
   providerHandleChain: [
-    { handle: { provider: 'claude', sessionId: 'provider-current', leafUuid: 'leaf-current' } }
+    { handle: claudeProviderHandle('provider-current', 'leaf-current') }
   ] as AgentSessionRecord['providerHandleChain']
 })
 
@@ -136,14 +138,11 @@ describe('claude structured launch resolution', () => {
   it('resumes the durable chain head by session id and carries its leaf as bookkeeping', async () => {
     const launch = await resolverFor(
       record({
+        // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: the resolver reads only each link's handle, so the link's other fields stay unset.
         providerHandleChain: [
-          { handle: { provider: 'claude', sessionId: 'provider-old', leafUuid: 'leaf-old' } },
+          { handle: claudeProviderHandle('provider-old', 'leaf-old') },
           {
-            handle: {
-              provider: 'claude',
-              sessionId: 'provider-current',
-              leafUuid: 'leaf-current'
-            }
+            handle: claudeProviderHandle('provider-current', 'leaf-current')
           }
         ] as AgentSessionRecord['providerHandleChain']
       })
@@ -194,7 +193,7 @@ describe('claude structured launch resolution', () => {
       resolve({
         identity: {
           ...IDENTITY,
-          providerHandle: { kind: 'claude', sessionId: 'provider-other', leafUuid: 'leaf-current' }
+          providerHandle: claudeProviderHandle('provider-other', 'leaf-current')
         }
       })
     ).rejects.toThrow('durable resume identity changed before spawn')
@@ -203,13 +202,10 @@ describe('claude structured launch resolution', () => {
   it('keeps session-only resume when the durable handle has no leaf', async () => {
     const launch = await resolverFor(
       record({
+        // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: the resolver reads only each link's handle, so the link's other fields stay unset.
         providerHandleChain: [
           {
-            handle: {
-              provider: 'claude',
-              sessionId: 'provider-current',
-              leafUuid: null
-            }
+            handle: claudeProviderHandle('provider-current', null)
           }
         ] as AgentSessionRecord['providerHandleChain']
       })
@@ -226,7 +222,7 @@ describe('claude structured launch resolution', () => {
       record({
         // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: the resolver reads only each link's handle.
         providerHandleChain: [
-          { handle: { provider: 'claude', sessionId: 'provider-current', leafUuid: null } }
+          { handle: claudeProviderHandle('provider-current', null) }
         ] as AgentSessionRecord['providerHandleChain']
       }),
       undefined,
diff --git a/src/main/claude/claude-structured-launch-resolution.ts b/src/main/claude/claude-structured-launch-resolution.ts
index 29703dfd8eb..979b5ae5963 100644
--- a/src/main/claude/claude-structured-launch-resolution.ts
+++ b/src/main/claude/claude-structured-launch-resolution.ts
@@ -5,7 +5,11 @@ import type {
   PermissionMode
 } from '@anthropic-ai/claude-agent-sdk'
 import type { AgentSessionJournalIdentity } from '../../shared/agent-session-journal-types'
-import { agentSessionProviderHandleChainHead } from '../../shared/agent-session-provider-handle'
+import {
+  agentSessionProviderHandleChainHead,
+  agentSessionProviderHandleRoot
+} from '../../shared/agent-session-provider-handle'
+import { claudeProviderHandleLeafUuid } from '../../shared/agent-session-provider-handle-encoding'
 import { LOCAL_EXECUTION_HOST_ID } from '../../shared/execution-host'
 import { withCliRuntimeOnPath } from '../../shared/node-cli-command-resolution'
 import { structuredSessionChildIdentityEnv } from '../runtime/structured-session-child-identity-env'
@@ -260,24 +264,25 @@ export function createClaudeStructuredLaunchResolver(
         gate && hasWslBoundClaudeAccount(gate) ? { reason: 'managedAccountUnsupported' } : {}
       )
     }
-    const head = agentSessionProviderHandleChainHead(record.providerHandleChain)
+    // A Claude record's chain holds only Claude handles; the record store refuses anything else.
+    const head = agentSessionProviderHandleChainHead(record.providerHandleChain)?.handle ?? null
     if (
-      head?.handle.provider === 'claude' &&
-      (identity.providerHandle.kind !== 'claude' ||
-        identity.providerHandle.sessionId !== head.handle.sessionId)
+      head &&
+      (!identity.providerHandle ||
+        agentSessionProviderHandleRoot(identity.providerHandle) !==
+          agentSessionProviderHandleRoot(head))
     ) {
       throw new Error('claude durable resume identity changed before spawn')
     }
-    const providerSessionId =
-      head?.handle.provider === 'claude'
-        ? head.handle.sessionId
-        : claudeSessionIdForOrcaSession(identity.sessionId)
-    const continuesChain = head?.handle.provider === 'claude'
+    const providerSessionId = head
+      ? head.nativeId
+      : claudeSessionIdForOrcaSession(identity.sessionId)
+    const continuesChain = head !== null
     // A start that failed before its first turn wrote no transcript, and `--resume` of an absent
     // one exits; launch that id fresh instead. With a transcript, `--session-id` would collide.
     const resumesTranscript =
-      head?.handle.provider === 'claude' &&
-      (head.handle.leafUuid !== null ||
+      head !== null &&
+      (claudeProviderHandleLeafUuid(head) !== null ||
         (await (deps.hasTranscript ?? claudeTranscriptExists)({
           providerSessionId,
           claudeConfigDir: record.accountHome.path
@@ -308,8 +313,7 @@ export function createClaudeStructuredLaunchResolver(
       env,
       claudeConfigDir: record.accountHome.path,
       providerSessionId,
-      resumeLeafUuid:
-        resumesTranscript && head?.handle.provider === 'claude' ? head.handle.leafUuid : null,
+      resumeLeafUuid: resumesTranscript && head ? claudeProviderHandleLeafUuid(head) : null,
       resumesTranscript,
       continuesChain
     }
diff --git a/src/main/claude/claude-structured-owner-identity.test.ts b/src/main/claude/claude-structured-owner-identity.test.ts
index 592b61df338..729aecbec87 100644
--- a/src/main/claude/claude-structured-owner-identity.test.ts
+++ b/src/main/claude/claude-structured-owner-identity.test.ts
@@ -1,12 +1,13 @@
 import { describe, expect, it, vi } from 'vitest'
 import { CLAUDE_SPAWN_TOKEN_ENV, claudeProcessIdentity } from './claude-structured-owner-identity'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY = {
   sessionId: 'session-identity',
   workspaceId: 'workspace-1',
   hostId: 'local',
   agent: 'claude' as const,
-  providerHandle: { kind: 'claude' as const, sessionId: 'session-1', leafUuid: 'leaf-1' }
+  providerHandle: claudeProviderHandle('session-1', 'leaf-1')
 }
 
 describe('claude structured owner identity', () => {
diff --git a/src/main/claude/claude-structured-owner-identity.ts b/src/main/claude/claude-structured-owner-identity.ts
index e8f251d41f9..80f6ca6977d 100644
--- a/src/main/claude/claude-structured-owner-identity.ts
+++ b/src/main/claude/claude-structured-owner-identity.ts
@@ -1,5 +1,6 @@
 import type { AgentSessionJournalIdentity } from '../../shared/agent-session-journal-types'
 import type { AgentSessionProviderHandleLink } from '../../shared/agent-session-provider-handle'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 import type { AgentSessionProcessIdentity } from '../../shared/agent-session-record'
 import { readProcessStartTimeMs } from '../runtime/agent-session-process-identity-probe'
 
@@ -16,7 +17,7 @@ export function claudeProviderHandleLink(input: {
     linkId:
       input.linkId ??
       `claude-${input.fence}-${input.sessionId}-${input.leafUuid ?? 'empty'}`.slice(0, 128),
-    handle: { provider: 'claude', sessionId: input.sessionId, leafUuid: input.leafUuid },
+    handle: claudeProviderHandle(input.sessionId, input.leafUuid),
     origin: input.origin ?? (input.resumed ? 'resumed' : 'created'),
     mintedAtFence: input.fence,
     observedAt: input.observedAt
diff --git a/src/main/claude/claude-structured-provider-fallback.test.ts b/src/main/claude/claude-structured-provider-fallback.test.ts
index 4cae8b465e9..3e67d35f7b4 100644
--- a/src/main/claude/claude-structured-provider-fallback.test.ts
+++ b/src/main/claude/claude-structured-provider-fallback.test.ts
@@ -12,13 +12,14 @@ import { createClaudeJournalTranslator } from './claude-structured-journal-trans
 import type { ClaudeStructuredSessionEvent } from './claude-structured-session-state'
 import { openTestJournalHostDatabase } from '../native-chat/agent-session-journal/journal-host-database-test-support'
 import { testEventSinkLogging } from '../native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'workspace-1',
   hostId: 'host-1',
   agent: 'claude',
-  providerHandle: { kind: 'claude', sessionId: 'provider-1', leafUuid: 'leaf-1' }
+  providerHandle: claudeProviderHandle('provider-1', 'leaf-1')
 }
 
 let root = ''
diff --git a/src/main/claude/claude-structured-real-cli-fold.test.ts b/src/main/claude/claude-structured-real-cli-fold.test.ts
index 5ce21d83f17..13e4ee5e672 100644
--- a/src/main/claude/claude-structured-real-cli-fold.test.ts
+++ b/src/main/claude/claude-structured-real-cli-fold.test.ts
@@ -27,6 +27,7 @@ import {
   realClaudeCommand,
   realClaudeLaunchHome
 } from './claude-real-cli-availability-test-support'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const SESSION_ID = 'real-cli-fold'
 // Pins the live proof order (SessionStart hook frame before system/init) and lets the
@@ -42,7 +43,7 @@ function identity(providerSessionId: string): AgentSessionJournalIdentity {
     workspaceId: 'real-cli-fold-workspace',
     hostId: 'local',
     agent: 'claude',
-    providerHandle: { kind: 'claude', sessionId: providerSessionId, leafUuid: null }
+    providerHandle: claudeProviderHandle(providerSessionId, null)
   }
 }
 
diff --git a/src/main/claude/claude-structured-real-cli.test.ts b/src/main/claude/claude-structured-real-cli.test.ts
index af6719938be..b12ca6ff1e0 100644
--- a/src/main/claude/claude-structured-real-cli.test.ts
+++ b/src/main/claude/claude-structured-real-cli.test.ts
@@ -21,6 +21,7 @@ import {
   type ClaudeStructuredSessionEvent
 } from './claude-structured-session-adapter'
 import type { ClaudeStructuredSessionAdapterDeps } from './claude-structured-session-state'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const command = realClaudeCommand
 const suiteTitle = `Claude structured real CLI handshake${realClaudeCliGate.skipReason ? ` (skipped: ${realClaudeCliGate.skipReason})` : ''}`
@@ -66,7 +67,7 @@ function identity(providerSessionId: string): AgentSessionJournalIdentity {
     workspaceId: 'real-cli-workspace',
     hostId: 'local',
     agent: 'claude',
-    providerHandle: { kind: 'claude', sessionId: providerSessionId, leafUuid: null }
+    providerHandle: claudeProviderHandle(providerSessionId, null)
   }
 }
 
@@ -158,13 +159,9 @@ describe.skipIf(!realClaudeAvailable)(suiteTitle, () => {
           event.type === 'message' ? [event.message.subtype] : []
         )
 
-        expect(acquisition.link.handle).toMatchObject({
-          provider: 'claude',
-          sessionId: providerSessionId,
-          // Init/SessionStart UUIDs are protocol frames, not resumable
-          // main-transcript leaves; no cursor exists before the first user turn.
-          leafUuid: null
-        })
+        // Init/SessionStart UUIDs are protocol frames, not resumable
+        // main-transcript leaves; no cursor exists before the first user turn.
+        expect(acquisition.link.handle).toEqual(claudeProviderHandle(providerSessionId, null))
         expect(observedSubtypes).toContain('hook_started')
         expect(adapter.readCommands('real-cli-handshake')).toContainEqual(
           expect.objectContaining({
diff --git a/src/main/claude/claude-structured-resume-point.test.ts b/src/main/claude/claude-structured-resume-point.test.ts
index 862909a2cd6..9465feba5d3 100644
--- a/src/main/claude/claude-structured-resume-point.test.ts
+++ b/src/main/claude/claude-structured-resume-point.test.ts
@@ -88,7 +88,7 @@ describe('Claude resume point is the last completed turn on every exit path', ()
       spawnToken: 'spawn-7',
       events: recordingJournalSink()
     })
-    expect(acquisition.link.handle).toMatchObject({ leafUuid: 'a3' })
+    expect(acquisition.link.handle).toMatchObject({ resumeCursor: 'a3' })
     await expect(adapter.closeSession('session-1')).resolves.toBe(true)
     expect(persisted).toEqual([expect.objectContaining({ leafUuid: 'a3' })])
   })
diff --git a/src/main/claude/claude-structured-session-acquisition-processless.test.ts b/src/main/claude/claude-structured-session-acquisition-processless.test.ts
index eb4babdb9ac..a75f82b72db 100644
--- a/src/main/claude/claude-structured-session-acquisition-processless.test.ts
+++ b/src/main/claude/claude-structured-session-acquisition-processless.test.ts
@@ -13,7 +13,7 @@ const IDENTITY: AgentSessionJournalIdentity = {
   workspaceId: 'workspace-1',
   hostId: 'local',
   agent: 'claude',
-  providerHandle: { kind: 'opaque', agent: 'claude', value: 'pending' }
+  providerHandle: null
 }
 
 describe('Claude structured processless acquisition', () => {
diff --git a/src/main/claude/claude-structured-session-adapter.test.ts b/src/main/claude/claude-structured-session-adapter.test.ts
index ee14b6b525a..cd5b4841de6 100644
--- a/src/main/claude/claude-structured-session-adapter.test.ts
+++ b/src/main/claude/claude-structured-session-adapter.test.ts
@@ -24,6 +24,7 @@ import {
   type FakeConnection
 } from './claude-structured-session-test-support'
 import { invokeCanUseTool } from './claude-can-use-tool-test-support'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 describe('ClaudeStructuredSessionAdapter.acquire', () => {
   it('pins the account and proves init without treating the system-frame uuid as a chain leaf', async () => {
@@ -57,7 +58,7 @@ describe('ClaudeStructuredSessionAdapter.acquire', () => {
     })
     expect(acquisition.link).toEqual({
       linkId: `claude-7-${PROVIDER_SESSION_ID}-empty`,
-      handle: { provider: 'claude', sessionId: PROVIDER_SESSION_ID, leafUuid: null },
+      handle: claudeProviderHandle(PROVIDER_SESSION_ID, null),
       origin: 'created',
       mintedAtFence: 7,
       observedAt: 1_700_000_000_500
@@ -424,11 +425,7 @@ describe('ClaudeStructuredSessionAdapter.acquire', () => {
       spawnToken: 'spawn-9'
     })
 
-    expect(acquisition.link.handle).toEqual({
-      provider: 'claude',
-      sessionId: PROVIDER_SESSION_ID,
-      leafUuid: null
-    })
+    expect(acquisition.link.handle).toEqual(claudeProviderHandle(PROVIDER_SESSION_ID, null))
     expect(events[0]).toMatchObject({
       type: 'message',
       message: { subtype: 'hook_started', hook_name: 'SessionStart:startup' }
@@ -476,11 +473,9 @@ describe('ClaudeStructuredSessionAdapter.acquire', () => {
       spawnToken: 'spawn-9'
     })
     expect(acquisition.link.origin).toBe('resumed')
-    expect(acquisition.link.handle).toEqual({
-      provider: 'claude',
-      sessionId: PROVIDER_SESSION_ID,
-      leafUuid: 'leaf-before'
-    })
+    expect(acquisition.link.handle).toEqual(
+      claudeProviderHandle(PROVIDER_SESSION_ID, 'leaf-before')
+    )
 
     const wrongClaude = fakeClaude({ initSessionId: 'different-session' })
     await expect(endedAtStartup(wrongClaude)).resolves.toMatchObject({
diff --git a/src/main/claude/claude-structured-session-recovery.test.ts b/src/main/claude/claude-structured-session-recovery.test.ts
index a91b1d7c193..86598780b45 100644
--- a/src/main/claude/claude-structured-session-recovery.test.ts
+++ b/src/main/claude/claude-structured-session-recovery.test.ts
@@ -13,6 +13,10 @@ import {
   tick
 } from './claude-structured-session-test-support'
 import { invokeCanUseTool } from './claude-can-use-tool-test-support'
+import {
+  claudeProviderHandle,
+  claudeProviderHandleLeafUuid
+} from '../../shared/agent-session-provider-handle-encoding'
 
 describe('ClaudeStructuredSessionAdapter close and exit recovery', () => {
   it('shares concurrent close finalization and emits lifecycle once', async () => {
@@ -296,9 +300,9 @@ describe('ClaudeStructuredSessionAdapter close and exit recovery', () => {
     let durableLeafUuid: string | null = null
     const resolveLaunch = vi.fn(async ({ identity }) => {
       if (
-        identity.providerHandle.kind !== 'claude' ||
-        identity.providerHandle.sessionId !== PROVIDER_SESSION_ID ||
-        identity.providerHandle.leafUuid !== durableLeafUuid
+        !identity.providerHandle ||
+        identity.providerHandle.nativeId !== PROVIDER_SESSION_ID ||
+        claudeProviderHandleLeafUuid(identity.providerHandle) !== durableLeafUuid
       ) {
         throw new Error('claude durable resume identity changed before spawn')
       }
@@ -385,11 +389,7 @@ describe('ClaudeStructuredSessionAdapter close and exit recovery', () => {
     const replacement = await adapter.acquire({
       identity: {
         ...identityFor(),
-        providerHandle: {
-          kind: 'claude',
-          sessionId: PROVIDER_SESSION_ID,
-          leafUuid: 'observed-retained-leaf'
-        }
+        providerHandle: claudeProviderHandle(PROVIDER_SESSION_ID, 'observed-retained-leaf')
       },
       fence: 8,
       spawnToken: 'spawn-10',
@@ -411,11 +411,7 @@ describe('ClaudeStructuredSessionAdapter close and exit recovery', () => {
     expect(resolveLaunch).toHaveBeenNthCalledWith(2, {
       identity: {
         ...identityFor(),
-        providerHandle: {
-          kind: 'claude',
-          sessionId: PROVIDER_SESSION_ID,
-          leafUuid: 'observed-retained-leaf'
-        }
+        providerHandle: claudeProviderHandle(PROVIDER_SESSION_ID, 'observed-retained-leaf')
       }
     })
     expect(oldPrompt.settled()).toBe(true)
@@ -432,11 +428,7 @@ describe('ClaudeStructuredSessionAdapter close and exit recovery', () => {
       }
     ])
     expect(replacement.link).toMatchObject({
-      handle: {
-        provider: 'claude',
-        sessionId: PROVIDER_SESSION_ID,
-        leafUuid: 'observed-retained-leaf'
-      },
+      handle: claudeProviderHandle(PROVIDER_SESSION_ID, 'observed-retained-leaf'),
       origin: 'resumed',
       mintedAtFence: 8
     })
diff --git a/src/main/claude/claude-structured-session-test-support.ts b/src/main/claude/claude-structured-session-test-support.ts
index dd7ad1e8d8c..02cf46aadc8 100644
--- a/src/main/claude/claude-structured-session-test-support.ts
+++ b/src/main/claude/claude-structured-session-test-support.ts
@@ -15,6 +15,7 @@ import {
   type ClaudeStructuredSessionEvent
 } from './claude-structured-session-adapter'
 import type { StructuredAgentSessionEventSink } from '../native-chat/agent-session-wire/structured-agent-session-event-sink'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 export const PROVIDER_SESSION_ID = '819cf9f8-e43c-4ad7-b50f-54aa158a726a'
 
@@ -30,7 +31,7 @@ export function identityFor(sessionId = 'session-1'): AgentSessionJournalIdentit
     workspaceId: 'workspace-1',
     hostId: 'host-1',
     agent: 'claude',
-    providerHandle: { kind: 'claude', sessionId: PROVIDER_SESSION_ID, leafUuid: null }
+    providerHandle: claudeProviderHandle(PROVIDER_SESSION_ID, null)
   }
 }
 
diff --git a/src/main/claude/claude-structured-turn-resume-point.test.ts b/src/main/claude/claude-structured-turn-resume-point.test.ts
index 4cb72eaa53a..3ffd74aff14 100644
--- a/src/main/claude/claude-structured-turn-resume-point.test.ts
+++ b/src/main/claude/claude-structured-turn-resume-point.test.ts
@@ -6,7 +6,7 @@ import {
 import type { AgentSessionRecord } from '../../shared/agent-session-record'
 import { LOCAL_EXECUTION_HOST_ID } from '../../shared/execution-host'
 import type { AgentSessionRecordStore } from '../runtime/agent-session-record-store'
-import { reviseAgentSessionClaudeResumePoint } from '../runtime/agent-session-provider-handle-transition'
+import { reviseAgentSessionProviderResumePoint } from '../runtime/agent-session-provider-handle-transition'
 import { createClaudeStructuredLaunchResolver } from './claude-structured-launch-resolution'
 import {
   ClaudeStructuredSessionAdapter,
@@ -20,6 +20,7 @@ import {
   recordingJournalSink,
   tick
 } from './claude-structured-session-test-support'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const FENCE = 7
 
@@ -36,14 +37,14 @@ function liveRecord(): AgentSessionRecord {
         origin: 'created',
         mintedAtFence: 1,
         observedAt: 500,
-        handle: { provider: 'claude', sessionId: PROVIDER_SESSION_ID, leafUuid: null }
+        handle: claudeProviderHandle(PROVIDER_SESSION_ID, null)
       },
       {
         linkId: 'published-link',
         origin: 'resumed',
         mintedAtFence: FENCE,
         observedAt: 1_000,
-        handle: { provider: 'claude', sessionId: PROVIDER_SESSION_ID, leafUuid: 'resumed-at' }
+        handle: claudeProviderHandle(PROVIDER_SESSION_ID, 'resumed-at')
       }
     ]
   }
@@ -78,11 +79,10 @@ async function liveOwner(
     persistResumePoint:
       persistResumePoint ??
       (async ({ providerSessionId, leafUuid, fence }) => {
-        store.record = reviseAgentSessionClaudeResumePoint({
+        store.record = reviseAgentSessionProviderResumePoint({
           record: store.record,
           fence,
-          providerSessionId,
-          leafUuid,
+          handle: claudeProviderHandle(providerSessionId, leafUuid),
           now: 2_000
         })
       })
@@ -115,12 +115,12 @@ describe('Claude durable resume point at turn end', () => {
     const { adapter, store, turn } = await liveOwner()
     try {
       await turn('u1', 'a1')
-      expect(store.record.providerHandleChain.at(-1)?.handle).toMatchObject({ leafUuid: 'a1' })
+      expect(store.record.providerHandleChain.at(-1)?.handle).toMatchObject({ resumeCursor: 'a1' })
       await turn('u2', 'a2')
       expect(store.record.providerHandleChain).toHaveLength(2)
       expect(store.record.providerHandleChain.at(-1)).toMatchObject({
         linkId: 'published-link',
-        handle: { leafUuid: 'a2' }
+        handle: { resumeCursor: 'a2' }
       })
     } finally {
       await adapter.closeAll()
@@ -135,7 +135,7 @@ describe('Claude durable resume point at turn end', () => {
     frame({ type: 'user', uuid: 'u3' })
     await tick()
     const head = store.record.providerHandleChain.at(-1)!.handle
-    expect(head).toMatchObject({ leafUuid: 'a2' })
+    expect(head).toMatchObject({ resumeCursor: 'a2' })
 
     const resolve = createClaudeStructuredLaunchResolver({
       // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: the resolver reads only getRecord from its store.
@@ -147,7 +147,7 @@ describe('Claude durable resume point at turn end', () => {
     const launch = await resolve({
       identity: {
         ...identityFor(store.record.sessionId),
-        providerHandle: { kind: 'claude', sessionId: PROVIDER_SESSION_ID, leafUuid: 'a2' }
+        providerHandle: claudeProviderHandle(PROVIDER_SESSION_ID, 'a2')
       }
     })
     // Bookkeeping only: Claude continues from the end of its own conversation.
diff --git a/src/main/claude/claude-subagent-resume-after-restart.test.ts b/src/main/claude/claude-subagent-resume-after-restart.test.ts
index c4b848eee44..d95dd3a48ff 100644
--- a/src/main/claude/claude-subagent-resume-after-restart.test.ts
+++ b/src/main/claude/claude-subagent-resume-after-restart.test.ts
@@ -17,6 +17,7 @@ import { createDeferredStructuredAgentSessionEventSink } from '../native-chat/ag
 import { createClaudeJournalTranslator } from './claude-structured-journal-translation'
 import { claudeSubagentGroupBody, claudeSubagentGroupIdentity } from './claude-subagent-group-row'
 import { testEventSinkLogging } from '../native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 // Frame orders are real sessions', scrubbed. A resumed agent's frames still name its ORIGINAL
 // spawn call while the announcement names the message call that resumed it, and a new provider
@@ -129,7 +130,7 @@ async function openJournal(): Promise<AgentSessionJournal> {
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'claude',
-      providerHandle: { kind: 'claude', sessionId: 'claude-session', leafUuid: null }
+      providerHandle: claudeProviderHandle('claude-session', null)
     },
     now: () => 9_000,
     stateDirectory: root
diff --git a/src/main/codex/codex-provider-retry-idle-sweep.test.ts b/src/main/codex/codex-provider-retry-idle-sweep.test.ts
index 0e3e8385685..722858828f2 100644
--- a/src/main/codex/codex-provider-retry-idle-sweep.test.ts
+++ b/src/main/codex/codex-provider-retry-idle-sweep.test.ts
@@ -19,6 +19,7 @@ import {
 import { createCodexJournalTranslator } from './codex-structured-journal-translation'
 import { openTestJournalHostDatabase } from '../native-chat/agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const SWEEP_MS = 5
 const RETRY_GAP_MS = 10 * 60_000
@@ -61,7 +62,7 @@ beforeEach(async () => {
         acquisitionGeneration: 'generation-1',
         link: {
           linkId: `link-${fence}`,
-          handle: { provider: 'codex', threadId: THREAD },
+          handle: codexProviderHandle(THREAD),
           origin: 'created',
           mintedAtFence: fence,
           observedAt: NOW
diff --git a/src/main/codex/codex-structured-acquisition-exit-proof.test.ts b/src/main/codex/codex-structured-acquisition-exit-proof.test.ts
index f0737fc36a3..f86d0aff6c1 100644
--- a/src/main/codex/codex-structured-acquisition-exit-proof.test.ts
+++ b/src/main/codex/codex-structured-acquisition-exit-proof.test.ts
@@ -3,13 +3,14 @@ import { describe, expect, it, vi } from 'vitest'
 import type { AgentSessionJournalIdentity } from '../../shared/agent-session-journal-types'
 import type { CodexAppServerConnection } from './codex-app-server-connection-types'
 import { CodexStructuredSessionAdapter } from './codex-structured-session-adapter'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'workspace-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 describe('Codex failed-acquisition exit proof', () => {
diff --git a/src/main/codex/codex-structured-dispatch-test-support.ts b/src/main/codex/codex-structured-dispatch-test-support.ts
index 7513ec1fbbe..9ac0f7f31bd 100644
--- a/src/main/codex/codex-structured-dispatch-test-support.ts
+++ b/src/main/codex/codex-structured-dispatch-test-support.ts
@@ -14,6 +14,7 @@ import type { StructuredAgentSessionEventSink } from '../native-chat/agent-sessi
 import { CodexStructuredSessionAdapter } from './codex-structured-session-adapter'
 import { codexTurnLifecycleFake } from './codex-turn-lifecycle-fake'
 import type { CodexStructuredSessionAdapterDeps } from './codex-structured-session-state'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 export const CODEX_TEST_THREAD_ID = 'thread-abc'
 
@@ -114,7 +115,7 @@ export async function acquiredCodexAdapter(input: {
     workspaceId: 'ws-1',
     hostId: 'host-1',
     agent: 'codex',
-    providerHandle: { kind: 'codex', threadId: CODEX_TEST_THREAD_ID }
+    providerHandle: codexProviderHandle(CODEX_TEST_THREAD_ID)
   }
   await adapter.acquire({
     identity,
diff --git a/src/main/codex/codex-structured-journal-goal-revision.test.ts b/src/main/codex/codex-structured-journal-goal-revision.test.ts
index aa455403ea7..11b559655b4 100644
--- a/src/main/codex/codex-structured-journal-goal-revision.test.ts
+++ b/src/main/codex/codex-structured-journal-goal-revision.test.ts
@@ -15,6 +15,7 @@ import { readAgentSessionHistory } from '../native-chat/agent-session-wire/agent
 import { createDeferredStructuredAgentSessionEventSink } from '../native-chat/agent-session-wire/structured-agent-session-event-sink'
 import { CodexJournalGoals } from './codex-structured-journal-goals'
 import { testEventSinkLogging } from '../native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const THREAD = '01a08cc2-f96e-76d0-bb74-88b9bc0b03fc'
 const IDENTITY: AgentSessionJournalIdentity = {
@@ -22,7 +23,7 @@ const IDENTITY: AgentSessionJournalIdentity = {
   workspaceId: 'workspace-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: THREAD }
+  providerHandle: codexProviderHandle(THREAD)
 }
 
 let root: string | null = null
diff --git a/src/main/codex/codex-structured-journal-subagent-readers.test.ts b/src/main/codex/codex-structured-journal-subagent-readers.test.ts
index a99b815bff4..87b888ec1a0 100644
--- a/src/main/codex/codex-structured-journal-subagent-readers.test.ts
+++ b/src/main/codex/codex-structured-journal-subagent-readers.test.ts
@@ -22,6 +22,7 @@ import { createCodexJournalTranslator } from './codex-structured-journal-transla
 import type { CodexThreadItem } from './codex-thread-item-identity'
 import { openTestJournalHostDatabase } from '../native-chat/agent-session-journal/journal-host-database-test-support'
 import { testEventSinkLogging } from '../native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'session-codex-children'
 const PARENT = 'thread-parent'
@@ -43,7 +44,7 @@ async function openJournal(root: string): Promise<AgentSessionJournal> {
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: PARENT }
+      providerHandle: codexProviderHandle(PARENT)
     },
     database: openTestJournalHostDatabase(root),
     now: () => 1_000
diff --git a/src/main/codex/codex-structured-journal-translation-turn-lifecycle.test.ts b/src/main/codex/codex-structured-journal-translation-turn-lifecycle.test.ts
index 07115c4b4e7..0f51961b64d 100644
--- a/src/main/codex/codex-structured-journal-translation-turn-lifecycle.test.ts
+++ b/src/main/codex/codex-structured-journal-translation-turn-lifecycle.test.ts
@@ -27,6 +27,7 @@ import { createCodexStructuredNotificationRetry } from './codex-structured-notif
 import type { CodexStructuredSessionEvent } from './codex-structured-session-adapter'
 import type { CodexSession } from './codex-structured-session-state'
 import { testEventSinkLogging } from '../native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const SESSION_ID = 'session-1'
 const THREAD_ID = 'thread-abc'
@@ -219,7 +220,7 @@ describe('codex turn lifecycle rows', () => {
         workspaceId: 'workspace-1',
         hostId: 'local',
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: THREAD_ID }
+        providerHandle: codexProviderHandle(THREAD_ID)
       },
       now: () => 9_000,
       stateDirectory: join(root, SESSION_ID)
diff --git a/src/main/codex/codex-structured-journal-turn-settles-once-journal.test.ts b/src/main/codex/codex-structured-journal-turn-settles-once-journal.test.ts
index da24f836d1a..05748ead80f 100644
--- a/src/main/codex/codex-structured-journal-turn-settles-once-journal.test.ts
+++ b/src/main/codex/codex-structured-journal-turn-settles-once-journal.test.ts
@@ -14,6 +14,7 @@ import { createTrackedJournalOpener } from '../native-chat/agent-session-journal
 import { createDeferredStructuredAgentSessionEventSink } from '../native-chat/agent-session-wire/structured-agent-session-event-sink'
 import { createCodexJournalTranslator } from './codex-structured-journal-translation'
 import { testEventSinkLogging } from '../native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'session-codex-failed-turn'
 const THREAD = 'thread-abc'
@@ -35,7 +36,7 @@ async function session() {
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: THREAD }
+      providerHandle: codexProviderHandle(THREAD)
     },
     stateDirectory: root,
     now: () => 1_000
diff --git a/src/main/codex/codex-structured-launch-resolution.test.ts b/src/main/codex/codex-structured-launch-resolution.test.ts
index 36ab39e3bab..1e6a6b4805e 100644
--- a/src/main/codex/codex-structured-launch-resolution.test.ts
+++ b/src/main/codex/codex-structured-launch-resolution.test.ts
@@ -5,6 +5,7 @@ import { LOCAL_EXECUTION_HOST_ID } from '../../shared/execution-host'
 import type { AgentSessionRecordStore } from '../runtime/agent-session-record-store'
 import { createCodexStructuredLaunchResolver } from './codex-structured-launch-resolution'
 import { codexStructuredPermissionPolicyForSettings } from './codex-structured-permission-policy'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const SESSION_ID = 'session-1'
 const IDENTITY = { sessionId: SESSION_ID } as Parameters<
@@ -105,9 +106,10 @@ describe('codex structured launch resolution', () => {
   it('resumes the last thread this session actually proved, not one a caller names', async () => {
     const launch = await resolverFor(
       record({
+        // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: the resolver reads only each link's handle, so the link's other fields stay unset.
         providerHandleChain: [
-          { handle: { provider: 'codex', threadId: 'thread-old' } },
-          { handle: { provider: 'codex', threadId: 'thread-current' } }
+          { handle: codexProviderHandle('thread-old') },
+          { handle: codexProviderHandle('thread-current') }
         ] as AgentSessionRecord['providerHandleChain']
       })
     )({ identity: IDENTITY })
@@ -121,7 +123,7 @@ describe('codex structured launch resolution', () => {
       mintedAtFence: number
     ): AgentSessionProviderHandleLink => ({
       linkId: `link-${mintedAtFence}`,
-      handle: { provider: 'codex', threadId: 't' },
+      handle: codexProviderHandle('t'),
       origin,
       mintedAtFence,
       observedAt: 1
@@ -204,8 +206,9 @@ describe('codex structured launch resolution', () => {
     const resolveRollout = vi.fn(async () => '/home/work/.codex/sessions/rollout.jsonl')
     const launch = await resolverFor(
       record({
+        // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: the resolver reads only each link's handle, so the link's other fields stay unset.
         providerHandleChain: [
-          { handle: { provider: 'codex', threadId: 'thread-current' } }
+          { handle: codexProviderHandle('thread-current') }
         ] as AgentSessionRecord['providerHandleChain']
       }),
       async (id) => `/repos/${id}`,
diff --git a/src/main/codex/codex-structured-launch-resolution.ts b/src/main/codex/codex-structured-launch-resolution.ts
index ebfdb27200a..19945c9a6c8 100644
--- a/src/main/codex/codex-structured-launch-resolution.ts
+++ b/src/main/codex/codex-structured-launch-resolution.ts
@@ -93,7 +93,8 @@ export function createCodexStructuredLaunchResolver(
     // concern, and the permission posture they used to smuggle in is derived per acquisition.
     const permissionPolicy = deps.resolvePermissionPolicy?.()
     const head = agentSessionProviderHandleChainHead(record.providerHandleChain)
-    const resumeThreadId = head?.handle.provider === 'codex' ? head.handle.threadId : null
+    // A Codex record's chain holds only Codex handles; the record store refuses anything else.
+    const resumeThreadId = head?.handle.nativeId ?? null
     // The same saved options every turn sends, so the thread and its turns name one model.
     const model = record.options?.model
     return {
diff --git a/src/main/codex/codex-structured-owner-identity.test.ts b/src/main/codex/codex-structured-owner-identity.test.ts
index c86885171e4..229da5e00bd 100644
--- a/src/main/codex/codex-structured-owner-identity.test.ts
+++ b/src/main/codex/codex-structured-owner-identity.test.ts
@@ -1,12 +1,13 @@
 import { describe, expect, it, vi } from 'vitest'
 import { codexProcessIdentity, codexProviderHandleLink } from './codex-structured-owner-identity'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY = {
   sessionId: 'session-identity',
   workspaceId: 'workspace-1',
   hostId: 'local',
   agent: 'codex' as const,
-  providerHandle: { kind: 'codex' as const, threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 describe('codex process identity', () => {
diff --git a/src/main/codex/codex-structured-owner-identity.ts b/src/main/codex/codex-structured-owner-identity.ts
index 805a767e620..9b0d3e8e548 100644
--- a/src/main/codex/codex-structured-owner-identity.ts
+++ b/src/main/codex/codex-structured-owner-identity.ts
@@ -3,6 +3,7 @@ import {
   agentSessionProviderHandleKey,
   type AgentSessionProviderHandleLink
 } from '../../shared/agent-session-provider-handle'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 import type { AgentSessionProcessIdentity } from '../../shared/agent-session-record'
 import { readProcessStartTimeMs } from '../runtime/agent-session-process-identity-probe'
 
