diff --git a/src/main/agent-cli-version-probe.ts b/src/main/agent-cli-version-probe.ts
index 8dc5c902262..61d55ec2106 100644
--- a/src/main/agent-cli-version-probe.ts
+++ b/src/main/agent-cli-version-probe.ts
@@ -18,6 +18,22 @@ export async function probeAgentCliVersion(
   input: Pick<ProcessSpec, 'program' | 'cwd' | 'env'>,
   supports: (version: string) => boolean
 ): Promise<boolean> {
+  const result = await readAgentCliVersion(input)
+  if (result.version === null) {
+    return false
+  }
+  if (!supports(result.version)) {
+    warnRefused(input.program, `${result.version} is not a supported release`)
+    return false
+  }
+  console.info(`[agent-cli-version] ${input.program} --version: ${result.version} is supported`)
+  return true
+}
+
+export async function readAgentCliVersion(
+  input: Pick<ProcessSpec, 'program' | 'cwd' | 'env'>,
+  parseVersion: typeof parseCliVersion = parseCliVersion
+): Promise<{ version: string | null }> {
   let result
   try {
     result = await runProcess({
@@ -29,7 +45,7 @@ export async function probeAgentCliVersion(
     })
   } catch (error) {
     warnRefused(input.program, `did not start (${String(error)})`)
-    return false
+    return { version: null }
   }
   const output = `${result.stdout}\n${result.stderr}`
   if (result.timedOut || result.outputTruncated || result.code !== 0) {
@@ -39,19 +55,14 @@ export async function probeAgentCliVersion(
         ? 'printed too much'
         : `exited ${result.code ?? result.signal}`
     warnRefused(input.program, why, output)
-    return false
+    return { version: null }
   }
-  const version = parseCliVersion(result.stdout)
+  const version = parseVersion(parseVersion === parseCliVersion ? result.stdout : output)
   if (version === null) {
     warnRefused(input.program, 'printed no version', output)
-    return false
+    return { version: null }
   }
-  if (!supports(version)) {
-    warnRefused(input.program, `${version} is not a supported release`)
-    return false
-  }
-  console.info(`[agent-cli-version] ${input.program} --version: ${version} is supported`)
-  return true
+  return { version }
 }
 
 /** A stable release at or after `floor`, on any later major line too. */
diff --git a/src/main/codex/codex-cli-installation-error.ts b/src/main/codex/codex-cli-installation-error.ts
new file mode 100644
index 00000000000..f4344046c45
--- /dev/null
+++ b/src/main/codex/codex-cli-installation-error.ts
@@ -0,0 +1,75 @@
+import type { CodexInstallationProblem } from '../../shared/codex-cli-installation'
+import { sayAgentSessionFailureEnglish } from '../../shared/agent-session-failure-copy'
+import { readCodexCliInstallation } from '../preflight/codex-cli-installation'
+import { AgentSessionPreSpawnError } from '../native-chat/agent-session-wire/structured-agent-session-adapter'
+import type { StructuredAgentLaunchResolver } from '../runtime/structured-agent-launch-composition'
+import {
+  resolveProviderChildEnv,
+  type ProviderProcessLaunch
+} from '../provider-process/provider-process-launch'
+
+export class CodexCliInstallationError extends AgentSessionPreSpawnError {
+  readonly codexInstallation: CodexInstallationProblem
+
+  constructor(problem: CodexInstallationProblem) {
+    super(
+      sayAgentSessionFailureEnglish(
+        problem.installedVersion === null ? 'cliMissing' : 'codexCliTooOld',
+        {
+          agent: 'Codex',
+          installedVersion: problem.installedVersion ?? '',
+          minimumVersion: problem.minimumVersion
+        }
+      )
+    )
+    this.codexInstallation = problem
+  }
+}
+
+export function codexInstallationProblemOf(
+  error: unknown,
+  depth = 0
+): CodexInstallationProblem | undefined {
+  if (depth >= 6 || !(error instanceof Error)) {
+    return undefined
+  }
+  if (error instanceof CodexCliInstallationError) {
+    return error.codexInstallation
+  }
+  return codexInstallationProblemOf(error.cause, depth + 1)
+}
+
+export async function requireSupportedCodexCli(
+  input: Parameters<typeof readCodexCliInstallation>[0],
+  readInstallation: typeof readCodexCliInstallation = readCodexCliInstallation
+): Promise<void> {
+  const result = await readInstallation(input)
+  if (result.status === 'unsupported') {
+    throw new CodexCliInstallationError({
+      installedVersion: result.version,
+      minimumVersion: result.minimumVersion
+    })
+  }
+  if (result.status === 'unknown') {
+    console.warn(`[codex-cli-version] Could not verify ${input.program}; allowing structured chat`)
+  }
+}
+
+/** Check every acquired child against the same sealed launch the app-server will use. */
+export function withSupportedCodexCli<L extends ProviderProcessLaunch>(
+  resolveLaunch: StructuredAgentLaunchResolver<L>,
+  readInstallation: typeof readCodexCliInstallation = readCodexCliInstallation
+): StructuredAgentLaunchResolver<L> {
+  return async (request) => {
+    const launch = await resolveLaunch(request)
+    await requireSupportedCodexCli(
+      {
+        program: launch.command,
+        cwd: launch.cwd,
+        env: resolveProviderChildEnv(launch, process.env)
+      },
