refactor(native-chat): unify host snapshot versioning

src/main/runtime/orca-runtime-apply-mobile-session-tab-navigation.ts

@@ -142,7 +142,7 @@ export class OrcaRuntimeWithApplyMobileSessionTabNavigation extends OrcaRuntimeW
       tabs
     }
     this.persistHeadlessTerminalActiveLeaf(worktreeId, activeTab)
-    this.mobileSessionTabsByWorktree.set(worktreeId, nextSnapshot)
+    this.storeMobileSessionSnapshot(worktreeId, nextSnapshot)
     this.emitMobileSessionTabsSnapshot(nextSnapshot)
   }
 

src/main/runtime/orca-runtime-close-headless-mobile-terminal-tab.ts

@@ -107,7 +107,7 @@ export class OrcaRuntimeWithCloseHeadlessMobileTerminalTab extends OrcaRuntimeWi
         : {}),
       tabs: nextTabs
     }
-    this.mobileSessionTabsByWorktree.set(worktreeId, nextSnapshot)
+    this.storeMobileSessionSnapshot(worktreeId, nextSnapshot)
     this.emitMobileSessionTabsSnapshot(nextSnapshot)
   }
 

src/main/runtime/orca-runtime-close-structured-agent-session-tab.ts

@@ -39,7 +39,7 @@ export class OrcaRuntimeWithCloseStructuredAgentSessionTab extends OrcaRuntimeWi
       })),
       tabs: nextTabs
     }
-    this.mobileSessionTabsByWorktree.set(worktreeId, nextSnapshot)
+    this.storeMobileSessionSnapshot(worktreeId, nextSnapshot)
     this.emitMobileSessionTabsSnapshot(nextSnapshot)
   }
 
@@ -49,7 +49,7 @@ export class OrcaRuntimeWithCloseStructuredAgentSessionTab extends OrcaRuntimeWi
   protected republishMobileSessionTabsSnapshot(worktreeId: string): void {
     const snapshot = this.mobileSessionTabsByWorktree.get(worktreeId)
     if (snapshot) {
-      this.mobileSessionTabsByWorktree.set(worktreeId, {
+      this.storeMobileSessionSnapshot(worktreeId, {
         ...snapshot,
         snapshotVersion: snapshot.snapshotVersion + 1
       })
@@ -161,7 +161,7 @@ export class OrcaRuntimeWithCloseStructuredAgentSessionTab extends OrcaRuntimeWi
       })),
       tabs: nextTabs
     }
-    this.mobileSessionTabsByWorktree.set(worktreeId, nextSnapshot)
+    this.storeMobileSessionSnapshot(worktreeId, nextSnapshot)
     this.emitMobileSessionTabsSnapshot(nextSnapshot)
     return true
   }
@@ -203,7 +203,7 @@ export class OrcaRuntimeWithCloseStructuredAgentSessionTab extends OrcaRuntimeWi
       focusesHost,
       publicationEpoch: `headless:${Date.now().toString(36)}`
     })
-    this.mobileSessionTabsByWorktree.set(worktreeId, nextSnapshot)
+    this.storeMobileSessionSnapshot(worktreeId, nextSnapshot)
     // Why: browser group membership is otherwise live-only; persist it so a
     // later rebuild keeps the browser in its group instead of coalescing left.
     if (placedInTargetGroup && nextSnapshot.tabGroupLayout) {

src/main/runtime/orca-runtime-create-runtime-owned-mobile-session-terminal.ts

@@ -139,7 +139,7 @@ export class OrcaRuntimeWithCreateRuntimeOwnedMobileSessionTerminal extends Orca
       ...(existing?.tabGroupLayout ? { tabGroupLayout: existing.tabGroupLayout } : {}),
       tabs
     }
-    this.mobileSessionTabsByWorktree.set(worktreeId, next)
+    this.storeMobileSessionSnapshot(worktreeId, next)
     const result = this.toMobileSessionTabsResult(next)
     const changeSequence = ++this.mobileSessionTabsChangeSequence
     for (const subscription of this.mobileSessionTabListeners) {