@@ -91,16 +92,15 @@ export function codexProviderHandleLink(
 ): AgentSessionProviderHandleLink {
   return {
     linkId: input.linkId ?? `codex-${input.fence}-${input.threadId}`.slice(0, 128),
-    handle: { provider: 'codex', threadId: input.threadId },
+    handle: codexProviderHandle(input.threadId),
     origin: input.origin ?? (input.resumed ? 'resumed' : 'created'),
     mintedAtFence: input.fence,
     observedAt: input.observedAt,
     ...(input.supersedesThreadId
       ? {
-          supersedesKey: agentSessionProviderHandleKey({
-            provider: 'codex',
-            threadId: input.supersedesThreadId
-          })
+          supersedesKey: agentSessionProviderHandleKey(
+            codexProviderHandle(input.supersedesThreadId)
+          )
         }
       : {})
   }
diff --git a/src/main/codex/codex-structured-question-order.test.ts b/src/main/codex/codex-structured-question-order.test.ts
index 78c197644e2..c63d78439ab 100644
--- a/src/main/codex/codex-structured-question-order.test.ts
+++ b/src/main/codex/codex-structured-question-order.test.ts
@@ -37,6 +37,7 @@ import {
 } from '../../renderer/src/components/native-chat/structured-agent-question-projection'
 import { openTestJournalHostDatabase } from '../native-chat/agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 
@@ -79,7 +80,7 @@ beforeEach(async () => {
         },
         link: {
           linkId: `link-${fence}`,
-          handle: { provider: 'codex', threadId: THREAD },
+          handle: codexProviderHandle(THREAD),
           origin: 'created',
           mintedAtFence: fence,
           observedAt: HOST_TEST_NOW
diff --git a/src/main/codex/codex-structured-session-acquire.ts b/src/main/codex/codex-structured-session-acquire.ts
index 1b704fa3946..170c142ba43 100644
--- a/src/main/codex/codex-structured-session-acquire.ts
+++ b/src/main/codex/codex-structured-session-acquire.ts
@@ -1,3 +1,7 @@
+import {
+  CODEX_STRUCTURED_HANDLE_NAMESPACE,
+  isAgentSessionProviderHandleInNamespace
+} from '../../shared/agent-session-provider-handle-encoding'
 import {
   AgentSessionAcquisitionRefusal,
   AgentSessionPreSpawnError,
@@ -71,9 +75,11 @@ export async function acquireCodexStructuredSession(input: {
   const { previousAttempt, attempt } = acquisitions.start(sessionId)
   const acquisition = attempt.window
   let unbindReadingControl: (() => void) | undefined
+  const provenHandle = acquireInput.identity.providerHandle
   let primaryThreadId =
-    acquireInput.identity.providerHandle.kind === 'codex'
-      ? acquireInput.identity.providerHandle.threadId
+    provenHandle &&
+    isAgentSessionProviderHandleInNamespace(provenHandle, CODEX_STRUCTURED_HANDLE_NAMESPACE)
+      ? provenHandle.nativeId
       : null
   const subagentExecutions = new CodexSubagentExecutions()
   const dispatchEchoes = createCodexDispatchEchoes()
diff --git a/src/main/codex/codex-structured-session-adapter-fixture.ts b/src/main/codex/codex-structured-session-adapter-fixture.ts
index 37d434ef1a4..6a7c9f2af5a 100644
--- a/src/main/codex/codex-structured-session-adapter-fixture.ts
+++ b/src/main/codex/codex-structured-session-adapter-fixture.ts
@@ -14,6 +14,7 @@ import {
   type CodexStructuredSessionEvent
 } from './codex-structured-session-adapter'
 import type { CodexStructuredSessionAdapterDeps } from './codex-structured-session-state'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 export const THREAD_ID = 'thread-abc'
 
@@ -23,7 +24,7 @@ export function identityFor(sessionId: string): AgentSessionJournalIdentity {
     workspaceId: 'ws-1',
     hostId: 'host-1',
     agent: 'codex',
-    providerHandle: { kind: 'codex', threadId: THREAD_ID }
+    providerHandle: codexProviderHandle(THREAD_ID)
   }
 }
 
diff --git a/src/main/codex/codex-structured-session-adapter-lifecycle.test.ts b/src/main/codex/codex-structured-session-adapter-lifecycle.test.ts
index 2e553cb9e0b..3066b561336 100644
--- a/src/main/codex/codex-structured-session-adapter-lifecycle.test.ts
+++ b/src/main/codex/codex-structured-session-adapter-lifecycle.test.ts
@@ -16,6 +16,7 @@ import {
   type CodexStructuredLaunch,
   type CodexStructuredSessionEvent
 } from './codex-structured-session-adapter'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const THREAD_ID = 'thread-abc'
 
@@ -25,7 +26,7 @@ function identityFor(sessionId: string): AgentSessionJournalIdentity {
     workspaceId: 'ws-1',
     hostId: 'host-1',
     agent: 'codex',
-    providerHandle: { kind: 'codex', threadId: THREAD_ID }
+    providerHandle: codexProviderHandle(THREAD_ID)
   }
 }
 
diff --git a/src/main/codex/codex-structured-session-adapter.test.ts b/src/main/codex/codex-structured-session-adapter.test.ts
index 0e674bf10de..c9e3c14cac9 100644
--- a/src/main/codex/codex-structured-session-adapter.test.ts
+++ b/src/main/codex/codex-structured-session-adapter.test.ts
@@ -20,6 +20,7 @@ import {
   fakeCodex,
   identityFor
 } from './codex-structured-session-adapter-fixture'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 describe('CodexStructuredSessionAdapter.acquire', () => {
   it('starts a new thread and reports the process and link the lease will prove', async () => {
@@ -58,7 +59,7 @@ describe('CodexStructuredSessionAdapter.acquire', () => {
     })
     expect(acquisition.link).toEqual({
       linkId: `codex-7-${THREAD_ID}`,
-      handle: { provider: 'codex', threadId: THREAD_ID },
+      handle: codexProviderHandle(THREAD_ID),
       origin: 'created',
       mintedAtFence: 7,
       observedAt: 1_700_000_000_500
@@ -102,7 +103,7 @@ describe('CodexStructuredSessionAdapter.acquire', () => {
       })
     })
     expect(acquisition.link.origin).toBe('resumed')
-    expect(acquisition.link.handle).toEqual({ provider: 'codex', threadId: 'thread-proven' })
+    expect(acquisition.link.handle).toEqual(codexProviderHandle('thread-proven'))
   })
 
   it('starts a thread in place of a creation Codex never saved, and says which it replaced', async () => {
@@ -132,7 +133,7 @@ describe('CodexStructuredSessionAdapter.acquire', () => {
     ])
     expect(acquisition.link).toEqual({
       linkId: `codex-9-${THREAD_ID}`,
-      handle: { provider: 'codex', threadId: THREAD_ID },
+      handle: codexProviderHandle(THREAD_ID),
       origin: 'created',
       supersedesKey: 'codex:"thread-unsaved"',
       mintedAtFence: 9,
diff --git a/src/main/codex/codex-structured-session-background-tasks.test.ts b/src/main/codex/codex-structured-session-background-tasks.test.ts
index 4e2515da7d4..466cadce8a1 100644
--- a/src/main/codex/codex-structured-session-background-tasks.test.ts
+++ b/src/main/codex/codex-structured-session-background-tasks.test.ts
@@ -10,6 +10,7 @@ import { CodexStructuredSessionAdapter } from './codex-structured-session-adapte
 import { CodexBackgroundTaskTracker } from './codex-background-task-tracker'
 import type { CodexStructuredSessionEvent } from './codex-structured-session-state'
 import type { StructuredAgentSessionEventSink } from '../native-chat/agent-session-wire/structured-agent-session-event-sink'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 // Proves the host's child records are actually REACHED from provider traffic: the tracker is
 // unit-tested separately, and a producer that is correct but unwired publishes nothing while
@@ -51,7 +52,7 @@ function identity(sessionId: string): AgentSessionJournalIdentity {
     workspaceId: 'ws-1',
     hostId: 'host-1',
     agent: 'codex',
-    providerHandle: { kind: 'codex', threadId: THREAD_ID }
+    providerHandle: codexProviderHandle(THREAD_ID)
   }
 }
 
diff --git a/src/main/codex/codex-structured-session-cancel.test.ts b/src/main/codex/codex-structured-session-cancel.test.ts
index 939d5faf0cd..2d1c999d19c 100644
--- a/src/main/codex/codex-structured-session-cancel.test.ts
+++ b/src/main/codex/codex-structured-session-cancel.test.ts
@@ -47,6 +47,7 @@ import {
   type CodexStructuredSessionAdapterDeps,
   type CodexStructuredSessionEvent
 } from './codex-structured-session-adapter'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const THREAD_ID = 'thread-abc'
 const USER_MESSAGE: AgentJournalMessageItem = {
@@ -69,7 +70,7 @@ function identity(): AgentSessionJournalIdentity {
     workspaceId: 'ws-1',
     hostId: 'host-1',
     agent: 'codex',
-    providerHandle: { kind: 'codex', threadId: THREAD_ID }
+    providerHandle: codexProviderHandle(THREAD_ID)
   }
 }
 
diff --git a/src/main/codex/codex-structured-session-close.test.ts b/src/main/codex/codex-structured-session-close.test.ts
index 54cebde991e..4f9f9a2ab0d 100644
--- a/src/main/codex/codex-structured-session-close.test.ts
+++ b/src/main/codex/codex-structured-session-close.test.ts
@@ -17,6 +17,7 @@ import { CodexPromptRegistry } from './codex-structured-prompt-replies'
 import type { CodexSession } from './codex-structured-session-state'
 import type { StructuredAgentSessionAdapter } from '../native-chat/agent-session-wire/structured-agent-session-adapter'
 import { StructuredAgentSessionAdapterRouter } from '../native-chat/agent-session-wire/structured-agent-session-adapter-router'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const THREAD = 'thread-1'
 
@@ -26,7 +27,7 @@ function identity(sessionId: string): AgentSessionJournalIdentity {
     workspaceId: 'workspace-1',
     hostId: 'host-1',
     agent: 'codex',
-    providerHandle: { kind: 'codex', threadId: THREAD }
+    providerHandle: codexProviderHandle(THREAD)
   }
 }
 
diff --git a/src/main/codex/codex-structured-session-shutdown.test.ts b/src/main/codex/codex-structured-session-shutdown.test.ts
index 3883dad4600..44ed5c93d41 100644
--- a/src/main/codex/codex-structured-session-shutdown.test.ts
+++ b/src/main/codex/codex-structured-session-shutdown.test.ts
@@ -8,6 +8,7 @@ import {
   CodexStructuredSessionAdapter,
   type CodexStructuredLaunch
 } from './codex-structured-session-adapter'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const SESSION_ID = 'session-1'
 const THREAD_ID = 'thread-1'
@@ -25,7 +26,7 @@ function identity(): AgentSessionJournalIdentity {
     workspaceId: 'workspace-1',
     hostId: 'host-1',
     agent: 'codex',
-    providerHandle: { kind: 'codex', threadId: THREAD_ID }
+    providerHandle: codexProviderHandle(THREAD_ID)
   }
 }
 
diff --git a/src/main/native-chat/agent-session-journal/journal-crash-boundary.test.ts b/src/main/native-chat/agent-session-journal/journal-crash-boundary.test.ts
index a6821cf8427..278fea93973 100644
--- a/src/main/native-chat/agent-session-journal/journal-crash-boundary.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-crash-boundary.test.ts
@@ -26,13 +26,14 @@ import {
   type ProviderHistoryWindow
 } from './journal-submission-reconciler'
 import { createTrackedJournalOpener } from './journal-host-database-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 const TURN_ID = '019fd8ca-edbe-7c43-b231-4c7aea3a2d89'
diff --git a/src/main/native-chat/agent-session-journal/journal-damage.test.ts b/src/main/native-chat/agent-session-journal/journal-damage.test.ts
index 2ced3e4b2a9..8b59940a6a1 100644
--- a/src/main/native-chat/agent-session-journal/journal-damage.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-damage.test.ts
@@ -14,6 +14,7 @@ import {
   type AgentJournalItemIdentity,
   type AgentSessionJournalIdentity
 } from '../../../shared/agent-session-journal-types'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 import type Database from '../../sqlite/sync-database'
 import type { openAgentSessionJournal } from './journal-store-factory'
 import {
@@ -31,7 +32,7 @@ const IDENTITY: AgentSessionJournalIdentity = {
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 const UNLOADABLE = {
diff --git a/src/main/native-chat/agent-session-journal/journal-dispatch-reason-bound.test.ts b/src/main/native-chat/agent-session-journal/journal-dispatch-reason-bound.test.ts
index cefd4bbe368..574dec492ee 100644
--- a/src/main/native-chat/agent-session-journal/journal-dispatch-reason-bound.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-dispatch-reason-bound.test.ts
@@ -11,13 +11,14 @@ import {
 import { DEFAULT_JOURNAL_PAYLOAD_LIMITS } from './journal-payload-bounds'
 import type { openAgentSessionJournal } from './journal-store-factory'
 import { createTrackedJournalOpener } from './journal-host-database-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 const HUGE = 'x'.repeat(4 * DEFAULT_JOURNAL_PAYLOAD_LIMITS.inlineHeadBytes)
diff --git a/src/main/native-chat/agent-session-journal/journal-epoch-replacement.test.ts b/src/main/native-chat/agent-session-journal/journal-epoch-replacement.test.ts
index 2992459a787..6337b00417b 100644
--- a/src/main/native-chat/agent-session-journal/journal-epoch-replacement.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-epoch-replacement.test.ts
@@ -19,19 +19,20 @@ import {
   openTestJournalHostDatabase,
   readTestJournalRows
 } from './journal-host-database-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 const PEER: AgentSessionJournalIdentity = {
   ...IDENTITY,
   sessionId: 'session-peer',
-  providerHandle: { kind: 'codex', threadId: 'thread-peer' }
+  providerHandle: codexProviderHandle('thread-peer')
 }
 
 let root: string
diff --git a/src/main/native-chat/agent-session-journal/journal-epoch-replacement.ts b/src/main/native-chat/agent-session-journal/journal-epoch-replacement.ts
index 1921bc82a45..da53b2e9a11 100644
--- a/src/main/native-chat/agent-session-journal/journal-epoch-replacement.ts
+++ b/src/main/native-chat/agent-session-journal/journal-epoch-replacement.ts
@@ -10,6 +10,7 @@ import type {
   AgentJournalTurnScope,
   AgentSessionJournalIdentity
 } from '../../../shared/agent-session-journal-types'
+import { agentSessionJournalProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 import type { JournalHostDatabase } from './journal-host-database'
 import type { JournalLoad } from './journal-open'
 import { applyJournalRow, createJournalReducerState } from './journal-reducer'
@@ -56,7 +57,7 @@ export function replaceJournalEpoch(input: {
   const epochRow: JournalRow = {
     kind: 'epoch',
     reason: input.reason,
-    providerHandle: input.identity.providerHandle,
+    providerHandle: agentSessionJournalProviderHandle(input.identity),
     ...journalRowBase(epoch, 1, input.fence, input.now())
   }
   const rows: JournalRow[] = [epochRow]
diff --git a/src/main/native-chat/agent-session-journal/journal-epoch-rollover.ts b/src/main/native-chat/agent-session-journal/journal-epoch-rollover.ts
index 7f9abfc408f..477a79f11ed 100644
--- a/src/main/native-chat/agent-session-journal/journal-epoch-rollover.ts
+++ b/src/main/native-chat/agent-session-journal/journal-epoch-rollover.ts
@@ -6,6 +6,7 @@
 
 import { journalRowSchemaVersion } from '../../../shared/agent-session-journal-types'
 import type { AgentSessionJournalIdentity } from '../../../shared/agent-session-journal-types'
+import { agentSessionJournalProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 import type { JournalHostDatabase } from './journal-host-database'
 import type { JournalLoad } from './journal-open'
 import { applyJournalRow, createJournalReducerState } from './journal-reducer'
@@ -30,7 +31,7 @@ export function publishNewEpoch(input: {
   const row: JournalRow = {
     kind: 'epoch',
     reason: input.reason,
-    providerHandle: input.identity.providerHandle,
+    providerHandle: agentSessionJournalProviderHandle(input.identity),
     // Carries no body: an older host must keep reading a turn-free session past row 1.
     v: journalRowSchemaVersion([]),
     epoch: input.epoch,
diff --git a/src/main/native-chat/agent-session-journal/journal-file-format-remnant.test.ts b/src/main/native-chat/agent-session-journal/journal-file-format-remnant.test.ts
index 84fb299fb05..eed26b20388 100644
--- a/src/main/native-chat/agent-session-journal/journal-file-format-remnant.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-file-format-remnant.test.ts
@@ -25,13 +25,14 @@ import {
   liveTestJournalRows,
   SAVED_BY_NEWER_ORCA
 } from './journal-host-database-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 const DISCLOSURE_ITEM_ID = agentJournalItemKey(JOURNAL_FILE_FORMAT_REMNANT_DISCLOSURE_IDENTITY)
diff --git a/src/main/native-chat/agent-session-journal/journal-host-database.test.ts b/src/main/native-chat/agent-session-journal/journal-host-database.test.ts
index 2b4e4a0819a..4f209c2f202 100644
--- a/src/main/native-chat/agent-session-journal/journal-host-database.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-host-database.test.ts
@@ -20,19 +20,20 @@ import {
   readTestJournalRows
 } from './journal-host-database-test-support'
 import type Database from '../../sqlite/sync-database'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'ws-1',
   hostId: 'local',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 const OTHER: AgentSessionJournalIdentity = {
   ...IDENTITY,
   sessionId: 'session-2',
-  providerHandle: { kind: 'codex', threadId: 'thread-2' }
+  providerHandle: codexProviderHandle('thread-2')
 }
 
 const SUBMISSION = {
diff --git a/src/main/native-chat/agent-session-journal/journal-legacy-import.test.ts b/src/main/native-chat/agent-session-journal/journal-legacy-import.test.ts
index 3d835c21b73..89e88b247ae 100644
--- a/src/main/native-chat/agent-session-journal/journal-legacy-import.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-legacy-import.test.ts
@@ -8,10 +8,8 @@ import { tmpdir } from 'node:os'
 import { join } from 'node:path'
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 import { agentJournalItemKey } from '../../../shared/agent-session-journal-item-key'
-import type {
-  AgentSessionJournalIdentity,
-  AgentSessionProviderHandle
-} from '../../../shared/agent-session-journal-types'
+import type { AgentSessionJournalIdentity } from '../../../shared/agent-session-journal-types'
+import type { AgentSessionProviderHandle } from '../../../shared/agent-session-provider-handle'
 import type { NativeChatMessage } from '../../../shared/native-chat-types'
 import type * as TranscriptLineDecoders from '../transcript-line-decoders'
 import { createLegacyIdentityTracker } from './journal-legacy-identity'
@@ -20,6 +18,10 @@ import { DEFAULT_JOURNAL_PAYLOAD_LIMITS } from './journal-payload-bounds'
 import { openAgentSessionJournal } from './journal-store-factory'
 import type { AgentSessionJournal } from './journal-store'
 import { openTestJournalHostDatabase } from './journal-host-database-test-support'
+import {
+  claudeProviderHandle,
+  codexProviderHandle
+} from '../../../shared/agent-session-provider-handle-encoding'
 
 // No shipped decoder emits a subagent roster, so the roster bounds are reached by standing one in.
 const decodedClaudeOverride = vi.hoisted((): { message: NativeChatMessage | null } => ({
@@ -50,11 +52,11 @@ type ImportAgent = 'claude' | 'codex' | 'grok' | 'omp'
 
 function providerHandle(agent: ImportAgent, sessionId: string): AgentSessionProviderHandle {
   if (agent === 'claude') {
-    return { kind: 'claude', sessionId, leafUuid: null }
+    return claudeProviderHandle(sessionId, null)
   }
   return agent === 'codex'
-    ? { kind: 'codex', threadId: sessionId }
-    : { kind: 'opaque', agent, value: sessionId }
+    ? codexProviderHandle(sessionId)
+    : { transport: 'terminal-transcript', agent, nativeId: sessionId }
 }
 
 function identity(agent: ImportAgent, sessionId: string): AgentSessionJournalIdentity {
diff --git a/src/main/native-chat/agent-session-journal/journal-per-session-import.test.ts b/src/main/native-chat/agent-session-journal/journal-per-session-import.test.ts
index 6c291c3a378..53397f87044 100644
--- a/src/main/native-chat/agent-session-journal/journal-per-session-import.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-per-session-import.test.ts
@@ -33,6 +33,7 @@ import { journalDirectoryFor, legacyJournalDatabaseFile } from './journal-paths'
 import { importPerSessionJournal, previewPerSessionJournal } from './journal-per-session-import'
 import { readJournalSessionEpoch, type JournalStoredRow } from './journal-row-table'
 import { createStructuredAgentSessionLogger } from '../agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 vi.mock('node:fs', async (importOriginal) => {
   const actual = await importOriginal<typeof NodeFs>()
@@ -44,7 +45,7 @@ const IDENTITY: AgentSessionJournalIdentity = {
   workspaceId: 'ws-1',
   hostId: 'local',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 let root: string
diff --git a/src/main/native-chat/agent-session-journal/journal-producer-inheritance.test.ts b/src/main/native-chat/agent-session-journal/journal-producer-inheritance.test.ts
index d41e9b363ed..8dea06cebee 100644
--- a/src/main/native-chat/agent-session-journal/journal-producer-inheritance.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-producer-inheritance.test.ts
@@ -16,6 +16,7 @@ import {
   journalLifecycleBatchRowBuilder
 } from './journal-row-builders'
 import { createTrackedJournalOpener } from './journal-host-database-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 // A row's producer is fixed by the write that created it. A revision naming no
 // producer — a settlement, a prompt answer, a reopen sweep — keeps it; a
@@ -170,7 +171,7 @@ describe('producer inheritance across a reopen', () => {
         workspaceId: 'workspace-1',
         hostId: 'local',
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: 'root' }
+        providerHandle: codexProviderHandle('root')
       },
       stateDirectory: root,
       now: () => 1_000
diff --git a/src/main/native-chat/agent-session-journal/journal-queued-rejection-batch.test.ts b/src/main/native-chat/agent-session-journal/journal-queued-rejection-batch.test.ts
index d218a356fae..cd14ce2fe94 100644
--- a/src/main/native-chat/agent-session-journal/journal-queued-rejection-batch.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-queued-rejection-batch.test.ts
@@ -8,6 +8,7 @@ import { afterEach, beforeEach, expect, it } from 'vitest'
 import { agentSessionFailureFact } from '../../../shared/agent-session-failure'
 import { agentSessionFailureWords } from '../../../shared/agent-session-failure-words'
 import { agentJournalSubmissionKey } from '../../../shared/agent-session-journal-item-key'
+import { claudeProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 import {
   AGENT_JOURNAL_THREAD_SCOPE,
   type AgentSessionJournalIdentity
@@ -23,7 +24,7 @@ const IDENTITY: AgentSessionJournalIdentity = {
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'claude',
-  providerHandle: { kind: 'claude', sessionId: 'native-1', leafUuid: null }
+  providerHandle: claudeProviderHandle('native-1', null)
 }
 
 const START_FAILED = agentSessionFailureWords(agentSessionFailureFact('providerStartFailed'), {
diff --git a/src/main/native-chat/agent-session-journal/journal-restart-reconciliation.test.ts b/src/main/native-chat/agent-session-journal/journal-restart-reconciliation.test.ts
index 2f28adf0d54..8e541f110b0 100644
--- a/src/main/native-chat/agent-session-journal/journal-restart-reconciliation.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-restart-reconciliation.test.ts
@@ -19,13 +19,14 @@ import { createTrackedJournalOpener } from './journal-host-database-test-support
 import { agentSessionFailureFact } from '../../../shared/agent-session-failure'
 import { agentSessionFailureWords } from '../../../shared/agent-session-failure-words'
 import { classifyDispatchRejection } from '../../../shared/structured-agent-session-dispatch-rejection'
+import { claudeProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'claude',
-  providerHandle: { kind: 'claude', sessionId: 'provider-1', leafUuid: null }
+  providerHandle: claudeProviderHandle('provider-1', null)
 }
 
 function claudeIdentity(uuid: string): AgentJournalItemIdentity {
diff --git a/src/main/native-chat/agent-session-journal/journal-row-builders.ts b/src/main/native-chat/agent-session-journal/journal-row-builders.ts
index 0865df3a41f..ed40d490951 100644
--- a/src/main/native-chat/agent-session-journal/journal-row-builders.ts
+++ b/src/main/native-chat/agent-session-journal/journal-row-builders.ts
@@ -5,8 +5,10 @@ import type {
   AgentJournalProducerLinkage,
   AgentJournalRowAttribution,
   AgentJournalTurnScope,
-  AgentSessionProviderHandle
+  AgentSessionJournalIdentity,
+  AgentSessionJournalProviderHandle
 } from '../../../shared/agent-session-journal-types'
+import { agentSessionJournalProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 import { journalRowSchemaVersion } from '../../../shared/agent-session-journal-types'
 import {
   agentJournalLinkageFields,
@@ -63,7 +65,7 @@ export function journalTombstoneRowBuilder(
 
 export function journalSubmissionRowBuilder(
   state: () => JournalReducerState,
-  providerHandle: AgentSessionProviderHandle,
+  identity: Pick<AgentSessionJournalIdentity, 'providerHandle' | 'agent'>,
   input: {
     clientMessageId: string
     payloadFingerprint: string
@@ -85,7 +87,7 @@ export function journalSubmissionRowBuilder(
     const queuedMessageId = consume?.messageId ?? input.queuedMessageId
     return buildJournalSubmissionRow({
       state: state(),
-      providerHandle,
+      providerHandle: agentSessionJournalProviderHandle(identity),
       ...input,
       ...(queuedMessageId !== undefined ? { queuedMessageId } : {}),
       seq,
@@ -300,7 +302,7 @@ export function buildJournalSubmissionRow(input: {
   state: JournalReducerState
   clientMessageId: string
   payloadFingerprint: string
-  providerHandle: AgentSessionProviderHandle
+  providerHandle: AgentSessionJournalProviderHandle
   body: AgentJournalMessageItem
   seq: number
   fence: number
diff --git a/src/main/native-chat/agent-session-journal/journal-row-context-usage.test.ts b/src/main/native-chat/agent-session-journal/journal-row-context-usage.test.ts
index 9dcced9944a..28dd96f9f54 100644
--- a/src/main/native-chat/agent-session-journal/journal-row-context-usage.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-row-context-usage.test.ts
@@ -19,13 +19,14 @@ import {
   liveTestJournalRows,
   updateTestJournalRowJson
 } from './journal-host-database-test-support'
+import { claudeProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'claude',
-  providerHandle: { kind: 'claude', sessionId: 'claude-session', leafUuid: null }
+  providerHandle: claudeProviderHandle('claude-session', null)
 }
 
 const USAGE = {
diff --git a/src/main/native-chat/agent-session-journal/journal-row-schema-version.test.ts b/src/main/native-chat/agent-session-journal/journal-row-schema-version.test.ts
index 616f4b55756..4fdaaa880b1 100644
--- a/src/main/native-chat/agent-session-journal/journal-row-schema-version.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-row-schema-version.test.ts
@@ -9,6 +9,7 @@ import {
   openTestJournalHostDatabase,
   liveTestJournalRows
 } from './journal-host-database-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 // Which rows an older host can still read: only rows that carry a turn item
 // are stamped with the version it does not know, and the epoch row never is.
@@ -33,7 +34,7 @@ describe('journal row schema versions', () => {
         workspaceId: 'workspace-1',
         hostId: 'local',
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: 'thread-1' }
+        providerHandle: codexProviderHandle('thread-1')
       },
       now: () => 1_000,
       stateDirectory: join(root, 'session-1')
diff --git a/src/main/native-chat/agent-session-journal/journal-row-schema.ts b/src/main/native-chat/agent-session-journal/journal-row-schema.ts
index f0ebac8622b..847c99734a2 100644
--- a/src/main/native-chat/agent-session-journal/journal-row-schema.ts
+++ b/src/main/native-chat/agent-session-journal/journal-row-schema.ts
@@ -29,7 +29,7 @@ import {
   type AgentJournalMessageItem,
   type AgentJournalProducerLinkage,
   type AgentJournalTurnScope,
-  type AgentSessionProviderHandle
+  type AgentSessionJournalProviderHandle
 } from '../../../shared/agent-session-journal-types'
 import {
   readAgentJournalItemBody,
@@ -67,7 +67,7 @@ type JournalRowBase = AgentJournalProducerLinkage & {
 export type JournalEpochRow = JournalRowBase & {
   kind: 'epoch'
   reason: AgentJournalEpochReason
-  providerHandle: AgentSessionProviderHandle
+  providerHandle: AgentSessionJournalProviderHandle
 }
 
 export const AGENT_JOURNAL_EPOCH_REASONS = [
@@ -131,7 +131,7 @@ export type JournalSubmissionRow = JournalRowBase & {
   kind: 'submission'
   clientMessageId: string
   payloadFingerprint: string
-  providerHandle: AgentSessionProviderHandle
+  providerHandle: AgentSessionJournalProviderHandle
   body: AgentJournalMessageItem
   /** Accepted to be handed over by a later `dispatch{pending}` row; absent on rows whose writer
    *  dispatched in the same step. Older readers keep the key and ignore it. */
diff --git a/src/main/native-chat/agent-session-journal/journal-stop-and-resume-rows.test.ts b/src/main/native-chat/agent-session-journal/journal-stop-and-resume-rows.test.ts
index 7b8e9fe5935..0785e156738 100644
--- a/src/main/native-chat/agent-session-journal/journal-stop-and-resume-rows.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-stop-and-resume-rows.test.ts
@@ -23,13 +23,17 @@ import {
   buildJournalQueueResumeRow,
   buildJournalStopEventRow
 } from './journal-stop-and-resume-rows'
+import {
+  agentSessionJournalProviderHandle,
+  codexProviderHandle
+} from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-s',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 const EPOCH = 'epoch-1'
 
@@ -64,7 +68,7 @@ function epochWith(
     {
       kind: 'epoch',
       reason,
-      providerHandle: IDENTITY.providerHandle,
+      providerHandle: agentSessionJournalProviderHandle(IDENTITY),
       ...journalRowBase(EPOCH, 1, 1, 1)
     }
   ]
diff --git a/src/main/native-chat/agent-session-journal/journal-store-schema.test.ts b/src/main/native-chat/agent-session-journal/journal-store-schema.test.ts
index 18cb7efa47a..75fd12db242 100644
--- a/src/main/native-chat/agent-session-journal/journal-store-schema.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-store-schema.test.ts
@@ -27,13 +27,14 @@ import {
   insertTestJournalRowJson,
   SAVED_BY_NEWER_ORCA
 } from './journal-host-database-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 let root: string
diff --git a/src/main/native-chat/agent-session-journal/journal-store.test.ts b/src/main/native-chat/agent-session-journal/journal-store.test.ts
index fcb541b8faa..a3bd5be348c 100644
--- a/src/main/native-chat/agent-session-journal/journal-store.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-store.test.ts
@@ -29,13 +29,14 @@ import {
   deleteTestJournalRow
 } from './journal-host-database-test-support'
 import type Database from '../../sqlite/sync-database'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 let root: string
diff --git a/src/main/native-chat/agent-session-journal/journal-store.ts b/src/main/native-chat/agent-session-journal/journal-store.ts
index 855c6ab3e98..90d5a826946 100644
--- a/src/main/native-chat/agent-session-journal/journal-store.ts
+++ b/src/main/native-chat/agent-session-journal/journal-store.ts
@@ -321,7 +321,7 @@ export class AgentSessionJournal {
     receipt?: JournalOperationReceipt
   ): Promise<AgentJournalCursor> {
     return this.rowWriter.append(
-      journalSubmissionRowBuilder(() => this.state, this.identity.providerHandle, input, consume),
+      journalSubmissionRowBuilder(() => this.state, this.identity, input, consume),
       consume && queuedMessageConsumeHook(this.queuedMessages, input.clientMessageId, consume),
       receipt
     )
diff --git a/src/main/native-chat/agent-session-journal/journal-subagent-liveness.test.ts b/src/main/native-chat/agent-session-journal/journal-subagent-liveness.test.ts
index 6b519ce35cd..4da76e0ba42 100644
--- a/src/main/native-chat/agent-session-journal/journal-subagent-liveness.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-subagent-liveness.test.ts
@@ -21,13 +21,14 @@ import {
 import type { openAgentSessionJournal } from './journal-store-factory'
 import { createTrackedJournalOpener } from './journal-host-database-test-support'
 import { staleSubagentRosterRevisions } from './journal-subagent-liveness'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 const GROUP_ID = 'thread-1:turn-1'
diff --git a/src/main/native-chat/agent-session-journal/journal-submission-queued-link.test.ts b/src/main/native-chat/agent-session-journal/journal-submission-queued-link.test.ts
index fc943164615..f9588b71ba3 100644
--- a/src/main/native-chat/agent-session-journal/journal-submission-queued-link.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-submission-queued-link.test.ts
@@ -15,13 +15,17 @@ import { createJournalReducerState, applyJournalRow } from './journal-reducer'
 import { parseJournalRow, serializeJournalRow, type JournalRow } from './journal-row-schema'
 import type { AgentSessionJournal } from './journal-store'
 import { createTrackedJournalOpener } from './journal-host-database-test-support'
+import {
+  agentSessionJournalProviderHandle,
+  claudeProviderHandle
+} from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-q',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'claude',
-  providerHandle: { kind: 'claude', sessionId: 'native-1', leafUuid: null }
+  providerHandle: claudeProviderHandle('native-1', null)
 }
 const BODY: AgentJournalMessageItem = {
   kind: 'message',
@@ -132,7 +136,7 @@ describe('the persisted row', () => {
     ts: 1,
     clientMessageId: 'handoff-1',
     payloadFingerprint: 'fp',
-    providerHandle: IDENTITY.providerHandle,
+    providerHandle: agentSessionJournalProviderHandle(IDENTITY),
     body: BODY,
     queuedMessageId: 'draft-1'
   }
diff --git a/src/main/native-chat/agent-session-journal/journal-unknown-content.test.ts b/src/main/native-chat/agent-session-journal/journal-unknown-content.test.ts
index e56bcc92c96..effd8a8136e 100644
--- a/src/main/native-chat/agent-session-journal/journal-unknown-content.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-unknown-content.test.ts
@@ -13,6 +13,7 @@ import {
   type AgentJournalItemIdentity,
   type AgentSessionJournalIdentity
 } from '../../../shared/agent-session-journal-types'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 import {
   closeTestJournalHostDatabase,
   createTrackedJournalOpener,
@@ -27,7 +28,7 @@ const IDENTITY: AgentSessionJournalIdentity = {
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 const SCOPE = { fence: 1, turnScope: AGENT_JOURNAL_THREAD_SCOPE }
 
diff --git a/src/main/native-chat/agent-session-journal/journal-unknown-row-kind.test.ts b/src/main/native-chat/agent-session-journal/journal-unknown-row-kind.test.ts
index bb965817b59..9aecd47da97 100644
--- a/src/main/native-chat/agent-session-journal/journal-unknown-row-kind.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-unknown-row-kind.test.ts
@@ -22,6 +22,10 @@ import {
   SAVED_BY_NEWER_ORCA
 } from './journal-host-database-test-support'
 import { parseJournalRow, type JournalRow } from './journal-row-schema'
+import {
+  agentSessionJournalProviderHandle,
+  codexProviderHandle
+} from '../../../shared/agent-session-provider-handle-encoding'
 
 const UNLOADABLE = {
   refusal: { code: 'agent_session_journal_unreadable', details: { reason: 'journalCorrupt' } }
@@ -32,7 +36,7 @@ const IDENTITY: AgentSessionJournalIdentity = {
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 const SCOPE = { fence: 1, turnScope: AGENT_JOURNAL_THREAD_SCOPE }
 