+      readInstallation
+    )
+    return launch
+  }
+}
diff --git a/src/main/codex/codex-minimum-version.test.ts b/src/main/codex/codex-minimum-version.test.ts
new file mode 100644
index 00000000000..1f94f6dca47
--- /dev/null
+++ b/src/main/codex/codex-minimum-version.test.ts
@@ -0,0 +1,215 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { createFakePipedChild } from '../../shared/__fixtures__/fake-spawned-child'
+import { codexCliInstallation } from '../../shared/codex-cli-installation'
+import { agentSessionRecordFixture } from '../../shared/agent-session-record.test-fixture'
+import type { AgentSessionRecord } from '../../shared/agent-session-record'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
+import { readWholeAgentSessionFailureFact } from '../../shared/agent-session-failure'
+import { resolveAgentLaunchCommand } from '../../shared/tui-agent-launch-command'
+import { readCodexCliInstallation } from '../preflight/codex-cli-installation'
+import {
+  failedAcquisitionRefusal,
+  failedAcquisitionSettlement
+} from '../native-chat/agent-session-wire/structured-agent-session-failed-create-refusal'
+import { structuredAgentSessionStartFailure } from '../native-chat/agent-session-wire/structured-agent-session-failure-text'
+import {
+  CodexCliInstallationError,
+  requireSupportedCodexCli,
+  withSupportedCodexCli
+} from './codex-cli-installation-error'
+import {
+  createCodexStructuredLaunchResolver,
+  TEST_SPAWN_TOKEN
+} from '../runtime/structured-agent-launch-composition.test-support'
+import { resolveProviderChildEnv } from '../provider-process/provider-process-launch'
+import { identityFor } from './codex-structured-session-adapter-fixture'
+import { openCodexAppServerConnection } from './codex-app-server-connection'
+
+vi.mock('../preflight/codex-cli-installation', () => ({ readCodexCliInstallation: vi.fn() }))
+beforeEach(() => {
+  vi.mocked(readCodexCliInstallation).mockReset()
+  vi.mocked(readCodexCliInstallation).mockResolvedValue(codexCliInstallation(true, '0.136.0'))
+})
+afterEach(() => vi.restoreAllMocks())
+
+function record(): AgentSessionRecord {
+  return {
+    ...agentSessionRecordFixture(),
+    provider: 'codex' as const,
+    providerHandleChain: [],
+    accountHome: { variable: 'CODEX_HOME' as const, path: '/account' }
+  }
+}
+
+describe('Codex structured launch version admission', () => {
+  it.each(['0.100.0', '0.135.0'])(
+    'refuses %s with concise repair copy and both version facts',
+    async (version) => {
+      vi.mocked(readCodexCliInstallation).mockResolvedValue(codexCliInstallation(true, version))
+      const caught = await requireSupportedCodexCli({ program: '/execution-host/codex' }).catch(
+        (error: unknown) => error
+      )
+      expect(caught).toBeInstanceOf(CodexCliInstallationError)
+      const wording = { record: record(), newSession: true }
+      const result = failedAcquisitionRefusal(caught, wording)
+      expect(result?.refusal.message).toBe(
+        `Codex ${version} is too old for chats. Update to 0.136.0 or newer.`
+      )
+      expect(result?.refusal.message).not.toContain('Settings → Agents')
+      expect(result?.refusal.message).not.toContain('codex update')
+      expect(failedAcquisitionSettlement(caught, wording).exitProof).toBe('processless')
+      const failure = structuredAgentSessionStartFailure({ error: caught })
+      expect(failure.reason).toBe(result?.refusal.message)
+      expect(readWholeAgentSessionFailureFact(failure.rejection)).toEqual(failure.rejection)
+      if (!result) {
+        throw new Error('Expected refusal')
+      }
+      expect(
+        structuredAgentSessionStartFailure({ refusal: result.refusal, newSession: true }).reason
+      ).toBe(failure.reason)
+    }
+  )
+
+  it('leaves a missing Codex to the existing spawn refusal', async () => {
+    vi.mocked(readCodexCliInstallation).mockResolvedValue(codexCliInstallation(false, null))
+    await expect(requireSupportedCodexCli({ program: 'codex' })).resolves.toBeUndefined()
+  })
+
+  it('reports Windows ENOENT through the existing not-found failure with one explanation', async () => {
+    vi.spyOn(process, 'platform', 'get').mockReturnValue('win32')
+    vi.mocked(readCodexCliInstallation).mockResolvedValue(codexCliInstallation(false, null))
+    await requireSupportedCodexCli({ program: 'codex.exe' })
+    const child = createFakePipedChild()
+    Object.assign(child, { pid: undefined })
+    const opening = openCodexAppServerConnection(
+      { command: 'codex.exe', args: ['app-server'] },
+      {},
+      () => child
+    ).catch((error: unknown) => error)
+    child.emit(
+      'error',
+      Object.assign(new Error('spawn codex.exe ENOENT'), { code: 'ENOENT', path: 'codex.exe' })
+    )
+    child.emit('close', -2, null)
+    const failure = structuredAgentSessionStartFailure(
+      { error: await opening },
+      { agentName: 'Codex' }
+    )
+    expect(failure.rejection.kind).toBe('cliMissing')
+    expect(failure.reason).toBe(
+      "Codex wasn't found on the computer running this chat. Install it, or check its Command in Settings → Agents."