src/main/runtime/orca-runtime-has-exact-persisted-terminal-surface-identity.ts

@@ -65,7 +65,7 @@ export class OrcaRuntimeWithHasExactPersistedTerminalSurfaceIdentity extends Orc
         exactOnly: true
       })
       if (retired) {
-        this.mobileSessionTabsByWorktree.set(candidate.worktreeId, retired.snapshot)
+        this.storeMobileSessionSnapshot(candidate.worktreeId, retired.snapshot)
         this.notifyMobileSessionTabsChanged(candidate.worktreeId)
       }
     }

src/main/runtime/orca-runtime-hydrate-headless-mobile-session-tabs-from-workspace-session.ts

@@ -236,7 +236,7 @@ export class OrcaRuntimeWithHydrateHeadlessMobileSessionTabsFromWorkspaceSession
       if (existing && headlessMobileSnapshotContentUnchanged(existing, nextSnapshot)) {
         continue
       }
-      this.mobileSessionTabsByWorktree.set(entryWorktreeId, nextSnapshot)
+      this.storeMobileSessionSnapshot(entryWorktreeId, nextSnapshot)
     }
     return reconciledWorktreeIds
   }

src/main/runtime/orca-runtime-move-headless-mobile-session-tab.ts

@@ -72,7 +72,7 @@ export class OrcaRuntimeWithMoveHeadlessMobileSessionTab extends OrcaRuntimeWith
     if (nextGroups.length > 1 && snapshot.tabGroupLayout) {
       this.persistHeadlessTabGroups(worktreeId, nextGroups, snapshot.tabGroupLayout)
     }
-    this.mobileSessionTabsByWorktree.set(worktreeId, nextSnapshot)
+    this.storeMobileSessionSnapshot(worktreeId, nextSnapshot)
     this.emitMobileSessionTabsSnapshot(nextSnapshot)
     return { moved: true }
   }
@@ -111,7 +111,7 @@ export class OrcaRuntimeWithMoveHeadlessMobileSessionTab extends OrcaRuntimeWith
       tabGroupLayout: split.layout
     }
     this.persistHeadlessTabGroups(worktreeId, split.groups, split.layout)
-    this.mobileSessionTabsByWorktree.set(worktreeId, nextSnapshot)
+    this.storeMobileSessionSnapshot(worktreeId, nextSnapshot)
     this.emitMobileSessionTabsSnapshot(nextSnapshot)
     return { moved: true }
   }
@@ -147,7 +147,7 @@ export class OrcaRuntimeWithMoveHeadlessMobileSessionTab extends OrcaRuntimeWith
       tabGroupLayout: layout
     }
     this.persistHeadlessTabGroups(worktreeId, moved.groups, layout)
-    this.mobileSessionTabsByWorktree.set(worktreeId, nextSnapshot)
+    this.storeMobileSessionSnapshot(worktreeId, nextSnapshot)
     this.emitMobileSessionTabsSnapshot(nextSnapshot)
     return { moved: true }
   }

src/main/runtime/orca-runtime-persist-headless-session-tab-props.ts

@@ -95,7 +95,7 @@ export class OrcaRuntimeWithPersistHeadlessSessionTabProps extends OrcaRuntimeWi
       snapshotVersion: snapshot.snapshotVersion + 1,
       tabs
     }
-    this.mobileSessionTabsByWorktree.set(worktreeId, nextSnapshot)
+    this.storeMobileSessionSnapshot(worktreeId, nextSnapshot)
     this.emitMobileSessionTabsSnapshot(nextSnapshot)
   }
 