@@ -116,7 +120,7 @@ async function journalWithOneItem(): Promise<string> {
  *  fails to compile. */
 function rowOfEveryKind(): { [Kind in JournalRow['kind']]: Extract<JournalRow, { kind: Kind }> } {
   const base = { v: AGENT_SESSION_JOURNAL_SCHEMA_VERSION, epoch: 'epoch-1', fence: 1, ts: 1 }
-  const providerHandle = IDENTITY.providerHandle
+  const providerHandle = agentSessionJournalProviderHandle(IDENTITY)
   return {
     epoch: { ...base, seq: 1, kind: 'epoch', reason: 'session_created', providerHandle },
     item: {
diff --git a/src/main/native-chat/agent-session-journal/journal-write-queue.test.ts b/src/main/native-chat/agent-session-journal/journal-write-queue.test.ts
index 3cdd554cc4e..9b5653b060f 100644
--- a/src/main/native-chat/agent-session-journal/journal-write-queue.test.ts
+++ b/src/main/native-chat/agent-session-journal/journal-write-queue.test.ts
@@ -20,13 +20,14 @@ import { openJournalOwingImport } from './journal-owed-import-test-support'
 import type { AgentSessionJournal } from './journal-store'
 import { openAgentSessionJournal } from './journal-store-factory'
 import { JournalWriteQueue } from './journal-write-queue'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY = {
   sessionId: 'session-1',
   workspaceId: 'workspace-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 } as const
 
 const reply = (text: string): AgentJournalMessageItem => ({
diff --git a/src/main/native-chat/agent-session-journal/queued-message-bookkeeping-failure.test.ts b/src/main/native-chat/agent-session-journal/queued-message-bookkeeping-failure.test.ts
index 15911b5e080..5f9a95a53d2 100644
--- a/src/main/native-chat/agent-session-journal/queued-message-bookkeeping-failure.test.ts
+++ b/src/main/native-chat/agent-session-journal/queued-message-bookkeeping-failure.test.ts
@@ -20,13 +20,14 @@ import {
   closeTestJournalHostDatabases,
   createTrackedJournalOpener
 } from './journal-host-database-test-support'
+import { claudeProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-q',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'claude',
-  providerHandle: { kind: 'claude', sessionId: 'native-1', leafUuid: null }
+  providerHandle: claudeProviderHandle('native-1', null)
 }
 const REFUSAL = agentSessionFailureWords(
   agentSessionFailureFact('providerRejected', {
diff --git a/src/main/native-chat/agent-session-journal/queued-message-delivered-echo.test.ts b/src/main/native-chat/agent-session-journal/queued-message-delivered-echo.test.ts
index 4ce62c6192b..a12630d6566 100644
--- a/src/main/native-chat/agent-session-journal/queued-message-delivered-echo.test.ts
+++ b/src/main/native-chat/agent-session-journal/queued-message-delivered-echo.test.ts
@@ -17,13 +17,14 @@ import { queuedMessageFingerprint } from '../agent-session-wire/structured-agent
 import { JournalQueuedMessages } from './journal-queued-messages'
 import type { AgentSessionJournal } from './journal-store'
 import { createTrackedJournalOpener } from './journal-host-database-test-support'
+import { claudeProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-q',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'claude',
-  providerHandle: { kind: 'claude', sessionId: 'native-1', leafUuid: null }
+  providerHandle: claudeProviderHandle('native-1', null)
 }
 const STOP_WITHDRAWAL = agentSessionFailureWords(agentSessionFailureFact('cancelled'), {
   surface: 'rejection'
diff --git a/src/main/native-chat/agent-session-journal/queued-message-pause.test.ts b/src/main/native-chat/agent-session-journal/queued-message-pause.test.ts
index b8e45e0ef59..a2fa19a6a5c 100644
--- a/src/main/native-chat/agent-session-journal/queued-message-pause.test.ts
+++ b/src/main/native-chat/agent-session-journal/queued-message-pause.test.ts
@@ -29,13 +29,14 @@ import {
 } from './queued-message-pause'
 import { agentSessionFailureFact } from '../../../shared/agent-session-failure'
 import { agentSessionFailureWords } from '../../../shared/agent-session-failure-words'
+import { claudeProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-p',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'claude',
-  providerHandle: { kind: 'claude', sessionId: 'native-1', leafUuid: null }
+  providerHandle: claudeProviderHandle('native-1', null)
 }
 const HOST = 'proc-1'
 
diff --git a/src/main/native-chat/agent-session-journal/queued-message-store.test.ts b/src/main/native-chat/agent-session-journal/queued-message-store.test.ts
index 6c609853d69..abad56fa6dd 100644
--- a/src/main/native-chat/agent-session-journal/queued-message-store.test.ts
+++ b/src/main/native-chat/agent-session-journal/queued-message-store.test.ts
@@ -26,13 +26,14 @@ import {
   closeTestJournalHostDatabases,
   createTrackedJournalOpener
 } from './journal-host-database-test-support'
+import { claudeProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-q',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'claude',
-  providerHandle: { kind: 'claude', sessionId: 'native-1', leafUuid: null }
+  providerHandle: claudeProviderHandle('native-1', null)
 }
 
 let root: string
diff --git a/src/main/native-chat/agent-session-wire/agent-session-history-byte-accounting.test.ts b/src/main/native-chat/agent-session-wire/agent-session-history-byte-accounting.test.ts
index 7711b670438..115e2248ea0 100644
--- a/src/main/native-chat/agent-session-wire/agent-session-history-byte-accounting.test.ts
+++ b/src/main/native-chat/agent-session-wire/agent-session-history-byte-accounting.test.ts
@@ -11,13 +11,14 @@ import type {
 import { createTrackedJournalOpener } from '../agent-session-journal/journal-host-database-test-support'
 import type { AgentSessionJournal } from '../agent-session-journal/journal-store'
 import { readAgentSessionHistory } from './agent-session-history-page'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 const journals = createTrackedJournalOpener()
diff --git a/src/main/native-chat/agent-session-wire/agent-session-history-conversation-window.test.ts b/src/main/native-chat/agent-session-wire/agent-session-history-conversation-window.test.ts
index 8438b40d122..9cbfb94a907 100644
--- a/src/main/native-chat/agent-session-wire/agent-session-history-conversation-window.test.ts
+++ b/src/main/native-chat/agent-session-wire/agent-session-history-conversation-window.test.ts
@@ -19,6 +19,7 @@ import {
   readAgentSessionHistory,
   readAgentSessionHydrationPage
 } from './agent-session-history-page'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 // A backward page windows over the session's own rows, and a subagent's rows in
 // that range ride along, so a burst cannot crowd the conversation off the page.
@@ -28,7 +29,7 @@ const IDENTITY: AgentSessionJournalIdentity = {
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 const child: AgentJournalProducerLinkage = { agentId: 'task-1', producerKind: 'agent' }
diff --git a/src/main/native-chat/agent-session-wire/agent-session-history-forward-read-budget.test.ts b/src/main/native-chat/agent-session-wire/agent-session-history-forward-read-budget.test.ts
index 8abfce258b8..f94624c26c6 100644
--- a/src/main/native-chat/agent-session-wire/agent-session-history-forward-read-budget.test.ts
+++ b/src/main/native-chat/agent-session-wire/agent-session-history-forward-read-budget.test.ts
@@ -20,13 +20,17 @@ import {
 } from '../agent-session-journal/journal-host-database-test-support'
 import { AgentSessionSubscribers } from './structured-agent-session-subscribers'
 import { readAgentSessionHistory } from './agent-session-history-page'
+import {
+  agentSessionJournalProviderHandle,
+  codexProviderHandle
+} from '../../../shared/agent-session-provider-handle-encoding'
 
 const identity: AgentSessionJournalIdentity = {
   sessionId: 'bounded-catch-up',
   workspaceId: 'folder-workspace',
   hostId: 'remote-host',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 const journals = createTrackedJournalOpener()
 let root: string | undefined
@@ -55,7 +59,7 @@ async function seedJournal(count: number) {
     kind: 'epoch',
     seq: 1,
     reason: 'session_created',
-    providerHandle: identity.providerHandle
+    providerHandle: agentSessionJournalProviderHandle(identity)
   })
   for (let index = 0; index < count; index += 1) {
     insertTestJournalRow(db, identity.sessionId, {
diff --git a/src/main/native-chat/agent-session-wire/agent-session-history-page.test.ts b/src/main/native-chat/agent-session-wire/agent-session-history-page.test.ts
index e40ebcf326e..de31297ee25 100644
--- a/src/main/native-chat/agent-session-wire/agent-session-history-page.test.ts
+++ b/src/main/native-chat/agent-session-wire/agent-session-history-page.test.ts
@@ -35,13 +35,14 @@ import type {
 import type { AgentSessionJournal } from '../agent-session-journal/journal-store'
 import { projectJournalBatch } from './agent-session-journal-batch'
 import { readAgentSessionHistory, resolveHistoryLimit } from './agent-session-history-page'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 const journals = createTrackedJournalOpener()
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-accept-then-deliver.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-accept-then-deliver.test.ts
index 1b4a4e95b8c..3f1b4046f54 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-accept-then-deliver.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-accept-then-deliver.test.ts
@@ -46,6 +46,7 @@ import { agentSessionFailureFact } from '../../../shared/agent-session-failure'
 import { agentSessionFailureWords } from '../../../shared/agent-session-failure-words'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 
@@ -66,7 +67,7 @@ const spawnChild: StructuredAgentSessionAdapter['acquire'] = async ({ fence, spa
   acquisitionGeneration: `generation-${acquire.mock.calls.length}`,
   link: {
     linkId: `link-${fence}`,
-    handle: { provider: 'codex' as const, threadId: THREAD },
+    handle: codexProviderHandle(THREAD),
     origin: store.getRecord(SESSION)?.providerHandleChain.length
       ? ('resumed' as const)
       : ('created' as const),
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-acquisition-options.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-acquisition-options.test.ts
index d73cbb7e0bd..3b2deed8c5a 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-acquisition-options.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-acquisition-options.test.ts
@@ -21,6 +21,7 @@ import { performAttach } from './structured-agent-session-attach-flow'
 import type { AgentSessionCreatePhaseRecorder } from '../../observability/agent-session-instrumentation'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const NOW = 1_800_000_000_000
 const SESSION = 'legacy-session'
@@ -90,7 +91,7 @@ function adapter(input: {
         },
         link: {
           linkId: `${input.origin}-link`,
-          handle: { provider: 'codex', threadId: 'legacy-thread' },
+          handle: codexProviderHandle('legacy-thread'),
           origin: input.origin,
           mintedAtFence: fence,
           observedAt: NOW
@@ -139,7 +140,7 @@ describe('structured session acquisition options', () => {
           },
           link: {
             linkId: `${origin}-link`,
-            handle: { provider: 'codex', threadId: 'legacy-thread' },
+            handle: codexProviderHandle('legacy-thread'),
             origin,
             mintedAtFence: input.fence,
             observedAt: NOW
@@ -460,7 +461,7 @@ describe('structured session acquisition options', () => {
           },
           link: {
             linkId: `link-${fence}`,
-            handle: { provider: 'codex', threadId: 'legacy-thread' },
+            handle: codexProviderHandle('legacy-thread'),
             origin: store.getRecord(SESSION)?.providerHandleChain.length ? 'resumed' : 'created',
             mintedAtFence: fence,
             observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-adapter-router.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-adapter-router.test.ts
index e22dd1bd289..076e2de7540 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-adapter-router.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-adapter-router.test.ts
@@ -8,6 +8,7 @@ import type {
   StructuredAgentSessionAdapter
 } from './structured-agent-session-adapter'
 import { StructuredAgentSessionAdapterRouter } from './structured-agent-session-adapter-router'
+import { claudeProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 function claudeIdentity(sessionId: string): AgentSessionJournalIdentity {
   return {
@@ -15,7 +16,7 @@ function claudeIdentity(sessionId: string): AgentSessionJournalIdentity {
     workspaceId: 'workspace-1',
     hostId: 'local',
     agent: 'claude',
-    providerHandle: { kind: 'claude', sessionId: 'provider-session-1', leafUuid: null }
+    providerHandle: claudeProviderHandle('provider-session-1', null)
   }
 }
 
@@ -24,7 +25,7 @@ function acquisition(fence: number, spawnToken: string): AgentSessionAcquisition
     process: { hostId: 'local', pid: 1, processStartTimeMs: 1, spawnToken },
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'claude', sessionId: 'provider-session-1', leafUuid: null },
+      handle: claudeProviderHandle('provider-session-1', null),
       origin: 'created',
       mintedAtFence: fence,
       observedAt: 1
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-adopted-import.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-adopted-import.test.ts
index 76a276abd23..4f532865452 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-adopted-import.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-adopted-import.test.ts
@@ -20,6 +20,7 @@ import * as legacyImport from '../agent-session-journal/journal-legacy-import'
 import { StructuredAgentSessionHost } from './structured-agent-session-host'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const NOW = 1_800_000_000_000
 const SESSION = 'codex_adopting_session'
@@ -101,7 +102,7 @@ function adapter(): StructuredAgentSessionAdapter {
         process: { hostId: 'local', pid: 4242, processStartTimeMs: NOW, spawnToken },
         link: {
           linkId: 'resumed-link',
-          handle: { provider: 'codex', threadId: THREAD },
+          handle: codexProviderHandle(THREAD),
           origin: 'resumed',
           mintedAtFence: fence,
           observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-adopted-import.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-adopted-import.ts
index 3eccc4f9457..e86e30d8f5d 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-adopted-import.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-adopted-import.ts
@@ -5,6 +5,7 @@ import {
   type AgentSessionWireRefusal
 } from '../../../shared/agent-session-wire'
 import type { AgentSessionRecord } from '../../../shared/agent-session-record'
+import { agentSessionProviderHandleFromWire } from '../../../shared/agent-session-provider-handle-encoding'
 import type { AgentSessionAttachParams, AttachedJournal } from './structured-agent-session-attach'
 import type { JournalReplacementItem } from '../agent-session-journal/journal-epoch-replacement'
 import {
@@ -49,10 +50,7 @@ async function readAdoptedTranscript(
   }
   const prepared = await prepareLegacyTranscriptImport({
     agent: params.agent,
-    sessionId:
-      adopt.providerHandle.kind === 'claude'
-        ? adopt.providerHandle.sessionId
-        : adopt.providerHandle.threadId,
+    sessionId: agentSessionProviderHandleFromWire(adopt.providerHandle).nativeId,
     options: { filePath: adopt.transcriptPath }
   })
   if (!prepared.ok) {
@@ -100,10 +98,7 @@ async function applyAdoptedTranscript(
   const imported = await importLegacyTranscriptIntoJournal({
     journal: attached.journal,
     agent: params.agent,
-    sessionId:
-      adopt.providerHandle.kind === 'claude'
-        ? adopt.providerHandle.sessionId
-        : adopt.providerHandle.threadId,
+    sessionId: agentSessionProviderHandleFromWire(adopt.providerHandle).nativeId,
     fence: record.lease.runtimeFence,
     options: { filePath: adopt.transcriptPath }
   })
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-append-delivery.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-append-delivery.test.ts
index 6111e902962..5c718da0f3b 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-append-delivery.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-append-delivery.test.ts
@@ -27,6 +27,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 const EXIT_REASON = 'Claude Code is not signed in. Sign in with the Claude CLI'
@@ -119,7 +120,7 @@ beforeEach(async () => {
     process: { hostId: 'local', pid: 4242, processStartTimeMs: 1_700_000_000_000, spawnToken },
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'codex', threadId: THREAD },
+      handle: codexProviderHandle(THREAD),
       origin: generation === 0 ? ('created' as const) : ('resumed' as const),
       mintedAtFence: fence,
       observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-at-rest-commands.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-at-rest-commands.test.ts
index 140a9920115..4b52c9446de 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-at-rest-commands.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-at-rest-commands.test.ts
@@ -28,6 +28,7 @@ import {
   resetHostTestOperationIds
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
+import { claudeProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const caller = { callerKey: 'desktop' }
 const CLAUDE_SESSION = '819cf9f8-e43c-4ad7-b50f-54aa158a726a'
@@ -56,7 +57,7 @@ function adapter(catalog: ClaudeAtRestCommandCatalog): StructuredAgentSessionAda
         mintedAtFence: input.fence,
         observedAt: HOST_TEST_NOW,
         origin: 'created' as const,
-        handle: { provider: 'claude' as const, sessionId: CLAUDE_SESSION, leafUuid: null }
+        handle: claudeProviderHandle(CLAUDE_SESSION, null)
       }
     })),
     atRestCommands: catalog,
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-attach.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-attach.ts
index 85f99056c3a..415e261ab3c 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-attach.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-attach.ts
@@ -5,15 +5,17 @@
 // the record store's compare-and-swap, which also owns the idempotency row, so
 // a retried attach replays instead of reserving a second owner.
 
-import type {
-  AgentSessionJournalIdentity,
-  AgentSessionProviderHandle
-} from '../../../shared/agent-session-journal-types'
+import type { AgentSessionJournalIdentity } from '../../../shared/agent-session-journal-types'
 import type { AgentSessionOwnerProbe } from '../../../shared/agent-session-lease-adjudication'
 import type {
   AgentSessionHandleProvider,
   AgentSessionProviderHandleLink
 } from '../../../shared/agent-session-provider-handle'
+import {
+  agentSessionProviderHandleBelongsTo,
+  agentSessionProviderHandleFromWire,
+  type AgentSessionWireProviderHandle
+} from '../../../shared/agent-session-provider-handle-encoding'
 import { claudeProviderHandleLink } from '../../claude/claude-structured-owner-identity'
 import { codexProviderHandleLink } from '../../codex/codex-structured-owner-identity'
 import type {
@@ -65,8 +67,9 @@ export type AgentSessionAttachParams = {
    *  attach fingerprint: which tab shows the chat is not which conversation it attaches to. */
   surfaceTabId?: string
   launchArgs?: string[]
-  /** Omitted only for create-by-intent; the adapter proves the durable handle. */
-  providerHandle?: Exclude<AgentSessionProviderHandle, { kind: 'opaque' }>
+  /** Omitted only for create-by-intent; the adapter proves the durable handle. In the wire's
+   *  form, because the attach fingerprint covers it as the client sent it. */
+  providerHandle?: AgentSessionWireProviderHandle
   /**
    * Host-resolved only. Present when this create adopts an existing provider conversation rather
    * than starting one: it seeds the handle chain so the adapter resumes instead of creating, and
@@ -76,7 +79,7 @@ export type AgentSessionAttachParams = {
    * without adopting — presence of a handle must never be what triggers a resume.
    */
   adopt?: {
-    providerHandle: Exclude<AgentSessionProviderHandle, { kind: 'opaque' }>
+    providerHandle: AgentSessionWireProviderHandle
     /** Omitted only when the exact committed operation replays an already-imported journal. */
     transcriptPath?: string
   }
@@ -119,7 +122,13 @@ export function attachFingerprintFields(params: AgentSessionAttachParams): Recor
 export function admitAttachOrRefuse(
   params: AgentSessionAttachParams
 ): { ok: true; fingerprint: string } | { ok: false; refusal: AgentSessionWireRefusal } {
-  if (params.providerHandle && params.providerHandle.kind !== params.provider) {
+  if (
+    params.providerHandle &&
+    !agentSessionProviderHandleBelongsTo(
+      agentSessionProviderHandleFromWire(params.providerHandle),
+      params.provider
+    )
+  ) {
     return {
       ok: false,
       refusal: refuse(
@@ -143,16 +152,9 @@ export function journalIdentityFor(
   params: AgentSessionAttachParams
 ): AgentSessionJournalIdentity {
   const head = agentSessionProviderHandleChainHead(record.providerHandleChain)
-  const providerHandle: AgentSessionProviderHandle =
-    head?.handle.provider === 'codex'
-      ? { kind: 'codex', threadId: head.handle.threadId }
-      : head?.handle.provider === 'claude'
-        ? {
-            kind: 'claude',
-            sessionId: head.handle.sessionId,
-            leafUuid: head.handle.leafUuid
-          }
-        : (params.providerHandle ?? { kind: 'opaque', agent: params.agent, value: 'pending' })
+  const providerHandle =
+    head?.handle ??
+    (params.providerHandle ? agentSessionProviderHandleFromWire(params.providerHandle) : null)
   return {
     sessionId: record.sessionId,
     workspaceId: params.location.workspaceId,
@@ -265,7 +267,7 @@ async function reconcileAgainstProviderHistory(input: {
 const ADOPTED_HANDLE_FENCE = 1
 
 function adoptedProviderHandleLink(
-  handle: Exclude<AgentSessionProviderHandle, { kind: 'opaque' }>,
+  handle: AgentSessionWireProviderHandle,
   observedAt: number
 ): AgentSessionProviderHandleLink {
   return handle.kind === 'claude'
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-claude-option-queue.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-claude-option-queue.test.ts
index 1bb3d36a5c4..868247eb37c 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-claude-option-queue.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-claude-option-queue.test.ts
@@ -17,6 +17,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { claudeProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-claude' }
 const CLAUDE_SESSION = '019fd532-7c11-7a90-b6de-4e1a2c3d5f61'
@@ -55,7 +56,7 @@ function adapter(): StructuredAgentSessionAdapter {
       process: { hostId: 'local', pid: 4200, processStartTimeMs: NOW, spawnToken },
       link: {
         linkId: `claude-native-${fence}`,
-        handle: { provider: 'claude', sessionId: CLAUDE_SESSION, leafUuid: 'native-leaf' },
+        handle: claudeProviderHandle(CLAUDE_SESSION, 'native-leaf'),
         origin: acquire.mock.calls.length === 1 ? 'created' : 'resumed',
         mintedAtFence: fence,
         observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-claude-stop-ends-session.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-claude-stop-ends-session.test.ts
index 9c920b45eb3..198c2418cf9 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-claude-stop-ends-session.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-claude-stop-ends-session.test.ts
@@ -524,7 +524,7 @@ it('starts a new child for the next send after a Stop, on the same Claude conver
   })
   // The wake resumes the same Claude conversation; the first test pins the leaf it resumes after.
   expect(store.getRecord(SESSION)?.providerHandleChain.at(-1)?.handle).toMatchObject({
-    sessionId: PROVIDER_SESSION_ID
+    nativeId: PROVIDER_SESSION_ID
   })
   expect(resumed.closed).toBe(false)
   expect(await dispatch(next)).toMatchObject({ state: 'pending' })
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-conversation-stop.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-conversation-stop.test.ts
index 4f8679578cf..a1e11e0c42d 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-conversation-stop.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-conversation-stop.test.ts
@@ -27,6 +27,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { recordingStructuredAgentSessionLogger } from './structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 
@@ -77,7 +78,7 @@ beforeEach(async () => {
           acquisitionGeneration: 'generation-1',
           link: {
             linkId: `link-${fence}`,
-            handle: { provider: 'codex' as const, threadId: THREAD },
+            handle: codexProviderHandle(THREAD),
             origin: 'created' as const,
             mintedAtFence: fence,
             observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-conversations.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-conversations.test.ts
index ec4c76e26ba..94d08c054c5 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-conversations.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-conversations.test.ts
@@ -10,13 +10,14 @@ import { StructuredAgentSessionConversations } from './structured-agent-session-
 import type { StructuredAgentSessionHostSession } from './structured-agent-session-host-types'
 import { hostTestAttachParams } from './structured-agent-session-host-test-data'
 import { recordingStructuredAgentSessionLogger } from './structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'workspace-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 const journals = createTrackedJournalOpener()
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-crash-turn-end.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-crash-turn-end.test.ts
index d31a79e5f54..a8e0f4be94f 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-crash-turn-end.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-crash-turn-end.test.ts
@@ -48,6 +48,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
 import { recordingStructuredAgentSessionLogger } from './structured-agent-session-logger-test-support'
+import { claudeProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const PROVIDER_SESSION = 'provider-session-alpha-1'
 /** The tool call's row: the last thing the provider wrote before the crash. */
@@ -71,7 +72,7 @@ function crashedClaudeRecord(): AgentSessionRecord {
     providerHandleChain: [
       {
         linkId,
-        handle: { provider: 'claude', sessionId: PROVIDER_SESSION, leafUuid: null },
+        handle: claudeProviderHandle(PROVIDER_SESSION, null),
         origin: 'created',
         mintedAtFence: 13,
         observedAt: TOOL_STARTED_AT - 60_000
@@ -120,7 +121,7 @@ async function seedClaudeToolTurn(): Promise<void> {
       workspaceId: LOCATION.workspaceId,
       hostId: LOCATION.executionHostId,
       agent: 'claude',
-      providerHandle: { kind: 'claude', sessionId: PROVIDER_SESSION, leafUuid: null }
+      providerHandle: claudeProviderHandle(PROVIDER_SESSION, null)
     },
     database: openTestJournalHostDatabase(root),
     now: () => now
@@ -435,7 +436,7 @@ describe('a turn a read reached before the reconcile proved its owner dead', ()
           process,
           link: {
             linkId: `claude-${fence}-link`,
-            handle: { provider: 'claude', sessionId: PROVIDER_SESSION, leafUuid: null },
+            handle: claudeProviderHandle(PROVIDER_SESSION, null),
             origin: 'resumed',
             mintedAtFence: fence,
             observedAt: RELAUNCHED_AT
@@ -513,7 +514,7 @@ async function hostWithFailingFirstStart(failure: Error) {
         process,
         link: {
           linkId: `claude-${fence}-link`,
-          handle: { provider: 'claude', sessionId: PROVIDER_SESSION, leafUuid: null },
+          handle: claudeProviderHandle(PROVIDER_SESSION, null),
           origin: 'resumed',
           mintedAtFence: fence,
           observedAt: now
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-dead-generation-settlement.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-dead-generation-settlement.test.ts
index b39790e6b2a..8c3c48c93ad 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-dead-generation-settlement.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-dead-generation-settlement.test.ts
@@ -17,6 +17,7 @@ import {
   unfinishedStructuredAgentSessionWorkWasInterrupted
 } from './structured-agent-session-dead-generation-settlement'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const UNEXPECTED_PROVIDER_EXIT_OUTCOME =
   'The agent stopped while this response was in progress. You can continue in this conversation.'
@@ -34,7 +35,7 @@ beforeEach(async () => {
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: THREAD }
+      providerHandle: codexProviderHandle(THREAD)
     },
     database: openTestJournalHostDatabase(root),
     now: () => 1_000
@@ -403,7 +404,7 @@ describe('dead structured-session generation settlement', () => {
         workspaceId: 'workspace-1',
         hostId: 'local',
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: THREAD }
+        providerHandle: codexProviderHandle(THREAD)
       },
       database: openTestJournalHostDatabase(root),
       now: () => 1_000
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-event-sink.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-event-sink.test.ts
index 483e88720fd..a2de3f33874 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-event-sink.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-event-sink.test.ts
@@ -25,6 +25,7 @@ import { openJournalOwingImport } from '../agent-session-journal/journal-owed-im
 import { createCodexJournalTranslator } from '../../codex/codex-structured-journal-translation'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
 import { testEventSinkLogging } from './structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const BODY: AgentJournalItemBody = {
   kind: 'message',
@@ -37,7 +38,7 @@ const JOURNAL_IDENTITY = {
   workspaceId: 'workspace-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 } as const
 
 function identity(ordinal: number): AgentJournalItemIdentity {
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-failed-create-owner-verdict.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-failed-create-owner-verdict.test.ts
index fca04e1028a..31e7bb71859 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-failed-create-owner-verdict.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-failed-create-owner-verdict.test.ts
@@ -24,6 +24,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 const EXIT_REASON = 'claude stream-json exited (code 1): stderr tail'
@@ -44,7 +45,7 @@ beforeEach(async () => {
     process: { hostId: 'local', pid: 4242, processStartTimeMs: 1_700_000_000_000, spawnToken },
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'codex', threadId: THREAD },
+      handle: codexProviderHandle(THREAD),
       origin: 'created',
       mintedAtFence: fence,
       observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-failed-create-sink-release.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-failed-create-sink-release.test.ts
index 38b85ca12d1..d6590d6c61a 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-failed-create-sink-release.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-failed-create-sink-release.test.ts
@@ -22,6 +22,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 const EXIT_REASON = 'claude stream-json exited (code 1): claude: not signed in'
@@ -38,7 +39,7 @@ beforeEach(async () => {
     process: { hostId: 'local', pid: 4242, processStartTimeMs: 1_700_000_000_000, spawnToken },
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'codex', threadId: THREAD },
+      handle: codexProviderHandle(THREAD),
       // A resume continues the chain the first start created.
       origin: store.getRecord(SESSION)?.providerHandleChain.length ? 'resumed' : 'created',
       mintedAtFence: fence,
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-forget-status.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-forget-status.test.ts
index 764d54377d0..f91ab9b822b 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-forget-status.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-forget-status.test.ts
@@ -25,6 +25,7 @@ import type { StructuredAgentSessionAttachContext } from './structured-agent-ses
 import type { StructuredAgentSessionHostSession } from './structured-agent-session-host-types'
 import { StructuredAgentSessionStatusFeed } from './structured-agent-session-status-feed'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 // Everything before the journal is out of scope here; what matters is what the orchestration does
 // when the attach throws after acquisition.
@@ -43,7 +44,7 @@ const IDENTITY: AgentSessionJournalIdentity = {
   workspaceId: 'repo-1::/workspace/app',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: SESSION }
+  providerHandle: codexProviderHandle(SESSION)
 }
 
 const SUBJECT = makeStructuredAgentStatusSubject(
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-grouped-prompt.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-grouped-prompt.test.ts
index b82499c2830..a4a12bfce7e 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-grouped-prompt.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-grouped-prompt.test.ts
@@ -25,6 +25,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 
@@ -125,7 +126,7 @@ beforeEach(async () => {
     },
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'codex', threadId: THREAD },
+      handle: codexProviderHandle(THREAD),
       origin: store.getRecord(SESSION)?.providerHandleChain.length ? 'resumed' : 'created',
       mintedAtFence: fence,
       observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-history-result.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-history-result.ts
index b282fc4df32..49fb06e83ba 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-history-result.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-history-result.ts
@@ -15,12 +15,7 @@ export function structuredAgentSessionProviderSessionMetadata(
   record: AgentSessionRecord | null
 ): AgentProviderSessionMetadata | undefined {
   const head = record ? agentSessionProviderHandleChainHead(record.providerHandleChain) : null
-  return head
-    ? {
-        key: 'session_id',
-        id: head.handle.provider === 'claude' ? head.handle.sessionId : head.handle.threadId
-      }
-    : undefined
+  return head ? { key: 'session_id', id: head.handle.nativeId } : undefined
 }
 
 export function readStructuredAgentSessionHistoryResult(input: {
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-host-test-abandon.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-host-test-abandon.test.ts
index ee0bb2bee92..c444f52c031 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-host-test-abandon.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-host-test-abandon.test.ts
@@ -20,6 +20,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 
@@ -50,7 +51,7 @@ describe('abandoning a structured agent-session host', () => {
           },
           link: {
             linkId: `link-${fence}`,
-            handle: { provider: 'codex', threadId: THREAD },
+            handle: codexProviderHandle(THREAD),
             origin: 'created',
             mintedAtFence: fence,
             observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-host-test-harness.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-host-test-harness.ts
index c7667531110..96fc601134b 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-host-test-harness.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-host-test-harness.ts
@@ -30,6 +30,7 @@ import {
   resetHostTestOperationIds
 } from './structured-agent-session-host-test-data'
 import { recordingProductionStructuredAgentSessionLogger } from './structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const journals = createTrackedJournalOpener()
 
@@ -141,7 +142,7 @@ beforeEach(async () => {
     },
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'codex', threadId: THREAD },
+      handle: codexProviderHandle(THREAD),
       origin: store.getRecord(SESSION)?.providerHandleChain.length ? 'resumed' : 'created',
       mintedAtFence: fence,
       observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-host.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-host.test.ts
index f66d2506804..16251f3cd40 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-host.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-host.test.ts
@@ -29,6 +29,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 let root: string
 let store: AgentSessionRecordStore
@@ -111,7 +112,7 @@ describe('attach', () => {
         },
         link: {
           linkId: 'stale-link',
-          handle: { provider: 'codex', threadId: THREAD },
+          handle: codexProviderHandle(THREAD),
           origin: 'created',
           mintedAtFence: fence + 1,
           observedAt: NOW
@@ -126,7 +127,7 @@ describe('attach', () => {
         },
         link: {
           linkId: `link-${fence}`,
-          handle: { provider: 'codex', threadId: THREAD },
+          handle: codexProviderHandle(THREAD),
           origin: 'created',
           mintedAtFence: fence,
           observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-late-settlement.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-late-settlement.test.ts
index f91fc57c055..81b7200c304 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-late-settlement.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-late-settlement.test.ts
@@ -30,6 +30,7 @@ import { agentSessionFailureFact } from '../../../shared/agent-session-failure'
 import { agentSessionFailureWords } from '../../../shared/agent-session-failure-words'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 
@@ -108,7 +109,7 @@ beforeEach(async () => {
         },
         link: {
           linkId: `link-${fence}`,
-          handle: { provider: 'codex' as const, threadId: THREAD },
+          handle: codexProviderHandle(THREAD),
           origin: 'created' as const,
           mintedAtFence: fence,
           observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-lease-renewer.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-lease-renewer.test.ts
index c3eb1e324e9..f428ab59a1b 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-lease-renewer.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-lease-renewer.test.ts
@@ -10,6 +10,7 @@ import type { AgentSessionRecordStore } from '../../runtime/agent-session-record
 import { openTestAgentSessionRecordStore } from '../../runtime/agent-session-record-store-test-harness'
 import { StructuredAgentSessionLeaseRenewer } from './structured-agent-session-lease-renewer'
 import { recordingStructuredAgentSessionLogger } from './structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const NOW = 1_800_000_000_000
 const roots: string[] = []
@@ -56,7 +57,7 @@ async function liveStore(): Promise<AgentSessionRecordStore> {
     fence: reserved.record.lease.runtimeFence,
     link: {
       linkId: 'link-renewal',
-      handle: { provider: 'codex', threadId: 'thread-renewal' },
+      handle: codexProviderHandle('thread-renewal'),
       origin: 'created',
       mintedAtFence: reserved.record.lease.runtimeFence,
       observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-legacy-handoff-record.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-legacy-handoff-record.test.ts
index c25640cc81c..00b9f617891 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-legacy-handoff-record.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-legacy-handoff-record.test.ts
@@ -25,6 +25,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 
@@ -125,7 +126,7 @@ beforeEach(async () => {
     process: { hostId: 'local', pid: 4242, processStartTimeMs: NOW - 1_000, spawnToken },
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'codex' as const, threadId: THREAD },
+      handle: codexProviderHandle(THREAD),
       origin: store.getRecord(SESSION)?.providerHandleChain.length
         ? ('resumed' as const)
         : ('created' as const),
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-main-agent-working-agreement.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-main-agent-working-agreement.test.ts
index 9ab31743cf4..b8bda4c1b78 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-main-agent-working-agreement.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-main-agent-working-agreement.test.ts
@@ -38,6 +38,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 const PROVIDER_ROW = { provider: 'codex' as const, threadId: THREAD, turnId: 'turn-1' }
@@ -78,7 +79,7 @@ beforeEach(async () => {
           acquisitionGeneration: 'generation-1',
           link: {
             linkId: `link-${input.fence}`,
-            handle: { provider: 'codex' as const, threadId: THREAD },
+            handle: codexProviderHandle(THREAD),
             origin: 'created' as const,
             mintedAtFence: input.fence,
             observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-operation-settlement.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-operation-settlement.test.ts
index c7901edc1c1..a5c44bdb0d0 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-operation-settlement.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-operation-settlement.test.ts
@@ -18,6 +18,7 @@ import {
 import type { AgentSessionTurnContext } from './structured-agent-session-turns'
 import { sendPlan } from './structured-agent-session-mutation-plans'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 async function context(): Promise<AgentSessionTurnContext> {
   return {
@@ -29,7 +30,7 @@ async function context(): Promise<AgentSessionTurnContext> {
         workspaceId: 'workspace',
         hostId: 'local',
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: THREAD }
+        providerHandle: codexProviderHandle(THREAD)
       },
       stateDirectory: join(hostTestState().root, 'settlement')
     }),
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-option-settlement.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-option-settlement.test.ts
index 8a9d93c35e7..62482870271 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-option-settlement.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-option-settlement.test.ts
@@ -22,6 +22,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 const DEFAULT_MODEL = 'gpt-default'
@@ -66,7 +67,7 @@ function adapter(): StructuredAgentSessionAdapter {
       },
       link: {
         linkId: `native-link-${fence}`,
-        handle: { provider: 'codex', threadId: THREAD },
+        handle: codexProviderHandle(THREAD),
         origin: acquire.mock.calls.length === 1 ? 'created' : 'resumed',
         mintedAtFence: fence,
         observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-processless-reservation.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-processless-reservation.test.ts
index c45ceac238c..1c55baa57b0 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-processless-reservation.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-processless-reservation.test.ts
@@ -16,6 +16,7 @@ import { openTestAttachConversation } from './structured-agent-session-attach-te
 import { performAttach } from './structured-agent-session-attach-flow'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const NOW = 1_800_000_000_000
 const SESSION = 'session-alpha'
@@ -114,13 +115,14 @@ describe('processless structured session reservation', () => {
       .mockReturnValueOnce(true)
       .mockReturnValueOnce(true)
       .mockReturnValueOnce(false)
+    // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: the attach reaches only `supportsCreate` and `acquire` on this fake adapter.
     const adapter = {
       supportsCreate,
       acquire: vi.fn(async ({ fence, spawnToken }) => ({
         process: { hostId: 'local', pid: 4242, processStartTimeMs: NOW, spawnToken },
         link: {
           linkId: 'link-1',
-          handle: { provider: 'codex' as const, threadId: 'thread-1' },
+          handle: codexProviderHandle('thread-1'),
           origin: 'created' as const,
           mintedAtFence: fence,
           observedAt: NOW
@@ -263,6 +265,7 @@ describe('processless structured session reservation', () => {
   it('does not rerun a settled pre-spawn failure and admits a fresh operation', async () => {
     root = await mkdtemp(join(tmpdir(), 'orca-processless-retry-'))
     const store = await openTestAgentSessionRecordStore(root)
+    // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: the attach reaches only the members this fake adapter defines.
     const adapter = {
       acquire: vi
         .fn<StructuredAgentSessionAdapter['acquire']>()
@@ -276,7 +279,7 @@ describe('processless structured session reservation', () => {
           },
           link: {
             linkId: 'link-1',
-            handle: { provider: 'codex', threadId: 'thread-1' },
+            handle: codexProviderHandle('thread-1'),
             origin: 'created',
             mintedAtFence: fence,
             observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-prompt-cancel.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-prompt-cancel.test.ts
index f98959bc0ad..d2348e2acfd 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-prompt-cancel.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-prompt-cancel.test.ts
@@ -17,13 +17,14 @@ import { performCancel, type AgentSessionTurnContext } from './structured-agent-
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
 import { cancelStructuredAgentSessionPrompt } from './structured-agent-session-prompt-cancel'
 import type { AgentSessionPromptCancelRoute } from './structured-agent-session-adapter-stop'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'workspace-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 const PROMPT_IDENTITY = {
   provider: 'codex' as const,
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-provider-child-record.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-provider-child-record.test.ts
index 6d42155fa38..c61d2bd117f 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-provider-child-record.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-provider-child-record.test.ts
@@ -41,6 +41,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 const CHAT_CLOSED = agentSessionFailureWords(agentSessionFailureFact('chatClosed'), {
@@ -67,7 +68,7 @@ const spawnChild: StructuredAgentSessionAdapter['acquire'] = async ({ fence, spa
   acquisitionGeneration: generation(),
   link: {
     linkId: `link-${fence}`,
-    handle: { provider: 'codex' as const, threadId: THREAD },
+    handle: codexProviderHandle(THREAD),
     origin: store.getRecord(SESSION)?.providerHandleChain.length
       ? ('resumed' as const)
       : ('created' as const),
@@ -337,7 +338,7 @@ describe('settling an earlier child before the next one takes its message', () =
         workspaceId: HOST_TEST_LOCATION.workspaceId,
         hostId: HOST_TEST_LOCATION.executionHostId,
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: THREAD }
+        providerHandle: codexProviderHandle(THREAD)
       },
       database: openTestJournalHostDatabase(root)
     })
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-provider-restore.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-provider-restore.test.ts
index de2951a6292..57d249d2dbe 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-provider-restore.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-provider-restore.test.ts
@@ -17,6 +17,7 @@ import { agentSessionFailureFact } from '../../../shared/agent-session-failure'
 import { agentSessionFailureWords } from '../../../shared/agent-session-failure-words'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { claudeProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CLAUDE_SESSION = 'claude-session'
 const hosts: StructuredAgentSessionHost[] = []
@@ -34,7 +35,7 @@ function claudeAdapter(): StructuredAgentSessionAdapter {
       },
       link: {
         linkId: `link-${fence}`,
-        handle: { provider: 'claude', sessionId: CLAUDE_SESSION, leafUuid: null },
+        handle: claudeProviderHandle(CLAUDE_SESSION, null),
         origin: 'created',
         mintedAtFence: fence,
         observedAt: HOST_TEST_NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-queued-message-rig.test-fixture.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-queued-message-rig.test-fixture.ts
index f94d091a5f9..f1271f4e339 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-queued-message-rig.test-fixture.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-queued-message-rig.test-fixture.ts
@@ -27,6 +27,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 export const QUEUED_RIG_CALLER = { callerKey: 'client-1' }
 