+    )
+  })
+
+  it('allows an unknown version with a log line', async () => {
+    vi.mocked(readCodexCliInstallation).mockResolvedValue(codexCliInstallation(true, null))
+    const log = vi.spyOn(console, 'warn').mockImplementation(() => {})
+    await expect(requireSupportedCodexCli({ program: '/host/codex' })).resolves.toBeUndefined()
+    expect(log).toHaveBeenCalledWith(expect.stringContaining('allowing structured chat'))
+    log.mockRestore()
+  })
+
+  it.each(['start', 'resume'] as const)(
+    'checks the exact host binary and launch environment before %s',
+    async (mode) => {
+      const value = record()
+      if (mode === 'resume') {
+        value.providerHandleChain = [
+          {
+            linkId: 'link',
+            handle: codexProviderHandle('thread'),
+            origin: 'created',
+            mintedAtFence: 1,
+            observedAt: 1
+          }
+        ]
+      }
+      const resolve = withSupportedCodexCli(
+        createCodexStructuredLaunchResolver({
+          store: { getRecord: () => value, pinLaunchDirectory: vi.fn() },
+          resolveCommand: () => '/host/bin/codex',
+          resolveEnvironment: async () => ({ PATH: '/host/bin', HOME: '/host/home' }),
+          resolveLaunchArgs: () => [],
+          resolveWorkspacePath: async () => '/folder',
+          resolveRollout: async () => null
+        })
+      )
+      vi.mocked(readCodexCliInstallation).mockResolvedValue(codexCliInstallation(true, '0.135.0'))
+      await expect(
+        resolve({ identity: identityFor(value.sessionId), spawnToken: TEST_SPAWN_TOKEN })
+      ).rejects.toThrow('0.135.0')
+      const probe = vi.mocked(readCodexCliInstallation).mock.calls.at(-1)?.[0]
+      expect(probe?.program).toBe('/host/bin/codex')
+      expect(probe?.cwd).toBe('/folder')
+      expect(probe?.env?.PATH).toContain('/host/bin')
+      expect(probe?.env?.HOME).toBe('/host/home')
+      expect(probe?.env?.CODEX_HOME).toBe('/account')
+      vi.mocked(readCodexCliInstallation).mockResolvedValue(codexCliInstallation(true, '0.136.0'))
+      const launch = await resolve({
+        identity: identityFor(value.sessionId),
+        spawnToken: TEST_SPAWN_TOKEN
+      })
+      expect(launch).toMatchObject({ command: '/host/bin/codex', args: ['app-server'] })
+      expect(vi.mocked(readCodexCliInstallation).mock.calls.at(-1)?.[0]).toEqual({
+        program: launch.command,
+        cwd: launch.cwd,
+        env: resolveProviderChildEnv(launch, process.env)
+      })
+    }
+  )
+
+  it.each(['start', 'resume'] as const)(
+    'admits the workspace-selected version on %s',
+    async (mode) => {
+      const value = record()
+      if (mode === 'resume') {
+        value.providerHandleChain = [
+          {
+            linkId: 'link',
+            handle: codexProviderHandle('thread'),
+            origin: 'created',
+            mintedAtFence: 1,
+            observedAt: 1
+          }
+        ]
+      }
+      vi.mocked(readCodexCliInstallation).mockImplementation(async (input) =>
+        codexCliInstallation(true, input.cwd === '/workspace' ? '0.136.0' : '0.135.0')
+      )
+      const resolve = withSupportedCodexCli(
+        createCodexStructuredLaunchResolver({
+          store: { getRecord: () => value, pinLaunchDirectory: vi.fn() },
+          resolveCommand: () => '/host/project-aware-codex',
+          resolveEnvironment: async () => ({ PATH: '/host/bin' }),
+          resolveLaunchArgs: () => [],
+          resolveWorkspacePath: async () => '/workspace',
+          resolveRollout: async () => null
+        })
+      )
+      expect(
+        (await resolve({ identity: identityFor(value.sessionId), spawnToken: TEST_SPAWN_TOKEN }))
+          .cwd
+      ).toBe('/workspace')
+    }
+  )
+
+  it.each(['posix', 'powershell', 'cmd'] as const)(
+    'leaves terminal Codex launch unchanged in %s',
+    (shell) => {
+      vi.mocked(readCodexCliInstallation).mockResolvedValue(codexCliInstallation(true, '0.135.0'))
+      expect(
+        resolveAgentLaunchCommand({
+          agent: 'codex',
+          cmdOverrides: {},
+          platform: shell === 'posix' ? 'linux' : 'win32',
+          shell,
+          agentArgs: '--model chosen'
+        })
+      ).toMatchObject({
+        ok: true,
+        command: shell === 'cmd' ? 'codex "--model" "chosen"' : "codex '--model' 'chosen'"
+      })
+      expect(readCodexCliInstallation).not.toHaveBeenCalled()
+    }
+  )
+})
diff --git a/src/main/codex/codex-structured-thread-open.test.ts b/src/main/codex/codex-structured-thread-open.test.ts
index efd32b666cd..21f71cdaa11 100644
--- a/src/main/codex/codex-structured-thread-open.test.ts
+++ b/src/main/codex/codex-structured-thread-open.test.ts
@@ -125,37 +125,23 @@ describe('openCodexThread', () => {
     )
   })
 
-  it('caches a narrowly proven excludeTurns refusal and uses one bounded fallback', async () => {
-    const request = vi.fn(async (_method: string, params?: Record<string, unknown>) => {
-      if (params?.excludeTurns) {
-        throw new CodexAppServerRequestError(
-          'thread/resume',
-          -32602,
-          'codex app-server thread/resume failed: unknown field `excludeTurns`'
-        )
-      }
-      return { thread: { id: 'thread-1', turns: [{ id: 'turn-1', items: [] }] } }
