diff --git a/config/scripts/vitest-caller-identity-env-setup.ts b/config/scripts/vitest-caller-identity-env-setup.ts
new file mode 100644
index 00000000000..1d14998e46c
--- /dev/null
+++ b/config/scripts/vitest-caller-identity-env-setup.ts
@@ -0,0 +1,8 @@
+/**
+ * Why: a structured chat exports its own orchestration caller identity to every child, including a
+ * test runner it launches. Inherited, it would decide which CLI identity branch a test exercises
+ * depending on who ran the suite; suites that need one set it themselves.
+ */
+for (const name of ['ORCA_AGENT_SESSION_ID', 'ORCA_STRUCTURED_SESSION']) {
+  delete process.env[name]
+}
diff --git a/config/tsconfig.node.json b/config/tsconfig.node.json
index c42b937a467..a998460a457 100644
--- a/config/tsconfig.node.json
+++ b/config/tsconfig.node.json
@@ -4,6 +4,7 @@
     "../electron.vite.config.*",
     "./build-plugins/**/*",
     "./scripts/vitest-host-ports-setup.ts",
+    "./scripts/vitest-caller-identity-env-setup.ts",
     "../src/main/**/*",
     "../src/renderer/src/lib/skill-freshness-display-status.ts",
     "../src/preload/**/*",
diff --git a/config/vitest.config.ts b/config/vitest.config.ts
index beaf82f4e12..2514067e7cc 100644
--- a/config/vitest.config.ts
+++ b/config/vitest.config.ts
@@ -26,7 +26,8 @@ export default defineConfig({
     setupFiles: [
       resolve('config/scripts/happy-dom-offscreen-canvas.ts'),
       resolve('config/scripts/happy-dom-mutation-observer-retention.ts'),
-      resolve('config/scripts/vitest-host-ports-setup.ts')
+      resolve('config/scripts/vitest-host-ports-setup.ts'),
+      resolve('config/scripts/vitest-caller-identity-env-setup.ts')
     ],
     include: [
       'src/**/*.test.ts',
diff --git a/src/cli/handlers/orchestration/message-check-handler.ts b/src/cli/handlers/orchestration/message-check-handler.ts
index f2af827ee04..26cefcc06ea 100644
--- a/src/cli/handlers/orchestration/message-check-handler.ts
+++ b/src/cli/handlers/orchestration/message-check-handler.ts
@@ -13,7 +13,7 @@ import { startCheckKeepalive } from './check-keepalive'
 import { callOrchestrationMutation } from './mutation-request'
 import { getOptionalPositiveIntegerValueFlag } from './numeric-flags'
 import { flushOrchestrationStdout, resolveCompatibilityCliCommand } from './runtime-compatibility'
-import { resolveOrchestrationTerminalHandle } from './terminal-identity'
+import { orchestrationCallerLabel, resolveOrchestrationTerminalHandle } from './terminal-identity'
 
 type CheckResult = {
   messages: MessageSummary[]
@@ -41,12 +41,16 @@ export const ORCHESTRATION_CHECK_HANDLER: Record<string, CommandHandler> = {
     const timeoutMs = getOptionalPositiveIntegerValueFlag(flags, 'timeout-ms')
     const explicitTerminal = getOptionalStringFlag(flags, 'terminal')
     const terminal = await resolveOrchestrationTerminalHandle(flags, cwd, client, 'terminal')
+    // Why: a session names itself by its id alone; a terminal view's pane is not its identity.
+    const paneKey =
+      explicitTerminal || terminal === undefined ? undefined : process.env.ORCA_PANE_KEY
+    const callerLabel = orchestrationCallerLabel(terminal)
     const stopKeepalive = wait ? startCheckKeepalive(timeoutMs) : null
     let result: Awaited<ReturnType<typeof client.call<CheckResult>>>
     try {
       result = await callOrchestrationMutation<CheckResult>(client, flags, 'orchestration.check', {
         terminal,
-        terminalPaneKey: explicitTerminal ? undefined : process.env.ORCA_PANE_KEY || undefined,
+        terminalPaneKey: paneKey || undefined,
         // Why: old runtimes degrade peek to non-consuming all mode instead of destructive mark-read.
         unread: flags.has('unread') ? true : peek ? false : undefined,
         peek: peek ? true : undefined,
@@ -68,9 +72,9 @@ export const ORCHESTRATION_CHECK_HANDLER: Record<string, CommandHandler> = {
     }
     result = {
       ...result,
-      result: prepareOrchestrationCheckOutput(result.result, terminal, flags.has('format'))
+      result: prepareOrchestrationCheckOutput(result.result, callerLabel, flags.has('format'))
     }
-    printResult(result, json, (value) => formatOrchestrationCheckText(value, terminal))
+    printResult(result, json, (value) => formatOrchestrationCheckText(value, callerLabel))
     const compatibilityAck = result.result.legacyCompatibility?.ackMessageIds
     if (compatibilityAck && compatibilityAck.length > 0) {
       await flushOrchestrationStdout()
diff --git a/src/cli/handlers/orchestration/message-send-handler.ts b/src/cli/handlers/orchestration/message-send-handler.ts
index 088d1361e69..f79a846328b 100644
--- a/src/cli/handlers/orchestration/message-send-handler.ts
+++ b/src/cli/handlers/orchestration/message-send-handler.ts
@@ -2,6 +2,7 @@ import type { CommandHandler } from '../../dispatch'
 import { printResult } from '../../format'
 import { getOptionalStringFlag, getRequiredStringFlag } from '../../flags'
 import { RuntimeClientError } from '../../runtime-client'
+import { readInjectedAgentSessionId } from '../../../shared/agent-session-caller-env'
 import { requireWorkerDoneSettlement } from '../orchestration-worker-settlement'
 import { getOptionalStructuredMessagePayload } from './message-payload'
 import { callOrchestrationMutation } from './mutation-request'
@@ -75,7 +76,8 @@ export const ORCHESTRATION_SEND_HANDLER: Record<string, CommandHandler> = {
     if (
       (type === 'worker_done' || type === 'heartbeat') &&
       !getOptionalStringFlag(flags, 'from') &&
-      !process.env.ORCA_TERMINAL_HANDLE
+      !process.env.ORCA_TERMINAL_HANDLE &&
+      !readInjectedAgentSessionId()
     ) {
       // Why: focus isn't lifecycle authority — an identity-less subprocess must fail closed rather than guess the worker.
       throwNoActiveSenderTerminal()
@@ -94,7 +96,8 @@ export const ORCHESTRATION_SEND_HANDLER: Record<string, CommandHandler> = {
       threadId: getOptionalStringFlag(flags, 'thread-id'),
       payload: getOptionalStructuredMessagePayload(flags),
       // Why: pane key is the remint-stable sender identity the runtime verifies lifecycle ownership against; older runtimes strip it.
-      senderPaneKey: process.env.ORCA_PANE_KEY || undefined,
+      // A session names itself by its id alone.
+      senderPaneKey: from === undefined ? undefined : process.env.ORCA_PANE_KEY || undefined,
       waitForLifecycleSettlement: type === 'worker_done' ? true : undefined,
       devMode: isDevCliInvocation()
     }
diff --git a/src/cli/handlers/orchestration/question-handler.ts b/src/cli/handlers/orchestration/question-handler.ts
index bd9e239b6d5..67aaeb16e4d 100644
--- a/src/cli/handlers/orchestration/question-handler.ts
+++ b/src/cli/handlers/orchestration/question-handler.ts
@@ -103,8 +103,8 @@ export const ORCHESTRATION_QUESTION_HANDLER: Record<string, CommandHandler> = {
                 resolveOrchestrationCliExecutable(),
                 'orchestration',
                 'ask',
-                '--from',
-                from,
+                // A session's resume is flagless: its injected id names it again.
+                ...(from ? ['--from', from] : []),
                 ...(dispatchCapability ? ['--dispatch-capability', dispatchCapability] : []),
                 '--resume',
                 messageId,
diff --git a/src/cli/handlers/orchestration/run-handlers.ts b/src/cli/handlers/orchestration/run-handlers.ts
index 7c77913df15..d8abe3533c2 100644
--- a/src/cli/handlers/orchestration/run-handlers.ts
+++ b/src/cli/handlers/orchestration/run-handlers.ts
@@ -39,7 +39,9 @@ export const ORCHESTRATION_RUN_HANDLERS: Record<string, CommandHandler> = {
       run: { id: string; objective: string } | null
     }>('orchestration.runCurrent', { from })
     printResult(result, json, (r) =>
-      r.run ? `${r.run.id} ${r.run.objective}` : 'No Run is bound to this terminal.'
+      r.run
+        ? `${r.run.id} ${r.run.objective}`
+        : `No Run is bound to this ${from === undefined ? 'session' : 'terminal'}.`
     )
   },
 