@@ -92,7 +93,7 @@ export async function createQueuedMessageTestRig(
             ...(options.starting ? { providerChildPhase: 'starting' as const } : {}),
             link: {
               linkId: `link-${fence}`,
-              handle: { provider: 'codex' as const, threadId: THREAD },
+              handle: codexProviderHandle(THREAD),
               origin: resumes ? ('resumed' as const) : ('created' as const),
               mintedAtFence: fence,
               observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-read-restore.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-read-restore.test.ts
index 6f59e5e7d5e..38b2453c3bf 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-read-restore.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-read-restore.test.ts
@@ -19,10 +19,12 @@ import {
 } from '../agent-session-journal/journal-host-database-test-support'
 import { restoreStructuredAgentSessionRead } from './structured-agent-session-read-restore'
 import { recordingStructuredAgentSessionLogger } from './structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const SESSION_ID = 'codex_read_restore_fixture'
 const WORKSPACE_ID = 'repo-1::/tmp/workspace'
 
+// oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: a literal record the read path only reads; its fields match the record shape.
 const RECORD = {
   schemaVersion: 2,
   sessionId: SESSION_ID,
@@ -36,7 +38,7 @@ const RECORD = {
   providerHandleChain: [
     {
       linkId: 'codex-1-thread-1',
-      handle: { provider: 'codex', threadId: 'thread-1' },
+      handle: codexProviderHandle('thread-1'),
       origin: 'created',
       mintedAtFence: 1,
       observedAt: 1
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-recovered-turn-clock.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-recovered-turn-clock.test.ts
index 0857e3565d6..cbcad01350a 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-recovered-turn-clock.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-recovered-turn-clock.test.ts
@@ -31,6 +31,7 @@ import { StructuredAgentSessionStatusFeed } from './structured-agent-session-sta
 import { indexedStatusFeedSession } from './structured-agent-session-status-feed-test-session'
 import { StructuredAgentSessionTurnCompletionFeed } from './structured-agent-session-turn-completion-feed'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'recovered-turn-session'
 const THREAD = 'thread-1'
@@ -60,7 +61,7 @@ async function sessionWithRunningTurn() {
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: THREAD }
+      providerHandle: codexProviderHandle(THREAD)
     },
     now: () => clock,
     stateDirectory: join(root, SESSION)
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-recovery-exits.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-recovery-exits.test.ts
index 228fa21fbc2..314e4012199 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-recovery-exits.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-recovery-exits.test.ts
@@ -23,6 +23,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 
@@ -110,7 +111,7 @@ beforeEach(async () => {
     },
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'codex', threadId: THREAD },
+      handle: codexProviderHandle(THREAD),
       origin: store.getRecord(SESSION)?.providerHandleChain.length ? 'resumed' : 'created',
       mintedAtFence: fence,
       observedAt: NOW
@@ -288,7 +289,7 @@ describe('recovery exits', () => {
       process: outgoing.process,
       link: {
         linkId: 'link-outgoing',
-        handle: { provider: 'codex', threadId: THREAD },
+        handle: codexProviderHandle(THREAD),
         origin: 'created',
         mintedAtFence: 1,
         observedAt: NOW
@@ -333,7 +334,7 @@ describe('recovery exits', () => {
       process: replacement.process,
       link: {
         linkId: 'link-replacement',
-        handle: { provider: 'codex', threadId: THREAD },
+        handle: codexProviderHandle(THREAD),
         origin: 'resumed',
         mintedAtFence: 3,
         observedAt: NOW + 2
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-recovery-resolution.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-recovery-resolution.test.ts
index 8e3be9d1f3d..bdeaa152784 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-recovery-resolution.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-recovery-resolution.test.ts
@@ -15,6 +15,7 @@ import {
   resolveStructuredSessionRecovery,
   type StructuredSessionRecoveryResolutionDeps
 } from './structured-agent-session-recovery-resolution'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const NOW = 1_800_000_000_000
 const MATCHED: AgentSessionOwnerProbe = { outcome: 'identity-matched', matchedOn: ['spawn-token'] }
@@ -81,7 +82,7 @@ async function liveOwner(store: AgentSessionRecordStore, pid = 4242) {
     fence,
     link: {
       linkId: 'link-recovery',
-      handle: { provider: 'codex', threadId: 'thread-recovery' },
+      handle: codexProviderHandle('thread-recovery'),
       origin: 'created',
       mintedAtFence: fence,
       observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-refusal-retry.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-refusal-retry.test.ts
index fefd91a8478..a16fa4f21d8 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-refusal-retry.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-refusal-retry.test.ts
@@ -30,6 +30,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 const METHODS = ['agentSession.setOption', 'agentSession.send'] as const
@@ -72,7 +73,7 @@ async function createHarness(options: { attached?: boolean } = {}) {
       },
       link: {
         linkId: `link-${fence}`,
-        handle: { provider: 'codex', threadId: THREAD },
+        handle: codexProviderHandle(THREAD),
         origin: 'created',
         mintedAtFence: fence,
         observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-repeat-press.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-repeat-press.test.ts
index a16ef1101a2..6fc7b6c2d52 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-repeat-press.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-repeat-press.test.ts
@@ -23,6 +23,7 @@ import {
   hostTestOperationId,
   resetHostTestOperationIds
 } from './structured-agent-session-host-test-data'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 
@@ -51,7 +52,7 @@ beforeEach(async () => {
         acquisitionGeneration: 'generation-1',
         link: {
           linkId: `link-${fence}`,
-          handle: { provider: 'codex' as const, threadId: THREAD },
+          handle: codexProviderHandle(THREAD),
           origin: fence > 1 ? ('resumed' as const) : ('created' as const),
           mintedAtFence: fence,
           observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-resolved-append.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-resolved-append.test.ts
index a2e843378a5..c14899af112 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-resolved-append.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-resolved-append.test.ts
@@ -17,6 +17,7 @@ import {
 } from './structured-agent-session-event-sink'
 import { estimateStructuredAgentSessionItemBytes } from './structured-agent-session-event-sink-estimate'
 import { testEventSinkLogging } from './structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const ROW: AgentJournalItemIdentity = { provider: 'orca', clientMessageId: 'row' }
 
@@ -45,7 +46,7 @@ beforeEach(async () => {
       workspaceId: 'workspace-1',
       hostId: 'host-1',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: 'thread-1' }
+      providerHandle: codexProviderHandle('thread-1')
     }
   }))
 })
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-rest-test-rig.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-rest-test-rig.ts
index 0045684ccb3..bd21fa3ff33 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-rest-test-rig.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-rest-test-rig.ts
@@ -34,6 +34,7 @@ import {
 import { STRUCTURED_AGENT_SESSION_IDLE_MS } from './structured-agent-session-idle-sweep'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 export const REST_TEST_CALLER = { callerKey: 'client-1' }
 export const IDLE_MS = STRUCTURED_AGENT_SESSION_IDLE_MS
@@ -145,7 +146,7 @@ export async function createRestTestRig(
       process: { hostId: 'local', pid: 4242, processStartTimeMs: 1_700_000_000_000, spawnToken },
       link: {
         linkId: `link-${fence}`,
-        handle: { provider: 'codex' as const, threadId: THREAD },
+        handle: codexProviderHandle(THREAD),
         origin: store.getRecord(SESSION)?.providerHandleChain.length
           ? ('resumed' as const)
           : ('created' as const),
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-restart-resume-test-harness.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-restart-resume-test-harness.ts
index 9f00c69aca4..e5fa9576f6a 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-restart-resume-test-harness.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-restart-resume-test-harness.ts
@@ -13,6 +13,10 @@ import type { AgentSessionRecord } from '../../../shared/agent-session-record'
 import type { AgentSessionResumeMarker } from '../../../shared/agent-session-resume-marker'
 import type { AgentChildWorkView } from '../../../shared/agent-status-child-work-view'
 import { structuredAgentSessionResumableSet } from './structured-agent-session-restart-resume-set'
+import {
+  claudeProviderHandle,
+  codexProviderHandle
+} from '../../../shared/agent-session-provider-handle-encoding'
 
 export const SESSION = 'session-working-1'
 export const THREAD = 'thread-1'
@@ -53,7 +57,7 @@ export function record(overrides: { chain?: AgentSessionRecord['providerHandleCh
     providerHandleChain: overrides.chain ?? [
       {
         linkId: 'link-1',
-        handle: { provider: 'codex', threadId: THREAD },
+        handle: codexProviderHandle(THREAD),
         origin: 'created',
         mintedAtFence: 1,
         observedAt: NOW
@@ -124,7 +128,7 @@ export function claudeRecord(
     providerHandleChain: [
       {
         linkId: 'link-1',
-        handle: { provider: 'claude', sessionId: providerSessionId, leafUuid },
+        handle: claudeProviderHandle(providerSessionId, leafUuid),
         origin: 'created',
         mintedAtFence: 1,
         observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-restart-status-publication.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-restart-status-publication.test.ts
index 6cde8d87b84..38a47a06ebe 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-restart-status-publication.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-restart-status-publication.test.ts
@@ -28,6 +28,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 
@@ -40,7 +41,7 @@ function adapter(): StructuredAgentSessionAdapter {
       process: { hostId: 'local', pid: 4242, processStartTimeMs: 1_700_000_000_000, spawnToken },
       link: {
         linkId: `link-${fence}`,
-        handle: { provider: 'codex', threadId: THREAD },
+        handle: codexProviderHandle(THREAD),
         origin: 'created',
         mintedAtFence: fence,
         observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-restore-without-import.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-restore-without-import.test.ts
index 4fa2811472a..20cd3b298d5 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-restore-without-import.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-restore-without-import.test.ts
@@ -40,6 +40,7 @@ import { createStructuredAgentSessionRestartOfferWithdrawal } from './structured
 import { restoreStructuredAgentSessionsOnRestart } from './structured-agent-session-restart-restore'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
 import { recordingStructuredAgentSessionLogger } from './structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const { readOnlyOpens, openReadOnly } = vi.hoisted(() => ({
   readOnlyOpens: new Array<string>(),
@@ -87,7 +88,7 @@ function recordFor(sessionId: string): AgentSessionRecord {
     providerHandleChain: [
       {
         linkId: `codex-1-${sessionId}`,
-        handle: { provider: 'codex', threadId: `thread-${sessionId}` },
+        handle: codexProviderHandle(`thread-${sessionId}`),
         origin: 'created',
         mintedAtFence: 1,
         observedAt: 1
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-reveal.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-reveal.test.ts
index 49a116ec7f7..a574010b34e 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-reveal.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-reveal.test.ts
@@ -15,6 +15,7 @@ import {
 } from '../../../shared/agent-session-record.test-fixture'
 import * as providerSupport from './structured-agent-session-provider-support'
 import { revealStructuredAgentSession } from './structured-agent-session-reveal'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 function recordFor(provider: 'claude' | 'codex', sessionId: string): AgentSessionRecord {
   const record = agentSessionRecordFixture(agentSessionLeaseFixture({ sessionId }))
@@ -26,7 +27,7 @@ function recordFor(provider: 'claude' | 'codex', sessionId: string): AgentSessio
         ? [
             {
               ...record.providerHandleChain[0]!,
-              handle: { provider: 'codex', threadId: `thread-${sessionId}` }
+              handle: codexProviderHandle(`thread-${sessionId}`)
             }
           ]
         : record.providerHandleChain
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-rewind-at-rest.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-rewind-at-rest.test.ts
index c7240eccd83..8d5d5d54cbb 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-rewind-at-rest.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-rewind-at-rest.test.ts
@@ -27,6 +27,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const caller = { callerKey: 'desktop' }
 const KEPT = { provider: 'codex' as const, threadId: THREAD, turnId: 'kept', ordinal: 0 }
@@ -61,7 +62,7 @@ function adapter(): StructuredAgentSessionAdapter {
           mintedAtFence: input.fence,
           observedAt: HOST_TEST_NOW,
           origin: acquires === 1 ? 'created' : 'resumed',
-          handle: { provider: 'codex', threadId: THREAD }
+          handle: codexProviderHandle(THREAD)
         }
       }
     },
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-rewind.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-rewind.test.ts
index 5a359deebad..6e60651d4bd 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-rewind.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-rewind.test.ts
@@ -33,6 +33,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const caller = { callerKey: 'desktop' }
 let directory: string
@@ -78,7 +79,7 @@ beforeEach(async () => {
           mintedAtFence: input.fence,
           observedAt: HOST_TEST_NOW,
           origin: acquires.length === 1 ? 'created' : 'resumed',
-          handle: { provider: 'codex', threadId: HOST_TEST_THREAD }
+          handle: codexProviderHandle(HOST_TEST_THREAD)
         }
       }
     },
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-rewind.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-rewind.ts
index ee9c69bf38c..6003bba605a 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-rewind.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-rewind.ts
@@ -96,13 +96,14 @@ export async function rewindStructuredAgentSession(
           }
           const selected = snapshot.items.findIndex((item) => item.itemId === params.itemId)
           const key = selected === -1 ? null : parseAgentJournalItemKey(providerKey(params.itemId))
+          // The head belongs to the record's provider: the record store refuses any other.
           const head = agentSessionProviderHandleChainHead(record.providerHandleChain)?.handle
-          if (!key || !head || key.provider !== head.provider) {
+          if (!key || !head || key.provider !== record.provider) {
             return rewindRefusal('invalid-target')
           }
           let boundary = selected
-          if (key.provider === 'codex' && head.provider === 'codex') {
-            if (key.threadId !== head.threadId) {
+          if (key.provider === 'codex') {
+            if (key.threadId !== head.nativeId) {
               return rewindRefusal('invalid-target')
             }
             boundary = snapshot.items.findIndex((item) => {
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-send-idempotency.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-send-idempotency.test.ts
index e170461095b..55acadfc562 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-send-idempotency.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-send-idempotency.test.ts
@@ -11,6 +11,7 @@ import type { StructuredAgentSessionAdapter } from './structured-agent-session-a
 import { performSend, type AgentSessionTurnContext } from './structured-agent-session-turns'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
 import { recordingStructuredAgentSessionLogger } from './structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const journals = createTrackedJournalOpener()
 
@@ -25,7 +26,7 @@ beforeEach(async () => {
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: 'thread-1' }
+      providerHandle: codexProviderHandle('thread-1')
     },
     stateDirectory: root
   })
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-send-preparation.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-send-preparation.test.ts
index 01f4868d380..c51219ae8e6 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-send-preparation.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-send-preparation.test.ts
@@ -25,6 +25,7 @@ import {
   resetHostTestOperationIds
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 
@@ -51,7 +52,7 @@ beforeEach(async () => {
     acquisitionGeneration: `generation-${++generation}`,
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'codex' as const, threadId: THREAD },
+      handle: codexProviderHandle(THREAD),
       origin: store.getRecord(SESSION)?.providerHandleChain.length
         ? ('resumed' as const)
         : ('created' as const),
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-send-restarts-failed-start.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-send-restarts-failed-start.test.ts
index 8c5e609b971..6cf15ca088c 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-send-restarts-failed-start.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-send-restarts-failed-start.test.ts
@@ -30,6 +30,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 
@@ -135,7 +136,7 @@ beforeEach(async () => {
     process: { hostId: 'local', pid: 4242, processStartTimeMs: 1_700_000_000_000, spawnToken },
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'codex', threadId: THREAD },
+      handle: codexProviderHandle(THREAD),
       // A re-acquire resumes the thread the first child minted, as a real adapter does.
       origin: generation === 0 ? ('created' as const) : ('resumed' as const),
       mintedAtFence: fence,
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-settled-attach-retry.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-settled-attach-retry.test.ts
index 429cb803794..bfc7db94ebd 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-settled-attach-retry.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-settled-attach-retry.test.ts
@@ -27,6 +27,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 
@@ -98,7 +99,7 @@ beforeEach(async () => {
     },
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'codex', threadId: THREAD },
+      handle: codexProviderHandle(THREAD),
       origin: store.getRecord(SESSION)?.providerHandleChain.length ? 'resumed' : 'created',
       mintedAtFence: fence,
       observedAt: NOW
@@ -186,7 +187,7 @@ describe('settled attach retry', () => {
         },
         link: {
           linkId: `link-${fence}`,
-          handle: { provider: 'codex', threadId: THREAD },
+          handle: codexProviderHandle(THREAD),
           origin: 'created',
           mintedAtFence: fence,
           observedAt: NOW
@@ -230,7 +231,7 @@ describe('settled attach retry', () => {
         },
         link: {
           linkId: `link-${fence}`,
-          handle: { provider: 'codex', threadId: THREAD },
+          handle: codexProviderHandle(THREAD),
           origin: 'created',
           mintedAtFence: fence,
           observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-stale-turn-verdict.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-stale-turn-verdict.test.ts
index 8a9deaad48c..90e5e84cf86 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-stale-turn-verdict.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-stale-turn-verdict.test.ts
@@ -19,6 +19,7 @@ import {
   turnVerdictFromDeathEvidence,
   UNVERIFIABLE_TURN_VERDICT
 } from './structured-agent-session-stale-turn-verdict'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const THREAD = 'thread-1'
 const RUNNING_IDENTITY = {
@@ -368,7 +369,7 @@ describe('stale session state on a cold acquire', () => {
           workspaceId: 'workspace-1',
           hostId: 'local',
           agent: 'codex',
-          providerHandle: { kind: 'codex', threadId: THREAD }
+          providerHandle: codexProviderHandle(THREAD)
         },
         stateDirectory: root,
         now: () => 1_000
@@ -422,7 +423,7 @@ describe('stale session state on a cold acquire', () => {
           workspaceId: 'workspace-1',
           hostId: 'local',
           agent: 'codex',
-          providerHandle: { kind: 'codex', threadId: THREAD }
+          providerHandle: codexProviderHandle(THREAD)
         },
         stateDirectory: root,
         now: () => now
@@ -488,7 +489,7 @@ describe('stale session state on a cold acquire', () => {
           workspaceId: 'workspace-1',
           hostId: 'local',
           agent: 'codex',
-          providerHandle: { kind: 'codex', threadId: THREAD }
+          providerHandle: codexProviderHandle(THREAD)
         },
         stateDirectory: root,
         now: () => now
@@ -559,7 +560,7 @@ describe('stale session state on a cold acquire', () => {
           workspaceId: 'workspace-1',
           hostId: 'local',
           agent: 'codex',
-          providerHandle: { kind: 'codex', threadId: THREAD }
+          providerHandle: codexProviderHandle(THREAD)
         },
         stateDirectory: root,
         now: () => now
@@ -619,7 +620,7 @@ describe('stale session state on a cold acquire', () => {
           workspaceId: 'workspace-1',
           hostId: 'local',
           agent: 'codex',
-          providerHandle: { kind: 'codex', threadId: THREAD }
+          providerHandle: codexProviderHandle(THREAD)
         },
         stateDirectory: root,
         now: () => now
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-start-failure-writer.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-start-failure-writer.test.ts
index 79227670238..0afc0a05077 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-start-failure-writer.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-start-failure-writer.test.ts
@@ -28,6 +28,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 const EXIT_REASON = 'Claude Code is not signed in. Sign in with the Claude CLI'
@@ -128,7 +129,7 @@ beforeEach(async () => {
         process: { hostId: 'local', pid: 4242, processStartTimeMs: 1_700_000_000_000, spawnToken },
         link: {
           linkId: `link-${fence}`,
-          handle: { provider: 'codex' as const, threadId: THREAD },
+          handle: codexProviderHandle(THREAD),
           origin: generation === 0 ? ('created' as const) : ('resumed' as const),
           mintedAtFence: fence,
           observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-child-work.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-child-work.test.ts
index cfb801c8fd6..386040a05a6 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-child-work.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-child-work.test.ts
@@ -11,6 +11,7 @@ import {
 } from './structured-agent-session-status-feed'
 import { indexedStatusFeedSession } from './structured-agent-session-status-feed-test-session'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'status-session'
 const EVIDENCE: AgentChildWorkEvidence[] = [{ type: 'session-ended', observedAt: 5 }]
@@ -33,7 +34,7 @@ async function feedWith(sink: StructuredAgentSessionStatusSink) {
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: 'thread-1' }
+      providerHandle: codexProviderHandle('thread-1')
     },
     stateDirectory: join(root, SESSION)
   })
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-child.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-child.test.ts
index a9c94cc4d2b..20a7fca25c1 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-child.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-child.test.ts
@@ -7,6 +7,7 @@ import { createTrackedJournalOpener } from '../agent-session-journal/journal-hos
 import { StructuredAgentSessionStatusFeed } from './structured-agent-session-status-feed'
 import { indexedStatusFeedSession } from './structured-agent-session-status-feed-test-session'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'status-session'
 const journals = createTrackedJournalOpener()
@@ -28,7 +29,7 @@ it('publishes the provider child startup phase, not which child it is', async ()
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: 'thread-1' }
+      providerHandle: codexProviderHandle('thread-1')
     },
     stateDirectory: root
   })
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-children.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-children.test.ts
index 30ddeea9678..89e47785983 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-children.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-children.test.ts
@@ -23,6 +23,7 @@ import {
   statusFeedChildView as childView
 } from './structured-agent-session-status-feed-test-session'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'status-session'
 const USER_IDENTITY = {
@@ -61,7 +62,7 @@ async function feedWithChildren(provider: AgentSessionHandleProvider = 'codex')
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: 'thread-1' }
+      providerHandle: codexProviderHandle('thread-1')
     },
     stateDirectory: join(root, SESSION)
   })
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-clock.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-clock.test.ts
index 09a3442985b..f7893ea0a44 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-clock.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed-clock.test.ts
@@ -15,6 +15,7 @@ import { createTrackedJournalOpener } from '../agent-session-journal/journal-hos
 import { StructuredAgentSessionStatusFeed } from './structured-agent-session-status-feed'
 import { indexedStatusFeedSession } from './structured-agent-session-status-feed-test-session'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'clock-session'
 const THREAD = 'thread-1'
@@ -55,7 +56,7 @@ async function openFeed() {
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: THREAD }
+      providerHandle: codexProviderHandle(THREAD)
     },
     now: () => (clock += 100),
     stateDirectory: join(root, SESSION)
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed.test.ts
index 6409c544129..828063da409 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-status-feed.test.ts
@@ -25,6 +25,7 @@ import {
 } from './structured-agent-session-status-feed'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
 import { testEventSinkLogging } from './structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'status-session'
 const TURN_IDENTITY = {
@@ -61,7 +62,7 @@ async function openJournal(sessionId = SESSION, now?: () => number) {
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: 'thread-1' }
+      providerHandle: codexProviderHandle('thread-1')
     },
     now,
     stateDirectory: join(root, sessionId)
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-status-reentry.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-status-reentry.test.ts
index aea5e93168a..611b27f08f9 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-status-reentry.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-status-reentry.test.ts
@@ -14,6 +14,7 @@ import {
   type StructuredAgentSessionStatusSink
 } from './structured-agent-session-status-feed'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'reenter-session'
 const journals = createTrackedJournalOpener()
@@ -35,7 +36,7 @@ async function openJournal(): Promise<AgentSessionJournal> {
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: 'thread-1' }
+      providerHandle: codexProviderHandle('thread-1')
     },
     stateDirectory: join(root, SESSION)
   })
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-stop-note-withdrawn-send.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-stop-note-withdrawn-send.test.ts
index a3c8853ef67..521f9d888cf 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-stop-note-withdrawn-send.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-stop-note-withdrawn-send.test.ts
@@ -12,6 +12,7 @@ import {
   AGENT_JOURNAL_THREAD_SCOPE,
   type AgentSessionJournalIdentity
 } from '../../../shared/agent-session-journal-types'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 import { createTrackedJournalOpener } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
 import { performCancel, type AgentSessionTurnContext } from './structured-agent-session-turns'
@@ -21,7 +22,7 @@ const IDENTITY: AgentSessionJournalIdentity = {
   workspaceId: 'workspace-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 let root: string | null = null
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-subagent-recency.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-subagent-recency.test.ts
index d47efcd4cad..3dcc899b081 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-subagent-recency.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-subagent-recency.test.ts
@@ -22,6 +22,7 @@ import { StructuredAgentSessionStatusFeed } from './structured-agent-session-sta
 import { indexedStatusFeedSession } from './structured-agent-session-status-feed-test-session'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
 import { testEventSinkLogging } from './structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'recency-session'
 const CODEX_THREAD = 'thread-parent'
@@ -54,7 +55,7 @@ async function openSession() {
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'claude',
-      providerHandle: { kind: 'codex', threadId: CODEX_THREAD }
+      providerHandle: codexProviderHandle(CODEX_THREAD)
     },
     now: tick,
     stateDirectory: join(root, SESSION)
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-subscribers.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-subscribers.test.ts
index 27ae0cb0608..a20302cba6a 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-subscribers.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-subscribers.test.ts
@@ -24,6 +24,10 @@ import { StructuredAgentSessionStatusFeed } from './structured-agent-session-sta
 import { MAX_RETAINED_SESSION_ACTIVITIES } from './structured-agent-session-activity-retention'
 import { AgentSessionSubscribers } from './structured-agent-session-subscribers'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import {
+  claudeProviderHandle,
+  codexProviderHandle
+} from '../../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'subscriber-session'
 
@@ -47,7 +51,7 @@ describe('AgentSessionSubscribers', () => {
         workspaceId: 'workspace-1',
         hostId: 'local',
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: 'thread-1' }
+        providerHandle: codexProviderHandle('thread-1')
       },
       stateDirectory: join(root, 'activity-churn-journal')
     })
@@ -67,7 +71,7 @@ describe('AgentSessionSubscribers', () => {
         workspaceId: 'workspace-1',
         hostId: 'local',
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: 'thread-1' }
+        providerHandle: codexProviderHandle('thread-1')
       },
       stateDirectory: join(root, 'checkpoint-journal')
     })
@@ -106,7 +110,7 @@ describe('AgentSessionSubscribers', () => {
         workspaceId: 'workspace-1',
         hostId: 'local',
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: 'thread-1' }
+        providerHandle: codexProviderHandle('thread-1')
       },
       stateDirectory: join(root, 'clock-journal')
     })
@@ -151,7 +155,7 @@ describe('AgentSessionSubscribers', () => {
         workspaceId: 'workspace-1',
         hostId: 'local',
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: 'thread-1' }
+        providerHandle: codexProviderHandle('thread-1')
       },
       stateDirectory: join(root, 'catalog-journal')
     })
@@ -194,7 +198,7 @@ describe('AgentSessionSubscribers', () => {
         workspaceId: 'workspace-1',
         hostId: 'local',
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: 'thread-1' }
+        providerHandle: codexProviderHandle('thread-1')
       },
       stateDirectory: join(root, 'hook-journal')
     })
@@ -222,7 +226,7 @@ describe('AgentSessionSubscribers', () => {
         workspaceId: 'workspace-1',
         hostId: 'local',
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: 'thread-1' }
+        providerHandle: codexProviderHandle('thread-1')
       },
       stateDirectory: join(root, 'unread-journal')
     })
@@ -288,7 +292,7 @@ describe('AgentSessionSubscribers', () => {
         workspaceId: 'workspace-1',
         hostId: 'local',
         agent: 'claude',
-        providerHandle: { kind: 'claude', sessionId: 'provider-1', leafUuid: null }
+        providerHandle: claudeProviderHandle('provider-1', null)
       },
       stateDirectory: join(root, 'background-journal')
     })
@@ -337,7 +341,7 @@ describe('AgentSessionSubscribers', () => {
         workspaceId: 'workspace-1',
         hostId: 'local',
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: 'thread-1' }
+        providerHandle: codexProviderHandle('thread-1')
       },
       stateDirectory: join(root, 'activity-journal')
     })
@@ -389,7 +393,7 @@ describe('AgentSessionSubscribers', () => {
         workspaceId: 'workspace-1',
         hostId: 'local',
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: 'thread-1' }
+        providerHandle: codexProviderHandle('thread-1')
       },
       stateDirectory: journalDir
     })
@@ -440,7 +444,7 @@ describe('AgentSessionSubscribers', () => {
         workspaceId: 'workspace-1',
         hostId: 'local',
         agent: 'codex',
-        providerHandle: { kind: 'codex', threadId: 'thread-1' }
+        providerHandle: codexProviderHandle('thread-1')
       },
       stateDirectory: journalDir
     })
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-surface-lifetime.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-surface-lifetime.test.ts
index c681369ce27..9db5951336e 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-surface-lifetime.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-surface-lifetime.test.ts
@@ -41,6 +41,7 @@ import {
 import { agentSessionFailureFact } from '../../../shared/agent-session-failure'
 import { agentSessionFailureWords } from '../../../shared/agent-session-failure-words'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const UNEXPECTED_PROVIDER_EXIT_OUTCOME =
   'Codex stopped while this response was in progress. You can continue in this conversation.'
@@ -221,7 +222,7 @@ beforeEach(async () => {
       acquisitionGeneration: `generation-${++generation}`,
       link: {
         linkId: `link-${fence}`,
-        handle: { provider: 'codex' as const, threadId: THREAD },
+        handle: codexProviderHandle(THREAD),
         origin: store.getRecord(SESSION)?.providerHandleChain.length
           ? ('resumed' as const)
           : ('created' as const),
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-thread-goal.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-thread-goal.test.ts
index 6349e7b8ef6..5ab883380d5 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-thread-goal.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-thread-goal.test.ts
@@ -17,13 +17,14 @@ import {
 } from './structured-agent-session-thread-goal'
 import type { AgentSessionTurnContext } from './structured-agent-session-turns'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'workspace-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 let root: string | null = null
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-turns.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-turns.test.ts
index b2f30032aa9..0cbf5b8ce6c 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-turns.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-turns.test.ts
@@ -12,13 +12,14 @@ import { createDeferredStructuredAgentSessionEventSink } from './structured-agen
 import { agentJournalItemKey } from '../../../shared/agent-session-journal-item-key'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
 import { testEventSinkLogging } from './structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const IDENTITY: AgentSessionJournalIdentity = {
   sessionId: 'session-1',
   workspaceId: 'workspace-1',
   hostId: 'host-1',
   agent: 'codex',
-  providerHandle: { kind: 'codex', threadId: 'thread-1' }
+  providerHandle: codexProviderHandle('thread-1')
 }
 
 let root: string | null = null
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-wedged-profile-migration.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-wedged-profile-migration.test.ts
index 08532f63c1f..242f7c22877 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-wedged-profile-migration.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-wedged-profile-migration.test.ts
@@ -51,6 +51,10 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import {
+  claudeProviderHandle,
+  codexProviderHandle
+} from '../../../shared/agent-session-provider-handle-encoding'
 