+  it('does not retry without excludeTurns after an unsupported-field refusal', async () => {
+    const refusal = new CodexAppServerRequestError(
+      'thread/resume',
+      -32602,
+      'unknown field excludeTurns'
+    )
+    const request = vi.fn(async () => {
+      throw refusal
     })
-    const connection = connectionFor(request)
-
-    const first = await openCodexThread(
-      connection,
-      { cwd: '/workspace', resumeThreadId: 'thread-1' },
-      2_000
-    )
-    const second = await openCodexThread(
-      connection,
-      { cwd: '/workspace', resumeThreadId: 'thread-1' },
-      2_000
-    )
-
-    expect(first.thread?.turns).toHaveLength(1)
-    expect(second.thread?.turns).toHaveLength(1)
-    expect(request.mock.calls.map(([, params]) => params)).toEqual([
-      expect.objectContaining({ excludeTurns: true }),
-      { threadId: 'thread-1', cwd: '/workspace' },
-      { threadId: 'thread-1', cwd: '/workspace' }
-    ])
+    await expect(
+      openCodexThread(
+        connectionFor(request),
+        { cwd: '/workspace', resumeThreadId: 'thread-1' },
+        2_000
+      )
+    ).rejects.toBe(refusal)
+    expect(request).toHaveBeenCalledOnce()
   })
 
   it('does not retry ambiguous invalid params or oversized history responses', async () => {
@@ -190,33 +176,6 @@ describe('openCodexThread', () => {
     expect(oversizedRequest).toHaveBeenCalledOnce()
   })
 
-  it('accepts a fallback result beyond the daemon wire limit', async () => {
-    const request = vi.fn(async (_method: string, params?: Record<string, unknown>) => {
-      if (params?.excludeTurns) {
-        throw new CodexAppServerRequestError(
-          'thread/resume',
-          -32602,
-          'codex app-server thread/resume failed: unsupported excludeTurns parameter'
-        )
-      }
-      return {
-        thread: {
-          id: 'thread-1',
-          turns: [{ id: 'turn-1', items: [{ output: 'x'.repeat(16 * 1024 * 1024 + 1) }] }]
-        }
-      }
-    })
-
-    await expect(
-      openCodexThread(
-        connectionFor(request),
-        { cwd: '/workspace', resumeThreadId: 'thread-1' },
-        2_000
-      )
-    ).resolves.toMatchObject({ threadId: 'thread-1' })
-    expect(request).toHaveBeenCalledTimes(2)
-  })
-
   describe('a thread Codex never saved', () => {
     const noRollout = (threadId: string, code = -32600) =>
       new CodexAppServerRequestError(
diff --git a/src/main/codex/codex-structured-thread-open.ts b/src/main/codex/codex-structured-thread-open.ts
index 6fd58ba17ec..c6e686869b7 100644
--- a/src/main/codex/codex-structured-thread-open.ts
+++ b/src/main/codex/codex-structured-thread-open.ts
@@ -28,41 +28,6 @@ function nonEmptyString(value: unknown): string | null {
   return typeof value === 'string' && value.trim() ? value : null
 }
 
-const resumeMetadataUnsupported = new WeakSet<object>()
-
-function isExcludeTurnsUnsupported(error: unknown): boolean {
-  return (
-    isCodexAppServerRequestError(error) &&
-    error.code === -32602 &&
-    /(?:unknown|unexpected|unsupported|unrecognized).{0,80}excludeTurns|excludeTurns.{0,80}(?:unknown|unexpected|unsupported|unrecognized)/i.test(
-      error.message
-    )
-  )
-}
-
-async function resumeCodexThread(
-  connection: Pick<CodexAppServerConnection, 'request'>,
-  params: Record<string, unknown>,
-  timeoutMs: number | undefined
-): Promise<unknown> {
-  if (resumeMetadataUnsupported.has(connection)) {
-    return connection.request('thread/resume', params, { timeoutMs })
-  }
-  try {
-    return await connection.request(
-      'thread/resume',
-      { ...params, excludeTurns: true },
-      { timeoutMs }
-    )
-  } catch (error) {
-    if (!isExcludeTurnsUnsupported(error)) {
-      throw error
-    }
-    resumeMetadataUnsupported.add(connection)
-    return connection.request('thread/resume', params, { timeoutMs })
-  }
-}
-
 /**
  * Codex's own answer that it holds no rollout for this exact thread: the thread was started but
  * never given input, so there is no conversation to lose. Codex matches the same exact text
@@ -120,7 +85,11 @@ export async function openCodexThread(
       ...(launch.resumePath ? { path: launch.resumePath } : {})
     }
     try {
-      opened = await resumeCodexThread(connection, resumeParams, timeoutMs)
+      opened = await connection.request(
+        'thread/resume',
+        { ...resumeParams, excludeTurns: true },
+        { timeoutMs }
+      )
     } catch (error) {
       if (!launch.supersedeIfUnsaved || !isCodexNoRolloutError(error, resumeThreadId)) {
         throw error
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-codex-version-recovery.test.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-codex-version-recovery.test.ts
new file mode 100644
index 00000000000..b01020f7203
--- /dev/null
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-codex-version-recovery.test.ts
@@ -0,0 +1,107 @@
+import { afterEach, beforeEach, expect, it } from 'vitest'
+import { CodexCliInstallationError } from '../../codex/codex-cli-installation-error'
+import { isStructuredAgentSessionStartFailureRow } from '../../../shared/structured-agent-session-start-failure-row-key'
+import { projectQueuedMessageCards } from '../../../renderer/src/components/native-chat/structured-agent-session-queued-cards'