diff --git a/src/cli/handlers/orchestration/terminal-identity.ts b/src/cli/handlers/orchestration/terminal-identity.ts
index e693d99079d..f9d72d76e3a 100644
--- a/src/cli/handlers/orchestration/terminal-identity.ts
+++ b/src/cli/handlers/orchestration/terminal-identity.ts
@@ -3,14 +3,25 @@ import { getOptionalStringFlag } from '../../flags'
 import { RuntimeClientError } from '../../runtime-client'
 import { getTerminalHandle } from '../../selectors'
 import { isStructuredSessionWithoutIdentity } from '../../../shared/structured-session-marker'
+import { readInjectedAgentSessionId } from '../../../shared/agent-session-caller-env'
+import { normalizeOrchestrationActor } from '../../../shared/orchestration-actor'
+import { isStructuredWorkerHandle } from '../../../shared/structured-worker-handle'
 
+/**
+ * The caller's terminal handle, or `undefined` when an injected agent session id names the caller:
+ * the orchestration envelope carries that id and the host binds the caller param to it, so nothing
+ * is resolved or guessed here.
+ */
 export async function resolveOrchestrationTerminalHandle(
   flags: Map<string, string | boolean>,
   cwd: string,
   client: RuntimeClient,
   flagName: 'from' | 'terminal',
   options: { validateEnvHandle?: boolean } = {}
-): Promise<string> {
+): Promise<string | undefined> {
+  if (resolveInjectedSessionCaller(flags, flagName)) {
+    return undefined
+  }
   const explicit = getOptionalStringFlag(flags, flagName)
   if (explicit) {
     return explicit
@@ -157,11 +168,51 @@ function getClientErrorMessage(err: unknown): string | undefined {
   return typeof message === 'string' ? message : undefined
 }
 
+/**
+ * The injected session id when this command runs as an agent session. The id wins over every other
+ * identity this process carries; a caller flag may restate that same session but never name
+ * another, and a conflicting one is refused here, before any request is sent.
+ */
+export function resolveInjectedSessionCaller(
+  flags: Map<string, string | boolean>,
+  flagName: 'from' | 'terminal'
+): string | undefined {
+  const sessionId = readInjectedAgentSessionId()
+  if (!sessionId) {
+    return undefined
+  }
+  const declared = getOptionalStringFlag(flags, flagName)
+  if (declared !== undefined && !namesInjectedSession(declared, sessionId)) {
+    throw new RuntimeClientError(
+      'consumer_fenced',
+      `This command runs as agent session ${sessionId}, so --${flagName} ${declared} would act as a ` +
+        `different caller. Drop --${flagName}: this session's orchestration commands already act as ` +
+        `session:${sessionId}. No request was sent.`
+    )
+  }
+  return sessionId
+}
+
+/** The session's own spellings, plus the handle a structured worker session was minted. */
+function namesInjectedSession(value: string, sessionId: string): boolean {
+  if (normalizeOrchestrationActor(value)?.id === sessionId) {
+    return true
+  }
+  const ownHandle = process.env.ORCA_TERMINAL_HANDLE
+  return isStructuredWorkerHandle(ownHandle) && value === ownHandle
+}
+
+/** How check output names its caller: the handle, or the session's address. */
+export function orchestrationCallerLabel(handle: string | undefined): string {
+  const sessionId = handle === undefined ? readInjectedAgentSessionId() : undefined
+  return handle ?? (sessionId ? `session:${sessionId}` : 'unknown')
+}
+
 export async function resolveCoordinatorTerminalHandle(
   flags: Map<string, string | boolean>,
   cwd: string,
   client: RuntimeClient
-): Promise<string> {
+): Promise<string | undefined> {
   return await resolveOrchestrationTerminalHandle(flags, cwd, client, 'from', {
     validateEnvHandle: true
   })
diff --git a/src/cli/handlers/orchestration/worker-list-run-scope.ts b/src/cli/handlers/orchestration/worker-list-run-scope.ts
index 13037616153..83bfcd5b9e0 100644
--- a/src/cli/handlers/orchestration/worker-list-run-scope.ts
+++ b/src/cli/handlers/orchestration/worker-list-run-scope.ts
@@ -1,6 +1,9 @@
 import { getOptionalStringFlag } from '../../flags'
 import type { RuntimeClient } from '../../runtime-client'
-import { resolveOrchestrationTerminalHandle } from './terminal-identity'
+import {
+  resolveInjectedSessionCaller,
+  resolveOrchestrationTerminalHandle
+} from './terminal-identity'
 