 const CALLER = { callerKey: 'client-1' }
 const DEAD_OWNER: AgentSessionProcessIdentity = {
@@ -159,7 +163,7 @@ beforeEach(async () => {
     },
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'codex', threadId: THREAD },
+      handle: codexProviderHandle(THREAD),
       origin: 'resumed' as const,
       mintedAtFence: fence,
       observedAt: NOW
@@ -196,8 +200,8 @@ async function seedRunningTurn(provider: 'codex' | 'claude' = 'codex'): Promise<
       agent: provider,
       providerHandle:
         provider === 'codex'
-          ? { kind: 'codex', threadId: THREAD }
-          : { kind: 'claude', sessionId: 'provider-session-alpha-1', leafUuid: null }
+          ? codexProviderHandle(THREAD)
+          : claudeProviderHandle('provider-session-alpha-1', null)
     },
     database: openTestJournalHostDatabase(root)
   })
@@ -604,7 +608,7 @@ describe('already-wedged profiles become usable on load', () => {
     // The conversation survived: the codex thread was resumed, not recreated.
     expect(store.getRecord(SESSION)?.providerHandleChain[0]).toMatchObject({
       linkId: 'codex-13-link',
-      handle: { threadId: THREAD }
+      handle: { nativeId: THREAD }
     })
     // Why NOT acquired here: startup spawning a provider child for every recovered record is the
     // accumulation this stack removed. Unlatching is the migration's job; spawning is a hold's.
@@ -679,7 +683,7 @@ describe('already-wedged profiles become usable on load', () => {
         process: { hostId: 'local', pid: 4242, processStartTimeMs: 1, spawnToken: 'spawn-new' },
         link: {
           linkId: `link-${fence}`,
-          handle: { provider: 'codex' as const, threadId: THREAD },
+          handle: codexProviderHandle(THREAD),
           origin: 'resumed' as const,
           mintedAtFence: fence,
           observedAt: NOW
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-wire-admission.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-wire-admission.test.ts
index 24ae62a872b..42cc18f923c 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-wire-admission.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-wire-admission.test.ts
@@ -22,6 +22,7 @@ import {
 } from '../agent-session-journal/journal-host-database-test-support'
 import { readAgentSessionHistory } from './agent-session-history-page'
 import { AgentSessionSubscribers } from './structured-agent-session-subscribers'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'wire-admission-session'
 const LARGE_TEXT = 'x'.repeat(250 * 1024)
@@ -38,7 +39,7 @@ beforeEach(async () => {
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: 'thread-1' }
+      providerHandle: codexProviderHandle('thread-1')
     },
     stateDirectory: root
   })
@@ -190,7 +191,7 @@ async function reopenWithOversizedRemoval(afterSequence: number): Promise<AgentS
       workspaceId: 'workspace-1',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: 'thread-1' }
+      providerHandle: codexProviderHandle('thread-1')
     },
     stateDirectory: root
   })
diff --git a/src/main/native-chat/agent-session-wire/structured-conversation-command.test.ts b/src/main/native-chat/agent-session-wire/structured-conversation-command.test.ts
index fc771000741..b50166cd98d 100644
--- a/src/main/native-chat/agent-session-wire/structured-conversation-command.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-conversation-command.test.ts
@@ -24,6 +24,7 @@ import {
 } from './structured-agent-session-host-test-data'
 import { openTestJournalHostDatabase } from '../agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from './structured-agent-session-logger'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const caller = { callerKey: 'desktop' }
 let directory: string
@@ -117,16 +118,13 @@ beforeEach(async () => {
           observedAt: HOST_TEST_NOW,
           // A start with no thread to resume creates one, whatever its fence.
           origin:
-            input.fence > 1 && input.identity.providerHandle.kind === 'codex'
+            input.fence > 1 && input.identity.providerHandle
               ? ('resumed' as const)
               : ('created' as const),
-          handle: {
-            provider: 'codex' as const,
-            threadId:
-              input.identity.providerHandle.kind === 'codex'
-                ? input.identity.providerHandle.threadId
-                : `00000000-0000-4000-8000-${String(acquisitions).padStart(12, '0')}`
-          }
+          handle: codexProviderHandle(
+            input.identity.providerHandle?.nativeId ??
+              `00000000-0000-4000-8000-${String(acquisitions).padStart(12, '0')}`
+          )
         }
       }
     }),
@@ -504,11 +502,7 @@ describe("the replacement's first send", () => {
       .mocked(adapter.acquire)
       .mock.calls.flatMap(([input]) => (input.identity.sessionId === replacement ? [input] : []))
     // No provider conversation to resume: the source's thread is not carried over.
-    expect(start?.identity.providerHandle).toEqual({
-      kind: 'opaque',
-      agent: 'codex',
-      value: 'pending'
-    })
+    expect(start?.identity.providerHandle).toBeNull()
     expect(start?.fence).toBe(2)
     expect(store.getRecord(replacement)?.lease).toMatchObject({ claimStatus: 'live' })
   })
diff --git a/src/main/native-chat/agent-session-wire/structured-conversation-compaction.test.ts b/src/main/native-chat/agent-session-wire/structured-conversation-compaction.test.ts
index 22766f28a41..41031cb3b3e 100644
--- a/src/main/native-chat/agent-session-wire/structured-conversation-compaction.test.ts
+++ b/src/main/native-chat/agent-session-wire/structured-conversation-compaction.test.ts
@@ -33,6 +33,7 @@ import {
   hostTestMessage
 } from './structured-agent-session-host-test-data'
 import type { StructuredConversationCommandOutcome } from './structured-conversation-command-outcome'
+import { codexProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 let state: ReturnType<typeof hostTestState>
 let compact: Mock<NonNullable<StructuredAgentSessionAdapter['compact']>>
@@ -589,7 +590,7 @@ it('writes one exit row when the child dies mid-command, and the loop writes not
     acquisitionGeneration: `generation-${fence}`,
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'codex', threadId: THREAD },
+      handle: codexProviderHandle(THREAD),
       // The next child resumes the thread, as a real one does.
       origin: state.store.getRecord(SESSION)?.providerHandleChain.length ? 'resumed' : 'created',
       mintedAtFence: fence,
@@ -639,7 +640,7 @@ it('delivers the next message after a command whose child died and whose settlem
     acquisitionGeneration: `generation-${fence}`,
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'codex', threadId: THREAD },
+      handle: codexProviderHandle(THREAD),
       origin: state.store.getRecord(SESSION)?.providerHandleChain.length ? 'resumed' : 'created',
       mintedAtFence: fence,
       observedAt: 1
diff --git a/src/main/native-chat/agent-session-wire/structured-provider-session-ownership.ts b/src/main/native-chat/agent-session-wire/structured-provider-session-ownership.ts
index ad211902433..d34bb5ac87f 100644
--- a/src/main/native-chat/agent-session-wire/structured-provider-session-ownership.ts
+++ b/src/main/native-chat/agent-session-wire/structured-provider-session-ownership.ts
@@ -16,8 +16,7 @@ export function listStructuredProviderSessionOwnership(
       sessionId: record.sessionId,
       workspaceId: record.location.workspaceId,
       provider: record.provider,
-      providerSessionId:
-        link.handle.provider === 'codex' ? link.handle.threadId : link.handle.sessionId,
+      providerSessionId: link.handle.nativeId,
       lease: record.lease
     }))
   )
diff --git a/src/main/native-chat/structured-agent-session-history-adoption.test.ts b/src/main/native-chat/structured-agent-session-history-adoption.test.ts
index 581bb29c364..cdfb26842eb 100644
--- a/src/main/native-chat/structured-agent-session-history-adoption.test.ts
+++ b/src/main/native-chat/structured-agent-session-history-adoption.test.ts
@@ -10,6 +10,10 @@ import {
   structuredAdoptionConflictError,
   type StructuredAgentSessionAdoptionOwnership
 } from './structured-agent-session-history-adoption'
+import {
+  claudeProviderHandle,
+  codexProviderHandle
+} from '../../shared/agent-session-provider-handle-encoding'
 
 const OPERATION = '1800000000000-00000000000000000000000000000001'
 
@@ -30,7 +34,7 @@ function committedReplay(overrides: { callerKey?: string; operationId?: string }
           origin: 'adopted',
           mintedAtFence: 1,
           observedAt: 1_800_000_000_000,
-          handle: { provider: 'codex', threadId: 'thread-1' }
+          handle: codexProviderHandle('thread-1')
         }
       ],
       accountHome: { variable: 'CODEX_HOME', path: '/home/dev/.codex-original' }
@@ -128,11 +132,7 @@ describe('findCommittedStructuredAgentSessionAdoptionReplay', () => {
     record.providerHandleChain[0] = {
       ...record.providerHandleChain[0]!,
       origin: 'adopted',
-      handle: {
-        provider: 'claude',
-        sessionId: 'provider-session-alpha-1',
-        leafUuid: 'leaf-1'
-      }
+      handle: claudeProviderHandle('provider-session-alpha-1', 'leaf-1')
     }
 
     expect(
diff --git a/src/main/native-chat/structured-agent-session-history-adoption.ts b/src/main/native-chat/structured-agent-session-history-adoption.ts
index e64e8f799d8..662b93dcb2c 100644
--- a/src/main/native-chat/structured-agent-session-history-adoption.ts
+++ b/src/main/native-chat/structured-agent-session-history-adoption.ts
@@ -7,7 +7,10 @@
 
 import { agentSessionRefusalError } from '../../shared/agent-session-wire-refusals'
 import type { AgentSessionOperationRow } from '../../shared/agent-session-operation-ledger'
-import type { AgentSessionProviderHandle } from '../../shared/agent-session-journal-types'
+import {
+  agentSessionWireProviderHandle,
+  type AgentSessionWireProviderHandle
+} from '../../shared/agent-session-provider-handle-encoding'
 import type { AgentSessionLease, AgentSessionRecord } from '../../shared/agent-session-record'
 import { agentSessionLeaseAdmitsWriter } from '../../shared/agent-session-lease-adjudication'
 
@@ -26,7 +29,7 @@ export type StructuredAgentSessionAdoption = {
 
 export type CommittedStructuredAgentSessionAdoptionReplay = {
   record: AgentSessionRecord
-  providerHandle: Exclude<AgentSessionProviderHandle, { kind: 'opaque' }>
+  providerHandle: AgentSessionWireProviderHandle
 }
 
 /** Exact committed-operation identity; attach still validates its fingerprint. */
@@ -58,22 +61,12 @@ export function findCommittedStructuredAgentSessionAdoptionReplay(input: {
   ) {
     return null
   }
-  const providerSessionId =
-    adopted.handle.provider === 'codex' ? adopted.handle.threadId : adopted.handle.sessionId
-  if (providerSessionId !== input.providerSessionId) {
+  // The replay re-sends the adoption as its create sent it, so it needs the wire's form.
+  const providerHandle = agentSessionWireProviderHandle(adopted.handle)
+  if (adopted.handle.nativeId !== input.providerSessionId || !providerHandle) {
     return null
   }
-  return {
-    record,
-    providerHandle:
-      adopted.handle.provider === 'codex'
-        ? { kind: 'codex', threadId: adopted.handle.threadId }
-        : {
-            kind: 'claude',
-            sessionId: adopted.handle.sessionId,
-            leafUuid: adopted.handle.leafUuid
-          }
-  }
+  return { record, providerHandle }
 }
 
 /**
diff --git a/src/main/runtime/agent-session-death-evidence-persistence.test.ts b/src/main/runtime/agent-session-death-evidence-persistence.test.ts
index 9904ca7994f..73d01b5b88e 100644
--- a/src/main/runtime/agent-session-death-evidence-persistence.test.ts
+++ b/src/main/runtime/agent-session-death-evidence-persistence.test.ts
@@ -13,6 +13,7 @@ import {
   openTestAgentSessionRecordStore,
   seedTestAgentSessionRecordStore
 } from './agent-session-record-store-test-harness'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'session-alpha-1'
 /** The fixture lease's last renewal. */
@@ -163,7 +164,7 @@ describe('a failed acquisition', () => {
           fence,
           link: {
             linkId: 'link-1',
-            handle: { provider: 'claude', sessionId: 'provider-session-1', leafUuid: null },
+            handle: claudeProviderHandle('provider-session-1', null),
             origin: 'created',
             mintedAtFence: fence,
             observedAt: NOW
@@ -203,7 +204,7 @@ describe('a failed acquisition', () => {
                 fence,
                 link: {
                   linkId: 'link-1',
-                  handle: { provider: 'claude', sessionId: 'provider-session-1', leafUuid: null },
+                  handle: claudeProviderHandle('provider-session-1', null),
                   origin: 'created',
                   mintedAtFence: fence,
                   observedAt: NOW
diff --git a/src/main/runtime/agent-session-lease-renewal.test.ts b/src/main/runtime/agent-session-lease-renewal.test.ts
index ec636a96eed..a20143780ec 100644
--- a/src/main/runtime/agent-session-lease-renewal.test.ts
+++ b/src/main/runtime/agent-session-lease-renewal.test.ts
@@ -8,6 +8,7 @@ import {
   openTestAgentSessionRecordStore,
   readPersistedTestAgentSessionStoreText
 } from './agent-session-record-store-test-harness'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const NOW = 1_800_000_000_000
 const MATCHED = { outcome: 'identity-matched', matchedOn: ['spawn-token'] } as const
@@ -54,7 +55,7 @@ async function establishOwner(
     fence,
     link: {
       linkId: `link-${suffix}`,
-      handle: { provider: 'codex', threadId: `thread-${suffix}` },
+      handle: codexProviderHandle(`thread-${suffix}`),
       origin: 'created',
       mintedAtFence: fence,
       observedAt: NOW
diff --git a/src/main/runtime/agent-session-lease-transitions.ts b/src/main/runtime/agent-session-lease-transitions.ts
index 0b5b6e5f2ef..1737ad45d3f 100644
--- a/src/main/runtime/agent-session-lease-transitions.ts
+++ b/src/main/runtime/agent-session-lease-transitions.ts
@@ -16,6 +16,7 @@ import {
   appendAgentSessionProviderHandleLink,
   type AgentSessionProviderHandleLink
 } from '../../shared/agent-session-provider-handle'
+import { agentSessionProviderHandleBelongsTo } from '../../shared/agent-session-provider-handle-encoding'
 import { nextAgentSessionFence } from '../../shared/agent-session-next-fence'
 import type {
   AgentSessionDeathEvidence,
@@ -145,7 +146,7 @@ export function proveAgentSessionOwner(args: {
       reason: 'spawnIdentityMismatch'
     })
   }
-  if (args.link.handle.provider !== record.provider) {
+  if (!agentSessionProviderHandleBelongsTo(args.link.handle, record.provider)) {
     throw new Error('agent_session_provider_handle_provider_mismatch')
   }
   if (args.link.mintedAtFence !== args.fence) {
diff --git a/src/main/runtime/agent-session-legacy-record-import.test.ts b/src/main/runtime/agent-session-legacy-record-import.test.ts
index bf2156d0710..3a9e47fe6c2 100644
--- a/src/main/runtime/agent-session-legacy-record-import.test.ts
+++ b/src/main/runtime/agent-session-legacy-record-import.test.ts
@@ -11,6 +11,10 @@ import {
   type AgentSessionOperationRow
 } from '../../shared/agent-session-operation-ledger'
 import type { AgentSessionLease, AgentSessionRecord } from '../../shared/agent-session-record'
+import {
+  encodePersistedAgentSessionProviderHandle,
+  isAgentSessionProviderHandle
+} from '../../shared/agent-session-provider-handle-encoding'
 import {
   agentSessionLeaseFixture,
   agentSessionRecordFixture
@@ -66,6 +70,24 @@ const OPERATION: AgentSessionOperationRow = {
   outcome: { status: 'succeeded', sessionId: ALPHA }
 }
 
+/** The records file only ever held handles in their stored form. */
+function storedForm(value: Record<string, unknown>): Record<string, unknown> {
+  const chain = value.providerHandleChain
+  return Array.isArray(chain)
+    ? {
+        ...value,
+        providerHandleChain: chain.map((link: unknown) =>
+          typeof link === 'object' &&
+          link !== null &&
+          'handle' in link &&
+          isAgentSessionProviderHandle(link.handle)
+            ? { ...link, handle: encodePersistedAgentSessionProviderHandle(link.handle) }
+            : link
+        )
+      }
+    : value
+}
+
 function legacyFile(
   records: readonly (Record<string, unknown> & { sessionId: string })[],
   extra: Record<string, unknown> = {}
@@ -73,7 +95,7 @@ function legacyFile(
   return {
     schemaVersion: 2,
     hostId: 'local',
-    records: Object.fromEntries(records.map((value) => [value.sessionId, value])),
+    records: Object.fromEntries(records.map((value) => [value.sessionId, storedForm(value)])),
     operations: {},
     retiredClaimKeys: [],
     unusableRecords: {},
@@ -246,7 +268,7 @@ describe('a record the file set aside', () => {
     const stored = database.db
       .prepare('SELECT record_json FROM agent_session_records WHERE session_id = ?')
       .get(ALPHA)
-    expect(JSON.parse(String(stored?.record_json))).toEqual(unsupported)
+    expect(JSON.parse(String(stored?.record_json))).toEqual(storedForm(unsupported))
   })
 
   // #23589: both copies exist only when an older build recovered the readable one from its backup,
@@ -385,7 +407,7 @@ describe('the tab index from before the table', () => {
     const owed = await install()
     owed.database.db
       .prepare('INSERT INTO agent_session_records (session_id, record_json) VALUES (?, ?)')
-      .run(BETA, JSON.stringify(record(BETA)))
+      .run(BETA, JSON.stringify(storedForm(record(BETA))))
     await AgentSessionRecordStore.open({
       journalDatabase: owed.database,
       hostId: 'local'
diff --git a/src/main/runtime/agent-session-legacy-record-import.ts b/src/main/runtime/agent-session-legacy-record-import.ts
index 0a0b4d49d5b..f632f008e76 100644
--- a/src/main/runtime/agent-session-legacy-record-import.ts
+++ b/src/main/runtime/agent-session-legacy-record-import.ts
@@ -9,6 +9,7 @@
 
 import { nextAgentSessionFence } from '../../shared/agent-session-next-fence'
 import type { AgentSessionRecord } from '../../shared/agent-session-record'
+import { encodeAgentSessionRecord } from '../../shared/agent-session-record-stored-form'
 import {
   NO_LEGACY_JOURNAL_RECORDS,
   type JournalLegacyRecordImport
@@ -106,11 +107,15 @@ function importRows(
   for (const [sessionId, loaded] of records) {
     const setAside = state.unreadableRecords.get(sessionId)
     const record = setAside ? withFloorAboveSetAsideCopy(loaded, setAside.raw) : loaded
-    const json = JSON.stringify({ ...record, lease: withoutRetiredLeaseLatches(record.lease) })
+    const json = JSON.stringify(
+      encodeAgentSessionRecord({ ...record, lease: withoutRetiredLeaseLatches(record.lease) })
+    )
     // A record the load rules refuse is kept as its bytes, which every load then sets aside.
     rows.push([
       sessionId,
-      isReadableAgentSessionStoreRecord(sessionId, JSON.parse(json)) ? json : JSON.stringify(loaded)
+      isReadableAgentSessionStoreRecord(sessionId, JSON.parse(json))
+        ? json
+        : JSON.stringify(encodeAgentSessionRecord(loaded))
     ])
   }
   for (const [sessionId, { raw }] of state.unreadableRecords) {
diff --git a/src/main/runtime/agent-session-provider-handle-transition.test.ts b/src/main/runtime/agent-session-provider-handle-transition.test.ts
index 7a61ea7bdfa..e58827d2fd5 100644
--- a/src/main/runtime/agent-session-provider-handle-transition.test.ts
+++ b/src/main/runtime/agent-session-provider-handle-transition.test.ts
@@ -5,15 +5,20 @@ import {
 } from '../../shared/agent-session-record.test-fixture'
 import type { AgentSessionProviderHandleLink } from '../../shared/agent-session-provider-handle'
 import { isPersistedAgentSessionRecord } from '../../shared/agent-session-record'
+import { encodeAgentSessionRecord } from '../../shared/agent-session-record-stored-form'
 import {
   recordAgentSessionProviderHandle,
-  reviseAgentSessionClaudeResumePoint
+  reviseAgentSessionProviderResumePoint
 } from './agent-session-provider-handle-transition'
+import {
+  claudeProviderHandle,
+  codexProviderHandle
+} from '../../shared/agent-session-provider-handle-encoding'
 
 function resumedLink(fence: number): AgentSessionProviderHandleLink {
   return {
     linkId: 'link-2',
-    handle: { provider: 'claude', sessionId: 'provider-session-alpha-1', leafUuid: 'leaf-2' },
+    handle: claudeProviderHandle('provider-session-alpha-1', 'leaf-2'),
     origin: 'resumed',
     mintedAtFence: fence,
     observedAt: 4_000
@@ -29,7 +34,7 @@ describe('recordAgentSessionProviderHandle', () => {
       link: resumedLink(record.lease.runtimeFence),
       now: 4_000
     })
-    expect(next.providerHandleChain.at(-1)?.handle).toMatchObject({ leafUuid: 'leaf-2' })
+    expect(next.providerHandleChain.at(-1)?.handle).toMatchObject({ resumeCursor: 'leaf-2' })
     expect(next.lease.provenHandleLinkId).toBe('link-2')
   })
 
@@ -46,18 +51,17 @@ describe('recordAgentSessionProviderHandle', () => {
       link: resumedLink(lease.runtimeFence),
       now: 4_000
     })
-    expect(next.providerHandleChain.at(-1)?.handle).toMatchObject({ leafUuid: 'leaf-2' })
+    expect(next.providerHandleChain.at(-1)?.handle).toMatchObject({ resumeCursor: 'leaf-2' })
     expect(next.lease).toMatchObject({ claimStatus: 'reserved', provenHandleLinkId: null })
   })
 })
 
-describe('reviseAgentSessionClaudeResumePoint', () => {
+describe('reviseAgentSessionProviderResumePoint', () => {
   const revise = (record = agentSessionRecordFixture(), leafUuid = 'leaf-2') =>
-    reviseAgentSessionClaudeResumePoint({
+    reviseAgentSessionProviderResumePoint({
       record,
       fence: record.lease.runtimeFence,
-      providerSessionId: 'provider-session-alpha-1',
-      leafUuid,
+      handle: claudeProviderHandle('provider-session-alpha-1', leafUuid),
       now: 5_000
     })
 
@@ -68,20 +72,19 @@ describe('reviseAgentSessionClaudeResumePoint', () => {
     expect(second.providerHandleChain.at(-1)).toMatchObject({
       linkId: 'link-1',
       origin: 'created',
-      handle: { leafUuid: 'leaf-3' }
+      handle: { resumeCursor: 'leaf-3' }
     })
     expect(second.lease.provenHandleLinkId).toBe('link-1')
-    expect(isPersistedAgentSessionRecord(second)).toBe(true)
+    expect(isPersistedAgentSessionRecord(encodeAgentSessionRecord(second))).toBe(true)
   })
 
   it('refuses a stale owner, a released lease, and a head minted by another owner', () => {
     const record = agentSessionRecordFixture()
     expect(() =>
-      reviseAgentSessionClaudeResumePoint({
+      reviseAgentSessionProviderResumePoint({
         record,
         fence: record.lease.runtimeFence - 1,
-        providerSessionId: 'provider-session-alpha-1',
-        leafUuid: 'leaf-2',
+        handle: claudeProviderHandle('provider-session-alpha-1', 'leaf-2'),
         now: 5_000
       })
     ).toThrow('agent_session_stale_fence')
@@ -96,11 +99,19 @@ describe('reviseAgentSessionClaudeResumePoint', () => {
       })
     ).toThrow('agent_session_provider_handle_invalid')
     expect(() =>
-      reviseAgentSessionClaudeResumePoint({
+      reviseAgentSessionProviderResumePoint({
         record,
         fence: record.lease.runtimeFence,
-        providerSessionId: 'another-provider-session',
-        leafUuid: 'leaf-2',
+        handle: claudeProviderHandle('another-provider-session', 'leaf-2'),
+        now: 5_000
+      })
+    ).toThrow('agent_session_provider_handle_invalid')
+    // Same id, another provider's namespace: a different conversation, never this one's leaf.
+    expect(() =>
+      reviseAgentSessionProviderResumePoint({
+        record,
+        fence: record.lease.runtimeFence,
+        handle: codexProviderHandle('provider-session-alpha-1'),
         now: 5_000
       })
     ).toThrow('agent_session_provider_handle_invalid')
diff --git a/src/main/runtime/agent-session-provider-handle-transition.ts b/src/main/runtime/agent-session-provider-handle-transition.ts
index 57d2ecb172c..a2c94244198 100644
--- a/src/main/runtime/agent-session-provider-handle-transition.ts
+++ b/src/main/runtime/agent-session-provider-handle-transition.ts
@@ -1,10 +1,14 @@
 import { agentSessionRefusalError } from '../../shared/agent-session-wire-refusals'
 import {
   agentSessionProviderHandleChainHead,
+  agentSessionProviderHandleRoot,
+  agentSessionProviderHandlesEqual,
   appendAgentSessionProviderHandleLink,
   isAgentSessionProviderHandleChain,
+  type AgentSessionProviderHandle,
   type AgentSessionProviderHandleLink
 } from '../../shared/agent-session-provider-handle'
+import { agentSessionProviderHandleBelongsTo } from '../../shared/agent-session-provider-handle-encoding'
 import type { AgentSessionRecord } from '../../shared/agent-session-record'
 
 export function recordAgentSessionProviderHandle(args: {
@@ -17,7 +21,10 @@ export function recordAgentSessionProviderHandle(args: {
   if (record.lease.runtimeFence !== args.fence) {
     throw new Error('agent_session_stale_fence')
   }
-  if (args.link.handle.provider !== record.provider || args.link.mintedAtFence !== args.fence) {
+  if (
+    !agentSessionProviderHandleBelongsTo(args.link.handle, record.provider) ||
+    args.link.mintedAtFence !== args.fence
+  ) {
     throw new Error('agent_session_provider_handle_invalid')
   }
   if (record.lease.claimStatus !== 'live' && record.lease.handoffStage !== 'new-owner-proving') {
@@ -44,14 +51,15 @@ export function recordAgentSessionProviderHandle(args: {
 }
 
 /**
- * Advance the live owner's Claude resume point in place. The head link this owner minted keeps
- * its id and provenance; only its leaf moves, so a long conversation does not grow the chain.
+ * Move the live owner's resume point in place: the head link this owner minted keeps its id and
+ * provenance, and only the adapter-owned data its handle carries changes, so a long conversation
+ * does not grow the chain. The adapter decides what that data means; this only refuses a handle
+ * that names another conversation.
  */
-export function reviseAgentSessionClaudeResumePoint(args: {
+export function reviseAgentSessionProviderResumePoint(args: {
   record: AgentSessionRecord
   fence: number
-  providerSessionId: string
-  leafUuid: string
+  handle: AgentSessionProviderHandle
   now: number
 }): AgentSessionRecord {
   const { record } = args
@@ -63,18 +71,18 @@ export function reviseAgentSessionClaudeResumePoint(args: {
   }
   const head = agentSessionProviderHandleChainHead(record.providerHandleChain)
   if (
-    head?.handle.provider !== 'claude' ||
-    head.handle.sessionId !== args.providerSessionId ||
+    !head ||
+    agentSessionProviderHandleRoot(head.handle) !== agentSessionProviderHandleRoot(args.handle) ||
     head.mintedAtFence !== args.fence
   ) {
     throw new Error('agent_session_provider_handle_invalid')
   }
-  if (head.handle.leafUuid === args.leafUuid) {
+  if (agentSessionProviderHandlesEqual(head.handle, args.handle)) {
     return record
   }
   const providerHandleChain = [
     ...record.providerHandleChain.slice(0, -1),
-    { ...head, handle: { ...head.handle, leafUuid: args.leafUuid }, observedAt: args.now }
+    { ...head, handle: args.handle, observedAt: args.now }
   ]
   // The revised chain must still read back as the same persisted chain.
   if (!isAgentSessionProviderHandleChain(providerHandleChain)) {
diff --git a/src/main/runtime/agent-session-record-conversation-name.test.ts b/src/main/runtime/agent-session-record-conversation-name.test.ts
index 084cc93ac4d..f9a3cfb3c91 100644
--- a/src/main/runtime/agent-session-record-conversation-name.test.ts
+++ b/src/main/runtime/agent-session-record-conversation-name.test.ts
@@ -1,14 +1,28 @@
 import { describe, expect, it } from 'vitest'
-import { isPersistedAgentSessionRecord } from '../../shared/agent-session-record'
+import {
+  isPersistedAgentSessionRecord,
+  type AgentSessionRecord
+} from '../../shared/agent-session-record'
+import { encodePersistedAgentSessionProviderHandleChain } from '../../shared/agent-session-provider-handle'
 import { agentSessionRecordFixture } from '../../shared/agent-session-record.test-fixture'
 import { setAgentSessionRecordConversationName } from './agent-session-record-conversation-name'
 
 const NOW = 9_000
 
+/** Validates the record as its row stores it. */
+function storedRecordIsValid(
+  record: Omit<AgentSessionRecord, 'conversationName'> & { conversationName?: unknown }
+): boolean {
+  return isPersistedAgentSessionRecord({
+    ...record,
+    providerHandleChain: encodePersistedAgentSessionProviderHandleChain(record.providerHandleChain)
+  })
+}
+
 describe('agent session record conversationName validation', () => {
   it('accepts a record carrying a bounded name', () => {
     expect(
-      isPersistedAgentSessionRecord({
+      storedRecordIsValid({
         ...agentSessionRecordFixture(),
         conversationName: 'Fix the lease probe'
       })
@@ -16,12 +30,12 @@ describe('agent session record conversationName validation', () => {
   })
 
   it('accepts a record with no name at all', () => {
-    expect(isPersistedAgentSessionRecord(agentSessionRecordFixture())).toBe(true)
+    expect(storedRecordIsValid(agentSessionRecordFixture())).toBe(true)
   })
 
   it('rejects a name past the stored maximum', () => {
     expect(
-      isPersistedAgentSessionRecord({
+      storedRecordIsValid({
         ...agentSessionRecordFixture(),
         conversationName: 'a'.repeat(201)
       })
@@ -29,23 +43,23 @@ describe('agent session record conversationName validation', () => {
   })
 
   it('rejects a name that is not a string', () => {
-    expect(
-      isPersistedAgentSessionRecord({ ...agentSessionRecordFixture(), conversationName: 42 })
-    ).toBe(false)
-    expect(
-      isPersistedAgentSessionRecord({ ...agentSessionRecordFixture(), conversationName: '' })
-    ).toBe(false)
+    expect(storedRecordIsValid({ ...agentSessionRecordFixture(), conversationName: 42 })).toBe(
+      false
+    )
+    expect(storedRecordIsValid({ ...agentSessionRecordFixture(), conversationName: '' })).toBe(
+      false
+    )
   })
 
   it('rejects persisted names that bypassed canonical normalization', () => {
     expect(
-      isPersistedAgentSessionRecord({
+      storedRecordIsValid({
         ...agentSessionRecordFixture(),
         conversationName: 'Fix\u202Egnp.exe probe'
       })
     ).toBe(false)
     expect(
-      isPersistedAgentSessionRecord({
+      storedRecordIsValid({
         ...agentSessionRecordFixture(),
         conversationName: 'Fix\nthe probe'
       })
@@ -63,7 +77,7 @@ describe('setAgentSessionRecordConversationName', () => {
 
     expect(next.conversationName).toBe('Fix the lease probe')
     expect(next.updatedAt).toBe(NOW)
-    expect(isPersistedAgentSessionRecord(next)).toBe(true)
+    expect(storedRecordIsValid(next)).toBe(true)
   })
 
   it('normalizes on the way in so the record stays valid whatever the caller sent', () => {
@@ -74,7 +88,7 @@ describe('setAgentSessionRecordConversationName', () => {
     )
 
     expect(next.conversationName).toBe('Fix the probe')
-    expect(isPersistedAgentSessionRecord(next)).toBe(true)
+    expect(storedRecordIsValid(next)).toBe(true)
   })
 
   it('bounds an over-long name rather than storing a record the validator would reject', () => {
@@ -85,7 +99,7 @@ describe('setAgentSessionRecordConversationName', () => {
     )
 
     expect(next.conversationName).toHaveLength(200)
-    expect(isPersistedAgentSessionRecord(next)).toBe(true)
+    expect(storedRecordIsValid(next)).toBe(true)
   })
 
   it('clears the name via null, deleting the key rather than storing an empty string', () => {
@@ -99,7 +113,7 @@ describe('setAgentSessionRecordConversationName', () => {
 
     expect(Object.hasOwn(cleared, 'conversationName')).toBe(false)
     expect(cleared.updatedAt).toBe(NOW + 1)
-    expect(isPersistedAgentSessionRecord(cleared)).toBe(true)
+    expect(storedRecordIsValid(cleared)).toBe(true)
   })
 
   it('treats a name that normalizes to nothing as a clear', () => {
diff --git a/src/main/runtime/agent-session-record-options.test.ts b/src/main/runtime/agent-session-record-options.test.ts
index 58385e29272..c092018ea27 100644
--- a/src/main/runtime/agent-session-record-options.test.ts
+++ b/src/main/runtime/agent-session-record-options.test.ts
@@ -4,6 +4,7 @@ import { join } from 'node:path'
 import { afterEach, beforeEach, expect, it } from 'vitest'
 import { readNativeSessionOptions } from '../native-chat/agent-session-wire/structured-agent-session-option-restoration'
 import { openTestAgentSessionRecordStore } from './agent-session-record-store-test-harness'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const NOW = 1_800_000_000_000
 const SESSION = 'session-options'
@@ -96,7 +97,7 @@ it('persists resumed provider options atomically with owner proof', async () =>
     fence,
     link: {
       linkId: 'codex-options-1',
-      handle: { provider: 'codex', threadId: 'thread-options' },
+      handle: codexProviderHandle('thread-options'),
       origin: 'created',
       mintedAtFence: fence,
       observedAt: NOW
diff --git a/src/main/runtime/agent-session-record-rows.ts b/src/main/runtime/agent-session-record-rows.ts
index be6f70f06e7..1b1fe6e1b3b 100644
--- a/src/main/runtime/agent-session-record-rows.ts
+++ b/src/main/runtime/agent-session-record-rows.ts
@@ -9,7 +9,7 @@ import {
   isPersistedAgentSessionRecord,
   type AgentSessionLease
 } from '../../shared/agent-session-record'
-import { normalizeLegacyHandoffRecord } from '../../shared/agent-session-legacy-handoff-lease'
+import { decodePersistedAgentSessionRecord } from '../../shared/agent-session-record-stored-form'
 import type Database from '../sqlite/sync-database'
 import type { SqliteRow } from '../sqlite/sqlite-statement'
 import {
@@ -112,7 +112,7 @@ export function loadAgentSessionStoreRows(
     const parsed = parseJson(text(row, 'record_json'))
     const value = parsed.ok ? parsed.value : text(row, 'record_json')
     if (parsed.ok && isReadableAgentSessionStoreRecord(sessionId, value)) {
-      const { record } = normalizeLegacyHandoffRecord(value)
+      const { record } = decodePersistedAgentSessionRecord(value)
       state.records.set(sessionId, {
         ...record,
         lease: { ...withoutRetiredLeaseLatches(record.lease), unreconciled: true }
diff --git a/src/main/runtime/agent-session-record-store-file.ts b/src/main/runtime/agent-session-record-store-file.ts
index 79e65388fbd..6b5632a87ab 100644
--- a/src/main/runtime/agent-session-record-store-file.ts
+++ b/src/main/runtime/agent-session-record-store-file.ts
@@ -16,7 +16,7 @@ import {
   isPersistedAgentSessionRecord,
   type AgentSessionRecord
 } from '../../shared/agent-session-record'
-import { normalizeLegacyHandoffRecord } from '../../shared/agent-session-legacy-handoff-lease'
+import { decodePersistedAgentSessionRecord } from '../../shared/agent-session-record-stored-form'
 import { parseAgentSessionTabTable, type AgentSessionTabTable } from './agent-session-tab-table'
 
 export const AGENT_SESSION_STORE_SCHEMA_VERSION = 2 as const
@@ -130,7 +130,7 @@ function parseState(raw: string, hostId: string): Pick<LoadedAgentSessionStore,
   if (typeof file.records === 'object' && file.records !== null) {
     for (const [sessionId, value] of Object.entries(file.records)) {
       const decoded = isPersistedAgentSessionRecord(value)
-        ? normalizeLegacyHandoffRecord(value)
+        ? decodePersistedAgentSessionRecord(value)
         : null
       const record = decoded?.record ?? null
       if (record?.sessionId === sessionId) {
diff --git a/src/main/runtime/agent-session-record-store-test-harness.ts b/src/main/runtime/agent-session-record-store-test-harness.ts
index eae3ae3baf4..ab879fa159b 100644
--- a/src/main/runtime/agent-session-record-store-test-harness.ts
+++ b/src/main/runtime/agent-session-record-store-test-harness.ts
@@ -7,6 +7,11 @@
 
 import type { AgentSessionOperationRow } from '../../shared/agent-session-operation-ledger'
 import type { PersistedAgentSessionRecord } from '../../shared/agent-session-legacy-handoff-lease'
+import {
+  encodePersistedAgentSessionProviderHandle,
+  isAgentSessionProviderHandle
+} from '../../shared/agent-session-provider-handle-encoding'
+import type { AgentSessionRecord } from '../../shared/agent-session-record'
 import { JOURNAL_DB_SCHEMA_VERSION } from '../native-chat/agent-session-journal/journal-database-schema'
 import {
   closeTestJournalHostDatabase,
@@ -98,15 +103,32 @@ function writePersisted(db: Database.Database, persisted: PersistedTestAgentSess
   }
 }
 