@@ -181,7 +181,7 @@ export class OrcaRuntimeWithPersistHeadlessSessionTabProps extends OrcaRuntimeWi
       snapshotVersion: snapshot.snapshotVersion + 1,
       tabs
     }
-    this.mobileSessionTabsByWorktree.set(worktreeId, nextSnapshot)
+    this.storeMobileSessionSnapshot(worktreeId, nextSnapshot)
     this.emitMobileSessionTabsSnapshot(nextSnapshot)
   }
 }

src/main/runtime/orca-runtime-persist-terminal-surface-retirements.ts

@@ -173,7 +173,7 @@ export class OrcaRuntimeWithPersistTerminalSurfaceRetirements extends OrcaRuntim
           : {})
       })
       if (retired) {
-        this.mobileSessionTabsByWorktree.set(worktreeId, retired.snapshot)
+        this.storeMobileSessionSnapshot(worktreeId, retired.snapshot)
         this.notifyMobileSessionTabsChanged(worktreeId)
       }
     }

src/main/runtime/orca-runtime-publish-pty-backed-mobile-session-terminal.ts

@@ -142,7 +142,7 @@ export class OrcaRuntimeWithPublishPtyBackedMobileSessionTerminal extends OrcaRu
       ...(existing?.tabGroupLayout ? { tabGroupLayout: existing.tabGroupLayout } : {}),
       tabs
     }
-    this.mobileSessionTabsByWorktree.set(worktreeId, next)
+    this.storeMobileSessionSnapshot(worktreeId, next)
     if (args.notify !== false) {
       this.notifyMobileSessionTabsChanged(worktreeId)
     }

src/main/runtime/orca-runtime-reconcile-headless-mobile-session-browser-tabs.ts

@@ -47,7 +47,7 @@ export class OrcaRuntimeWithReconcileHeadlessMobileSessionBrowserTabs extends Or
     const active = activeStillPresent
       ? null
       : (nextTabs.find((tab) => tab.isActive) ?? nextTabs[0] ?? null)
-    this.mobileSessionTabsByWorktree.set(worktreeId, {
+    this.storeMobileSessionSnapshot(worktreeId, {
       ...existing,
       publicationEpoch: `headless-hydrated:${Date.now().toString(36)}`,
       snapshotVersion: existing.snapshotVersion + 1,

src/main/runtime/orca-runtime-restore-live-paired-renderer-session-owned-mobile-terminals.ts

@@ -39,7 +39,7 @@ export class OrcaRuntimeWithRestoreLivePairedRendererSessionOwnedMobileTerminals
         continue
       }
       if (!existing) {
-        this.mobileSessionTabsByWorktree.set(targetWorktreeId, {
+        this.storeMobileSessionSnapshot(targetWorktreeId, {
           worktree: targetWorktreeId,
           publicationEpoch: `renderer-rescue:${Date.now().toString(36)}`,
           snapshotVersion: 0,

src/main/runtime/orca-runtime-restore-structured-agent-session-tabs-once.ts

@@ -94,7 +94,7 @@ export class OrcaRuntimeWithRestoreStructuredAgentSessionTabsOnce extends OrcaRu
         ),
         tabs: existing.tabs.map((tab) => ({ ...tab, isActive: tab.id === id }))
       }
-      this.mobileSessionTabsByWorktree.set(input.workspaceId, snapshot)
+      this.storeMobileSessionSnapshot(input.workspaceId, snapshot)
       if (input.notify !== false) {
         this.emitMobileSessionTabsSnapshot(snapshot)
       }
@@ -143,7 +143,7 @@ export class OrcaRuntimeWithRestoreStructuredAgentSessionTabsOnce extends OrcaRu
       ...(existing?.tabGroupLayout ? { tabGroupLayout: existing.tabGroupLayout } : {}),
       tabs
     }
-    this.mobileSessionTabsByWorktree.set(input.workspaceId, snapshot)
+    this.storeMobileSessionSnapshot(input.workspaceId, snapshot)
     if (input.notify !== false) {
       this.emitMobileSessionTabsSnapshot(snapshot)
     }

src/main/runtime/orca-runtime-runtime-id.ts

@@ -96,6 +96,21 @@ export class OrcaRuntimeWithRuntimeId {
 
   protected mobileSessionTabsByWorktree = new Map<string, RuntimeMobileSessionTabsSnapshot>()
 