 /** Which Run `worker-list` enumerated, and why. Additive: old readers ignore it. */
 export type WorkerListRunScope = { run?: string; source: 'flag' | 'bound' | 'all' }
@@ -20,6 +23,9 @@ export async function resolveWorkerListRunScope(
   if (explicit) {
     return { run: explicit, source: 'flag' }
   }
+  // Outside the catch: a --terminal naming someone other than this session is refused, never
+  // widened into an unscoped listing.
+  resolveInjectedSessionCaller(flags, 'terminal')
   try {
     const terminal = await resolveOrchestrationTerminalHandle(flags, cwd, client, 'terminal')
     const current = await client.call<{ run: { id: string } | null }>('orchestration.runCurrent', {
diff --git a/src/cli/runtime/orchestration-compatibility-envelope.ts b/src/cli/runtime/orchestration-compatibility-envelope.ts
index 8172e556dc1..7d6c0dfda80 100644
--- a/src/cli/runtime/orchestration-compatibility-envelope.ts
+++ b/src/cli/runtime/orchestration-compatibility-envelope.ts
@@ -1,12 +1,17 @@
 import { randomUUID } from 'node:crypto'
+import { readInjectedAgentSessionId } from '../../shared/agent-session-caller-env'
 import { readOrchestrationCompatibilityEvidence } from '../../shared/orchestration-compatibility-evidence'
 import type { RuntimeOrchestrationEnvelope } from '../../shared/runtime-rpc-envelope'
 
 export function createOrchestrationCompatibilityEnvelope(
   env: NodeJS.ProcessEnv
 ): RuntimeOrchestrationEnvelope {
+  const evidence = readOrchestrationCompatibilityEvidence(env)
+  // Read here, from this CLI's own environment only: the SSH paths build evidence from a remote
+  // shell's environment, where a session id could never name a session on this host.
+  const agentSessionId = readInjectedAgentSessionId(env)
   return {
     compatibilityInvocationId: randomUUID(),
-    orchestrationCompatibilityEvidence: readOrchestrationCompatibilityEvidence(env)
+    orchestrationCompatibilityEvidence: agentSessionId ? { ...evidence, agentSessionId } : evidence
   }
 }
diff --git a/src/main/claude/claude-structured-launch-resolution.ts b/src/main/claude/claude-structured-launch-resolution.ts
index a2b3d41bbfd..9821b6ab8ae 100644
--- a/src/main/claude/claude-structured-launch-resolution.ts
+++ b/src/main/claude/claude-structured-launch-resolution.ts
@@ -8,7 +8,7 @@ import type { AgentSessionJournalIdentity } from '../../shared/agent-session-jou
 import { agentSessionProviderHandleChainHead } from '../../shared/agent-session-provider-handle'
 import { LOCAL_EXECUTION_HOST_ID } from '../../shared/execution-host'
 import { withCliRuntimeOnPath } from '../../shared/node-cli-command-resolution'
-import { structuredWorkerChildIdentityEnv } from '../runtime/structured-worker-child-identity-env'
+import { structuredSessionChildIdentityEnv } from '../runtime/structured-session-child-identity-env'
 import {
   CLAUDE_AUTH_ENV_CONFLICT_MESSAGE,
   CLAUDE_AUTH_SWITCH_IN_PROGRESS_MESSAGE,
@@ -283,9 +283,8 @@ export function createClaudeStructuredLaunchResolver(
       (await deps.resolvePermissionMode?.()) ?? 'default'
     )
     const { command, env } = await resolveClaudeStructuredInvocation(deps, (base) =>
-      // Only a dispatched structured worker gets the orchestration identity and the Orca CLI on
-      // PATH; an ordinary chat session's env passes through untouched.
-      structuredWorkerChildIdentityEnv(record.sessionId, {
+      // Every structured session speaks orchestration as itself: its injected id and the Orca CLI.
+      structuredSessionChildIdentityEnv(record.sessionId, {
         ...base,
         // The turn translator relies on Claude's authoritative idle frame when no result arrives.
         [CLAUDE_SESSION_STATE_EVENTS_ENV]: '1'
diff --git a/src/main/codex/codex-structured-child-environment.ts b/src/main/codex/codex-structured-child-environment.ts
index 72bf17a1bce..38ea91abe26 100644
--- a/src/main/codex/codex-structured-child-environment.ts
+++ b/src/main/codex/codex-structured-child-environment.ts
@@ -1,6 +1,6 @@
 import type { CodexStructuredLaunch } from './codex-structured-session-state'
 import { CODEX_SPAWN_TOKEN_ENV } from './codex-structured-owner-identity'
-import { structuredWorkerChildIdentityEnv } from '../runtime/structured-worker-child-identity-env'
+import { structuredSessionChildIdentityEnv } from '../runtime/structured-session-child-identity-env'
 
 export function buildCodexStructuredChildEnvironment(
   launch: CodexStructuredLaunch,
@@ -8,9 +8,8 @@ export function buildCodexStructuredChildEnvironment(
   sessionId: string
 ): Record<string, string> {
   return {
-    // Only a dispatched structured worker gets the orchestration identity and the Orca CLI on
-    // PATH; an ordinary chat session's env passes through untouched.
-    ...structuredWorkerChildIdentityEnv(sessionId, {
+    // Every structured session speaks orchestration as itself: its injected id and the Orca CLI.
+    ...structuredSessionChildIdentityEnv(sessionId, {
       ...launch.env,
       ...(launch.codexHome ? { CODEX_HOME: launch.codexHome } : {})
     }),
diff --git a/src/main/ipc/pty/host-env/pi-agent.ts b/src/main/ipc/pty/host-env/pi-agent.ts
index 545d04d063d..aa8a7d2a21c 100644
--- a/src/main/ipc/pty/host-env/pi-agent.ts
+++ b/src/main/ipc/pty/host-env/pi-agent.ts
@@ -8,7 +8,11 @@ import {
   type PiAgentKind
 } from '../../../../shared/pi-agent-kind'
 import { readSessionShellStartupEnvVar } from '../../../pty/shell-startup-env'
-import { AGENT_HOOK_RUNTIME_ENV_KEYS, CLAUDE_CHILD_SESSION_STAMP_ENV_KEYS } from './spawn-env-keys'
+import {
+  AGENT_HOOK_RUNTIME_ENV_KEYS,
+  CLAUDE_CHILD_SESSION_STAMP_ENV_KEYS,
+  ORCA_AGENT_SESSION_CALLER_ENV_KEYS
+} from './spawn-env-keys'
 
 export function readEnvWithProcessFallback(
   baseEnv: Record<string, string>,
@@ -133,13 +137,15 @@ export function getInheritedAgentHookEnvKeysToDelete(
   return AGENT_HOOK_RUNTIME_ENV_KEYS.filter((key) => env[key] === undefined)
 }
 
-export function getInheritedClaudeSessionStampEnvKeysToDelete(
+export function getInheritedAgentSessionStampEnvKeysToDelete(
   spawnEnv: Record<string, string> | undefined
 ): string[] {
   const env = spawnEnv ?? {}
   // Why: strip only values inherited from the pty host; a caller that explicitly
-  // provides a stamp (deliberately spawning a nested Claude child) keeps it.
-  return CLAUDE_CHILD_SESSION_STAMP_ENV_KEYS.filter((key) => env[key] === undefined)
+  // provides a stamp (a nested Claude child, a structured session's terminal view) keeps it.
+  return [...CLAUDE_CHILD_SESSION_STAMP_ENV_KEYS, ...ORCA_AGENT_SESSION_CALLER_ENV_KEYS].filter(
+    (key) => env[key] === undefined
+  )
 }
 