+/** A seed may be an in-memory fixture or a hand-written row; a row holds handles in stored form. */
+export function storedTestAgentSessionRecord(
+  record: AgentSessionRecord | PersistedAgentSessionRecord
+): PersistedAgentSessionRecord {
+  return {
+    ...record,
+    providerHandleChain: record.providerHandleChain.map((link) => ({
+      ...link,
+      handle: isAgentSessionProviderHandle(link.handle)
+        ? encodePersistedAgentSessionProviderHandle(link.handle)
+        : link.handle
+    }))
+  }
+}
+
 /** Leaves `records` behind as an earlier run of the app would have, before anything opens it. */
 export async function seedTestAgentSessionRecordStore(
   stateDirectory: string,
-  seed: { records: readonly PersistedAgentSessionRecord[] }
+  seed: { records: readonly (AgentSessionRecord | PersistedAgentSessionRecord)[] }
 ): Promise<void> {
   writePersisted(databaseFor(stateDirectory), {
     schemaVersion: AGENT_SESSION_STORE_SCHEMA_VERSION,
     hostId: TEST_HOST_ID,
-    records: Object.fromEntries(seed.records.map((record) => [record.sessionId, record])),
+    records: Object.fromEntries(
+      seed.records.map((record) => [record.sessionId, storedTestAgentSessionRecord(record)])
+    ),
     operations: {},
     retiredClaimKeys: [],
     unusableRecords: {}
diff --git a/src/main/runtime/agent-session-record-store.test.ts b/src/main/runtime/agent-session-record-store.test.ts
index 12aa70b330c..cc0a83cc55f 100644
--- a/src/main/runtime/agent-session-record-store.test.ts
+++ b/src/main/runtime/agent-session-record-store.test.ts
@@ -21,6 +21,10 @@ import {
 import { AGENT_SESSION_CLAIM_KEY_RETENTION_MS } from './agent-session-claim-key-retention'
 import { openTestJournalHostDatabase } from '../native-chat/agent-session-journal/journal-host-database-test-support'
 import type { AgentSessionReserveRequest } from './agent-session-reservation-admission'
+import {
+  claudeProviderHandle,
+  codexProviderHandle
+} from '../../shared/agent-session-provider-handle-encoding'
 
 const NOW = 1_800_000_000_000
 
@@ -87,7 +91,7 @@ function handleLink(
 ): AgentSessionProviderHandleLink {
   return {
     linkId: 'link-1',
-    handle: { provider: 'claude', sessionId: 'provider-session-1', leafUuid: 'leaf-1' },
+    handle: claudeProviderHandle('provider-session-1', 'leaf-1'),
     origin: 'created',
     mintedAtFence: 1,
     observedAt: NOW,
@@ -218,7 +222,7 @@ describe('acquisition path', () => {
         sessionId: 'session-alpha',
         fence: 1,
         link: handleLink({
-          handle: { provider: 'codex', threadId: 'thread-1' }
+          handle: codexProviderHandle('thread-1')
         }),
         now: NOW
       })
@@ -739,6 +743,29 @@ describe('claim keys and unreadable rows', () => {
     expect((await open()).isSessionUnreadable('session-alpha')).toBe(true)
   })
 
+  it('sets aside a row whose handle is in both stored forms and never rewrites it', async () => {
+    const first = await open()
+    await establishOwner(first)
+    let ambiguous: PersistedAgentSessionRecord | undefined
+    await editPersistedTestAgentSessionStore(directory, (persisted) => {
+      ambiguous = persisted.records['session-alpha']
+      Object.assign(ambiguous.providerHandleChain[0].handle, {
+        transport: 'acp',
+        agent: 'grok',
+        nativeId: 'acp-thread',
+        resumeCursor: 'resume-token'
+      })
+    })
+    const reopened = await open()
+    expect(reopened.isSessionUnreadable('session-alpha')).toBe(true)
+    // Another chat's write must carry the set-aside row through untouched.
+    await establishOwner(reopened, { sessionId: 'session-beta', claimKeyId: 'key-2' })
+    expect((await open()).isSessionUnreadable('session-alpha')).toBe(true)
+    expect((await readPersistedTestAgentSessionStore(directory)).records['session-alpha']).toEqual(
+      ambiguous
+    )
+  })
+
   it('refuses to write a store a newer Orca wrote, with the refusal clients print as "update"', async () => {
     await seedTestAgentSessionStoreFromNewerBuild(directory)
     const store = await open()
diff --git a/src/main/runtime/agent-session-released-reservation-replay.test.ts b/src/main/runtime/agent-session-released-reservation-replay.test.ts
index e5f54265dcb..8e02a2660af 100644
--- a/src/main/runtime/agent-session-released-reservation-replay.test.ts
+++ b/src/main/runtime/agent-session-released-reservation-replay.test.ts
@@ -15,6 +15,7 @@ import type { AgentSessionLease } from '../../shared/agent-session-record'
 import type { AgentSessionRecordStore } from './agent-session-record-store'
 import { openTestAgentSessionRecordStore } from './agent-session-record-store-test-harness'
 import type { AgentSessionReserveRequest } from './agent-session-reservation-admission'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const NOW = 1_800_000_000_000
 const SESSION = 'session-alpha'
@@ -137,7 +138,7 @@ describe('a create retried after recovery released its reservation', () => {
       fence: 1,
       link: {
         linkId: 'link-1',
-        handle: { provider: 'codex', threadId: 'thread-1' },
+        handle: codexProviderHandle('thread-1'),
         origin: 'created',
         mintedAtFence: 1,
         observedAt: NOW
diff --git a/src/main/runtime/agent-session-reservation-admission.test.ts b/src/main/runtime/agent-session-reservation-admission.test.ts
index cad534931e6..0729ebfc35b 100644
--- a/src/main/runtime/agent-session-reservation-admission.test.ts
+++ b/src/main/runtime/agent-session-reservation-admission.test.ts
@@ -16,6 +16,10 @@ import {
   type AgentSessionReserveRequest
 } from './agent-session-reservation-admission'
 import type { AgentSessionStoreState } from './agent-session-record-store-file'
+import {
+  claudeProviderHandle,
+  codexProviderHandle
+} from '../../shared/agent-session-provider-handle-encoding'
 
 const NOW = 1_800_000_000_000
 const LEASE_TTL_MS = 60_000
@@ -34,7 +38,7 @@ function adoptedLink(
 ): AgentSessionProviderHandleLink {
   return {
     linkId: 'claude-1-provider-session-alpha-1-empty',
-    handle: { provider: 'claude', sessionId: 'provider-session-alpha-1', leafUuid: null },
+    handle: claudeProviderHandle('provider-session-alpha-1', null),
     origin: 'adopted',
     mintedAtFence: 1,
     observedAt: NOW,
@@ -118,7 +122,7 @@ describe('adopted conversation ownership', () => {
         storeState([holder]),
         reserveRequest({
           adoptedHandleLink: adoptedLink({
-            handle: { provider: 'claude', sessionId: 'provider-session-other', leafUuid: null }
+            handle: claudeProviderHandle('provider-session-other', null)
           })
         }),
         LEASE_TTL_MS
@@ -170,7 +174,7 @@ describe('adopted conversation ownership', () => {
       providerHandleChain: [
         {
           linkId: 'codex-1-thread-1',
-          handle: { provider: 'codex', threadId: 'thread-1' },
+          handle: codexProviderHandle('thread-1'),
           origin: 'created',
           mintedAtFence: 7,
           observedAt: NOW
@@ -187,7 +191,7 @@ describe('adopted conversation ownership', () => {
           accountHome: { variable: 'CODEX_HOME', path: '/home/dev/.codex' },
           adoptedHandleLink: adoptedLink({
             linkId: 'codex-1-thread-1-adopted',
-            handle: { provider: 'codex', threadId: 'thread-1' }
+            handle: codexProviderHandle('thread-1')
           })
         }),
         LEASE_TTL_MS
diff --git a/src/main/runtime/agent-session-store-draft.ts b/src/main/runtime/agent-session-store-draft.ts
index 2afdfc13484..e39027d0042 100644
--- a/src/main/runtime/agent-session-store-draft.ts
+++ b/src/main/runtime/agent-session-store-draft.ts
@@ -3,6 +3,7 @@
  * only once its rows have committed, so no reader ever sees a change that might still roll back.
  */
 
+import { encodeAgentSessionRecord } from '../../shared/agent-session-record-stored-form'
 import type {
   AgentSessionStoreState,
   RetiredAgentSessionClaimKey
@@ -42,7 +43,8 @@ export type AgentSessionStoreRowWrites = {
 function serializeChangedRows<V>(
   published: ReadonlyMap<string, V>,
   next: ReadonlyMap<string, V>,
-  readable: (key: string, written: unknown) => boolean
+  readable: (key: string, written: unknown) => boolean,
+  stored: (value: V) => unknown = (value) => value
 ): KeyedRowWrites {
   const writes: KeyedRowWrites = { upsert: [], remove: [] }
   let added = 0
@@ -51,7 +53,7 @@ function serializeChangedRows<V>(
     if (prior === value) {
       continue
     }
-    const json = JSON.stringify(value)
+    const json = JSON.stringify(stored(value))
     if (json === undefined || !readable(key, JSON.parse(json))) {
       throw new Error('agent_session_store_write_invalid')
     }
@@ -85,8 +87,11 @@ export function agentSessionStoreDraftRowWrites(
   published: AgentSessionStoreState,
   draft: AgentSessionStoreState
 ): AgentSessionStoreRowWrites | null {
-  const records = serializeChangedRows(published.records, draft.records, (sessionId, written) =>
-    isReadableAgentSessionStoreRecord(sessionId, written)
+  const records = serializeChangedRows(
+    published.records,
+    draft.records,
+    (sessionId, written) => isReadableAgentSessionStoreRecord(sessionId, written),
+    encodeAgentSessionRecord
   )
   const operations = serializeChangedRows(published.operations, draft.operations, (key, written) =>
     isReadableAgentSessionStoreOperation(key, written)
diff --git a/src/main/runtime/agent-session-store-transactions.test.ts b/src/main/runtime/agent-session-store-transactions.test.ts
index ab268c08db7..ec04a35c38d 100644
--- a/src/main/runtime/agent-session-store-transactions.test.ts
+++ b/src/main/runtime/agent-session-store-transactions.test.ts
@@ -16,6 +16,7 @@ import {
   openTestAgentSessionRecordStore,
   readPersistedTestAgentSessionStore
 } from './agent-session-record-store-test-harness'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const NOW = 1_800_000_000_000
 
@@ -76,7 +77,7 @@ async function liveChat(
     fence,
     link: {
       linkId: `link-${counter}`,
-      handle: { provider: 'claude', sessionId: `provider-${counter}`, leafUuid: null },
+      handle: claudeProviderHandle(`provider-${counter}`, null),
       origin: 'created',
       mintedAtFence: fence,
       observedAt: NOW
diff --git a/src/main/runtime/agent-session-unsaved-creation-supersession.test.ts b/src/main/runtime/agent-session-unsaved-creation-supersession.test.ts
index 31e473fb5e6..a6f002170db 100644
--- a/src/main/runtime/agent-session-unsaved-creation-supersession.test.ts
+++ b/src/main/runtime/agent-session-unsaved-creation-supersession.test.ts
@@ -7,6 +7,7 @@ import { codexProviderHandleLink } from '../codex/codex-structured-owner-identit
 import type { AgentSessionRecordStore } from './agent-session-record-store'
 import { openTestAgentSessionRecordStore } from './agent-session-record-store-test-harness'
 import type { AgentSessionReserveRequest } from './agent-session-reservation-admission'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const NOW = 1_800_000_000_000
 const SESSION = 'session-codex'
@@ -116,7 +117,7 @@ describe('a Codex thread started in place of one Codex never saved', () => {
     expect(proved.lease.claimStatus).toBe('live')
     expect(proved.providerHandleChain).toEqual([
       expect.objectContaining({
-        handle: { provider: 'codex', threadId: 'thread-new' },
+        handle: codexProviderHandle('thread-new'),
         origin: 'created',
         supersedesKey: 'codex:"thread-unsaved"'
       })
diff --git a/src/main/runtime/claude-structured-session-integration.test.ts b/src/main/runtime/claude-structured-session-integration.test.ts
index b75b4a06024..bbafd5f1aae 100644
--- a/src/main/runtime/claude-structured-session-integration.test.ts
+++ b/src/main/runtime/claude-structured-session-integration.test.ts
@@ -29,6 +29,7 @@ import {
   waitForStructuredAgentSessionRecovery
 } from './structured-agent-session-runtime'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'claude-integration-1'
 const PROVIDER_SESSION = claudeSessionIdForOrcaSession(SESSION)
@@ -769,19 +770,20 @@ describe('a structured Claude session over agentSession.*', () => {
     ).resolves.toMatchObject({ turnId: 'provider-opened-assistant', cancelled: true })
     expect(claude.live().calls.at(-1)).toMatchObject({ subtype: 'interrupt' })
 
+    // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: test-only view of the host's store; only `getRecord` is read.
     const host = getStructuredAgentSessionHost() as unknown as {
       deps: {
         store: {
           getRecord: (sessionId: string) => {
-            providerHandleChain: { handle: { provider: string; leafUuid?: string | null } }[]
+            providerHandleChain: { handle: { transport: string; resumeCursor?: string } }[]
           }
         }
       }
     }
     // A completed turn advances the durable resume point in place while the owner is live.
     expect(host.deps.store.getRecord(SESSION).providerHandleChain.at(-1)?.handle).toMatchObject({
-      provider: 'claude',
-      leafUuid: 'assistant-leaf'
+      transport: 'claude-sdk',
+      resumeCursor: 'assistant-leaf'
     })
     // A Claude Stop ends its child once Claude ends the stopped turn, so the chat rests; the next
     // open resumes the conversation.
@@ -807,11 +809,7 @@ describe('a structured Claude session over agentSession.*', () => {
     expect(claude.live().launch.options).toMatchObject({ resume: PROVIDER_SESSION })
     expect(claude.live().launch.options).not.toHaveProperty('resumeSessionAt')
     const lastCompletedTurn = {
-      handle: {
-        provider: 'claude',
-        sessionId: PROVIDER_SESSION,
-        leafUuid: 'provider-opened-assistant'
-      },
+      handle: claudeProviderHandle(PROVIDER_SESSION, 'provider-opened-assistant'),
       origin: 'resumed'
     }
     expect(host.deps.store.getRecord(SESSION).providerHandleChain.at(-1)).toMatchObject(
diff --git a/src/main/runtime/orchestration/structured-session-mail-address.ts b/src/main/runtime/orchestration/structured-session-mail-address.ts
index a5dffbeb48a..839f80f2b81 100644
--- a/src/main/runtime/orchestration/structured-session-mail-address.ts
+++ b/src/main/runtime/orchestration/structured-session-mail-address.ts
@@ -35,11 +35,7 @@ export function lookupOrcaAgentSession(
   }
   const owner = store
     .listRecords()
-    .find((candidate) =>
-      candidate.providerHandleChain.some(({ handle }) =>
-        handle.provider === 'claude' ? handle.sessionId === id : handle.threadId === id
-      )
-    )
+    .find((candidate) => candidate.providerHandleChain.some(({ handle }) => handle.nativeId === id))
   return owner ? { kind: 'provider-id', orcaSessionId: owner.sessionId } : { kind: 'unknown' }
 }
 
diff --git a/src/main/runtime/orchestration/structured-worker-journal-page.test.ts b/src/main/runtime/orchestration/structured-worker-journal-page.test.ts
index d00d411a067..b6e580fc77e 100644
--- a/src/main/runtime/orchestration/structured-worker-journal-page.test.ts
+++ b/src/main/runtime/orchestration/structured-worker-journal-page.test.ts
@@ -17,6 +17,7 @@ import {
   readStructuredJournalPage,
   STRUCTURED_JOURNAL_PAGE_LIMIT
 } from './structured-worker-journal-page'
+import { claudeProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 const host = vi.hoisted(() => {
   const state: { journal: AgentSessionJournal | null } = { journal: null }
@@ -71,7 +72,7 @@ beforeEach(async () => {
       workspaceId: 'ws-1',
       hostId: 'host-1',
       agent: 'claude',
-      providerHandle: { kind: 'claude', sessionId: 'claude-1', leafUuid: null }
+      providerHandle: claudeProviderHandle('claude-1', null)
     },
     stateDirectory: root,
     now: () => ++clock,
diff --git a/src/main/runtime/rpc/methods/structured-agent-session-adoption-replay.test.ts b/src/main/runtime/rpc/methods/structured-agent-session-adoption-replay.test.ts
index a68ffe4492e..1992d3c785a 100644
--- a/src/main/runtime/rpc/methods/structured-agent-session-adoption-replay.test.ts
+++ b/src/main/runtime/rpc/methods/structured-agent-session-adoption-replay.test.ts
@@ -15,6 +15,7 @@ import { RpcDispatcher } from '../dispatcher'
 import { STRUCTURED_AGENT_SESSION_METHODS } from './structured-agent-session'
 import { openTestJournalHostDatabase } from '../../../native-chat/agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from '../../../native-chat/agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../../../shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'session-adoption-replay'
 const THREAD = 'thread-adoption-replay'
@@ -43,7 +44,7 @@ function adapter(): StructuredAgentSessionAdapter {
         },
         link: {
           linkId: `codex-${fence}-${THREAD}`,
-          handle: { provider: 'codex', threadId: THREAD },
+          handle: codexProviderHandle(THREAD),
           origin: 'resumed',
           mintedAtFence: fence,
           observedAt: 1_800_000_000_000
diff --git a/src/main/runtime/rpc/methods/structured-agent-session-hold.test.ts b/src/main/runtime/rpc/methods/structured-agent-session-hold.test.ts
index 5c9633a5690..7b13887e1aa 100644
--- a/src/main/runtime/rpc/methods/structured-agent-session-hold.test.ts
+++ b/src/main/runtime/rpc/methods/structured-agent-session-hold.test.ts
@@ -30,6 +30,7 @@ import { agentSessionFailureFact } from '../../../../shared/agent-session-failur
 import { agentSessionFailureWords } from '../../../../shared/agent-session-failure-words'
 import { openTestJournalHostDatabase } from '../../../native-chat/agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from '../../../native-chat/agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../../../shared/agent-session-provider-handle-encoding'
 
 const CONNECTION = 'connection-1'
 const CLIENT = {
@@ -70,7 +71,7 @@ beforeEach(async () => {
     process: { hostId: 'local', pid: 4242, processStartTimeMs: 1_700_000_000_000, spawnToken },
     link: {
       linkId: `link-${fence}`,
-      handle: { provider: 'codex' as const, threadId: THREAD },
+      handle: codexProviderHandle(THREAD),
       origin: store.getRecord(SESSION)?.providerHandleChain.length
         ? ('resumed' as const)
         : ('created' as const),
diff --git a/src/main/runtime/rpc/methods/structured-chat-tab-table.test.ts b/src/main/runtime/rpc/methods/structured-chat-tab-table.test.ts
index 9fe1f2083bb..bea8b49039b 100644
--- a/src/main/runtime/rpc/methods/structured-chat-tab-table.test.ts
+++ b/src/main/runtime/rpc/methods/structured-chat-tab-table.test.ts
@@ -40,6 +40,7 @@ import { commitStructuredAgentSessionCreate } from './structured-agent-session-c
 import { closeStructuredAgentSessionChild } from '../../structured-agent-session-close'
 import { openTestJournalHostDatabase } from '../../../native-chat/agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from '../../../native-chat/agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../../../shared/agent-session-provider-handle-encoding'
 
 const WORKTREE = `id:${HOST_TEST_LOCATION.workspaceId}`
 const SOURCE_TAB = `structured-agent-session-${HOST_TEST_SESSION}`
@@ -75,10 +76,9 @@ function providerAdapter(): StructuredAgentSessionAdapter {
           mintedAtFence: input.fence,
           observedAt: HOST_TEST_NOW,
           origin: 'created' as const,
-          handle: {
-            provider: 'codex' as const,
-            threadId: `00000000-0000-4000-8000-${String(acquisitions).padStart(12, '0')}`
-          }
+          handle: codexProviderHandle(
+            `00000000-0000-4000-8000-${String(acquisitions).padStart(12, '0')}`
+          )
         }
       }
     }),
diff --git a/src/main/runtime/rpc/orchestration-session-caller-test-fixture.ts b/src/main/runtime/rpc/orchestration-session-caller-test-fixture.ts
index 396b0b2bec7..e200260a7e2 100644
--- a/src/main/runtime/rpc/orchestration-session-caller-test-fixture.ts
+++ b/src/main/runtime/rpc/orchestration-session-caller-test-fixture.ts
@@ -14,6 +14,7 @@ import { structuredWorkerIdentities } from '../structured-worker-identity'
 import type { RpcRequest, RpcResponse } from './core'
 import { RpcDispatcher } from './dispatcher'
 import { ORCHESTRATION_METHODS } from './methods/orchestration'
+import { claudeProviderHandle } from '../../../shared/agent-session-provider-handle-encoding'
 
 export const SESSION_X = testOrcaSessionId('4a1f6c2e-8b3d-4e7a-9c15-0d2b6e8f1a37')
 export const SESSION_Y = testOrcaSessionId('7e3b9d15-2c4a-4f86-a0b1-5c9e2d7f3b64')
@@ -43,11 +44,7 @@ export function sessionRecord(
     location: { ...base.location, workspaceId: WORKSPACE_X, ...overrides.location },
     providerHandleChain: base.providerHandleChain.map((link) => ({
       ...link,
-      handle: {
-        provider: 'claude' as const,
-        sessionId: overrides.providerId ?? `provider-${sessionId}`,
-        leafUuid: null
-      }
+      handle: claudeProviderHandle(overrides.providerId ?? `provider-${sessionId}`, null)
     }))
   }
 }
diff --git a/src/main/runtime/runtime-worktree-agent-rows-verdict.test.ts b/src/main/runtime/runtime-worktree-agent-rows-verdict.test.ts
index 25379632875..ff82a61406e 100644
--- a/src/main/runtime/runtime-worktree-agent-rows-verdict.test.ts
+++ b/src/main/runtime/runtime-worktree-agent-rows-verdict.test.ts
@@ -21,6 +21,7 @@ import { indexedStatusFeedSession } from '../native-chat/agent-session-wire/stru
 import { attachRuntimeWorktreeAgentRows } from './runtime-worktree-agent-rows'
 import { collectRuntimeWorktreeAgentSources } from './runtime-worktree-agent-sources'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 vi.mock('../telemetry/client', () => ({ track: vi.fn() }))
 vi.mock('../telemetry/cohort-classifier', () => ({
@@ -67,7 +68,7 @@ async function openJournal(): Promise<AgentSessionJournal> {
       workspaceId: WORKSPACE_ID,
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: 'thread-1' }
+      providerHandle: codexProviderHandle('thread-1')
     },
     stateDirectory: join(root, SESSION)
   })
diff --git a/src/main/runtime/runtime-worktree-structured-agent-rows-liveness.test.ts b/src/main/runtime/runtime-worktree-structured-agent-rows-liveness.test.ts
index 5afd2d2e770..5f6020e8d0f 100644
--- a/src/main/runtime/runtime-worktree-structured-agent-rows-liveness.test.ts
+++ b/src/main/runtime/runtime-worktree-structured-agent-rows-liveness.test.ts
@@ -12,6 +12,7 @@ import type { RuntimeWorktreePsSummary } from '../../shared/runtime-types'
 import { AgentHookServer, _internals } from '../agent-hooks/server'
 import { attachRuntimeWorktreeAgentRows } from './runtime-worktree-agent-rows'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 vi.mock('../telemetry/client', () => ({ track: vi.fn() }))
 vi.mock('../telemetry/cohort-classifier', () => ({
@@ -66,7 +67,7 @@ async function awaitingApproval() {
       workspaceId: WORKTREE_ID,
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: 'thread-1' }
+      providerHandle: codexProviderHandle('thread-1')
     },
     stateDirectory: join(root, SESSION)
   })
diff --git a/src/main/runtime/structured-agent-session-integration-replay.test.ts b/src/main/runtime/structured-agent-session-integration-replay.test.ts
index 9926aaba2dc..c55bdb2f932 100644
--- a/src/main/runtime/structured-agent-session-integration-replay.test.ts
+++ b/src/main/runtime/structured-agent-session-integration-replay.test.ts
@@ -21,6 +21,7 @@ import {
   TURN,
   type StructuredCodexRpcHarness
 } from './structured-codex-session-rpc-test-harness'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const { journalOpenHold } = vi.hoisted(() => {
   const journalOpenHold: { next: { entered: () => void; released: Promise<void> } | null } = {
@@ -137,7 +138,7 @@ describe('a structured codex session over agentSession.*', () => {
       workspaceId: WORKSPACE,
       hostId: 'local',
       agent: 'codex' as const,
-      providerHandle: { kind: 'codex' as const, threadId: THREAD }
+      providerHandle: codexProviderHandle(THREAD)
     }
     const reopened = await journals.open({
       identity,
diff --git a/src/main/runtime/structured-agent-session-integration.test.ts b/src/main/runtime/structured-agent-session-integration.test.ts
index 571e903dde3..5ff7cb3029f 100644
--- a/src/main/runtime/structured-agent-session-integration.test.ts
+++ b/src/main/runtime/structured-agent-session-integration.test.ts
@@ -45,6 +45,7 @@ import {
   stopStructuredAgentSessionRuntime
 } from './structured-agent-session-runtime'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 const journals = createTrackedJournalOpener()
 
@@ -52,6 +53,13 @@ const SESSION = 'session-integration-1'
 const THREAD = 'thread-integration'
 const TURN = 'turn-1'
 const WORKSPACE = 'workspace-1'
+const JOURNAL_IDENTITY = {
+  sessionId: SESSION,
+  workspaceId: WORKSPACE,
+  hostId: 'local',
+  agent: 'codex' as const,
+  providerHandle: codexProviderHandle(THREAD)
+}
 // The capability set the desktop renderer advertises. Without the pending-send
 // one the host holds the reply until the send settles, which is a shim for
 // clients too old to render a pending bubble — not what this suite models.
@@ -402,15 +410,8 @@ afterEach(async () => {
 
 describe('a structured codex session over agentSession.*', () => {
   it('hydrates provider options after activating a legacy-imported journal', async () => {
-    const identity = {
-      sessionId: SESSION,
-      workspaceId: WORKSPACE,
-      hostId: 'local',
-      agent: 'codex' as const,
-      providerHandle: { kind: 'codex' as const, threadId: THREAD }
-    }
     const journal = await journals.open({
-      identity,
+      identity: JOURNAL_IDENTITY,
       stateDirectory: root
     })
     const rollout = join(root, 'legacy-rollout.jsonl')
@@ -823,15 +824,8 @@ describe('a structured codex session over agentSession.*', () => {
     await stopping
 
     expect(waitedForFinalAppend).toBe(true)
-    const identity = {
-      sessionId: SESSION,
-      workspaceId: WORKSPACE,
-      hostId: 'local',
-      agent: 'codex' as const,
-      providerHandle: { kind: 'codex' as const, threadId: THREAD }
-    }
     const reopened = await journals.open({
-      identity,
+      identity: JOURNAL_IDENTITY,
       stateDirectory: root
     })
     expect(reopened.snapshot().items.map(textOf)).toContain('Final text before shutdown.')
diff --git a/src/main/runtime/structured-agent-session-record-import-install.test.ts b/src/main/runtime/structured-agent-session-record-import-install.test.ts
index dd76d01e6c6..5c2256ad882 100644
--- a/src/main/runtime/structured-agent-session-record-import-install.test.ts
+++ b/src/main/runtime/structured-agent-session-record-import-install.test.ts
@@ -18,6 +18,7 @@ import {
   stopStructuredAgentSessionRuntime
 } from './structured-agent-session-runtime'
 import { recordingStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { storedTestAgentSessionRecord } from './agent-session-record-store-test-harness'
 
 const NOW = 1_800_000_000_000
 const IMPORTED = 'session-alpha-1'
@@ -45,7 +46,7 @@ const legacyFile = (): string =>
   JSON.stringify({
     schemaVersion: 2,
     hostId: 'local',
-    records: { [IMPORTED]: agentSessionRecordFixture() },
+    records: { [IMPORTED]: storedTestAgentSessionRecord(agentSessionRecordFixture()) },
     operations: {},
     retiredClaimKeys: [],
     unusableRecords: {}
diff --git a/src/main/runtime/structured-agent-session-runtime-exit.test.ts b/src/main/runtime/structured-agent-session-runtime-exit.test.ts
index 2727b2389f2..706b4de5bce 100644
--- a/src/main/runtime/structured-agent-session-runtime-exit.test.ts
+++ b/src/main/runtime/structured-agent-session-runtime-exit.test.ts
@@ -18,6 +18,7 @@ import {
   stopStructuredAgentSessionRuntime
 } from './structured-agent-session-runtime'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 describe('structured session runtime provider-exit wiring', () => {
   let root: string | null = null
@@ -231,10 +232,9 @@ describe('structured session runtime provider-exit wiring', () => {
     await restarted.restoreReadableSessions()
     const history = await restarted.history({ sessionId: SESSION, direction: 'tail' })
     expect(history.ok && history.page.items.some((item) => item.body.kind === 'status')).toBe(false)
-    expect(restarted.deps.store.getRecord(SESSION)?.providerHandleChain.at(-1)?.handle).toEqual({
-      provider: 'codex',
-      threadId: 'thread-runtime-close'
-    })
+    expect(restarted.deps.store.getRecord(SESSION)?.providerHandleChain.at(-1)?.handle).toEqual(
+      codexProviderHandle('thread-runtime-close')
+    )
   })
 
   it('waits for a start a send began before tearing down the runtime', async () => {
diff --git a/src/main/runtime/structured-agent-session-spawn-token-descendants.test.ts b/src/main/runtime/structured-agent-session-spawn-token-descendants.test.ts
index aee47ab15ba..16cb94a812f 100644
--- a/src/main/runtime/structured-agent-session-spawn-token-descendants.test.ts
+++ b/src/main/runtime/structured-agent-session-spawn-token-descendants.test.ts
@@ -18,6 +18,7 @@ import {
   stopStructuredAgentSessionRuntime
 } from './structured-agent-session-runtime'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 /** pid -> the NUL-separated environment block `/proc/<pid>/environ` serves. */
 const fakeProc = vi.hoisted(() => ({ environs: new Map<number, string>() }))
@@ -113,7 +114,7 @@ describe('a process that inherited a spawn token', () => {
       fence,
       link: {
         linkId: 'link-1',
-        handle: { provider: 'codex', threadId: 'thread-1' },
+        handle: codexProviderHandle('thread-1'),
         origin: 'created',
         mintedAtFence: fence,
         observedAt: NOW
diff --git a/src/main/runtime/structured-agent-session-startup-tab-restore.test.ts b/src/main/runtime/structured-agent-session-startup-tab-restore.test.ts
index e0bfa5bbdd3..c01c30b6b89 100644
--- a/src/main/runtime/structured-agent-session-startup-tab-restore.test.ts
+++ b/src/main/runtime/structured-agent-session-startup-tab-restore.test.ts
@@ -30,7 +30,8 @@ import {
 } from './agent-session-record-store-file'
 import {
   readPersistedTestAgentSessionStore,
-  seedTestAgentSessionStoreFromNewerBuild
+  seedTestAgentSessionStoreFromNewerBuild,
+  storedTestAgentSessionRecord
 } from './agent-session-record-store-test-harness'
 import { openStructuredAgentSessionJournalDatabase } from './structured-agent-session-journal-open'
 import { OrcaRuntimeService } from './orca-runtime'
@@ -40,6 +41,7 @@ import {
 } from './structured-agent-session-runtime'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
 import { recordingStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 
 // `failing` fails every record write; `grants` lets that many more through, then fails.
 const writes = vi.hoisted(() => ({ failing: false, grants: Infinity, refused: 0 }))
@@ -97,7 +99,7 @@ function chatRecord(
         provider: 'codex' as const,
         providerHandleChain: record.providerHandleChain.map((link) => ({
           ...link,
-          handle: { provider: 'codex' as const, threadId: `thread-${sessionId}` }
+          handle: codexProviderHandle(`thread-${sessionId}`)
         })),
         accountHome: { variable: 'CODEX_HOME' as const, path: join(root, 'codex-home') }
       }
@@ -131,7 +133,9 @@ async function seedProfile(
     JSON.stringify({
       schemaVersion: AGENT_SESSION_STORE_SCHEMA_VERSION,
       hostId: 'local',
-      records: Object.fromEntries(records.map((record) => [record.sessionId, record])),
+      records: Object.fromEntries(
+        records.map((record) => [record.sessionId, storedTestAgentSessionRecord(record)])
+      ),
       operations: {},
       retiredClaimKeys: [],
       unusableRecords: {},
@@ -185,7 +189,7 @@ async function seedChatOpenedWhileOwed(record: AgentSessionRecord, tabId: string
   })
   database.db
     .prepare('INSERT INTO agent_session_records (session_id, record_json) VALUES (?, ?)')
-    .run(record.sessionId, JSON.stringify(record))
+    .run(record.sessionId, JSON.stringify(storedTestAgentSessionRecord(record)))
   await AgentSessionRecordStore.open({
     journalDatabase: database,
     hostId: 'local'
diff --git a/src/main/runtime/structured-chat-coordinator-mail.test.ts b/src/main/runtime/structured-chat-coordinator-mail.test.ts
index 0ec0418184d..29a2d5bb79f 100644
--- a/src/main/runtime/structured-chat-coordinator-mail.test.ts
+++ b/src/main/runtime/structured-chat-coordinator-mail.test.ts
@@ -105,8 +105,7 @@ function connectionFor(sessionId: string): FakeConnection {
   const head = agentSessionProviderHandleChainHead(
     host.deps.store.getRecord(sessionId)?.providerHandleChain ?? []
   )
-  const thread =
-    threadBySession.get(sessionId) ?? (head?.handle.provider === 'codex' && head.handle.threadId)
+  const thread = threadBySession.get(sessionId) ?? head?.handle.nativeId
   const connection = codex.connections.findLast((candidate) => candidate.threadId === thread)
   if (!connection) {
     throw new Error(`no app-server for ${sessionId}`)
diff --git a/src/main/runtime/structured-claude-runtime-adapter.ts b/src/main/runtime/structured-claude-runtime-adapter.ts
index 732515cdde6..8b4b70f8bc2 100644
--- a/src/main/runtime/structured-claude-runtime-adapter.ts
+++ b/src/main/runtime/structured-claude-runtime-adapter.ts
@@ -1,5 +1,6 @@
 import type { PermissionMode } from '@anthropic-ai/claude-agent-sdk'
 import type { AgentSessionRecord } from '../../shared/agent-session-record'
+import { claudeProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
 import { resolveClaudeCommand } from '../codex-cli/command'
 import type { ClaudeStructuredAuthPolicy } from '../claude-accounts/claude-structured-auth-policy'
 import { createClaudeStructuredLaunchResolver } from '../claude/claude-structured-launch-resolution'
@@ -12,7 +13,7 @@ import type { StructuredAgentSessionLifecycleEvent } from '../native-chat/agent-
 import type { ClaudeStructuredSessionEvent } from '../claude/claude-structured-session-state'
 import {
   recordAgentSessionProviderHandle,
-  reviseAgentSessionClaudeResumePoint
+  reviseAgentSessionProviderResumePoint
 } from './agent-session-provider-handle-transition'
 import type { ClaudeManagedAccountGateSettings } from '../native-chat/claude-structured-managed-account-support'
 import type { AgentSessionRecordStore } from './agent-session-record-store'
@@ -115,11 +116,10 @@ export function createStructuredClaudeRuntimeAdapter(
     },
     persistResumePoint: async ({ sessionId, providerSessionId, leafUuid, fence }) => {
       await store.transitionHandoff(sessionId, (record: AgentSessionRecord) =>
-        reviseAgentSessionClaudeResumePoint({
+        reviseAgentSessionProviderResumePoint({
           record,
           fence,
-          providerSessionId,
-          leafUuid,
+          handle: claudeProviderHandle(providerSessionId, leafUuid),
           now: Date.now()
         })
       )
diff --git a/src/shared/agent-session-journal-types.ts b/src/shared/agent-session-journal-types.ts
index 9613afa8a84..d53015fc725 100644
--- a/src/shared/agent-session-journal-types.ts
+++ b/src/shared/agent-session-journal-types.ts
@@ -15,6 +15,7 @@ import type { AgentSessionQuestionAnswer } from './agent-session-question-answer
 import type { AgentJournalTurnOutcome } from './agent-turn-outcome'
 import type { NativeChatToolMetadata } from './native-chat-tool-identity'
 import type { AgentSessionContextUsage } from './agent-session-context-usage'
+import type { AgentSessionProviderHandle } from './agent-session-provider-handle'
 import type { NativeChatBlock, NativeChatRole } from './native-chat-types'
 
 export { type AgentType }
@@ -39,10 +40,11 @@ export type AgentJournalCursor = {
   sequence: number
 }
 