+import { HOST_TEST_SESSION, hostTestMessage } from './structured-agent-session-host-test-data'
+import { structuredAgentSessionHostInstance } from './structured-agent-session-queued-pause'
+import {
+  createQueuedMessageTestRig,
+  eventually,
+  type QueuedMessageTestRig
+} from './structured-agent-session-queued-message-rig.test-fixture'
+
+let rig: QueuedMessageTestRig
+beforeEach(async () => {
+  rig = await createQueuedMessageTestRig({
+    restartable: true,
+    idleSweep: { idleMs: 0, intervalMs: 60 * 60 * 1000 }
+  })
+})
+afterEach(() => rig.dispose())
+
+async function retainedCards() {
+  const result = await rig.host.history({ sessionId: HOST_TEST_SESSION, direction: 'tail' })
+  if (!result.ok) {
+    throw new Error('History refused')
+  }
+  const { page } = result
+  const cards = projectQueuedMessageCards(page.queuedMessages, page.submissions, {
+    queuePaused: Boolean(page.queuePause)
+  })
+  return { page, cards }
+}
+
+async function retainedDraft() {
+  const working = await rig.workingSend()
+  const queued = await rig.send('retained instruction', 'queue-if-active').result
+  if (!queued.ok || !('queued' in queued.value)) {
+    throw new Error('Expected a queued draft')
+  }
+  await rig.stop()
+  await rig.settleAccepted(working, 'earlier-turn')
+  await rig.host.collaboratorsForTests().lifetime.idleSweep.tick()
+  rig.starts.mockImplementationOnce(() => {
+    throw new CodexCliInstallationError({
+      installedVersion: '0.135.0',
+      minimumVersion: '0.136.0'
+    })
+  })
+  return queued.value.queued.messageId
+}
+
+it.each(['returned', 'held'] as const)(
+  'uses per-message Send after an existing conversation restart is version-refused with a %s draft and no pause',
+  async (kind) => {
+    let id = await retainedDraft()
+    expect(await rig.resume()).toMatchObject({ ok: true, value: { resumed: true } })
+    await eventually(async () => expect((await rig.handoff(id))?.dispatchState).toBe('rejected'))
+    const rejected = await rig.handoffId(id)
+    if (kind === 'held') {
+      await rig.deleteQueued(id)
+      id = 'held-draft'
+      const journal = rig.host.collaboratorsForTests().sessions.get(HOST_TEST_SESSION)?.journal
+      if (!journal) {
+        throw new Error('Missing journal')
+      }
+      await journal.queuedMessages.insert({
+        messageId: id,
+        body: hostTestMessage('retained instruction'),
+        fingerprint: 'retained-instruction',
+        hostInstance: structuredAgentSessionHostInstance(),
+        holdReason: 'send_failed'
+      })
+    }
+    const { page, cards } = await retainedCards()
+    expect(page.queuePause ?? null).toBeNull()
+    expect(cards).toMatchObject([{ messageId: id, hold: kind === 'held' ? 'paused' : 'returned' }])
+    expect(
+      page.items.filter((item) => isStructuredAgentSessionStartFailureRow(item.itemId))
+    ).toMatchObject([
+      {
+        body: {
+          text: 'Codex 0.135.0 is too old for chats. Update to 0.136.0 or newer.',
+          tone: 'error',
+          failure: { refusal: { details: { codexInstallation: { installedVersion: '0.135.0' } } } }
+        }
+      }
+    ])
+    expect(await rig.resume()).toMatchObject({ ok: true, value: { resumed: false } })
+    const attempts = rig.starts.mock.calls.length
+    expect((await rig.submission(rejected))?.handedOverAt).toBeUndefined()
+    expect(rig.starts).toHaveBeenCalledTimes(attempts)
+    expect(await rig.sendNow(id)).toMatchObject({ ok: true })
+    await eventually(async () => expect((await rig.handoff(id))?.handedOverAt).toBeDefined())
+    expect(await rig.handoffId(id)).not.toBe(rejected)
+    expect(rig.starts).toHaveBeenCalledTimes(attempts + 1)
+    expect((await rig.submission(rejected))?.dispatchState).toBe('rejected')
+  }
+)
+
+it('keeps an actual pause after a version refusal and releases it through the host', async () => {
+  const id = await retainedDraft()
+  rig.starts.mockReset()
+  expect(await rig.queuePause()).not.toBeNull()
+  expect(await rig.resume()).toMatchObject({ ok: true, value: { resumed: true } })
+  await eventually(async () => expect((await rig.handoff(id))?.handedOverAt).toBeDefined())
+  expect(await rig.queuePause()).toBeNull()
+})
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-failed-create-refusal.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-failed-create-refusal.ts
index 82188da9286..d88997c46c6 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-failed-create-refusal.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-failed-create-refusal.ts
@@ -30,6 +30,7 @@ import {
 import { structuredAgentSessionFailureWordsContext } from './structured-agent-session-send-preparation'
 import { providerExecutableMissing } from '../../provider-process/provider-executable-missing'
 import { argumentProblemOf } from '../structured-agent-arguments-error'
+import { codexInstallationProblemOf } from '../../codex/codex-cli-installation-error'
 import { providerDiagnosticOf } from '../../../shared/agent-session-failure'
 
 /** Who a failed acquisition's sentence names, and whether it was the session's first start. */
@@ -113,6 +114,10 @@ function isExitProvenAcquisitionFailure(error: unknown): error is Error {