 // Why: a nested terminal can inherit prior OpenCode/Pi/OMP overlay env; restore the user's recorded source dir, else strip only Orca-owned values.
diff --git a/src/main/ipc/pty/host-env/spawn-env-keys.ts b/src/main/ipc/pty/host-env/spawn-env-keys.ts
index cabbde7b0ec..ed070c7d043 100644
--- a/src/main/ipc/pty/host-env/spawn-env-keys.ts
+++ b/src/main/ipc/pty/host-env/spawn-env-keys.ts
@@ -1,3 +1,6 @@
+import { ORCA_AGENT_SESSION_ID_ENV } from '../../../../shared/agent-session-caller-env'
+import { ORCA_STRUCTURED_SESSION_ENV } from '../../../../shared/structured-session-marker'
+
 export const AGENT_HOOK_RUNTIME_ENV_KEYS = [
   'ORCA_AGENT_HOOK_PORT',
   'ORCA_AGENT_HOOK_TOKEN',
@@ -15,3 +18,9 @@ export const CLAUDE_CHILD_SESSION_STAMP_ENV_KEYS = [
   'CLAUDE_CODE_SESSION_ID',
   'CLAUDE_CODE_BRIDGE_SESSION_ID'
 ] as const
+
+// Why: Orca writes these only into a structured session's own spawn, so an inherited value means a pty host launched from inside one — every pane would claim that session as its orchestration caller.
+export const ORCA_AGENT_SESSION_CALLER_ENV_KEYS = [
+  ORCA_AGENT_SESSION_ID_ENV,
+  ORCA_STRUCTURED_SESSION_ENV
+] as const
diff --git a/src/main/ipc/pty/ipc/spawn-options.ts b/src/main/ipc/pty/ipc/spawn-options.ts
index a2adf48771b..eedbcefcf2a 100644
--- a/src/main/ipc/pty/ipc/spawn-options.ts
+++ b/src/main/ipc/pty/ipc/spawn-options.ts
@@ -7,7 +7,7 @@ import {
   mergePtyEnvDeletions,
   removeCodexHomeDeletionRequests,
   getInheritedAgentHookEnvKeysToDelete,
-  getInheritedClaudeSessionStampEnvKeysToDelete
+  getInheritedAgentSessionStampEnvKeysToDelete
 } from '../host-env/pi-agent'
 import { promoteAgentTeamsShimPath, deleteRequestedEnvKeys } from '../host-env/path'
 import { beginPtySpawnForWorktree } from '../host-env/fresh-spawn-routing'
@@ -43,7 +43,7 @@ export async function buildPtyIpcSpawnOptions(
     // Why: disable old hosts without removing ORCA_REAL_* while their Windows shim remains on PATH.
     ctx.isDaemonHostSpawn || args.connectionId ? LEGACY_TERMINAL_SHIM_REMOTE_ENV_KEYS : [],
     ctx.isDaemonHostSpawn ? getInheritedAgentHookEnvKeysToDelete(ctx.spawnEnv) : [],
-    getInheritedClaudeSessionStampEnvKeysToDelete(ctx.spawnEnv),
+    getInheritedAgentSessionStampEnvKeysToDelete(ctx.spawnEnv),
     ctx.skipCodexHomeEnv ? CODEX_HOME_ENV_KEYS : [],
     // Why: the persistent daemon compares its own merged CODEX_HOME pair;
     // main cannot safely decide ownership for a process it may not parent.
diff --git a/src/main/ipc/pty/runtime/spawn-options.ts b/src/main/ipc/pty/runtime/spawn-options.ts
index 67c633560e9..0a8b8cff801 100644
--- a/src/main/ipc/pty/runtime/spawn-options.ts
+++ b/src/main/ipc/pty/runtime/spawn-options.ts
@@ -9,7 +9,7 @@ import {
   mergePtyEnvDeletions,
   removeCodexHomeDeletionRequests,
   getInheritedAgentHookEnvKeysToDelete,
-  getInheritedClaudeSessionStampEnvKeysToDelete
+  getInheritedAgentSessionStampEnvKeysToDelete
 } from '../host-env/pi-agent'
 import { promoteAgentTeamsShimPath, deleteRequestedEnvKeys } from '../host-env/path'
 import {
@@ -73,7 +73,7 @@ export async function buildRuntimePtySpawnOptions(
     ctx.isDaemonHostSpawn || args.connectionId ? LEGACY_TERMINAL_SHIM_REMOTE_ENV_KEYS : [],
     ctx.isDaemonHostSpawn ? getInheritedAgentHookEnvKeysToDelete(ctx.env) : [],
     // Why: ungated, unlike the agent-hook keys — the local provider and the relay host also spread their own process.env into every spawn.
-    getInheritedClaudeSessionStampEnvKeysToDelete(ctx.env)
+    getInheritedAgentSessionStampEnvKeysToDelete(ctx.env)
   )
   if (ctx.skipCodexHomeEnv) {
     ctx.spawnOptions.envToDelete = mergePtyEnvDeletions(
diff --git a/src/main/pty/wsl-orca-env.ts b/src/main/pty/wsl-orca-env.ts
index 04035a957ca..5e89e4eb350 100644
--- a/src/main/pty/wsl-orca-env.ts
+++ b/src/main/pty/wsl-orca-env.ts
@@ -9,6 +9,7 @@ import {
   SETUP_AGENT_SEQUENCE_STARTUP_SCRIPT_ENV
 } from '../../shared/setup-agent-sequencing'
 import { getShellReadyWrapperRoot } from '../providers/local-pty-shell-ready-wrapper-root'
+import { ORCA_AGENT_SESSION_ID_ENV } from '../../shared/agent-session-caller-env'
 import { ORCA_IMAGE_PROTOCOL_ENV } from '../../shared/terminal-image-protocol'
 