-/** The durable provider session a journal is bound to.
- *  Codex is one thread id; Claude needs the leaf because concurrent resumes of
- *  one session id branch the same transcript. */
-export type AgentSessionProviderHandle =
+/** A provider handle as journal rows record it, and (without `opaque`) as
+ *  `agentSession.attach` carries it. Persisted and on the wire: never reshape an
+ *  arm. Derived from the in-memory handle by `agentSessionJournalProviderHandle`;
+ *  `opaque` names any other transport, or `pending` before a handle is proved. */
+export type AgentSessionJournalProviderHandle =
   | { kind: 'codex'; threadId: string }
   | { kind: 'claude'; sessionId: string; leafUuid: string | null }
   | { kind: 'opaque'; agent: AgentType; value: string }
@@ -58,7 +60,8 @@ export type AgentSessionJournalIdentity = {
   /** Execution host that owns the process, so a client restart adjudicates nothing. */
   hostId: string
   agent: AgentType
-  providerHandle: AgentSessionProviderHandle
+  /** The record's proved handle; null before the provider has proved one. */
+  providerHandle: AgentSessionProviderHandle | null
 }
 
 // ─── Item identity ──────────────────────────────────────────────────────────
diff --git a/src/shared/agent-session-legacy-handoff-lease.test.ts b/src/shared/agent-session-legacy-handoff-lease.test.ts
index 49a10558b81..5bd90fbc71e 100644
--- a/src/shared/agent-session-legacy-handoff-lease.test.ts
+++ b/src/shared/agent-session-legacy-handoff-lease.test.ts
@@ -2,15 +2,11 @@ import { describe, expect, it } from 'vitest'
 import {
   leaseCarriesLegacyHandoffValues,
   normalizeLegacyHandoffLease,
-  normalizeLegacyHandoffRecord,
   terminalOwnerRefusalMessage,
   type PersistedAgentSessionLease
 } from './agent-session-legacy-handoff-lease'
 import type { AgentSessionClaimStatus, AgentSessionHandoffStage } from './agent-session-record'
-import {
-  agentSessionLeaseFixture,
-  agentSessionRecordFixture
-} from './agent-session-record.test-fixture'
+import { agentSessionLeaseFixture } from './agent-session-record.test-fixture'
 
 const CLAIMS: AgentSessionClaimStatus[] = ['reserved', 'live', 'conflicted', 'released']
 const STAGES: (AgentSessionHandoffStage | null)[] = [null, 'new-owner-proving', 'recovering']
@@ -70,16 +66,6 @@ describe('normalizing a lease the removed terminal handoff wrote', () => {
       claimStatus: 'conflicted'
     })
   })
-
-  it('reports whether a record needed normalizing', () => {
-    const record = agentSessionRecordFixture()
-    expect(normalizeLegacyHandoffRecord(record)).toEqual({ record, normalized: false })
-    const legacy = { ...record, lease: persisted({ runtimeKind: 'tui' }) }
-    expect(normalizeLegacyHandoffRecord(legacy)).toEqual({
-      record: { ...record, lease: { ...record.lease, claimStatus: 'conflicted' } },
-      normalized: true
-    })
-  })
 })
 
 describe('the refusal for a chat a terminal agent holds', () => {
diff --git a/src/shared/agent-session-legacy-handoff-lease.ts b/src/shared/agent-session-legacy-handoff-lease.ts
index ea4ef2909e8..ce06ddce0eb 100644
--- a/src/shared/agent-session-legacy-handoff-lease.ts
+++ b/src/shared/agent-session-legacy-handoff-lease.ts
@@ -13,6 +13,7 @@ import type {
   AgentSessionOwnerRuntimeKind,
   AgentSessionRecord
 } from './agent-session-record'
+import type { PersistedAgentSessionProviderHandleLink } from './agent-session-provider-handle'
 
 type LegacyHandoffRuntimeKind = 'tui'
 type LegacyHandoffStage = 'preparing' | 'old-owner-stopped' | 'manual-recovery'
@@ -28,8 +29,13 @@ export type PersistedAgentSessionLease = Omit<AgentSessionLease, 'runtimeKind' |
   handoffStage: PersistedAgentSessionHandoffStage | null
 }
 
-export type PersistedAgentSessionRecord = Omit<AgentSessionRecord, 'lease'> & {
+/** A record as a row stores it. Decode through `decodePersistedAgentSessionRecord`. */
+export type PersistedAgentSessionRecord = Omit<
+  AgentSessionRecord,
+  'lease' | 'providerHandleChain'
+> & {
   lease: PersistedAgentSessionLease
+  providerHandleChain: PersistedAgentSessionProviderHandleLink[]
 }
 
 export function isPersistedAgentSessionRuntimeKind(
@@ -85,14 +91,3 @@ export function terminalOwnerRefusalMessage(lease: AgentSessionLease): string {
   const process = owner?.processStartTimeMs != null ? ` (process ${owner.pid})` : ''
   return `This chat is still open in a terminal agent${process}. Quit that agent to continue the chat here.`
 }
-
-/** The in-memory record, plus whether decode changed anything the store must write back. */
-export function normalizeLegacyHandoffRecord(record: PersistedAgentSessionRecord): {
-  record: AgentSessionRecord
-  normalized: boolean
-} {
-  return {
-    record: { ...record, lease: normalizeLegacyHandoffLease(record.lease) },
-    normalized: leaseCarriesLegacyHandoffValues(record.lease)
-  }
-}
diff --git a/src/shared/agent-session-provider-handle-encoding.ts b/src/shared/agent-session-provider-handle-encoding.ts
new file mode 100644
index 00000000000..c0c2f6c6f57
--- /dev/null
+++ b/src/shared/agent-session-provider-handle-encoding.ts
@@ -0,0 +1,307 @@
+/**
+ * How a provider handle is stored and sent, and the only module that knows the two typed shapes
+ * the first structured transports were stored in.
+ *
+ * Claude and Codex handles are persisted and sent exactly as before this module existed, so an
+ * older build sharing the database or the wire still reads them. Every other transport is stored
+ * in the neutral shape, which an older build refuses as unreadable rather than mistaking for one
+ * of its own. Decoding is strict: each handle has exactly one stored form, and the key and root
+ * strings derived from it are persisted elsewhere, so none of them may ever change.
+ *
+ * A stored handle has a closed field set, and a rewrite drops anything else. A later build adds new
+ * per-link data on the chain link, which every build preserves, never on the handle.
+ */
+
+import type {
+  AgentSessionHandleProvider,
+  AgentSessionProviderHandle,
+  AgentSessionProviderHandleNamespace
+} from './agent-session-provider-handle'
+import type {
+  AgentSessionJournalIdentity,
+  AgentSessionJournalProviderHandle
+} from './agent-session-journal-types'
+
+export const CLAUDE_STRUCTURED_HANDLE_NAMESPACE = {
+  transport: 'claude-sdk',
+  agent: 'claude'
+} as const satisfies AgentSessionProviderHandleNamespace
+
+export const CODEX_STRUCTURED_HANDLE_NAMESPACE = {
+  transport: 'codex-app-server',
+  agent: 'codex'
+} as const satisfies AgentSessionProviderHandleNamespace
+
+/** The namespace a record's handles live in, from the structured lane it was created on. */
+export function agentSessionProviderHandleNamespace(
+  provider: AgentSessionHandleProvider
+): AgentSessionProviderHandleNamespace {
+  return provider === 'claude'
+    ? CLAUDE_STRUCTURED_HANDLE_NAMESPACE
+    : CODEX_STRUCTURED_HANDLE_NAMESPACE
+}
+
+export function isAgentSessionProviderHandleInNamespace(
+  handle: AgentSessionProviderHandleNamespace,
+  namespace: AgentSessionProviderHandleNamespace
+): boolean {
+  return handle.transport === namespace.transport && handle.agent === namespace.agent
+}
+
+/** Whether a handle belongs to a record of this lane. Compares namespaces; never reads its data. */
+export function agentSessionProviderHandleBelongsTo(
+  handle: AgentSessionProviderHandle,
+  provider: AgentSessionHandleProvider
+): boolean {
+  return isAgentSessionProviderHandleInNamespace(
+    handle,
+    agentSessionProviderHandleNamespace(provider)
+  )
+}
+
+/** Claude's resume cursor is its leaf: the transcript entry a resume continues from. */
+export function claudeProviderHandle(
+  sessionId: string,
+  leafUuid: string | null
+): AgentSessionProviderHandle {
+  return {
+    ...CLAUDE_STRUCTURED_HANDLE_NAMESPACE,
+    nativeId: sessionId,
+    ...(leafUuid === null ? {} : { resumeCursor: leafUuid })
+  }
+}
+
+export function claudeProviderHandleLeafUuid(handle: AgentSessionProviderHandle): string | null {
+  return handle.resumeCursor ?? null
+}
+
+export function codexProviderHandle(threadId: string): AgentSessionProviderHandle {
+  return { ...CODEX_STRUCTURED_HANDLE_NAMESPACE, nativeId: threadId }
+}
+
+// ─── Validation ─────────────────────────────────────────────────────────────
+
+const MAX_HANDLE_FIELD_LENGTH = 512
+/** A generic handle's key carries escaped ids, so it may outgrow a legacy key's bound. */
+const MAX_NEUTRAL_HANDLE_KEY_LENGTH = 8192
+const MAX_RESUME_CURSOR_LENGTH = 4096
+const NAMESPACE_PART_PATTERN = /^[A-Za-z][A-Za-z0-9_-]{0,63}$/
+
+export function isAgentSessionProviderHandleField(value: unknown): value is string {
+  return (
+    typeof value === 'string' &&
+    value.length > 0 &&
+    value.length <= MAX_HANDLE_FIELD_LENGTH &&
+    value === value.trim()
+  )
+}
+
+function isNamespacePart(value: unknown): value is string {
+  return typeof value === 'string' && NAMESPACE_PART_PATTERN.test(value)
+}
+
+function isLegacyNamespace(handle: AgentSessionProviderHandleNamespace): boolean {
+  return (
+    isAgentSessionProviderHandleInNamespace(handle, CLAUDE_STRUCTURED_HANDLE_NAMESPACE) ||
+    isAgentSessionProviderHandleInNamespace(handle, CODEX_STRUCTURED_HANDLE_NAMESPACE)
+  )
+}
+
+/**
+ * An in-memory handle. A Claude or Codex handle must also fit its typed stored shape: Claude's
+ * resume cursor is a leaf id, and Codex has none.
+ */
+export function isAgentSessionProviderHandle(value: unknown): value is AgentSessionProviderHandle {
+  if (typeof value !== 'object' || value === null || Object.hasOwn(value, 'provider')) {
+    return false
+  }
+  const transport = 'transport' in value ? value.transport : undefined
+  const agent = 'agent' in value ? value.agent : undefined
+  const nativeId = 'nativeId' in value ? value.nativeId : undefined
+  const resumeCursor = 'resumeCursor' in value ? value.resumeCursor : undefined
+  if (
+    !isNamespacePart(transport) ||
+    !isNamespacePart(agent) ||
+    !isAgentSessionProviderHandleField(nativeId)
+  ) {
+    return false
+  }
+  const namespace = { transport, agent }
+  if (isAgentSessionProviderHandleInNamespace(namespace, CODEX_STRUCTURED_HANDLE_NAMESPACE)) {
+    return resumeCursor === undefined
+  }
+  if (isAgentSessionProviderHandleInNamespace(namespace, CLAUDE_STRUCTURED_HANDLE_NAMESPACE)) {
+    return resumeCursor === undefined || isAgentSessionProviderHandleField(resumeCursor)
+  }
+  return (
+    resumeCursor === undefined ||
+    (typeof resumeCursor === 'string' &&
+      resumeCursor.length > 0 &&
+      resumeCursor.length <= MAX_RESUME_CURSOR_LENGTH)
+  )
+}
+
+/** Bound for a persisted key that names a handle in this namespace (`forkedFromKey`, `supersedesKey`). */
+export function isAgentSessionProviderHandleKeyFor(
+  handle: AgentSessionProviderHandle,
+  value: unknown
+): value is string {
+  return isLegacyNamespace(handle)
+    ? isAgentSessionProviderHandleField(value)
+    : typeof value === 'string' && value.length > 0 && value.length <= MAX_NEUTRAL_HANDLE_KEY_LENGTH
+}
+
+// ─── Stored form ────────────────────────────────────────────────────────────
+
+type StoredClaudeProviderHandle = { provider: 'claude'; sessionId: string; leafUuid: string | null }
+type StoredCodexProviderHandle = { provider: 'codex'; threadId: string }
+
+/** A handle as a record row stores it. */
+export type PersistedAgentSessionProviderHandle =
+  | StoredClaudeProviderHandle
+  | StoredCodexProviderHandle
+  | AgentSessionProviderHandle
+
+export function encodePersistedAgentSessionProviderHandle(
+  handle: AgentSessionProviderHandle
+): PersistedAgentSessionProviderHandle {
+  if (isAgentSessionProviderHandleInNamespace(handle, CLAUDE_STRUCTURED_HANDLE_NAMESPACE)) {
+    return { provider: 'claude', sessionId: handle.nativeId, leafUuid: handle.resumeCursor ?? null }
+  }
+  if (isAgentSessionProviderHandleInNamespace(handle, CODEX_STRUCTURED_HANDLE_NAMESPACE)) {
+    return { provider: 'codex', threadId: handle.nativeId }
+  }
+  return {
+    transport: handle.transport,
+    agent: handle.agent,
+    nativeId: handle.nativeId,
+    ...(handle.resumeCursor === undefined ? {} : { resumeCursor: handle.resumeCursor })
+  }
+}
+
+/** The neutral form's discriminator and identity fields; a typed stored handle carries none of them. */
+const NEUTRAL_HANDLE_FIELDS = ['transport', 'agent', 'nativeId', 'resumeCursor'] as const
+
+export function decodePersistedAgentSessionProviderHandle(
+  value: unknown
+): AgentSessionProviderHandle | null {
+  if (typeof value !== 'object' || value === null) {
+    return null
+  }
+  // Why: a row in both forms names two identities; reading it as either would erase the other on
+  // the next write, so it stays unreadable.
+  if (
+    Object.hasOwn(value, 'provider') &&
+    NEUTRAL_HANDLE_FIELDS.some((field) => Object.hasOwn(value, field))
+  ) {
+    return null
+  }
+  const provider = 'provider' in value ? value.provider : undefined
+  if (provider === 'claude') {
+    const sessionId = 'sessionId' in value ? value.sessionId : undefined
+    // Why: a null leaf and a missing one were never the same stored value; keep refusing the second.
+    const leafUuid = 'leafUuid' in value ? value.leafUuid : undefined
+    return isAgentSessionProviderHandleField(sessionId) &&
+      (leafUuid === null || isAgentSessionProviderHandleField(leafUuid))
+      ? claudeProviderHandle(sessionId, leafUuid)
+      : null
+  }
+  if (provider === 'codex') {
+    const threadId = 'threadId' in value ? value.threadId : undefined
+    return isAgentSessionProviderHandleField(threadId) ? codexProviderHandle(threadId) : null
+  }
+  // A Claude or Codex handle has exactly one stored form, the typed one.
+  if (!isAgentSessionProviderHandle(value) || isLegacyNamespace(value)) {
+    return null
+  }
+  return {
+    transport: value.transport,
+    agent: value.agent,
+    nativeId: value.nativeId,
+    ...(value.resumeCursor === undefined ? {} : { resumeCursor: value.resumeCursor })
+  }
+}
+
+// ─── Identity strings (persisted: never change them) ────────────────────────
+
+/** Stable string identity for one handle. Two handles with the same key name the same writer target. */
+export function agentSessionProviderHandleKey(handle: AgentSessionProviderHandle): string {
+  const stored = encodePersistedAgentSessionProviderHandle(handle)
+  if ('provider' in stored) {
+    return stored.provider === 'claude'
+      ? `claude:${JSON.stringify([stored.sessionId, stored.leafUuid])}`
+      : `codex:${JSON.stringify(stored.threadId)}`
+  }
+  // Why: the resume cursor is resume state the adapter owns, not identity; only Claude's leaf, a
+  // branch cursor, was ever part of a key, and its key above is fixed by records already written.
+  return agentSessionProviderHandleRoot(handle)
+}
+
+/**
+ * Identity root: the part that a resume must preserve. A resume that changes the root is a fork,
+ * whatever the provider called it.
+ */
+export function agentSessionProviderHandleRoot(handle: AgentSessionProviderHandle): string {
+  const stored = encodePersistedAgentSessionProviderHandle(handle)
+  if ('provider' in stored) {
+    return stored.provider === 'claude'
+      ? `claude:${JSON.stringify(stored.sessionId)}`
+      : `codex:${JSON.stringify(stored.threadId)}`
+  }
+  // Namespace parts cannot hold `/` or `:`, so this never reads as a typed root.
+  return `${handle.transport}/${handle.agent}:${JSON.stringify(handle.nativeId)}`
+}
+
+// ─── Wire and journal forms ─────────────────────────────────────────────────
+
+/** A handle as `agentSession.attach` carries it and an attach fingerprint covers it. */
+export type AgentSessionWireProviderHandle = Exclude<
+  AgentSessionJournalProviderHandle,
+  { kind: 'opaque' }
+>
+
+export function agentSessionProviderHandleFromWire(
+  wire: AgentSessionWireProviderHandle
+): AgentSessionProviderHandle {
+  return wire.kind === 'claude'
+    ? claudeProviderHandle(wire.sessionId, wire.leafUuid)
+    : codexProviderHandle(wire.threadId)
+}
+
+/** Null for a transport the attach wire cannot carry. */
+export function agentSessionWireProviderHandle(
+  handle: AgentSessionProviderHandle
+): AgentSessionWireProviderHandle | null {
+  const stored = encodePersistedAgentSessionProviderHandle(handle)
+  if (!('provider' in stored)) {
+    return null
+  }
+  return stored.provider === 'claude'
+    ? { kind: 'claude', sessionId: stored.sessionId, leafUuid: stored.leafUuid }
+    : { kind: 'codex', threadId: stored.threadId }
+}
+
+/** What a journal row records before the provider has proved any handle. */
+export const AGENT_SESSION_PENDING_PROVIDER_HANDLE_VALUE = 'pending'
+
+/** The handle a journal row records for this identity. Write-only: rows keep it for diagnosis,
+ *  nothing reads it. */
+export function agentSessionJournalProviderHandle(
+  identity: Pick<AgentSessionJournalIdentity, 'agent' | 'providerHandle'>
+): AgentSessionJournalProviderHandle {
+  const handle = identity.providerHandle
+  if (!handle) {
+    return {
+      kind: 'opaque',
+      agent: identity.agent,
+      value: AGENT_SESSION_PENDING_PROVIDER_HANDLE_VALUE
+    }
+  }
+  return (
+    agentSessionWireProviderHandle(handle) ?? {
+      kind: 'opaque',
+      agent: handle.agent,
+      value: handle.nativeId
+    }
+  )
+}
diff --git a/src/shared/agent-session-provider-handle.test.ts b/src/shared/agent-session-provider-handle.test.ts
index 7474c751cbe..d66c0356815 100644
--- a/src/shared/agent-session-provider-handle.test.ts
+++ b/src/shared/agent-session-provider-handle.test.ts
@@ -13,12 +13,9 @@ import {
   type AgentSessionProviderHandle,
   type AgentSessionProviderHandleLink
 } from './agent-session-provider-handle'
+import { claudeProviderHandle, codexProviderHandle } from './agent-session-provider-handle-encoding'
 
-const CLAUDE: AgentSessionProviderHandle = {
-  provider: 'claude',
-  sessionId: 'sess-1',
-  leafUuid: 'leaf-1'
-}
+const CLAUDE: AgentSessionProviderHandle = claudeProviderHandle('sess-1', 'leaf-1')
 
 function link(overrides: Partial<AgentSessionProviderHandleLink> = {}) {
   return {
@@ -42,41 +39,35 @@ describe('handle identity', () => {
   it('keys a Claude handle by session id AND leaf, so two branches are two handles', () => {
     // Concurrent resumes branch one transcript silently; the session id alone cannot name a writer.
     const branchA = agentSessionProviderHandleKey(CLAUDE)
-    const branchB = agentSessionProviderHandleKey({ ...CLAUDE, leafUuid: 'leaf-2' })
+    const branchB = agentSessionProviderHandleKey(claudeProviderHandle('sess-1', 'leaf-2'))
     expect(branchA).not.toEqual(branchB)
     expect(agentSessionProviderHandleRoot(CLAUDE)).toEqual(
-      agentSessionProviderHandleRoot({ ...CLAUDE, leafUuid: 'leaf-2' })
+      agentSessionProviderHandleRoot(claudeProviderHandle('sess-1', 'leaf-2'))
     )
   })
 
   it('keys a Codex handle by thread id alone', () => {
-    const codex: AgentSessionProviderHandle = { provider: 'codex', threadId: 'thread-1' }
+    const codex: AgentSessionProviderHandle = codexProviderHandle('thread-1')
     expect(agentSessionProviderHandleKey(codex)).toBe('codex:"thread-1"')
     expect(agentSessionProviderHandleRoot(codex)).toBe('codex:"thread-1"')
-    expect(
-      agentSessionProviderHandlesEqual(codex, { provider: 'codex', threadId: 'thread-2' })
-    ).toBe(false)
+    expect(agentSessionProviderHandlesEqual(codex, codexProviderHandle('thread-2'))).toBe(false)
   })
 
   it('distinguishes a null leaf from an empty-string leaf and rejects malformed handles', () => {
-    expect(isAgentSessionProviderHandle({ ...CLAUDE, leafUuid: null })).toBe(true)
-    expect(isAgentSessionProviderHandle({ ...CLAUDE, leafUuid: '' })).toBe(false)
-    expect(isAgentSessionProviderHandle({ provider: 'claude', sessionId: '' })).toBe(false)
+    expect(isAgentSessionProviderHandle(claudeProviderHandle('sess-1', null))).toBe(true)
+    expect(isAgentSessionProviderHandle({ ...CLAUDE, resumeCursor: '' })).toBe(false)
+    expect(isAgentSessionProviderHandle({ ...CLAUDE, nativeId: '' })).toBe(false)
+    expect(isAgentSessionProviderHandle({ ...CLAUDE, nativeId: ' sess-1 ' })).toBe(false)
+    // A stored typed shape is not an in-memory handle: it must be decoded first.
+    expect(
+      isAgentSessionProviderHandle({ provider: 'claude', sessionId: 'x', leafUuid: null })
+    ).toBe(false)
     expect(isAgentSessionProviderHandle({ provider: 'gemini', sessionId: 'x' })).toBe(false)
-    expect(isAgentSessionProviderHandle({ ...CLAUDE, sessionId: ' sess-1 ' })).toBe(false)
   })
 
   it('uses collision-free keys when Claude ids contain delimiters', () => {
-    const left: AgentSessionProviderHandle = {
-      provider: 'claude',
-      sessionId: 'a#b',
-      leafUuid: 'c'
-    }
-    const right: AgentSessionProviderHandle = {
-      provider: 'claude',
-      sessionId: 'a',
-      leafUuid: 'b#c'
-    }
+    const left = claudeProviderHandle('a#b', 'c')
+    const right = claudeProviderHandle('a', 'b#c')
     expect(agentSessionProviderHandleKey(left)).not.toBe(agentSessionProviderHandleKey(right))
     expect(agentSessionProviderHandlesEqual(left, right)).toBe(false)
   })
@@ -101,7 +92,7 @@ describe('chain append', () => {
         link({
           linkId: 'link-2',
           origin: 'resumed',
-          handle: { provider: 'claude', sessionId: 'sess-2', leafUuid: 'leaf-9' },
+          handle: claudeProviderHandle('sess-2', 'leaf-9'),
           mintedAtFence: 2
         })
       )
@@ -113,7 +104,7 @@ describe('chain append', () => {
     const forked = link({
       linkId: 'link-2',
       origin: 'forked',
-      handle: { provider: 'claude', sessionId: 'sess-2', leafUuid: 'leaf-9' },
+      handle: claudeProviderHandle('sess-2', 'leaf-9'),
       mintedAtFence: 2,
       forkedFromKey: agentSessionProviderHandleKey(CLAUDE)
     })
@@ -138,7 +129,7 @@ describe('chain append', () => {
         link({
           linkId: 'link-2',
           origin: 'resumed',
-          handle: { ...CLAUDE, leafUuid: 'leaf-2' },
+          handle: claudeProviderHandle('sess-1', 'leaf-2'),
           mintedAtFence: 4
         })
       )
@@ -152,7 +143,7 @@ describe('chain append', () => {
         link({
           linkId: 'link-2',
           origin: 'resumed',
-          handle: { provider: 'codex', threadId: 'thread-1' },
+          handle: codexProviderHandle('thread-1'),
           mintedAtFence: 2
         })
       )
@@ -182,7 +173,7 @@ describe('chain append', () => {
         [link()],
         link({
           origin: 'resumed',
-          handle: { ...CLAUDE, leafUuid: 'leaf-2' },
+          handle: claudeProviderHandle('sess-1', 'leaf-2'),
           mintedAtFence: 2
         })
       )
@@ -196,7 +187,7 @@ describe('chain append', () => {
         link({
           linkId: `link-${index + 1}`,
           origin: 'resumed',
-          handle: { ...CLAUDE, leafUuid: `leaf-${index + 1}` },
+          handle: claudeProviderHandle('sess-1', `leaf-${index + 1}`),
           mintedAtFence: index + 1
         })
       )
@@ -208,7 +199,7 @@ describe('chain append', () => {
         link({
           linkId: 'link-overflow',
           origin: 'resumed',
-          handle: { ...CLAUDE, leafUuid: 'leaf-overflow' },
+          handle: claudeProviderHandle('sess-1', 'leaf-overflow'),
           mintedAtFence: 999
         })
       )
@@ -226,7 +217,7 @@ describe('chain append', () => {
       link({
         linkId: 'link-2',
         origin: 'resumed',
-        handle: { ...CLAUDE, leafUuid: 'leaf-2' },
+        handle: claudeProviderHandle('sess-1', 'leaf-2'),
         mintedAtFence: 2
       })
     )
@@ -241,7 +232,7 @@ describe('chain lookup and validation', () => {
       link({
         linkId: 'link-2',
         origin: 'resumed',
-        handle: { ...CLAUDE, leafUuid: 'leaf-2' },
+        handle: claudeProviderHandle('sess-1', 'leaf-2'),
         mintedAtFence: 2
       })
     )
@@ -282,7 +273,7 @@ describe('chain lookup and validation', () => {
         link(),
         link({
           origin: 'resumed',
-          handle: { ...CLAUDE, leafUuid: 'leaf-2' },
+          handle: claudeProviderHandle('sess-1', 'leaf-2'),
           mintedAtFence: 2
         })
       ])
@@ -293,7 +284,7 @@ describe('chain lookup and validation', () => {
         link({
           linkId: 'link-2',
           origin: 'resumed',
-          handle: { provider: 'claude', sessionId: 'sess-2', leafUuid: 'leaf-2' },
+          handle: claudeProviderHandle('sess-2', 'leaf-2'),
           mintedAtFence: 2
         })
       ])
@@ -308,7 +299,7 @@ describe('adopted chain heads', () => {
     link({
       linkId: 'claude-1-sess-1-empty',
       origin: 'adopted',
-      handle: { ...CLAUDE, leafUuid: null },
+      handle: claudeProviderHandle('sess-1', null),
       ...overrides
     })
 
@@ -333,7 +324,7 @@ describe('adopted chain heads', () => {
       link({
         linkId: 'claude-1-sess-1-empty-retry',
         origin: 'resumed',
-        handle: { ...CLAUDE, leafUuid: null },
+        handle: claudeProviderHandle('sess-1', null),
         mintedAtFence: 1
       })
     )
@@ -345,12 +336,12 @@ describe('adopted chain heads', () => {
     const codexAdopted = link({
       linkId: 'codex-1-thread-1',
       origin: 'adopted',
-      handle: { provider: 'codex', threadId: 'thread-1' }
+      handle: codexProviderHandle('thread-1')
     })
     const reproved = link({
       linkId: 'codex-1-thread-1-retry',
       origin: 'resumed',
-      handle: { provider: 'codex', threadId: 'thread-1' },
+      handle: codexProviderHandle('thread-1'),
       mintedAtFence: 1
     })
 
@@ -380,7 +371,7 @@ describe('adopted chain heads', () => {
         link({
           linkId: 'claude-1-sess-9-leaf-9',
           origin: 'resumed',
-          handle: { provider: 'claude', sessionId: 'sess-9', leafUuid: 'leaf-9' },
+          handle: claudeProviderHandle('sess-9', 'leaf-9'),
           mintedAtFence: 1
         })
       )
@@ -393,12 +384,12 @@ describe('adopted chain heads', () => {
 })
 
 describe('superseding a creation the provider never saved', () => {
-  const unsaved: AgentSessionProviderHandle = { provider: 'codex', threadId: 'thread-unsaved' }
+  const unsaved: AgentSessionProviderHandle = codexProviderHandle('thread-unsaved')
   const created = link({ linkId: 'codex-1-thread-unsaved', handle: unsaved })
   function replacement(overrides: Partial<AgentSessionProviderHandleLink> = {}) {
     return link({
       linkId: 'codex-3-thread-new',
-      handle: { provider: 'codex', threadId: 'thread-new' },
+      handle: codexProviderHandle('thread-new'),
       mintedAtFence: 3,
       supersedesKey: agentSessionProviderHandleKey(unsaved),
       ...overrides
@@ -414,13 +405,13 @@ describe('superseding a creation the provider never saved', () => {
       chain,
       replacement({
         linkId: 'codex-5-thread-newer',
-        handle: { provider: 'codex', threadId: 'thread-newer' },
+        handle: codexProviderHandle('thread-newer'),
         mintedAtFence: 5,
-        supersedesKey: agentSessionProviderHandleKey({ provider: 'codex', threadId: 'thread-new' })
+        supersedesKey: agentSessionProviderHandleKey(codexProviderHandle('thread-new'))
       })
     )
     expect(again).toHaveLength(1)
-    expect(again[0]?.handle).toEqual({ provider: 'codex', threadId: 'thread-newer' })
+    expect(again[0]?.handle).toEqual(codexProviderHandle('thread-newer'))
   })
 
   it('never supersedes a conversation a resume, fork or adoption proved', () => {
@@ -467,3 +458,64 @@ describe('superseding a creation the provider never saved', () => {
     expect(isAgentSessionProviderHandleChain([created, replacement()])).toBe(false)
   })
 })
+
+describe('a transport shared code has never heard of', () => {
+  const acp = (nativeId: string, resumeCursor?: string): AgentSessionProviderHandle => ({
+    transport: 'acp',
+    agent: 'grok',
+    nativeId,
+    ...(resumeCursor === undefined ? {} : { resumeCursor })
+  })
+
+  it('chains resumes and forks by its native id alone', () => {
+    const created = link({ handle: acp('s-1', '{"cwd":"/a"}') })
+    const resumed = link({
+      linkId: 'link-2',
+      origin: 'resumed',
+      handle: acp('s-1', '{"cwd":"/b"}'),
+      mintedAtFence: 2
+    })
+    const chain = appendAgentSessionProviderHandleLink([created], resumed)
+    expect(chain).toHaveLength(2)
+    expect(isAgentSessionProviderHandleChain(chain)).toBe(true)
+    expect(() =>
+      appendAgentSessionProviderHandleLink(chain, {
+        ...resumed,
+        linkId: 'link-3',
+        handle: acp('s-2')
+      })
+    ).toThrow('agent_session_provider_handle_forked')
+    const forked = appendAgentSessionProviderHandleLink(chain, {
+      ...resumed,
+      linkId: 'link-3',
+      origin: 'forked',
+      handle: acp('s-2'),
+      forkedFromKey: agentSessionProviderHandleKey(resumed.handle)
+    })
+    expect(forked.at(-1)?.handle.nativeId).toBe('s-2')
+  })
+
+  it('records a same-fence resume that only moved the resume cursor instead of eliding it', () => {
+    const created = link({ handle: acp('s-1', 'a') })
+    const moved = link({ linkId: 'link-2', origin: 'resumed', handle: acp('s-1', 'b') })
+    expect(appendAgentSessionProviderHandleLink([created], moved)).toHaveLength(2)
+    expect(
+      appendAgentSessionProviderHandleLink([created], { ...moved, handle: acp('s-1', 'a') })
+    ).toHaveLength(1)
+  })
+
+  it('never joins a chain of another transport or agent, even with the same id', () => {
+    const chain = [link({ handle: codexProviderHandle('shared-id') })]
+    for (const handle of [
+      acp('shared-id'),
+      { transport: 'codex-app-server', agent: 'grok', nativeId: 'shared-id' }
+    ]) {
+      expect(() =>
+        appendAgentSessionProviderHandleLink(
+          chain,
+          link({ linkId: 'link-2', origin: 'resumed', handle, mintedAtFence: 2 })
+        )
+      ).toThrow()
+    }
+  })
+})
diff --git a/src/shared/agent-session-provider-handle.ts b/src/shared/agent-session-provider-handle.ts
index ea789dcdfe4..3bf8fb69b06 100644
--- a/src/shared/agent-session-provider-handle.ts
+++ b/src/shared/agent-session-provider-handle.ts
@@ -1,14 +1,36 @@
 /**
  * Durable provider handle chain for an agent session.
  *
- * Handles are keyed per provider because the two structured lanes disagree about what
- * identifies a conversation. Claude's session id is the identity root and its leaf uuid is a
- * branch cursor; Codex's thread id is the whole key. Resumes extend the chain, forks start a new
- * identity root, and the chain records which is which so a fork is never presented as a resume.
- * A creation the provider never saved can be superseded by a new creation, which takes its place
- * instead of standing beside it: the unsaved handle was never a conversation to continue.
+ * A handle names one provider conversation without saying what the provider means by it. Shared
+ * code reads only its transport, its agent, and the provider's own conversation id; anything else
+ * the provider needs to resume is `resumeCursor`, which only that provider's adapter reads. How a
+ * handle is stored and sent lives in agent-session-provider-handle-encoding.ts.
+ *
+ * Resumes extend the chain, forks start a new identity root, and the chain records which is which
+ * so a fork is never presented as a resume. A creation the provider never saved can be superseded
+ * by a new creation, which takes its place instead of standing beside it: the unsaved handle was
+ * never a conversation to continue.
  */
 
+import type { AgentType } from './agent-status-types'
+import {
+  agentSessionProviderHandleKey,
+  agentSessionProviderHandleRoot,
+  decodePersistedAgentSessionProviderHandle,
+  encodePersistedAgentSessionProviderHandle,
+  isAgentSessionProviderHandle,
+  isAgentSessionProviderHandleInNamespace,
+  isAgentSessionProviderHandleKeyFor,
+  type PersistedAgentSessionProviderHandle
+} from './agent-session-provider-handle-encoding'
+
+export {
+  agentSessionProviderHandleKey,
+  agentSessionProviderHandleRoot,
+  isAgentSessionProviderHandle
+} from './agent-session-provider-handle-encoding'
+
+/** The structured lanes this build drives. A record names one; a handle never does. */
 export const AGENT_SESSION_PROVIDER_HANDLE_PROVIDERS = ['claude', 'codex'] as const
 
 export type AgentSessionHandleProvider = (typeof AGENT_SESSION_PROVIDER_HANDLE_PROVIDERS)[number]
@@ -18,9 +40,31 @@ export function isAgentSessionHandleProvider(value: unknown): value is AgentSess
   return value === 'claude' || value === 'codex'
 }
 
-export type AgentSessionProviderHandle =
-  | { provider: 'claude'; sessionId: string; leafUuid: string | null }
-  | { provider: 'codex'; threadId: string }
+/** The protocol whose id space a handle's `nativeId` lives in. Open: a new transport adds no arm. */
+export type AgentSessionProviderTransport = 'claude-sdk' | 'codex-app-server' | (string & {})
+
+export type AgentSessionProviderHandle = {
+  /**
+   * The id space `nativeId` was minted in, which can differ from the agent's current transport. A
+   * mismatch with the running build makes the chat not resumable there, never the record unreadable.
+   */
+  transport: AgentSessionProviderTransport
+  /** Orca agent whose binary resumes the conversation; one transport serves many agents. */
+  agent: AgentType
+  /** The provider's own conversation id: Claude's session id, Codex's thread id. */
+  nativeId: string
+  /**
+   * Adapter-owned resume position (Claude: transcript leaf). Shared code never parses it; it is never
+   * identity, except inside Claude's legacy handle key.
+   */
+  resumeCursor?: string
+}
+
+/** Which provider a handle belongs to. Records and leases compare this, never the handle's data. */
+export type AgentSessionProviderHandleNamespace = Pick<
+  AgentSessionProviderHandle,
+  'transport' | 'agent'
+>
 
 export type AgentSessionProviderHandleOrigin = 'created' | 'adopted' | 'resumed' | 'forked'
 
