fix(ai-vault): humanize runtime scanner errors

src/main/runtime/rpc/methods/ai-vault.test.ts

@@ -79,6 +79,14 @@ function makeDispatcher(): RpcDispatcher {
   return new RpcDispatcher({ runtime, methods: AI_VAULT_METHODS })
 }
 
+function makeFailingDispatcher(error: Error): RpcDispatcher {
+  const runtime = {
+    getRuntimeId: () => 'test-runtime',
+    listAiVaultSessions: vi.fn().mockRejectedValue(error)
+  } as unknown as OrcaRuntimeService
+  return new RpcDispatcher({ runtime, methods: AI_VAULT_METHODS })
+}
+
 describe('aiVault.resolveSessionTitles handler', () => {
   beforeEach(() => {
     resolveAiVaultSessionTitlesInWorker.mockReset()
@@ -229,6 +237,17 @@ describe('aiVault.listSessions handler + shared cache', () => {
     expect(response).toMatchObject({ ok: true, result: makeResult() })
   })
 
+  it('humanizes scanner supervision errors for remote clients', async () => {
+    const dispatcher = makeFailingDispatcher(new Error('AI Vault service restart circuit is open.'))
+
+    await expect(
+      dispatcher.dispatch(makeRequest('aiVault.listSessions', { limit: 500 }))
+    ).resolves.toMatchObject({
+      ok: false,
+      error: { message: 'Session scanning paused after repeated failures. Refresh to try again.' }
+    })
+  })
+
   it('passes only the first 64 scopePaths to the scanner when a request exceeds the cap', async () => {
     const dispatcher = makeDispatcher()
     const scopePaths = Array.from({ length: 65 }, (_, index) => `/p/${index}`)

src/main/runtime/rpc/methods/ai-vault.ts

@@ -5,6 +5,7 @@ import { restampAiVaultListResult } from '../../../ai-vault/session-list-results
 import { AI_VAULT_AGENTS, AI_VAULT_SCOPE_PATHS_MAX_COUNT } from '../../../../shared/ai-vault-types'
 import { AI_VAULT_SESSION_TITLE_REQUEST_MAX_COUNT } from '../../../../shared/ai-vault-session-title'
 import { LOCAL_EXECUTION_HOST_ID, parseExecutionHostId } from '../../../../shared/execution-host'
+import { describeAiVaultScanError } from '../../../../shared/ai-vault-scan-error-message'
 
 // Why: bound limit + scopePaths so a client cannot force an unbounded scan.
 // Each scopePath is a host-local match prefix (validated/capped, never used for
@@ -83,12 +84,18 @@ export const AI_VAULT_METHODS: RpcMethod[] = [
     name: 'aiVault.listSessions',
     params: AiVaultListSessionsParams,
     handler: async (params, { runtime }) => {
-      const result = await runtime.listAiVaultSessions({
-        limit: params.unlimited ? undefined : params.limit,
-        unlimited: params.unlimited,
-        force: params.force,
-        scopePaths: params.scopePaths
-      })
+      let result
+      try {
+        result = await runtime.listAiVaultSessions({
+          limit: params.unlimited ? undefined : params.limit,
+          unlimited: params.unlimited,
+          force: params.force,
+          scopePaths: params.scopePaths
+        })
+      } catch (error) {
+        const raw = error instanceof Error ? error.message : String(error)
+        throw new Error(describeAiVaultScanError(raw))
+      }
       // Why: web clients consume this response directly (no parent-side retag),
       // so sessions must come back stamped as the runtime host they addressed.
       return params.executionHostId