diff --git a/config/tsconfig.cli.json b/config/tsconfig.cli.json
index a4df2dab4a9..c2dff7a1c0d 100644
--- a/config/tsconfig.cli.json
+++ b/config/tsconfig.cli.json
@@ -12,6 +12,7 @@
     "../src/main/claude/hook-settings.ts",
     "../src/main/claude/hook-service.ts",
     "../src/main/codex/codex-app-server-capability-cache.ts",
+    "../src/main/codex/codex-app-server-capability-signal.ts",
     "../src/main/codex/codex-app-server-client.ts",
     "../src/main/codex/codex-app-server-grant-bridge.ts",
     "../src/main/codex/codex-app-server-grant-envelope.ts",
diff --git a/src/main/codex/codex-app-server-capability-signal.ts b/src/main/codex/codex-app-server-capability-signal.ts
new file mode 100644
index 00000000000..a35518f0ded
--- /dev/null
+++ b/src/main/codex/codex-app-server-capability-signal.ts
@@ -0,0 +1,7 @@
+// Why: only an argv parse failure that names app-server proves the RPC surface
+// is absent; unrelated stderr must remain transient rather than poison the cache.
+export function stderrIndicatesMissingAppServer(stderrTail: string): boolean {
+  return /^(?=.*\bapp-server\b).*(?:unrecognized subcommand|unexpected argument|invalid subcommand)/im.test(
+    stderrTail
+  )
+}
diff --git a/src/main/codex/codex-app-server-client.test.ts b/src/main/codex/codex-app-server-client.test.ts
index 5bb01ae5614..804cd50ae82 100644
--- a/src/main/codex/codex-app-server-client.test.ts
+++ b/src/main/codex/codex-app-server-client.test.ts
@@ -49,6 +49,11 @@ if (config.scenario === 'no-subcommand') {
   process.stderr.write("error: unrecognized subcommand 'app-server'\\n")
   process.exit(2)
 }
+if (config.scenario === 'transient-stderr') {
+  process.stderr.write('config loader: unexpected argument in value\\n')
+  process.exit(1)
+}
+if (config.scenario === 'silent-exit-0') process.exit(0)
 process.stdin.setEncoding('utf8')
 process.stdin.on('data', (chunk) => {
   buffer += chunk
@@ -278,6 +283,32 @@ describe('runCodexHookTrustGrantSession', () => {
     expect(isCodexAppServerUnsupportedError(error)).toBe(true)
   })
 
+  it('does not classify unrelated stderr as a missing app-server capability', async () => {
+    const { request } = createStubRequest({
+      scenario: 'transient-stderr',
+      hooks: [],
+      expectedTrustKeys: ['k'],
+      managedCommand: MANAGED_COMMAND
+    })
+
+    const error = await runCodexHookTrustGrantSession(request).catch((caught: unknown) => caught)
+    expect(error).toBeInstanceOf(Error)
+    expect(isCodexAppServerUnsupportedError(error)).toBe(false)
+  })
+
+  it('treats a silent exit zero before initialize as transient', async () => {
+    const { request } = createStubRequest({
+      scenario: 'silent-exit-0',
+      hooks: [],
+      expectedTrustKeys: ['k'],
+      managedCommand: MANAGED_COMMAND
+    })
+
+    const error = await runCodexHookTrustGrantSession(request).catch((caught: unknown) => caught)
+    expect(error).toBeInstanceOf(Error)
+    expect(isCodexAppServerUnsupportedError(error)).toBe(false)
+  })
+
   it('kills a hung server at the session deadline', async () => {
     const keys = ['/home/a/.codex/hooks.json:session_start:0:0']
     const { request, pidFile } = createStubRequest({
diff --git a/src/main/codex/codex-app-server-client.ts b/src/main/codex/codex-app-server-client.ts
index ab5dced425c..4e58c8348cc 100644
--- a/src/main/codex/codex-app-server-client.ts
+++ b/src/main/codex/codex-app-server-client.ts
@@ -1,6 +1,7 @@
 import { spawn, type ChildProcessWithoutNullStreams } from 'node:child_process'
 import { normalizeHookTrustKeyForLookup } from './config-toml-trust'
 import { waitForProcessExitUntil } from './codex-process-exit-deadline'
+import { stderrIndicatesMissingAppServer } from './codex-app-server-capability-signal'
 
 // Why: Codex gates hooks on a `trusted_hash` it computes from a private
 // canonical-JSON identity. Orca used to replicate that algorithm
@@ -94,12 +95,6 @@ function isMethodNotFoundError(error: { code?: number; message?: string }): bool
   return error.code === JSON_RPC_METHOD_NOT_FOUND || /method not found/i.test(error.message ?? '')
 }
 
-// Why: a CLI predating the app-server subcommand fails argv parsing before
-// speaking any JSON-RPC; that shape is a capability signal, not a transient.
-function stderrIndicatesMissingAppServer(stderrTail: string): boolean {
-  return /unrecognized subcommand|unexpected argument|invalid subcommand/i.test(stderrTail)
-}
-
 function collectHookListings(result: unknown): CodexHookListing[] {
   const data =
     result && typeof result === 'object' && Array.isArray((result as { data?: unknown }).data)