+  /** Single host writer for mobile session snapshots; versions are total-order stamps. */
+  protected storeMobileSessionSnapshot(
+    worktreeId: string,
+    snapshot: RuntimeMobileSessionTabsSnapshot
+  ): RuntimeMobileSessionTabsSnapshot {
+    const existing = this.mobileSessionTabsByWorktree.get(worktreeId)
+    const snapshotVersion = existing
+      ? Math.max(snapshot.snapshotVersion, existing.snapshotVersion + 1)
+      : snapshot.snapshotVersion
+    const stamped =
+      snapshotVersion === snapshot.snapshotVersion ? snapshot : { ...snapshot, snapshotVersion }
+    this.mobileSessionTabsByWorktree.set(worktreeId, stamped)
+    return stamped
+  }
+
   protected structuredAgentSessionTabRestorePromise: Promise<void> | null = null
 
   protected structuredAgentSessionStartupRestorePromise: Promise<void> | null = null

src/main/runtime/orca-runtime-stop-requested-pty-ids.ts

@@ -57,7 +57,7 @@ export class OrcaRuntimeWithStopRequestedPtyIds extends OrcaRuntimeWithRuntimeId
     resolveOwner: (handle) => this.resolveNativeChatLaunchDraftOwner(handle),
     listMobileSnapshots: () => this.mobileSessionTabsByWorktree,
     setMobileSnapshot: (worktreeId, snapshot) =>
-      this.mobileSessionTabsByWorktree.set(worktreeId, snapshot),
+      this.storeMobileSessionSnapshot(worktreeId, snapshot),
     scheduleMobileSnapshot: (worktreeId) => this.scheduleMobileSessionTabsChanged(worktreeId),
     notifyResolved: (tabId, resolution, event) => {
       this.notifier?.nativeChatLaunchDraftResolved?.(tabId, resolution)

src/main/runtime/orca-runtime-stored-mobile-snapshot-has-stale-preserved-tab.ts

@@ -8,7 +8,6 @@ import type {
 import { getMobileSessionSnapshotTabIdentityKeys } from './mobile-session-tab-merge'
 import { getRuntimeBrowserPageRegistry } from './runtime-browser-page-registry'
 import { sameRuntimeBrowserPlacement } from '../../shared/runtime-browser-placement'
-import { createHash } from 'node:crypto'
 import type { ClientHostedBrowserRowsEvent } from '../../shared/client-hosted-browser-rows'
 
 export class OrcaRuntimeWithStoredMobileSnapshotHasStalePreservedTab extends OrcaRuntimeWithMergePreservedHeadlessMobileSessionTabs {
@@ -115,23 +114,14 @@ export class OrcaRuntimeWithStoredMobileSnapshotHasStalePreservedTab extends Orc
 
   protected getMergedMobileSessionPublicationEpoch(
     snapshot: RuntimeMobileSessionTabsSnapshot,
-    preservedTabs: readonly RuntimeMobileSessionSnapshotTab[]
+    _preservedTabs: readonly RuntimeMobileSessionSnapshotTab[]
   ): string {
     // Why: preserved snapshots can merge repeatedly; strip the prior merge suffix first so the publication epoch stays idempotent.
     const normalizedPublicationEpoch = snapshot.publicationEpoch.split(':headless-merge:')[0]
-    const signature = createHash('sha1')
-      .update(
-        preservedTabs
-          .map((tab) =>
-            tab.type === 'terminal'
-              ? `${tab.id}:${tab.parentTabId}:${tab.ptyId ?? ''}:${tab.leafId}`
-              : tab.id
-          )
-          .join('|')
-      )
-      .digest('hex')
-      .slice(0, 12)
-    return `${normalizedPublicationEpoch}:headless-merge:${signature}`
+    // The epoch identifies the publisher generation, not the merged content.
+    // Content changes are ordered by snapshotVersion, so encoding a merge hash
+    // here would make the identity oscillate and permanently fence later rows.
+    return normalizedPublicationEpoch
   }
 