 function failedAcquisitionDetails(
   error: unknown
 ): AgentSessionRefusalDetailsByCode['agent_session_operation_invalid'] | undefined {
+  const codexInstallation = codexInstallationProblemOf(error)
+  if (codexInstallation) {
+    return { reason: 'attachFailed', codexInstallation }
+  }
   const argumentProblem = argumentProblemOf(error)
   if (argumentProblem) {
     return { reason: 'attachFailed', argumentProblem }
@@ -142,7 +147,8 @@ export function failedAcquisitionRefusal(
   if (
     error instanceof AgentSessionAcquisitionRefusal ||
     isExitProvenAcquisitionFailure(error) ||
-    (isAgentSessionPreSpawnError(error) && argumentProblemOf(error))
+    (isAgentSessionPreSpawnError(error) &&
+      (argumentProblemOf(error) || codexInstallationProblemOf(error)))
   ) {
     return {
       ok: false,
diff --git a/src/main/native-chat/agent-session-wire/structured-agent-session-failure-text.ts b/src/main/native-chat/agent-session-wire/structured-agent-session-failure-text.ts
index 37f728808b2..02d248288e1 100644
--- a/src/main/native-chat/agent-session-wire/structured-agent-session-failure-text.ts
+++ b/src/main/native-chat/agent-session-wire/structured-agent-session-failure-text.ts
@@ -22,6 +22,7 @@ import {
 import { AgentSessionAcquisitionRefusal } from './structured-agent-session-adapter'
 import { providerExecutableMissing } from '../../provider-process/provider-executable-missing'
 import { argumentProblemOf } from '../structured-agent-arguments-error'
+import { codexInstallationProblemOf } from '../../codex/codex-cli-installation-error'
 
 /** Start refusals whose situation is itself what the person reads, with its own next step. */
 const TYPED_START_REFUSALS = [
@@ -72,6 +73,15 @@ export function providerExitObserved(error: unknown, depth = 0): boolean {
  *  adapter observed says the provider stopped; anything else blames no one — it may be Orca's, or
  *  a spawn that failed. Either keeps the provider's diagnostic when the error carried one. */
 export function providerStartupFailureFact(cause?: unknown): SubmissionRejectionFact {
+  const codexInstallation = codexInstallationProblemOf(cause)
+  if (codexInstallation) {
+    return agentSessionFailureFact('startFailed', {
+      refusal: {
+        code: 'agent_session_operation_invalid',
+        details: { reason: 'attachFailed', codexInstallation }
+      }
+    })
+  }
   const typed = typedStartRefusal(
     cause instanceof AgentSessionAcquisitionRefusal ? cause.reason : undefined
   )
diff --git a/src/main/preflight/codex-cli-installation.test.ts b/src/main/preflight/codex-cli-installation.test.ts
new file mode 100644
index 00000000000..6ffe6aadbad
--- /dev/null
+++ b/src/main/preflight/codex-cli-installation.test.ts
@@ -0,0 +1,56 @@
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import { readCodexCliInstallation } from './codex-cli-installation'
+
+const { runProcess } = vi.hoisted(() => ({ runProcess: vi.fn() }))
+vi.mock('@orca/process-host', async (original) => ({
+  ...(await original<object>()),
+  runProcess
+}))
+
+function prints(stdout: string, timedOut = false): void {
+  runProcess.mockResolvedValue({ code: 0, stdout, stderr: '', timedOut })
+}
+afterEach(() => {
+  vi.restoreAllMocks()
+  vi.useRealTimers()
+  runProcess.mockReset()
+})
+
+describe('Codex installation version probes', () => {
+  it('probes every read and sees changes behind an unchanged launcher', async () => {
+    const program = '/fake/codex'
+    const input = { program, env: { PATH: '/launch/path' } }
+    for (const version of ['0.135.0', '0.136.0', '0.135.0']) {
+      prints(`company-wrapper 0.1.0\ncodex-cli ${version}`)
+      expect((await readCodexCliInstallation(input)).version).toBe(version)
+    }
+    expect(runProcess).toHaveBeenCalledTimes(3)
+    expect(runProcess).toHaveBeenCalledWith(
+      expect.objectContaining({
+        program,
+        env: input.env,
+        args: ['--version'],
+        timeoutMs: 5_000,
+        maxOutputBytes: 4_096
+      })
+    )
+  })
+
+  it('allows a timeout and reads the next version without waiting', async () => {
+    const program = '/fake/codex'
+    prints('codex-cli 0.135.0', true)
+    expect((await readCodexCliInstallation({ program })).status).toBe('unknown')
+    prints('codex-cli 0.136.0')
+    expect((await readCodexCliInstallation({ program })).status).toBe('ready')
+    expect(runProcess).toHaveBeenCalledTimes(2)
+  })
+
+  it.each(['ENOENT', 'EACCES'])(
+    'leaves a failed version spawn (%s) to the existing chat failure',
+    async (code) => {
+      const program = '/fake/codex'
+      runProcess.mockRejectedValue(Object.assign(new Error('unavailable'), { code }))
+      expect((await readCodexCliInstallation({ program })).status).toBe('unknown')
+    }
+  )
+})
diff --git a/src/main/preflight/codex-cli-installation.ts b/src/main/preflight/codex-cli-installation.ts
new file mode 100644
index 00000000000..d33d192b1f1
--- /dev/null
+++ b/src/main/preflight/codex-cli-installation.ts
@@ -0,0 +1,14 @@
+import {
+  codexCliInstallation,
+  parseCodexCliVersion,
+  type CodexCliInstallation
+} from '../../shared/codex-cli-installation'
+import type { ProcessSpec } from '@orca/process-host/process-spec'
+import { readAgentCliVersion } from '../agent-cli-version-probe'
