diff --git a/src/renderer/src/components/right-sidebar/ai-vault-session-resume.ts b/src/renderer/src/components/right-sidebar/ai-vault-session-resume.ts
index a166adf011c..9465144b705 100644
--- a/src/renderer/src/components/right-sidebar/ai-vault-session-resume.ts
+++ b/src/renderer/src/components/right-sidebar/ai-vault-session-resume.ts
@@ -9,6 +9,7 @@ import {
   type AiVaultSession
 } from '../../../../shared/ai-vault-types'
 import type { AppState } from '@/store/types'
+import { getIndexedWorktreeMap } from '@/store/worktree-repo-index'
 import { translate } from '@/i18n/i18n'
 import { parseWorkspaceKey } from '../../../../shared/workspace-scope'
 import {
@@ -145,9 +146,7 @@ export function isKnownAiVaultResumeWorkspaceTarget(
   }
 
   const worktreeId = workspaceKey?.type === 'worktree' ? workspaceKey.worktreeId : workspaceId
-  return Object.values(state.worktreesByRepo).some((worktrees) =>
-    worktrees.some((worktree) => worktree.id === worktreeId)
-  )
+  return getIndexedWorktreeMap(state.worktreesByRepo).has(worktreeId)
 }
 
 function resolveSupportedResumeWorktreeId(args: {
diff --git a/src/renderer/src/lib/ai-vault-resume-target.ts b/src/renderer/src/lib/ai-vault-resume-target.ts
index f52e26c62e8..3c9206ae372 100644
--- a/src/renderer/src/lib/ai-vault-resume-target.ts
+++ b/src/renderer/src/lib/ai-vault-resume-target.ts
@@ -11,6 +11,7 @@ import { getRepoIdFromWorktreeId } from '../../../shared/worktree-id'
 import { parseWorkspaceKey } from '../../../shared/workspace-scope'
 import { isWslUncPath } from '../../../shared/wsl-paths'
 import type { AppState } from '@/store/types'
+import { getIndexedWorktreeMap } from '@/store/worktree-repo-index'
 import { getFolderWorkspaceCandidateRepos } from './folder-workspace-connection'
 
 export type AiVaultResumeTargetStatus = 'local' | 'ssh' | 'runtime' | 'unknown'
@@ -132,9 +133,7 @@ export function getAiVaultResumeWorkspaceExecutionHostId(
   }
 
   const worktreeId = workspaceKey?.type === 'worktree' ? workspaceKey.worktreeId : workspaceId
-  const worktree = Object.values(state.worktreesByRepo ?? {})
-    .flat()
-    .find((candidate) => candidate.id === worktreeId)
+  const worktree = getIndexedWorktreeMap(state.worktreesByRepo ?? {}).get(worktreeId)
   const worktreeHostId = normalizeExecutionHostId(worktree?.hostId)
   if (worktreeHostId) {
     return worktreeHostId
@@ -158,9 +157,7 @@ export function getAiVaultResumeWorkspaceTargetStatus(
   }
 
   const worktreeId = workspaceKey?.type === 'worktree' ? workspaceKey.worktreeId : workspaceId
-  const worktree = Object.values(state.worktreesByRepo ?? {})
-    .flat()
-    .find((candidate) => candidate.id === worktreeId)
+  const worktree = getIndexedWorktreeMap(state.worktreesByRepo ?? {}).get(worktreeId)
   const worktreeHost = getAiVaultResumeExecutionHostTargetStatus(worktree?.hostId)
   if (worktreeHost !== 'unknown') {
     return worktreeHost