   /** Serves a hydrating host renderer; the publisher counts this as a delivery, not a read. */

src/main/runtime/orca-runtime-sync-mobile-session-tabs.ts

@@ -167,7 +167,7 @@ export class OrcaRuntimeWithSyncMobileSessionTabs extends OrcaRuntimeWithWriteOr
       const storedVersion = existing
         ? Math.max(nextSnapshot.snapshotVersion, existing.snapshotVersion + 1)
         : nextSnapshot.snapshotVersion
-      this.mobileSessionTabsByWorktree.set(
+      this.storeMobileSessionSnapshot(
         snapshot.worktree,
         storedVersion === nextSnapshot.snapshotVersion
           ? nextSnapshot
@@ -195,7 +195,7 @@ export class OrcaRuntimeWithSyncMobileSessionTabs extends OrcaRuntimeWithWriteOr
             preserved.tabs.length === existing.tabs.length &&
             preserved.tabs.every((tab, index) => tab === existing.tabs[index])
           if (!preservedIsNoOp) {
-            this.mobileSessionTabsByWorktree.set(worktreeId, preserved)
+            this.storeMobileSessionSnapshot(worktreeId, preserved)
           }
           // Why: the stored entry is no longer the renderer's publication, so a
           // future renderer frame must be re-merged even if it reuses the pair.

src/main/runtime/orca-runtime-sync-window-graph.ts

@@ -238,7 +238,7 @@ export class OrcaRuntimeWithSyncWindowGraph extends OrcaRuntimeWithAttachWindow
       // the PTY touch path does) or the re-emitted payload — e.g. the
       // pending-handle → ready flip — is discarded and the client stays stale.
       // The accepted-renderer tracking is untouched: this is a main-local bump.
-      this.mobileSessionTabsByWorktree.set(worktreeId, {
+      this.storeMobileSessionSnapshot(worktreeId, {
         ...stored,
         snapshotVersion: stored.snapshotVersion + 1
       })

src/main/runtime/orca-runtime-tests/mobile-session-tabs-part-06.spec.ts

@@ -595,7 +595,7 @@ describe('OrcaRuntimeService', () => {
     const secondMerge = await runtime.listMobileSessionTabs(`id:${TEST_WORKTREE_ID}`)
 
     expect(secondMerge.publicationEpoch).toBe(firstMerge.publicationEpoch)
-    expect(secondMerge.publicationEpoch.match(/:headless-merge:/g) ?? []).toHaveLength(1)
+    expect(secondMerge.publicationEpoch).toBe('headless:stable-epoch')
   })
 
   it('keeps the graph ready when a mobile snapshot references a removed folder workspace', () => {

src/main/runtime/orca-runtime-touch-mobile-session-tabs-for-worktree.ts

@@ -21,7 +21,7 @@ export class OrcaRuntimeWithTouchMobileSessionTabsForWorktree extends OrcaRuntim
     if (!snapshot) {
       return
     }
-    this.mobileSessionTabsByWorktree.set(worktreeId, {
+    this.storeMobileSessionSnapshot(worktreeId, {
       ...snapshot,
       snapshotVersion: snapshot.snapshotVersion + 1
     })

src/renderer/src/runtime/local-structured-session-tabs-sync.test.ts

@@ -6,7 +6,8 @@ import { buildPersistedUnifiedTabSessionData } from '../lib/workspace-session-un
 import { buildHydratedTabState } from '../store/slices/tabs-hydration'
 import {
   applyLocalStructuredSessionTabSnapshots,
-  projectLocalStructuredSessionTabs
+  projectLocalStructuredSessionTabs,
+  resetLocalStructuredSessionVersionForTests
 } from './local-structured-session-tabs-sync'
 import {
   applyWebSessionTabsSnapshot,
@@ -25,6 +26,7 @@ const PRIMARY_GROUP = 'primary-group'
 const SECONDARY_GROUP = 'secondary-group'
 
 afterEach(() => {
+  resetLocalStructuredSessionVersionForTests()
   resetWebSessionFocusIntentForTests()
   resetWebSessionTabsSnapshotFreshnessForTests()
 })
@@ -148,6 +150,49 @@ function expectExactSplit(state: {
 }
 