+
+export async function readCodexCliInstallation(
+  input: Pick<ProcessSpec, 'program' | 'cwd' | 'env'>
+): Promise<CodexCliInstallation> {
+  const result = await readAgentCliVersion(input, parseCodexCliVersion)
+  return codexCliInstallation(true, result.version)
+}
diff --git a/src/main/preflight/codex-workspace-relative-path.test.ts b/src/main/preflight/codex-workspace-relative-path.test.ts
new file mode 100644
index 00000000000..d162c4c3b29
--- /dev/null
+++ b/src/main/preflight/codex-workspace-relative-path.test.ts
@@ -0,0 +1,128 @@
+import { mkdir, mkdtemp, rm, writeFile } from 'node:fs/promises'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import { agentSessionRecordFixture } from '../../shared/agent-session-record.test-fixture'
+import type { AgentSessionRecord } from '../../shared/agent-session-record'
+import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
+import { runProcess } from '@orca/process-host'
+import {
+  createCodexStructuredLaunchResolver,
+  TEST_SPAWN_TOKEN
+} from '../runtime/structured-agent-launch-composition.test-support'
+import { withSupportedCodexCli } from '../codex/codex-cli-installation-error'
+import { resolveStructuredAgentCommand } from '../native-chat/structured-agent-command-resolution'
+import { resolveTuiAgentLaunchEnv } from '../../shared/tui-agent-launch-defaults'
+import { createStructuredAgentEnvironmentResolvers } from '../runtime/structured-agent-shell-environment'
+import { identityFor } from '../codex/codex-structured-session-adapter-fixture'
+import { readCodexCliInstallation } from './codex-cli-installation'
+import type * as CommandResolution from '../../shared/node-cli-command-resolution'
+
+vi.mock('../startup/login-shell-environment', () => ({
+  resolveLoginShellEnvironment: async () => ({})
+}))
+vi.mock('../../shared/node-cli-command-resolution', async (original) => {
+  const actual = await original<typeof CommandResolution>()
+  return {
+    ...actual,
+    // Keep the stock resolver from substituting any real host installation.
+    resolveCliCommand: (name: string) => name
+  }
+})
+
+let root: string | undefined
+afterEach(async () => {
+  if (root) {
+    await rm(root, { recursive: true, force: true })
+  }
+})
+
+describe.skipIf(process.platform === 'win32')('workspace-relative Codex selection', () => {
+  it.each(['bin', 'node_modules/.bin', '.'])(
+    'admits the child selected through PATH=%s and recovers once it is updated',
+    async (entry) => {
+      root = await mkdtemp(join(tmpdir(), 'codex-relative-path-'))
+      const cwd = root
+      const directory = join(cwd, entry)
+      await mkdir(directory, { recursive: true })
+      const program = join(directory, 'codex')
+      const versionFile = `${program}.version`
+      await writeFile(versionFile, '0.136.0')
+      await writeFile(
+        program,
+        `#!${process.execPath}\nconst fs = require('node:fs')\n` +
+          `const file = __filename + '.version'\n` +
+          `console.log('codex-cli ' + fs.readFileSync(file, 'utf8'))\n`,
+        { mode: 0o755 }
+      )
+      const settings = { agentDefaultEnv: { codex: { PATH: entry } } }
+      const sources = {
+        resolveCommand: (options?: { pathEnv?: string | null; homePath?: string }) =>
+          resolveStructuredAgentCommand('codex', settings, options),
+        resolveAgentLaunchEnv: () => resolveTuiAgentLaunchEnv('codex', settings.agentDefaultEnv)
+      }
+      const environment = createStructuredAgentEnvironmentResolvers(sources)
+      const record: AgentSessionRecord = {
+        ...agentSessionRecordFixture(),
+        provider: 'codex' as const,
+        providerHandleChain: [],
+        accountHome: { variable: 'CODEX_HOME' as const, path: join(cwd, 'account') },
+        location: { ...agentSessionRecordFixture().location, workspaceKind: 'folder' as const }
+      }
+      const resolve = withSupportedCodexCli(
+        createCodexStructuredLaunchResolver({
+          store: { getRecord: () => record, pinLaunchDirectory: vi.fn() },
+          resolveCommand: sources.resolveCommand,
+          resolveEnvironment: () => environment.resolveAgentEnvironment('codex'),
+          resolveLaunchArgs: () => [],
+          resolveWorkspacePath: async () => cwd,
+          resolveRollout: async () => null
+        })
+      )
+      for (const resume of [false, true]) {
+        const value = agentSessionRecordFixture()
+        record.providerHandleChain = resume
+          ? [{ ...value.providerHandleChain[0], handle: codexProviderHandle('thread') }]
+          : []
+        const launch = await resolve({
+          identity: identityFor(record.sessionId),
+          spawnToken: TEST_SPAWN_TOKEN
+        })
+        const actual = await runProcess({
+          program: launch.command,
+          cwd: launch.cwd,
+          env: launch.env,
+          args: ['--version']
+        })
+        expect(actual.code).toBe(0)
+        expect(actual.stdout.trim()).toBe('codex-cli 0.136.0')
+        await writeFile(versionFile, '0.135.0')
+        await expect(
+          resolve({ identity: identityFor(record.sessionId), spawnToken: TEST_SPAWN_TOKEN })
+        ).rejects.toThrow('0.135.0')
+        // An external update is checked again on the next chat start.