 const WSLENV_ENTRY_SEPARATOR = ':'
@@ -74,6 +75,9 @@ export function addOrcaWslInteropEnv(env: Record<string, string>): void {
   // Why: wsl.exe only imports selected Windows env vars, so WSL needs the wrapper root, pane identity, and hook/OMP coordinates at start.
   const passthroughEntries = [
     'ORCA_TERMINAL_HANDLE/u',
+    // Why: a structured session's terminal view in a WSL shell must still present its id, so the
+    // host refuses the cross-host claim instead of the pane handle silently becoming its caller.
+    `${ORCA_AGENT_SESSION_ID_ENV}/u`,
     'ORCA_USER_DATA_PATH/p',
     // Why /p: the guest reads the content-addressed wrapper tree through /mnt/c,
     // and it cannot derive the hash segment from ORCA_USER_DATA_PATH alone.
diff --git a/src/main/runtime/rpc/methods/orchestration-structured-worker-session.test.ts b/src/main/runtime/rpc/methods/orchestration-structured-worker-session.test.ts
index 493f9d092c3..501897b8731 100644
--- a/src/main/runtime/rpc/methods/orchestration-structured-worker-session.test.ts
+++ b/src/main/runtime/rpc/methods/orchestration-structured-worker-session.test.ts
@@ -19,8 +19,8 @@ const {
 } = await import('./orchestration-structured-worker-session')
 const { isUnknownWorkerStartOutcome } = await import('./orchestration/worker/worker-topology')
 const { structuredWorkerIdentities } = await import('../../structured-worker-identity')
-const { structuredWorkerChildIdentityEnv } =
-  await import('../../structured-worker-child-identity-env')
+const { structuredSessionChildIdentityEnv } =
+  await import('../../structured-session-child-identity-env')
 
 function installHost() {
   const hold = vi.fn(async () => {})
@@ -83,7 +83,7 @@ describe('structured worker session hold', () => {
     createSpy.mockImplementation(async (args: { envelope: { sessionId: string } }) => {
       // `attach` is what spawns the provider child, and the child's env is read from the registry
       // at spawn time. Registering afterwards ships a worker with no ORCA_TERMINAL_HANDLE.
-      envAtSpawn = structuredWorkerChildIdentityEnv(args.envelope.sessionId, {})
+      envAtSpawn = structuredSessionChildIdentityEnv(args.envelope.sessionId, {})
       return { ok: true, value: { sessionId: args.envelope.sessionId } }
     })
     const created = await createStructuredWorkerSession({
diff --git a/src/main/runtime/rpc/orchestration-session-caller.test.ts b/src/main/runtime/rpc/orchestration-session-caller.test.ts
index d96e214d442..c91ad0ff169 100644
--- a/src/main/runtime/rpc/orchestration-session-caller.test.ts
+++ b/src/main/runtime/rpc/orchestration-session-caller.test.ts
@@ -43,7 +43,6 @@ const PARTY_NAMING_FIELDS = ['to', 'from', 'terminal', 'callerTerminalHandle'] a
 const NAMES_NO_RESOLVED_PARTY: Readonly<Record<string, string>> = {
   'orchestration.run from': 'retired; refused before any handler',
   'orchestration.runShow from': 'reads a Run by id; `from` is unused',
-  'orchestration.dispatchShow from': '`from` only fills the preview preamble text',
   'orchestration.workerStart terminal': 'adopts an existing PTY pane, which a session never has',
   'orchestration.federationAttachStart terminal': 'names the remote worker terminal',
   'orchestration.workerTerminalUserInput terminal': 'names the worker terminal'
@@ -59,6 +58,7 @@ const MINIMAL_PARAMS: Readonly<Record<string, Record<string, unknown>>> = {
   'orchestration.reply': { id: 'msg_missing', body: 'b' },
   'orchestration.ask': { question: 'q', to: 'term_worker' },
   'orchestration.dispatch': { task: 'task_missing', to: 'term_worker' },
+  'orchestration.dispatchShow': { task: 'task_missing', preamble: true },
   'orchestration.gateCreate': { task: 'task_missing', question: 'q' },
   'orchestration.gateResolve': { id: 'gate_missing', resolution: 'r' },
   'orchestration.gateList': {},
diff --git a/src/main/runtime/rpc/orchestration-session-caller.ts b/src/main/runtime/rpc/orchestration-session-caller.ts
index e4bd09f2619..deeeb397ca3 100644
--- a/src/main/runtime/rpc/orchestration-session-caller.ts
+++ b/src/main/runtime/rpc/orchestration-session-caller.ts
@@ -50,6 +50,8 @@ export const ORCHESTRATION_CALLER_PARAM: Readonly<Record<string, CallerParam>> =
   'orchestration.reply': 'from',
   'orchestration.ask': 'from',
   'orchestration.dispatch': 'from',
+  // The preview names its caller as the coordinator, exactly as the dispatch it previews does.
+  'orchestration.dispatchShow': 'from',
   'orchestration.gateCreate': 'from',
   'orchestration.gateResolve': 'from',
   'orchestration.gateList': 'from',
diff --git a/src/main/runtime/structured-worker-child-identity-env.test.ts b/src/main/runtime/structured-session-child-identity-env.test.ts
similarity index 88%
rename from src/main/runtime/structured-worker-child-identity-env.test.ts
rename to src/main/runtime/structured-session-child-identity-env.test.ts
index e966dd55824..7fe19c491e5 100644
--- a/src/main/runtime/structured-worker-child-identity-env.test.ts
+++ b/src/main/runtime/structured-session-child-identity-env.test.ts
@@ -5,7 +5,7 @@ import { installFakeAppEnvironment } from '../../../config/scripts/vitest-host-p
 const shim = vi.hoisted(() => ({ ensureLinuxTerminalOrcaCliShimDir: vi.fn() }))
 vi.mock('../cli/linux-terminal-orca-cli-shim', () => shim)
 
-import { structuredWorkerChildIdentityEnv } from './structured-worker-child-identity-env'
+import { structuredSessionChildIdentityEnv } from './structured-session-child-identity-env'
 import {
   mintStructuredWorkerHandle,
   mintStructuredWorkerPaneKey,
@@ -56,7 +56,7 @@ afterEach(() => {
   }
 })
 
-describe('structuredWorkerChildIdentityEnv', () => {
+describe('structuredSessionChildIdentityEnv', () => {
   it('marks an ordinary chat session as having NO identity, and grants it nothing', () => {
     // The marker names nothing — no handle, no pane key, no session id, no token — so it cannot be
     // replayed or impersonated, and it does not reach the hook, agent-row or mobile-projection
@@ -66,7 +66,7 @@ describe('structuredWorkerChildIdentityEnv', () => {
     pinPlatform('linux')
     installFakeAppEnvironment({ isPackaged: () => true, getPath: () => USER_DATA })
     const childEnv = { PATH: '/usr/bin' }
-    const env = structuredWorkerChildIdentityEnv(SESSION_ID, childEnv)
+    const env = structuredSessionChildIdentityEnv(SESSION_ID, childEnv)
     expect(env).toEqual({ PATH: '/usr/bin', ORCA_STRUCTURED_SESSION: '1' })
     expect(env.ORCA_TERMINAL_HANDLE).toBeUndefined()
     expect(env.ORCA_PANE_KEY).toBeUndefined()
@@ -82,7 +82,7 @@ describe('structuredWorkerChildIdentityEnv', () => {
     pinPlatform('linux')
     installFakeAppEnvironment({ isPackaged: () => true, getPath: () => USER_DATA })
     const handle = registerWorker()
-    const env = structuredWorkerChildIdentityEnv(SESSION_ID, { PATH: '/usr/bin:/bin' })
+    const env = structuredSessionChildIdentityEnv(SESSION_ID, { PATH: '/usr/bin:/bin' })
     expect(env.ORCA_TERMINAL_HANDLE).toBe(handle)
     expect(env.ORCA_CLI_COMMAND).toBe('orca')
     expect(env.PATH).toBe(`${SHIM_DIR}:/usr/bin:/bin`)
@@ -92,7 +92,7 @@ describe('structuredWorkerChildIdentityEnv', () => {
     pinPlatform('darwin')
     installFakeAppEnvironment({ isPackaged: () => true, getPath: () => USER_DATA })
     registerWorker()
-    const env = structuredWorkerChildIdentityEnv(SESSION_ID, { PATH: '/usr/bin' })
+    const env = structuredSessionChildIdentityEnv(SESSION_ID, { PATH: '/usr/bin' })
     expect(env.PATH).toBe(`${join(RESOURCES, 'bin')}:/usr/bin`)
   })
 