 describe('local structured session tab projection', () => {
+  it('accepts a newer session after merged content returns to the base epoch', () => {
+    const state = createSnapshot()
+    const base = {
+      ...({
+        worktree: WORKTREE_ID,
+        publicationEpoch: 'renderer:generation-1',
+        snapshotVersion: 4,
+        activeGroupId: null,
+        activeTabId: null,
+        activeTabType: null,
+        tabs: []
+      } satisfies RuntimeMobileSessionTabsResult)
+    }
+    const withChat = {
+      ...base,
+      snapshotVersion: 5,
+      tabs: [
+        {
+          type: 'agent-session' as const,
+          id: STRUCTURED_ID,
+          title: 'Codex Chat',
+          sessionId: 'codex-1',
+          agent: 'codex' as const,
+          isActive: true
+        }
+      ]
+    }
+    const afterClose = { ...base, snapshotVersion: 6 }
+    const next = applyLocalStructuredSessionTabSnapshots(
+      state,
+      [
+        base,
+        withChat,
+        afterClose,
+        { ...base, snapshotVersion: 7, tabs: [{ ...withChat.tabs[0], isActive: true }] }
+      ],
+      'local-structured-session'
+    )
+    expect(next.unifiedTabsByWorktree[WORKTREE_ID]).toEqual(
+      expect.arrayContaining([expect.objectContaining({ contentType: 'agent-session' })])
+    )
+  })
+
   it('drops terminal topology while retaining structured tabs', () => {
     const snapshot = {
       worktree: 'workspace-1',

src/renderer/src/runtime/local-structured-session-tabs-sync.ts

@@ -4,15 +4,19 @@ import type { RuntimeMobileSessionTabsResult } from '../../../shared/runtime-typ
 import { useAppStore } from '../store'
 import type { WorktreeRuntimeOwnerState } from '../lib/worktree-runtime-owner'
 import { getExecutionHostIdForWorktree } from '../lib/worktree-runtime-owner'
-import {
-  applyWebSessionTabsSnapshot,
-  applyWebSessionTabsStorePatch,
-  decideWebSessionTabsSnapshot
-} from './web-session-tabs-sync'
+import { applyWebSessionTabsSnapshot, applyWebSessionTabsStorePatch } from './web-session-tabs-sync'
 import type { WebSessionTabsSyncState } from './web-session-tabs-sync'
 
 export const LOCAL_STRUCTURED_SESSION_OWNER = 'local-structured-session'
 let localStructuredSessionTabsRestorePromise: Promise<void> | null = null
+const localStructuredSessionVersionByWorktree = new Map<
+  string,
+  { publicationEpoch: string; snapshotVersion: number }
+>()
+
+export function resetLocalStructuredSessionVersionForTests(): void {
+  localStructuredSessionVersionByWorktree.clear()
+}
 
 type SessionTabsEvent =
   | (RuntimeMobileSessionTabsResult & { type: 'snapshot' | 'updated' })
@@ -79,7 +83,9 @@ export function applyLocalStructuredSessionTabSnapshots<
     if (getExecutionHostIdForWorktree(next, snapshot.worktree) !== 'local') {
       continue
     }
-    if (!decideWebSessionTabsSnapshot(snapshot, owner).apply) {
+    const prior = localStructuredSessionVersionByWorktree.get(snapshot.worktree)
+    const isNewerPublisher = prior?.publicationEpoch !== snapshot.publicationEpoch
+    if (prior && !isNewerPublisher && snapshot.snapshotVersion <= prior.snapshotVersion) {
       continue
     }
     const patch = applyWebSessionTabsSnapshot(
@@ -94,6 +100,10 @@ export function applyLocalStructuredSessionTabSnapshots<
       }
     )
     next = patch === next ? next : ({ ...next, ...patch } as State)
+    localStructuredSessionVersionByWorktree.set(snapshot.worktree, {
+      publicationEpoch: snapshot.publicationEpoch,
+      snapshotVersion: snapshot.snapshotVersion
+    })
   }
   return next
 }