diff --git a/src/main/ipc/crash-reporting.ts b/src/main/ipc/crash-reporting.ts
index 4cdd4bdbbb4..5a00669176c 100644
--- a/src/main/ipc/crash-reporting.ts
+++ b/src/main/ipc/crash-reporting.ts
@@ -331,6 +331,7 @@ const COALESCED_RENDERER_BREADCRUMB_NAMES = new Set([
   'renderer_unhandled_rejection',
   'terminal_park_verdict_churn',
   'terminal_safe_fit_retry_exhausted',
+  'terminal_tab_id_owned_by_multiple_worktrees',
   TERMINAL_WEBGL_DIAGNOSTIC_BREADCRUMB
 ])
 const RENDERER_BREADCRUMB_COALESCE_MS = 30_000
@@ -343,9 +344,14 @@ const RENDERER_BREADCRUMB_COALESCE_MS = 30_000
 // mounted pane within ~60ms. Windows crash F0BKR84AHEH lost 26-90% of its
 // 30-entry ring to two such bursts. `suppressedSinceLast` keeps the pane count
 // — the only signal these carry — in one slot.
+//
+// terminal_tab_id_owned_by_multiple_worktrees: its renderer-side guard is
+// once-per-tab-id, not once-per-session, so one stale worktree map duplicates
+// every tab id at once and emits a crumb per tab.
 const NAME_ONLY_COALESCED_BREADCRUMB_NAMES = new Set([
   'terminal_park_verdict_churn',
-  'terminal_safe_fit_retry_exhausted'
+  'terminal_safe_fit_retry_exhausted',
+  'terminal_tab_id_owned_by_multiple_worktrees'
 ])
 
 function rendererBreadcrumbCoalesceKey(
diff --git a/src/renderer/src/components/terminal/active-terminal-repair-loop.react185.test.tsx b/src/renderer/src/components/terminal/active-terminal-repair-loop.react185.test.tsx
index cedfa68d20a..5ee768436d4 100644
--- a/src/renderer/src/components/terminal/active-terminal-repair-loop.react185.test.tsx
+++ b/src/renderer/src/components/terminal/active-terminal-repair-loop.react185.test.tsx
@@ -115,6 +115,27 @@ describe('active-terminal repair effect cannot drive a React #185 update loop',
     expect(useAppStore.getState().activeTabIdByWorktree['wt-active']).toBe('t1')
   })
 
+  it('does not reallocate activeTabIdByWorktree when the tab is already active', () => {
+    // Why: that map is a dependency of both the repair effect and the parked
+    // watcher sync, so a redundant activation must not re-run either.
+    useAppStore.setState({
+      activeWorktreeId: 'wt-active',
+      activeTabType: 'terminal',
+      activeTabId: 't1',
+      activeTabIdByWorktree: {},
+      tabsByWorktree: { 'wt-active': [terminalTab('t1', 'wt-active')] },
+      unifiedTabsByWorktree: {}
+    })
+    act(() => {
+      useAppStore.getState().setActiveTab('t1')
+    })
+    const settled = useAppStore.getState().activeTabIdByWorktree
+    act(() => {
+      useAppStore.getState().setActiveTab('t1')
+    })
+    expect(useAppStore.getState().activeTabIdByWorktree).toBe(settled)
+  })
+
   it('keeps bell attribution off a background worktree tab', () => {
     useAppStore.setState({
       activeWorktreeId: 'wt-active',
diff --git a/src/renderer/src/store/slices/active-tab-owner-worktree.ts b/src/renderer/src/store/slices/active-tab-owner-worktree.ts
index 9ff0291797e..3d188ef9870 100644
--- a/src/renderer/src/store/slices/active-tab-owner-worktree.ts
+++ b/src/renderer/src/store/slices/active-tab-owner-worktree.ts
@@ -23,6 +23,9 @@ export function resolveActiveTabOwnerWorktreeId(
 ): string | null {
   let firstOwnerId: string | null = null
   let ownerCount = 0
+  // Why tracked in-loop rather than re-read by key: `tabsByWorktree[activeWorktreeId]`
+  // resolves inherited members for ids like `toString`, and `?.some` would then throw.
+  let activeWorktreeOwnsTab = false
   for (const [worktreeId, tabs] of Object.entries(tabsByWorktree)) {
     if (!tabs.some((tab) => tab.id === tabId)) {
       continue
@@ -31,6 +34,9 @@ export function resolveActiveTabOwnerWorktreeId(
     if (firstOwnerId === null) {
       firstOwnerId = worktreeId
     }
+    if (worktreeId === activeWorktreeId) {
+      activeWorktreeOwnsTab = true
+    }
   }
 
   // Why breadcrumb: no production origin for a duplicated tab id is known yet,
@@ -39,17 +45,11 @@ export function resolveActiveTabOwnerWorktreeId(
     reportedDuplicateTabIds.add(tabId)
     recordRendererCrashBreadcrumb('terminal_tab_id_owned_by_multiple_worktrees', {
       ownerCount,
-      resolvedToActiveWorktree: Boolean(
-        activeWorktreeId && tabsByWorktree[activeWorktreeId]?.some((tab) => tab.id === tabId)
-      )
+      resolvedToActiveWorktree: activeWorktreeOwnsTab
     })
   }
 
-  if (
-    ownerCount > 1 &&
-    activeWorktreeId &&
-    tabsByWorktree[activeWorktreeId]?.some((tab) => tab.id === tabId)
-  ) {
+  if (ownerCount > 1 && activeWorktreeId && activeWorktreeOwnsTab) {
     return activeWorktreeId
   }
   return firstOwnerId