@@ -100,7 +100,7 @@ describe('structuredWorkerChildIdentityEnv', () => {
     pinPlatform('win32')
     installFakeAppEnvironment({ isPackaged: () => true, getPath: () => USER_DATA })
     registerWorker()
-    const env = structuredWorkerChildIdentityEnv(SESSION_ID, { Path: 'C:\\Windows' })
+    const env = structuredSessionChildIdentityEnv(SESSION_ID, { Path: 'C:\\Windows' })
     expect(env.Path).toBe(`${join(RESOURCES, 'bin')};C:\\Windows`)
     expect(env.PATH).toBeUndefined()
   })
@@ -109,7 +109,7 @@ describe('structuredWorkerChildIdentityEnv', () => {
     pinPlatform('darwin')
     installFakeAppEnvironment({ isPackaged: () => false, getPath: () => USER_DATA })
     registerWorker()
-    const env = structuredWorkerChildIdentityEnv(SESSION_ID, { PATH: '/usr/bin' })
+    const env = structuredSessionChildIdentityEnv(SESSION_ID, { PATH: '/usr/bin' })
     expect(env.PATH).toBe(`${join(USER_DATA, 'cli', 'bin')}:/usr/bin`)
   })
 
@@ -119,7 +119,7 @@ describe('structuredWorkerChildIdentityEnv', () => {
     pinPlatform('linux')
     installFakeAppEnvironment({ isPackaged: () => true, getPath: () => USER_DATA })
     registerWorker()
-    const env = structuredWorkerChildIdentityEnv(SESSION_ID, { PATH: '/usr/bin' })
+    const env = structuredSessionChildIdentityEnv(SESSION_ID, { PATH: '/usr/bin' })
     expect(env.ORCA_PANE_KEY).toBeUndefined()
     expect(Object.keys(env).filter((key) => key.includes('PANE'))).toEqual([])
   })
@@ -140,7 +140,7 @@ describe('structuredWorkerChildIdentityEnv', () => {
     installFakeAppEnvironment({ isPackaged: () => true, getPath: () => USER_DATA })
     registerWorker()
     expect(
-      structuredWorkerChildIdentityEnv(SESSION_ID, { PATH: '/usr/bin' }).ORCA_CLI_COMMAND
+      structuredSessionChildIdentityEnv(SESSION_ID, { PATH: '/usr/bin' }).ORCA_CLI_COMMAND
     ).not.toBe('orca-ide')
   })
 })
diff --git a/src/main/runtime/structured-worker-child-identity-env.ts b/src/main/runtime/structured-session-child-identity-env.ts
similarity index 50%
rename from src/main/runtime/structured-worker-child-identity-env.ts
rename to src/main/runtime/structured-session-child-identity-env.ts
index 6cf9f46e910..f2ab92b3d66 100644
--- a/src/main/runtime/structured-worker-child-identity-env.ts
+++ b/src/main/runtime/structured-session-child-identity-env.ts
@@ -1,62 +1,67 @@
 /**
- * The orchestration identity — and the CLI reachability — a structured worker's own child needs
- * to speak for itself.
+ * The orchestration identity — and the CLI reachability — a structured session's own child needs to
+ * speak for itself. Both providers' native launches (Claude, Codex) build their child env here.
  *
- * Without `ORCA_TERMINAL_HANDLE` the worker's Bash tool has nothing to pass as `--from`, and
- * `resolveOrchestrationTerminalHandle` falls back to a cwd lookup that returns whichever leaf in
- * the worktree comes first. Two attacks follow from that: a bare `check` reads and consumes a
- * SIBLING's dispatch mailbox, and a bare `send --type worker_done` can settle a sibling's
- * context-only dispatch, a tier that has no capability token to reject on.
+ * Every structured session carries `ORCA_AGENT_SESSION_ID`, the id Orca minted for it — never the
+ * provider's, which rotates on `/clear`. The CLI sends it as the caller, so a bare
+ * `orca orchestration check` acts as this session instead of guessing a terminal: with no pane of
+ * its own, every guess landed on a sibling, and a destructive `check` consumed that sibling's mail.
+ * Identity by session id assumes one machine and one user; crossing a host boundary (SSH, a paired
+ * peer) re-opens that decision, and the host refuses a session claim from across one.
+ *
+ * A dispatched structured worker also keeps the `structworker_` handle it was minted, for the
+ * handle-based surfaces outside orchestration; for orchestration the id wins and the host maps it
+ * back to that handle, so the worker keeps one identity.
  *
  * `ORCA_CLI_COMMAND: 'orca'` is honest ONLY because of the PATH prepend below. Orca's Linux CLI
  * installs as `orca-ide` so it never claims GNOME Orca's /usr/bin/orca (stablyai/orca#7904), and
  * on packaged macOS/Windows the bundled launcher is reachable only from the app's own resources
- * dir. A PTY worker gets that treatment from `buildPtyHostEnv`; a structured worker has no PTY,
- * so it applies the SAME function here rather than a second, drifting copy of the rule.
+ * dir. A PTY agent gets that treatment from `buildPtyHostEnv`; a structured session has no PTY, so
+ * it applies the SAME function here rather than a second, drifting copy of the rule.
  *
  * Deliberately NOT `ORCA_PANE_KEY`. Claude structured sessions run hooks, and a pane key in their
  * environment starts flowing into hook-emitted agent-status payloads and the hook-attestation,
  * agent-row and mobile-projection pipelines, every one of which assumes a pane key names a live
  * PTY leaf. It would also open `selectExactWorkerProviderSession`, which is fail-closed today
- * precisely because a structured session emits no hook agent status. The CLI needs none of it once
- * the handle is present.
+ * precisely because a structured session emits no hook agent status.
  *
- * A session that is not a dispatched worker gets ONE variable, `ORCA_STRUCTURED_SESSION`, and it
- * names nothing: no handle, no pane key, no session id, no token. Its only meaning is "this child
- * is a structured session with no orchestration identity", which is what a verb needs in order to
- * REFUSE rather than guess one. Because it names nothing it cannot be replayed, cannot impersonate,
- * and cannot flow into the hook, agent-row or mobile-projection pipelines the way a pane key would
- * — which is why it is a different decision from withholding `ORCA_PANE_KEY`, not a reversal of it.
- * Without it, `check` fell through to the active-terminal guess and destructively consumed a
- * SIBLING pane's oldest unread batch; `requireUnambiguous` only narrows that, because with exactly
- * one terminal pane in the worktree the guess still resolves — to a sibling.
+ * The identity-less marker (`ORCA_STRUCTURED_SESSION`) is no longer written: a child with an id is
+ * never identity-less, so a marker inherited from an Orca launched inside an older session is inert.
  *
  * The handle is read from the registry at spawn time, so an in-host recovery respawn re-bakes the
  * SAME handle rather than a stale or fresh one.
  */
 