@@ -43,54 +87,19 @@ export type AgentSessionProviderHandleChain = readonly AgentSessionProviderHandl
 /** Bounded so one session cannot grow an unbounded persisted record. */
 export const MAX_AGENT_SESSION_PROVIDER_HANDLE_LINKS = 256
 
-const MAX_HANDLE_FIELD_LENGTH = 512
 const LINK_ID_PATTERN = /^[A-Za-z0-9_-]{1,128}$/
 
-function isHandleField(value: unknown): value is string {
-  return (
-    typeof value === 'string' &&
-    value.length > 0 &&
-    value.length <= MAX_HANDLE_FIELD_LENGTH &&
-    value === value.trim()
-  )
-}
-
-export function isAgentSessionProviderHandle(value: unknown): value is AgentSessionProviderHandle {
-  if (typeof value !== 'object' || value === null) {
-    return false
-  }
-  const handle = value as Partial<AgentSessionProviderHandle> & Record<string, unknown>
-  if (handle.provider === 'claude') {
-    return (
-      isHandleField(handle.sessionId) &&
-      (handle.leafUuid === null || isHandleField(handle.leafUuid))
-    )
-  }
-  return handle.provider === 'codex' && isHandleField(handle.threadId)
-}
-
-/** Stable string identity for one handle. Two handles with the same key name the same writer target. */
-export function agentSessionProviderHandleKey(handle: AgentSessionProviderHandle): string {
-  return handle.provider === 'claude'
-    ? `claude:${JSON.stringify([handle.sessionId, handle.leafUuid])}`
-    : `codex:${JSON.stringify(handle.threadId)}`
-}
-
-/**
- * Identity root: the part that a resume must preserve. A resume that changes the root is a fork,
- * whatever the provider called it.
- */
-export function agentSessionProviderHandleRoot(handle: AgentSessionProviderHandle): string {
-  return handle.provider === 'claude'
-    ? `claude:${JSON.stringify(handle.sessionId)}`
-    : `codex:${JSON.stringify(handle.threadId)}`
-}
-
+/** Every field, resume cursor included: a resume that only moved the adapter's state is still news. */
 export function agentSessionProviderHandlesEqual(
   left: AgentSessionProviderHandle,
   right: AgentSessionProviderHandle
 ): boolean {
-  return agentSessionProviderHandleKey(left) === agentSessionProviderHandleKey(right)
+  return (
+    left.transport === right.transport &&
+    left.agent === right.agent &&
+    left.nativeId === right.nativeId &&
+    left.resumeCursor === right.resumeCursor
+  )
 }
 
 export function agentSessionProviderHandleChainHead(
@@ -113,6 +122,10 @@ export function isAgentSessionProviderHandleLink(
     return false
   }
   const link = value as Partial<AgentSessionProviderHandleLink>
+  if (!isAgentSessionProviderHandle(link.handle)) {
+    return false
+  }
+  const handle = link.handle
   const originValid =
     link.origin === 'created' ||
     link.origin === 'adopted' ||
@@ -121,16 +134,15 @@ export function isAgentSessionProviderHandleLink(
   return (
     typeof link.linkId === 'string' &&
     LINK_ID_PATTERN.test(link.linkId) &&
-    isAgentSessionProviderHandle(link.handle) &&
     originValid &&
     Number.isSafeInteger(link.mintedAtFence) &&
     (link.mintedAtFence as number) >= 0 &&
     Number.isSafeInteger(link.observedAt) &&
     (link.origin === 'forked'
-      ? isHandleField(link.forkedFromKey)
+      ? isAgentSessionProviderHandleKeyFor(handle, link.forkedFromKey)
       : link.forkedFromKey === undefined) &&
     (link.supersedesKey === undefined ||
-      (link.origin === 'created' && isHandleField(link.supersedesKey)))
+      (link.origin === 'created' && isAgentSessionProviderHandleKeyFor(handle, link.supersedesKey)))
   )
 }
 
@@ -177,7 +189,7 @@ export function appendAgentSessionProviderHandleLink(
     }
     return [link]
   }
-  if (link.handle.provider !== head.handle.provider) {
+  if (!isAgentSessionProviderHandleInNamespace(link.handle, head.handle)) {
     throw new Error('agent_session_provider_handle_provider_mismatch')
   }
   if (link.mintedAtFence < head.mintedAtFence) {
@@ -245,3 +257,43 @@ function supersedeUnsavedCreation(
   // Why: in place, so a chat reopened unused across many restarts never grows toward the cap.
   return [link]
 }
+
+// ─── Stored form ────────────────────────────────────────────────────────────
+
+/** A link as a record row stores it: only the handle has a stored form of its own. */
+export type PersistedAgentSessionProviderHandleLink = Omit<
+  AgentSessionProviderHandleLink,
+  'handle'
+> & {
+  handle: PersistedAgentSessionProviderHandle
+}
+
+export function encodePersistedAgentSessionProviderHandleChain(
+  chain: AgentSessionProviderHandleChain
+): PersistedAgentSessionProviderHandleLink[] {
+  return chain.map((link) => ({
+    ...link,
+    handle: encodePersistedAgentSessionProviderHandle(link.handle)
+  }))
+}
+
+/** The in-memory chain a stored one names, or null when any link or the chain itself is invalid. */
+export function decodePersistedAgentSessionProviderHandleChain(
+  value: unknown
+): AgentSessionProviderHandleLink[] | null {
+  if (!Array.isArray(value) || value.length > MAX_AGENT_SESSION_PROVIDER_HANDLE_LINKS) {
+    return null
+  }
+  const decoded: unknown[] = []
+  for (const link of value) {
+    const handle =
+      typeof link === 'object' && link !== null && 'handle' in link
+        ? decodePersistedAgentSessionProviderHandle(link.handle)
+        : null
+    if (!handle) {
+      return null
+    }
+    decoded.push({ ...link, handle })
+  }
+  return isAgentSessionProviderHandleChain(decoded) ? decoded : null
+}
diff --git a/src/shared/agent-session-record-stored-form.test.ts b/src/shared/agent-session-record-stored-form.test.ts
new file mode 100644
index 00000000000..22ef2b54a9a
--- /dev/null
+++ b/src/shared/agent-session-record-stored-form.test.ts
@@ -0,0 +1,318 @@
+import { describe, expect, it } from 'vitest'
+import { isAgentSessionHandleProvider } from './agent-session-provider-handle'
+import {
+  agentSessionJournalProviderHandle,
+  agentSessionProviderHandleFromWire,
+  agentSessionProviderHandleKey,
+  agentSessionProviderHandleRoot,
+  agentSessionWireProviderHandle,
+  claudeProviderHandle,
+  codexProviderHandle,
+  decodePersistedAgentSessionProviderHandle,
+  encodePersistedAgentSessionProviderHandle
+} from './agent-session-provider-handle-encoding'
+import { isPersistedAgentSessionRecord } from './agent-session-record'
+import {
+  decodePersistedAgentSessionRecord,
+  encodeAgentSessionRecord
+} from './agent-session-record-stored-form'
+import {
+  agentSessionLeaseFixture,
+  agentSessionRecordFixture
+} from './agent-session-record.test-fixture'
+
+/** The rules of the handle guard builds before the neutral handle shipped ran on every stored one. */
+function olderBuildReadsHandle(value: unknown): boolean {
+  const isHandleField = (field: unknown): boolean =>
+    typeof field === 'string' && field.length > 0 && field.length <= 512 && field === field.trim()
+  if (typeof value !== 'object' || value === null || !('provider' in value)) {
+    return false
+  }
+  if (value.provider === 'claude') {
+    return (
+      'sessionId' in value &&
+      isHandleField(value.sessionId) &&
+      'leafUuid' in value &&
+      (value.leafUuid === null || isHandleField(value.leafUuid))
+    )
+  }
+  return value.provider === 'codex' && 'threadId' in value && isHandleField(value.threadId)
+}
+
+/** A Claude record row exactly as builds before this change wrote it: a fork with its seed key. */
+const STORED_CLAUDE_ROW = JSON.stringify({
+  schemaVersion: 2,
+  sessionId: 'session-alpha-1',
+  location: {
+    executionHostId: 'local',
+    wslDistro: null,
+    workspaceId: 'workspace-1',
+    workspaceKind: 'git-worktree'
+  },
+  provider: 'claude',
+  providerHandleChain: [
+    {
+      linkId: 'link-1',
+      handle: { provider: 'claude', sessionId: 'sess-1', leafUuid: 'leaf-1' },
+      origin: 'created',
+      mintedAtFence: 6,
+      observedAt: 1000
+    },
+    {
+      linkId: 'link-2',
+      handle: { provider: 'claude', sessionId: 'sess-2', leafUuid: null },
+      origin: 'forked',
+      mintedAtFence: 7,
+      observedAt: 1500,
+      forkedFromKey: 'claude:["sess-1","leaf-1"]'
+    }
+  ],
+  accountHome: { variable: 'CLAUDE_CONFIG_DIR', path: '/home/user/.claude' },
+  lease: agentSessionLeaseFixture({ provenHandleLinkId: 'link-2' }),
+  createdAt: 1000,
+  updatedAt: 2000
+})
+
+/** A Codex row with a creation that replaced one Codex never saved. */
+const STORED_CODEX_ROW = JSON.stringify({
+  ...JSON.parse(STORED_CLAUDE_ROW),
+  provider: 'codex',
+  providerHandleChain: [
+    {
+      linkId: 'codex-7-thread-new',
+      handle: { provider: 'codex', threadId: 'thread-new' },
+      origin: 'created',
+      mintedAtFence: 7,
+      observedAt: 1500,
+      supersedesKey: 'codex:"thread-unsaved"'
+    }
+  ],
+  accountHome: { variable: 'CODEX_HOME', path: '/home/user/.codex' },
+  lease: agentSessionLeaseFixture({ provenHandleLinkId: 'codex-7-thread-new' })
+})
+
+describe('a record row older builds wrote', () => {
+  it.each([
+    ['Claude', STORED_CLAUDE_ROW],
+    ['Codex', STORED_CODEX_ROW]
+  ])('reads a %s row and writes it back byte for byte', (_name, row) => {
+    const stored: unknown = JSON.parse(row)
+    expect(isPersistedAgentSessionRecord(stored)).toBe(true)
+    if (!isPersistedAgentSessionRecord(stored)) {
+      return
+    }
+    const { record, normalized } = decodePersistedAgentSessionRecord(stored)
+    expect(normalized).toBe(false)
+    expect(JSON.stringify(encodeAgentSessionRecord(record))).toBe(row)
+  })
+
+  it('hands shared code only the neutral handle', () => {
+    const stored: unknown = JSON.parse(STORED_CLAUDE_ROW)
+    if (!isPersistedAgentSessionRecord(stored)) {
+      throw new Error('fixture row must be readable')
+    }
+    const { record } = decodePersistedAgentSessionRecord(stored)
+    expect(record.providerHandleChain.map((link) => link.handle)).toEqual([
+      { transport: 'claude-sdk', agent: 'claude', nativeId: 'sess-1', resumeCursor: 'leaf-1' },
+      { transport: 'claude-sdk', agent: 'claude', nativeId: 'sess-2' }
+    ])
+  })
+
+  it('still reports a lease only the removed terminal handoff wrote', () => {
+    const record = agentSessionRecordFixture()
+    const stored = encodeAgentSessionRecord(record)
+    expect(decodePersistedAgentSessionRecord(stored)).toEqual({ record, normalized: false })
+    const legacy = { ...stored, lease: { ...stored.lease, runtimeKind: 'tui' as const } }
+    expect(decodePersistedAgentSessionRecord(legacy)).toEqual({
+      record: { ...record, lease: { ...record.lease, claimStatus: 'conflicted' } },
+      normalized: true
+    })
+  })
+})
+
+describe('what this build writes', () => {
+  it('stores Claude and Codex handles in the typed form older builds read', () => {
+    const claude = claudeProviderHandle('sess-1', 'leaf-1')
+    const codex = codexProviderHandle('thread-1')
+    expect(encodePersistedAgentSessionProviderHandle(claude)).toEqual({
+      provider: 'claude',
+      sessionId: 'sess-1',
+      leafUuid: 'leaf-1'
+    })
+    expect(encodePersistedAgentSessionProviderHandle(claudeProviderHandle('sess-1', null))).toEqual(
+      { provider: 'claude', sessionId: 'sess-1', leafUuid: null }
+    )
+    expect(encodePersistedAgentSessionProviderHandle(codex)).toEqual({
+      provider: 'codex',
+      threadId: 'thread-1'
+    })
+    for (const handle of [claude, codex]) {
+      const stored = encodePersistedAgentSessionProviderHandle(handle)
+      expect(olderBuildReadsHandle(stored)).toBe(true)
+      expect(decodePersistedAgentSessionProviderHandle(stored)).toEqual(handle)
+    }
+  })
+
+  it('keeps the persisted key and root strings older builds derived', () => {
+    // Fork seeds, superseded creations and resume offers store these; a new spelling strands them.
+    const claude = claudeProviderHandle('sess-1', 'leaf-1')
+    expect(agentSessionProviderHandleKey(claude)).toBe('claude:["sess-1","leaf-1"]')
+    expect(agentSessionProviderHandleKey(claudeProviderHandle('sess-1', null))).toBe(
+      'claude:["sess-1",null]'
+    )
+    expect(agentSessionProviderHandleRoot(claude)).toBe('claude:"sess-1"')
+    expect(agentSessionProviderHandleKey(codexProviderHandle('t'))).toBe('codex:"t"')
+    expect(agentSessionProviderHandleRoot(codexProviderHandle('t'))).toBe('codex:"t"')
+  })
+
+  it('round-trips another transport in the neutral form, which an older build refuses', () => {
+    const grok = {
+      transport: 'acp',
+      agent: 'grok',
+      nativeId: 'acp-session-1',
+      resumeCursor: '{"cwd":"/repo"}'
+    }
+    const stored = encodePersistedAgentSessionProviderHandle(grok)
+    expect(stored).toEqual(grok)
+    expect(decodePersistedAgentSessionProviderHandle(JSON.parse(JSON.stringify(stored)))).toEqual(
+      grok
+    )
+    // Unknown providers must never impersonate Codex on an older build.
+    expect(olderBuildReadsHandle(stored)).toBe(false)
+    expect(isAgentSessionHandleProvider(grok.agent)).toBe(false)
+    expect(agentSessionWireProviderHandle(grok)).toBeNull()
+    // Root, not the resume cursor: the cursor is resume state, not identity.
+    expect(agentSessionProviderHandleRoot(grok)).toBe('acp/grok:"acp-session-1"')
+    expect(agentSessionProviderHandleKey(grok)).toBe(agentSessionProviderHandleRoot(grok))
+  })
+
+  it('refuses a stored handle that is not the one form its transport writes', () => {
+    for (const value of [
+      // Claude or Codex in the neutral form: no build writes it.
+      { transport: 'claude-sdk', agent: 'claude', nativeId: 'sess-1' },
+      { transport: 'codex-app-server', agent: 'codex', nativeId: 'thread-1' },
+      // Both forms at once: reading either identity would erase the other.
+      { provider: 'grok', transport: 'acp', agent: 'grok', nativeId: 'x' },
+      {
+        provider: 'codex',
+        threadId: 'thread-1',
+        transport: 'acp',
+        agent: 'grok',
+        nativeId: 'acp-thread',
+        resumeCursor: 'resume-token'
+      },
+      { provider: 'codex', threadId: 'thread-1', nativeId: 'other-thread' },
+      {
+        provider: 'claude',
+        sessionId: 'sess-1',
+        leafUuid: null,
+        transport: 'acp',
+        agent: 'grok',
+        nativeId: 'other'
+      },
+      { provider: 'claude', sessionId: 'sess-1', leafUuid: null, resumeCursor: 'leaf-2' },
+      { provider: 'claude', sessionId: 'sess-1' },
+      { provider: 'claude', sessionId: 'sess-1', leafUuid: '' },
+      { provider: 'codex', threadId: ' padded ' },
+      { transport: 'a:b', agent: 'grok', nativeId: 'x' },
+      { transport: 'acp', agent: 'grok', nativeId: 'x', resumeCursor: '' },
+      null
+    ]) {
+      expect(decodePersistedAgentSessionProviderHandle(value)).toBeNull()
+    }
+  })
+
+  it('still reads a typed handle that carries an unrelated field', () => {
+    expect(
+      decodePersistedAgentSessionProviderHandle({ provider: 'codex', threadId: 't', note: 1 })
+    ).toEqual(codexProviderHandle('t'))
+    expect(
+      decodePersistedAgentSessionProviderHandle({
+        provider: 'claude',
+        sessionId: 'sess-1',
+        leafUuid: 'leaf-1',
+        note: 1
+      })
+    ).toEqual(claudeProviderHandle('sess-1', 'leaf-1'))
+  })
+
+  it('drops a field a later build put on a handle, but keeps one on the link or record', () => {
+    const stored = JSON.parse(STORED_CODEX_ROW)
+    stored.providerHandleChain[0].handle.laterHandleField = 'x'
+    stored.providerHandleChain[0].laterLinkField = 'y'
+    stored.laterRecordField = 'z'
+    expect(isPersistedAgentSessionRecord(stored)).toBe(true)
+    if (!isPersistedAgentSessionRecord(stored)) {
+      return
+    }
+    const written = JSON.parse(
+      JSON.stringify(encodeAgentSessionRecord(decodePersistedAgentSessionRecord(stored).record))
+    )
+    expect(written.laterRecordField).toBe('z')
+    expect(written.providerHandleChain[0].laterLinkField).toBe('y')
+    expect(written.providerHandleChain[0].handle).toEqual({
+      provider: 'codex',
+      threadId: 'thread-new'
+    })
+
+    const neutral = { transport: 'acp', agent: 'grok', nativeId: 's', resumeCursor: 'c' }
+    const decoded = decodePersistedAgentSessionProviderHandle({ ...neutral, laterHandleField: 1 })
+    expect(decoded && encodePersistedAgentSessionProviderHandle(decoded)).toEqual(neutral)
+  })
+
+  it.each([
+    ['Claude', STORED_CLAUDE_ROW],
+    ['Codex', STORED_CODEX_ROW]
+  ])('refuses a whole %s row whose handle also names a neutral identity', (_name, row) => {
+    const stored = JSON.parse(row)
+    Object.assign(stored.providerHandleChain[0].handle, {
+      transport: 'acp',
+      agent: 'grok',
+      nativeId: 'acp-thread',
+      resumeCursor: 'resume-token'
+    })
+    expect(isPersistedAgentSessionRecord(stored)).toBe(false)
+  })
+})
+
+describe('the wire and journal forms', () => {
+  it('maps the attach wire handle both ways for Claude and Codex', () => {
+    const claudeWire = { kind: 'claude', sessionId: 'sess-1', leafUuid: null } as const
+    const codexWire = { kind: 'codex', threadId: 'thread-1' } as const
+    expect(agentSessionProviderHandleFromWire(claudeWire)).toEqual(
+      claudeProviderHandle('sess-1', null)
+    )
+    expect(agentSessionWireProviderHandle(agentSessionProviderHandleFromWire(claudeWire))).toEqual(
+      claudeWire
+    )
+    expect(agentSessionWireProviderHandle(agentSessionProviderHandleFromWire(codexWire))).toEqual(
+      codexWire
+    )
+  })
+
+  it('records the journal rows exactly as before, and another transport as opaque', () => {
+    expect(
+      agentSessionJournalProviderHandle({
+        agent: 'claude',
+        providerHandle: claudeProviderHandle('sess-1', 'leaf-1')
+      })
+    ).toEqual({ kind: 'claude', sessionId: 'sess-1', leafUuid: 'leaf-1' })
+    expect(
+      agentSessionJournalProviderHandle({
+        agent: 'codex',
+        providerHandle: codexProviderHandle('t')
+      })
+    ).toEqual({ kind: 'codex', threadId: 't' })
+    expect(agentSessionJournalProviderHandle({ agent: 'codex', providerHandle: null })).toEqual({
+      kind: 'opaque',
+      agent: 'codex',
+      value: 'pending'
+    })
+    expect(
+      agentSessionJournalProviderHandle({
+        agent: 'grok',
+        providerHandle: { transport: 'acp', agent: 'grok', nativeId: 's' }
+      })
+    ).toEqual({ kind: 'opaque', agent: 'grok', value: 's' })
+  })
+})
diff --git a/src/shared/agent-session-record-stored-form.ts b/src/shared/agent-session-record-stored-form.ts
new file mode 100644
index 00000000000..ca6d242d24a
--- /dev/null
+++ b/src/shared/agent-session-record-stored-form.ts
@@ -0,0 +1,41 @@
+/**
+ * An agent-session record between its stored row and memory. The stored row keeps what older
+ * builds read: Claude and Codex handles in their typed form and lease values only they wrote.
+ */
+
+import {
+  leaseCarriesLegacyHandoffValues,
+  normalizeLegacyHandoffLease,
+  type PersistedAgentSessionRecord
+} from './agent-session-legacy-handoff-lease'
+import {
+  decodePersistedAgentSessionProviderHandleChain,
+  encodePersistedAgentSessionProviderHandleChain
+} from './agent-session-provider-handle'
+import type { AgentSessionRecord } from './agent-session-record'
+
+/** The in-memory record, plus whether decode changed anything the store must write back. A
+ *  handle's stored form is not such a change: every build writes it the same way. */
+export function decodePersistedAgentSessionRecord(record: PersistedAgentSessionRecord): {
+  record: AgentSessionRecord
+  normalized: boolean
+} {
+  const providerHandleChain = decodePersistedAgentSessionProviderHandleChain(
+    record.providerHandleChain
+  )
+  if (!providerHandleChain) {
+    throw new Error('agent_session_provider_handle_invalid')
+  }
+  return {
+    record: { ...record, providerHandleChain, lease: normalizeLegacyHandoffLease(record.lease) },
+    normalized: leaseCarriesLegacyHandoffValues(record.lease)
+  }
+}
+
+/** The record as a row stores it; Claude and Codex handles keep the typed form older builds read. */
+export function encodeAgentSessionRecord(record: AgentSessionRecord): PersistedAgentSessionRecord {
+  return {
+    ...record,
+    providerHandleChain: encodePersistedAgentSessionProviderHandleChain(record.providerHandleChain)
+  }
+}
diff --git a/src/shared/agent-session-record.test-fixture.ts b/src/shared/agent-session-record.test-fixture.ts
index 3e2270d368b..68a190fbbca 100644
--- a/src/shared/agent-session-record.test-fixture.ts
+++ b/src/shared/agent-session-record.test-fixture.ts
@@ -5,6 +5,7 @@ import {
   type AgentSessionLease,
   type AgentSessionRecord
 } from './agent-session-record'
+import { claudeProviderHandle } from './agent-session-provider-handle-encoding'
 
 const OWNER_PROCESS = {
   hostId: 'local',
@@ -56,7 +57,7 @@ export function agentSessionRecordFixture(
         origin: 'created',
         mintedAtFence: lease.runtimeFence,
         observedAt: 1_000,
-        handle: { provider: 'claude', sessionId: 'provider-session-alpha-1', leafUuid: null }
+        handle: claudeProviderHandle('provider-session-alpha-1', null)
       }
     ],
     accountHome: { variable: 'CLAUDE_CONFIG_DIR', path: '/home/user/.claude' },
diff --git a/src/shared/agent-session-record.ts b/src/shared/agent-session-record.ts
index a9d563392f0..3bdef0ea1e8 100644
--- a/src/shared/agent-session-record.ts
+++ b/src/shared/agent-session-record.ts
@@ -21,10 +21,11 @@ import {
   type AgentSessionConversationCommandRecord
 } from './agent-session-conversation-command'
 import {
-  isAgentSessionProviderHandleChain,
+  decodePersistedAgentSessionProviderHandleChain,
   type AgentSessionHandleProvider,
   type AgentSessionProviderHandleLink
 } from './agent-session-provider-handle'
+import { agentSessionProviderHandleBelongsTo } from './agent-session-provider-handle-encoding'
 
 export const AGENT_SESSION_RECORD_SCHEMA_VERSION = 2 as const
 
@@ -335,8 +336,8 @@ function isPersistedAgentSessionLease(value: unknown): value is PersistedAgentSe
   )
 }
 
-/** The on-disk shape, which still admits the removed terminal handoff's lease values. Decode
- *  through `normalizeLegacyHandoffRecord` before anything reads the lease. */
+/** The on-disk shape, which still admits the removed terminal handoff's lease values and stores
+ *  handles in their typed form. Decode through `decodePersistedAgentSessionRecord` before use. */
 export function isPersistedAgentSessionRecord(
   value: unknown
 ): value is PersistedAgentSessionRecord {
@@ -349,7 +350,6 @@ export function isPersistedAgentSessionRecord(
     isAgentSessionId(record.sessionId) &&
     isAgentSessionExecutionLocation(record.location) &&
     (record.provider === 'claude' || record.provider === 'codex') &&
-    isAgentSessionProviderHandleChain(record.providerHandleChain) &&
     isAgentSessionAccountHome(record.accountHome) &&
     (record.options === undefined || isAgentSessionOptions(record.options)) &&
     (record.rewind === undefined || isAgentSessionRewindRecord(record.rewind)) &&
@@ -367,9 +367,12 @@ export function isPersistedAgentSessionRecord(
     return false
   }
   const validated = record as AgentSessionRecord
-  const head = validated.providerHandleChain.at(-1)
+  // The row holds stored handles; validate the chain they decode to.
+  const chain = decodePersistedAgentSessionProviderHandleChain(validated.providerHandleChain)
+  const head = chain?.at(-1)
   return (
-    validated.providerHandleChain.every((link) => link.handle.provider === validated.provider) &&
+    chain !== null &&
+    chain.every((link) => agentSessionProviderHandleBelongsTo(link.handle, validated.provider)) &&
     (validated.lease.claimStatus !== 'live' ||
       (validated.lease.ownerProcess !== null &&
         head?.linkId === validated.lease.provenHandleLinkId &&
diff --git a/tests/e2e/codex-child-approval-activity-row.unit.test.ts b/tests/e2e/codex-child-approval-activity-row.unit.test.ts
index 54e44d7fa88..9b1dc2306e2 100644
--- a/tests/e2e/codex-child-approval-activity-row.unit.test.ts
+++ b/tests/e2e/codex-child-approval-activity-row.unit.test.ts
@@ -76,6 +76,7 @@ import { StructuredAgentSessionStatusBridge } from '../../src/renderer/src/compo
 import { resetStructuredAgentSessionStatusFeedsForTests } from '../../src/renderer/src/runtime/structured-agent-session-status-feed'
 import { createStructuredAgentSessionLogger } from '../../src/main/native-chat/agent-session-wire/structured-agent-session-logger'
 import { testEventSinkLogging } from '../../src/main/native-chat/agent-session-wire/structured-agent-session-logger-test-support'
+import { codexProviderHandle } from '../../src/shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'codex-child-approval'
 const CODEX_THREAD = 'thread-parent'
@@ -142,7 +143,7 @@ async function openHost() {
       workspaceId: 'wt-1',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: CODEX_THREAD }
+      providerHandle: codexProviderHandle(CODEX_THREAD)
     },
     now: tick,
     stateDirectory: join(root, SESSION)
diff --git a/tests/e2e/cross-version-wire/agent-session-newer-chat-refusal.unit.test.ts b/tests/e2e/cross-version-wire/agent-session-newer-chat-refusal.unit.test.ts
index 42f5856e35c..f7abbe134dc 100644
--- a/tests/e2e/cross-version-wire/agent-session-newer-chat-refusal.unit.test.ts
+++ b/tests/e2e/cross-version-wire/agent-session-newer-chat-refusal.unit.test.ts
@@ -5,8 +5,10 @@ import { afterAll, beforeAll, describe, expect, it } from 'vitest'
 import {
   AGENT_JOURNAL_THREAD_SCOPE,
   AGENT_SESSION_JOURNAL_SCHEMA_VERSION,
-  type AgentSessionJournalIdentity
+  type AgentSessionJournalIdentity,
+  type AgentSessionJournalProviderHandle
 } from '../../../src/shared/agent-session-journal-types'
+import { codexProviderHandle } from '../../../src/shared/agent-session-provider-handle-encoding'
 import type { AgentSessionRefusalReference } from '../../../src/shared/agent-session-wire-refusals'
 import {
   closeTestJournalHostDatabase,
@@ -43,6 +45,16 @@ const IDENTITY: AgentSessionJournalIdentity = {
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
+  providerHandle: codexProviderHandle('thread-1')
+}
+
+/** The identity as builds before the neutral provider handle took it. */
+type OlderJournalIdentity = Omit<AgentSessionJournalIdentity, 'providerHandle'> & {
+  providerHandle: AgentSessionJournalProviderHandle
+}
+
+const OLDER_IDENTITY: OlderJournalIdentity = {
+  ...IDENTITY,
   providerHandle: { kind: 'codex', threadId: 'thread-1' }
 }
 
@@ -218,14 +230,14 @@ describe('a chat a newer Orca saved, across versions', () => {
       const older = releaseExport<
         () => {
           open: (options: {
-            identity: AgentSessionJournalIdentity
+            identity: OlderJournalIdentity
             stateDirectory: string
           }) => Promise<unknown>
           closeAll: () => Promise<void>
         }
       >(support, 'createTrackedJournalOpener')()
       try {
-        await older.open({ identity: IDENTITY, stateDirectory: directory })
+        await older.open({ identity: OLDER_IDENTITY, stateDirectory: directory })
       } finally {
         await older.closeAll()
       }
diff --git a/tests/e2e/cross-version-wire/agent-session-stop-event-downgrade.unit.test.ts b/tests/e2e/cross-version-wire/agent-session-stop-event-downgrade.unit.test.ts
index 3fc06f9d2dc..d7444e2c77e 100644
--- a/tests/e2e/cross-version-wire/agent-session-stop-event-downgrade.unit.test.ts
+++ b/tests/e2e/cross-version-wire/agent-session-stop-event-downgrade.unit.test.ts
@@ -6,8 +6,10 @@ import {
   AGENT_JOURNAL_THREAD_SCOPE,
   AGENT_SESSION_JOURNAL_SCHEMA_VERSION,
   type AgentJournalItemIdentity,
-  type AgentSessionJournalIdentity
+  type AgentSessionJournalIdentity,
+  type AgentSessionJournalProviderHandle
 } from '../../../src/shared/agent-session-journal-types'
+import { codexProviderHandle } from '../../../src/shared/agent-session-provider-handle-encoding'
 import Database from '../../../src/main/sqlite/sync-database'
 import { journalDatabasePath } from '../../../src/main/native-chat/agent-session-journal/journal-host-database'
 import {
@@ -34,6 +36,16 @@ const IDENTITY: AgentSessionJournalIdentity = {
   workspaceId: 'ws-1',
   hostId: 'host-1',
   agent: 'codex',
+  providerHandle: codexProviderHandle('thread-1')
+}
+
+/** The identity as builds before the neutral provider handle took it. */
+type OlderJournalIdentity = Omit<AgentSessionJournalIdentity, 'providerHandle'> & {
+  providerHandle: AgentSessionJournalProviderHandle
+}
+
+const OLDER_IDENTITY: OlderJournalIdentity = {
+  ...IDENTITY,
   providerHandle: { kind: 'codex', threadId: 'thread-1' }
 }
 
@@ -164,7 +176,7 @@ type OlderJournal = {
 
 type OlderOpener = {
   open: (options: {
-    identity: AgentSessionJournalIdentity
+    identity: OlderJournalIdentity
     stateDirectory: string
   }) => Promise<OlderJournal>
   closeAll: () => Promise<void>
@@ -204,7 +216,7 @@ test("an older build opens this build's journal writable and appends to it; the
     )
     const older = releaseExport<() => OlderOpener>(support, 'createTrackedJournalOpener')()
     try {
-      const downgraded = await older.open({ identity: IDENTITY, stateDirectory: directory })
+      const downgraded = await older.open({ identity: OLDER_IDENTITY, stateDirectory: directory })
       expect(downgraded.isReadOnly).toBe(false)
       expect(downgraded.cursor()).toEqual(wrote.cursor)
       expect(itemIds(downgraded)).toEqual(wrote.items)
@@ -277,7 +289,7 @@ test("this build keeps a newer build's row kind and refuses the load; a build be
     )
     const older = releaseExport<() => OlderOpener>(support, 'createTrackedJournalOpener')()
     try {
-      await older.open({ identity: IDENTITY, stateDirectory: directory })
+      await older.open({ identity: OLDER_IDENTITY, stateDirectory: directory })
     } finally {
       await older.closeAll()
     }
diff --git a/tests/e2e/cross-version-wire/cross-version-agent-session-wire.unit.test.ts b/tests/e2e/cross-version-wire/cross-version-agent-session-wire.unit.test.ts
index 1980ed95c55..d427eb5109a 100644
--- a/tests/e2e/cross-version-wire/cross-version-agent-session-wire.unit.test.ts
+++ b/tests/e2e/cross-version-wire/cross-version-agent-session-wire.unit.test.ts
@@ -64,6 +64,7 @@ import {
 } from './versioned-agent-session-wire'
 import { openTestJournalHostDatabase } from '../../../src/main/native-chat/agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from '../../../src/main/native-chat/agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../../src/shared/agent-session-provider-handle-encoding'
 
 // Why: a cold CI run extracts the baseline checkout before the first pairing.
 const SUITE_TIMEOUT_MS = 180_000
@@ -561,7 +562,7 @@ describe('cross-version structured agent sessions', () => {
             },
             link: {
               linkId: `link-${fence}`,
-              handle: { provider: 'codex', threadId: THREAD },
+              handle: codexProviderHandle(THREAD),
               origin: 'created',
               mintedAtFence: fence,
               observedAt: NOW
@@ -752,7 +753,7 @@ describe('cross-version structured agent sessions', () => {
             },
             link: {
               linkId: `link-${fence}`,
-              handle: { provider: 'codex', threadId: THREAD },
+              handle: codexProviderHandle(THREAD),
               // A restarted host re-proves the thread it inherited; only the first
               // owner of a session may claim to have created it.
               origin: store.getRecord(SESSION)?.providerHandleChain.length ? 'resumed' : 'created',
diff --git a/tests/e2e/structured-agent-session-read-owner.unit.test.ts b/tests/e2e/structured-agent-session-read-owner.unit.test.ts
index b7734f2759d..0220a33e59a 100644
--- a/tests/e2e/structured-agent-session-read-owner.unit.test.ts
+++ b/tests/e2e/structured-agent-session-read-owner.unit.test.ts
@@ -33,6 +33,7 @@ import {
   resetStructuredAgentSessionReadOwnersForTests
 } from '../../src/renderer/src/components/native-chat/structured-agent-session-read-owner'
 import { createStructuredAgentSessionLogger } from '../../src/main/native-chat/agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../src/shared/agent-session-provider-handle-encoding'
 
 const SESSION = 'cursor-body-regression'
 const target = { kind: 'local' } as const
@@ -56,7 +57,7 @@ async function fixture() {
       workspaceId: 'folder-workspace',
       hostId: 'local',
       agent: 'codex',
-      providerHandle: { kind: 'codex', threadId: 'thread-1' }
+      providerHandle: codexProviderHandle('thread-1')
     },
     stateDirectory: join(root, 'journal')
   })
diff --git a/tests/e2e/structured-chat-owner-status-activation.unit.test.ts b/tests/e2e/structured-chat-owner-status-activation.unit.test.ts
index 4968af98a93..abf2f994004 100644
--- a/tests/e2e/structured-chat-owner-status-activation.unit.test.ts
+++ b/tests/e2e/structured-chat-owner-status-activation.unit.test.ts
@@ -26,6 +26,7 @@ import { readWorktreeStructuredActivationInventory } from '../../src/renderer/sr
 import type { RuntimeMobileSessionTabsResult } from '../../src/shared/runtime-types'
 import { openTestJournalHostDatabase } from '../../src/main/native-chat/agent-session-journal/journal-host-database-test-support'
 import { createStructuredAgentSessionLogger } from '../../src/main/native-chat/agent-session-wire/structured-agent-session-logger'
+import { codexProviderHandle } from '../../src/shared/agent-session-provider-handle-encoding'
 
 const WORKTREE = 'repo-1::/workspace/repo'
 
@@ -44,7 +45,7 @@ function openHost(): void {
         process: { hostId: 'local', pid: 4242, processStartTimeMs: 1_700_000_000_000, spawnToken },
         link: {
           linkId: `link-${fence}`,
-          handle: { provider: 'codex', threadId: THREAD },
+          handle: codexProviderHandle(THREAD),
           origin: store.getRecord(SESSION)?.providerHandleChain.length ? 'resumed' : 'created',
           mintedAtFence: fence,
           observedAt: NOW