 import { getAppEnvironment, hasAppEnvironment } from '../../shared/app-environment'
+import { ORCA_AGENT_SESSION_ID_ENV } from '../../shared/agent-session-caller-env'
 import { prependOrcaCliDirToChildPath } from '../cli/orca-cli-child-path'
-import { ORCA_STRUCTURED_SESSION_ENV } from '../../shared/structured-session-marker'
 import { structuredWorkerIdentities } from './structured-worker-identity'
 
-export function structuredWorkerChildIdentityEnv(
+export function structuredSessionChildIdentityEnv(
   sessionId: string,
   childEnv: Record<string, string>
 ): Record<string, string> {
   const identity = structuredWorkerIdentities.getBySessionId(sessionId)
-  if (!identity) {
-    return { ...childEnv, [ORCA_STRUCTURED_SESSION_ENV]: '1' }
-  }
   const env: Record<string, string> = {
     ...childEnv,
-    ORCA_TERMINAL_HANDLE: identity.handle,
+    ...(identity ? { ORCA_TERMINAL_HANDLE: identity.handle } : {}),
+    [ORCA_AGENT_SESSION_ID_ENV]: sessionId,
     ORCA_CLI_COMMAND: 'orca'
   }
   applyOrcaCliPath(env)
   return env
 }
 
+/**
+ * The same session id for its terminal view, so switching views never changes who the session is.
+ * Same-host only, as above: the host refuses the claim from a terminal that runs in WSL or over SSH.
+ */
+export function structuredSessionTerminalViewEnv(
+  sessionId: string | undefined
+): Record<string, string> {
+  return sessionId ? { [ORCA_AGENT_SESSION_ID_ENV]: sessionId } : {}
+}
+
 /**
  * A host with no app environment installed — a plain-Node fork, or a unit test — has no userData
  * root to resolve, and inventing one would write a shim into the wrong directory.
diff --git a/src/main/runtime/structured-worker-identity.test.ts b/src/main/runtime/structured-worker-identity.test.ts
index 98989a85891..21d56d7fa37 100644
--- a/src/main/runtime/structured-worker-identity.test.ts
+++ b/src/main/runtime/structured-worker-identity.test.ts
@@ -5,7 +5,7 @@ import {
   structuredAgentSessionTabId
 } from '../../shared/structured-agent-session-projection'
 import { selectExactWorkerProviderSession } from './orchestration/worker-provider-session'
-import { structuredWorkerChildIdentityEnv } from './structured-worker-child-identity-env'
+import { structuredSessionChildIdentityEnv } from './structured-session-child-identity-env'
 import {
   StructuredWorkerIdentityRegistry,
   isStructuredWorkerHandle,
@@ -294,7 +294,7 @@ describe('structured workers stay outside the PTY-only fail-closed paths', () =>
       hostScope: { kind: 'local', hostId: 'local' }
     })
     try {
-      const env = structuredWorkerChildIdentityEnv(SESSION_ID, {})
+      const env = structuredSessionChildIdentityEnv(SESSION_ID, {})
       // Registered, so this is a populated env — not the empty one an unregistered session gets,
       // which would satisfy the pane-key assertion for the wrong reason.
       expect(env.ORCA_TERMINAL_HANDLE).toBe(handle)
diff --git a/src/main/runtime/structured-worker-identity.ts b/src/main/runtime/structured-worker-identity.ts
index c32d6c37f15..77357cf1e99 100644
--- a/src/main/runtime/structured-worker-identity.ts
+++ b/src/main/runtime/structured-worker-identity.ts
@@ -26,14 +26,19 @@ import {
 } from '../../shared/structured-agent-session-projection'
 import { isTerminalLeafId, makePaneKey, parsePaneKey } from '../../shared/stable-pane-id'
 import { isOrcaSessionId, type OrcaSessionId } from '../../shared/orca-session-address'
+import {
+  STRUCTURED_WORKER_HANDLE_PREFIX,
+  isStructuredWorkerHandle
+} from '../../shared/structured-worker-handle'
 import {
   parseWorkerTerminalHostScope,
   type WorkerTerminalHostScope
 } from './orchestration/worker-terminal-process-liveness'
 
-// Deliberately not `term_`: `issueHandle` revalidates the renderer graph epoch against the
-// renderer-driven leaves map, so a main-minted `term_` leaf evaporates on the next window reload.
-export const STRUCTURED_WORKER_HANDLE_PREFIX = 'structworker_'
+export {
+  STRUCTURED_WORKER_HANDLE_PREFIX,
+  isStructuredWorkerHandle
+} from '../../shared/structured-worker-handle'
 export const STRUCTURED_WORKER_INCARNATION_PREFIX = 'structured:'
 
 export type StructuredWorkerIdentity = {
@@ -47,10 +52,6 @@ export type StructuredWorkerIdentity = {
   hostScope: WorkerTerminalHostScope
 }
 
-export function isStructuredWorkerHandle(handle: string | null | undefined): boolean {
-  return typeof handle === 'string' && handle.startsWith(STRUCTURED_WORKER_HANDLE_PREFIX)
-}
-
 export function mintStructuredWorkerHandle(): string {
   return `${STRUCTURED_WORKER_HANDLE_PREFIX}${randomUUID()}`
 }
diff --git a/src/main/ssh/ssh-remote-cli-host-passthrough.ts b/src/main/ssh/ssh-remote-cli-host-passthrough.ts
index d62a23d8e30..4490343504f 100644
--- a/src/main/ssh/ssh-remote-cli-host-passthrough.ts
+++ b/src/main/ssh/ssh-remote-cli-host-passthrough.ts
@@ -13,6 +13,8 @@ import {
   ORCHESTRATION_COMPATIBILITY_HOST_INCARNATION_ENV,
   ORCHESTRATION_COMPATIBILITY_HOST_KIND_ENV
 } from '../../shared/orchestration-compatibility-evidence'
+import { ORCA_AGENT_SESSION_ID_ENV } from '../../shared/agent-session-caller-env'
+import { ORCA_STRUCTURED_SESSION_ENV } from '../../shared/structured-session-marker'
 import {
   REMOTE_ARTIFACT_INPUT_ENV,
   sshArtifactSourceKey,
@@ -131,6 +133,10 @@ export function buildHostCliEnv(args: {
   delete env[ORCHESTRATION_COMPATIBILITY_HOST_INCARNATION_ENV]
   delete env[ORCHESTRATION_COMPATIBILITY_ATTACHMENT_ENV]
   delete env[REMOTE_ARTIFACT_INPUT_ENV]
+  // Why: a remote command must never claim a local agent session. The host's env carries one only
+  // when Orca was launched inside a session, and identity by session id is same-host only.
+  delete env[ORCA_AGENT_SESSION_ID_ENV]
+  delete env[ORCA_STRUCTURED_SESSION_ENV]
   if (args.runtimeAuthority) {
     env[ORCHESTRATION_COMPATIBILITY_HOST_KIND_ENV] = 'ssh'
     env[ORCHESTRATION_COMPATIBILITY_HOST_ID_ENV] = args.runtimeAuthority.targetId
diff --git a/src/shared/agent-session-caller-env.ts b/src/shared/agent-session-caller-env.ts
new file mode 100644
index 00000000000..d0f5e860559
--- /dev/null
+++ b/src/shared/agent-session-caller-env.ts
@@ -0,0 +1,17 @@
+/**
+ * The Orca-minted agent session id, injected into a structured session's own child processes, in
+ * native chat and in terminal view alike. When it is present it IS the orchestration caller: the
+ * CLI sends it in the orchestration envelope and the host resolves it to the session's actor, so no
+ * terminal is resolved or guessed on its behalf.
+ *
+ * Identity by session id assumes one machine and one user. A host boundary (SSH, a paired peer,
+ * WSL) re-opens that decision, which is why nothing forwards the id across one as a caller.
+ */
+export const ORCA_AGENT_SESSION_ID_ENV = 'ORCA_AGENT_SESSION_ID'
+
+export function readInjectedAgentSessionId(
+  env: Readonly<Record<string, string | undefined>> = process.env
+): string | undefined {
+  const value = env[ORCA_AGENT_SESSION_ID_ENV]?.trim()
+  return value ? value : undefined
+}
diff --git a/src/shared/orca-session-address.ts b/src/shared/orca-session-address.ts
index 339ccb01f43..9762b95d63c 100644
--- a/src/shared/orca-session-address.ts
+++ b/src/shared/orca-session-address.ts
@@ -1,11 +1,12 @@
 import { isAgentSessionId } from './agent-session-record'
+import { STRUCTURED_WORKER_HANDLE_PREFIX } from './structured-worker-handle'
 
 /**
- * The Orca session id is the id Orca minted for a structured session (its session record id), never
- * the provider's own session id. Orchestration stores, bare, the one the agent is addressed by: for
- * a `/clear`ed chat, its lineage root's, not the live session's. Mail addresses the session as
- * `session:<id>`, beside `run:<id>` and `dispatch:<id>`, and derives that spelling here rather than
- * storing it.
+ * The Orca session id is the id Orca minted for a structured session (its session record id, the
+ * value of `ORCA_AGENT_SESSION_ID`), never the provider's own session id. Orchestration stores,
+ * bare, the one the agent is addressed by: for a `/clear`ed chat, its lineage root's, not the live
+ * session's. Mail addresses the session as `session:<id>`, beside `run:<id>` and `dispatch:<id>`,
+ * and derives that spelling here rather than storing it.
  *
  * Where the session runs is not part of the id; it is read from the session record when needed. PTY
  * agents have none today, and never a pane-keyed one: a pane outlives the agent in it, so such an id
@@ -24,7 +25,7 @@ export type OrcaSessionAddress = string & { readonly [orcaSessionAddressBrand]:
 // Terminal handles (`term_` from the PTY runtime, `structworker_` from structured-worker-identity)
 // share the session-id charset. A handle is never a session, so one handed over by mistake must not
 // become a durable Orca session id.
-const TERMINAL_HANDLE_PREFIXES = ['term_', 'structworker_'] as const
+const TERMINAL_HANDLE_PREFIXES = ['term_', STRUCTURED_WORKER_HANDLE_PREFIX] as const
 
 export function isOrcaSessionId(id: string): id is OrcaSessionId {
   return isAgentSessionId(id) && !TERMINAL_HANDLE_PREFIXES.some((prefix) => id.startsWith(prefix))
diff --git a/src/shared/structured-session-marker.ts b/src/shared/structured-session-marker.ts
index 36c90f432ee..1725a6ef337 100644
--- a/src/shared/structured-session-marker.ts
+++ b/src/shared/structured-session-marker.ts
@@ -1,13 +1,20 @@
+import { readInjectedAgentSessionId } from './agent-session-caller-env'
+
 /**
- * The marker a structured chat session's child carries when it has NO orchestration identity.
+ * The marker a structured chat session's child carried when it had NO orchestration identity.
  *
- * It names nothing on purpose — no handle, no pane key, no session id, no token — so it grants no
- * authority and cannot be replayed or impersonated. Its only job is to let a CLI verb that would
- * otherwise GUESS an implicit terminal refuse instead: a structured session has no pane, so every
- * guess resolves to a sibling, and `orchestration check` is destructive by default.
+ * Current hosts no longer write it: every structured child carries its injected session id
+ * instead. The reader stays for a child spawned by an Orca that predates injection, which can still
+ * reach a newer CLI through a global install — it must refuse, not guess, because a structured
+ * session has no pane, so every implicit-terminal guess resolves to a sibling and
+ * `orchestration check` is destructive by default.
  */
 export const ORCA_STRUCTURED_SESSION_ENV = 'ORCA_STRUCTURED_SESSION'
 
+/** An injected session id is an identity, so a child carrying one is never identity-less. */
 export function isStructuredSessionWithoutIdentity(env: NodeJS.ProcessEnv = process.env): boolean {
-  return (env[ORCA_STRUCTURED_SESSION_ENV] ?? '').length > 0
+  return (
+    (env[ORCA_STRUCTURED_SESSION_ENV] ?? '').length > 0 &&
+    readInjectedAgentSessionId(env) === undefined
+  )
 }
diff --git a/src/shared/structured-worker-handle.ts b/src/shared/structured-worker-handle.ts
new file mode 100644
index 00000000000..e36df813570
--- /dev/null
+++ b/src/shared/structured-worker-handle.ts
@@ -0,0 +1,7 @@
+// Deliberately not `term_`: `issueHandle` revalidates the renderer graph epoch against the
+// renderer-driven leaves map, so a main-minted `term_` leaf evaporates on the next window reload.
+export const STRUCTURED_WORKER_HANDLE_PREFIX = 'structworker_'
+
+export function isStructuredWorkerHandle(handle: string | null | undefined): boolean {
+  return typeof handle === 'string' && handle.startsWith(STRUCTURED_WORKER_HANDLE_PREFIX)
+}