+        await writeFile(versionFile, '0.136.0')
+        await expect(
+          resolve({ identity: identityFor(record.sessionId), spawnToken: TEST_SPAWN_TOKEN })
+        ).resolves.toMatchObject({
+          cwd
+        })
+      }
+    }
+  )
+
+  it('resolves a relative command path before probing it', async () => {
+    root = await mkdtemp(join(tmpdir(), 'codex-relative-command-'))
+    await mkdir(join(root, 'bin'))
+    const file = join(root, 'bin', 'codex')
+    await writeFile(file, `#!${process.execPath}\nconsole.log('codex-cli 0.136.0')\n`, {
+      mode: 0o755
+    })
+    const input = { program: join('bin', 'codex'), cwd: root, env: { PATH: '' } }
+    expect((await readCodexCliInstallation(input)).status).toBe('ready')
+    await writeFile(file, `#!${process.execPath}\nconsole.log('codex-cli 0.135.0')\n`, {
+      mode: 0o755
+    })
+    expect((await readCodexCliInstallation(input)).status).toBe('unsupported')
+  })
+})
diff --git a/src/main/runtime/scripted-codex-transport.test-fixture.ts b/src/main/runtime/scripted-codex-transport.test-fixture.ts
new file mode 100644
index 00000000000..851e0d36f32
--- /dev/null
+++ b/src/main/runtime/scripted-codex-transport.test-fixture.ts
@@ -0,0 +1,20 @@
+import {
+  CODEX_MINIMUM_SUPPORTED_VERSION,
+  codexCliInstallation
+} from '../../shared/codex-cli-installation'
+import type { StructuredAgentSessionRuntimeDeps } from './structured-agent-session-runtime'
+
+/** Runtime deps that put a scripted Codex child where the real app-server would spawn. It speaks
+ *  the supported protocol, so it reports that version; its fake pid has a fixed start time. */
+export function scriptedCodexTransport(
+  openConnection: NonNullable<StructuredAgentSessionRuntimeDeps['openCodexConnection']>
+): Pick<
+  StructuredAgentSessionRuntimeDeps,
+  'openCodexConnection' | 'readCodexInstallation' | 'readProcessStartTime'
+> {
+  return {
+    openCodexConnection: openConnection,
+    readCodexInstallation: async () => codexCliInstallation(true, CODEX_MINIMUM_SUPPORTED_VERSION),
+    readProcessStartTime: async () => 1_700_000_000_000
+  }
+}
diff --git a/src/main/runtime/structured-agent-launch-parity.test.ts b/src/main/runtime/structured-agent-launch-parity.test.ts
index 40b498046b4..ba7e25bd891 100644
--- a/src/main/runtime/structured-agent-launch-parity.test.ts
+++ b/src/main/runtime/structured-agent-launch-parity.test.ts
@@ -156,7 +156,7 @@ type Agent = (typeof AGENTS)[number]
 /** What each fake binary prints for `--version`: a release every launch gate accepts. */
 const VERSIONS: Record<Agent, string> = {
   claude: '2.1.120 (Claude Code)',
-  codex: 'codex-cli 0.130.0',
+  codex: 'codex-cli 0.136.0',
   grok: '1.0.50',
   opencode: '2.0.20',
   omp: '17.1.0',
diff --git a/src/main/runtime/structured-agent-runtime-registrations.ts b/src/main/runtime/structured-agent-runtime-registrations.ts
index 59afa69a92c..170a48a18f9 100644
--- a/src/main/runtime/structured-agent-runtime-registrations.ts
+++ b/src/main/runtime/structured-agent-runtime-registrations.ts
@@ -1,5 +1,6 @@
 // Each runtime registration owns its adapter, location support and account resolution at start.
 
+import { withSupportedCodexCli } from '../codex/codex-cli-installation-error'
 import { codexStructuredLaunchPart } from '../codex/codex-structured-launch-resolution'
 import { claudeStructuredLaunchPart } from '../claude/claude-structured-launch-resolution'
 import { supportsCodexStructuredLocation } from '../codex/codex-structured-location-support'
@@ -131,16 +132,19 @@ function createCodexAdapter(context: StructuredAgentAdapterContext): StructuredA
   const { deps, followUps, host } = context
   return new CodexStructuredSessionAdapter({
     resolveAccountKind: deps.resolveCodexAccountKind,
-    resolveLaunch: composeStructuredLaunch(
-      CODEX_STRUCTURED_AGENT,
-      structuredAgentLaunchSources(context),
-      codexStructuredLaunchPart({
-        resolveLaunchArgs: () => deps.resolveLaunchArgs('codex'),
-        ...(deps.resolveCodexPermissionPolicy
-          ? { resolvePermissionPolicy: deps.resolveCodexPermissionPolicy }
-          : {}),
-        ...(deps.resolveCodexCommand ? { resolveCommand: deps.resolveCodexCommand } : {})
-      })
+    resolveLaunch: withSupportedCodexCli(
+      composeStructuredLaunch(
+        CODEX_STRUCTURED_AGENT,
+        structuredAgentLaunchSources(context),
+        codexStructuredLaunchPart({
+          resolveLaunchArgs: () => deps.resolveLaunchArgs('codex'),
+          ...(deps.resolveCodexPermissionPolicy
+            ? { resolvePermissionPolicy: deps.resolveCodexPermissionPolicy }
+            : {}),
+          ...(deps.resolveCodexCommand ? { resolveCommand: deps.resolveCodexCommand } : {})
+        })
+      ),
+      deps.readCodexInstallation
     ),
     ...(deps.openCodexConnection ? { openConnection: deps.openCodexConnection } : {}),
     ...(deps.readProcessStartTime ? { readProcessStartTime: deps.readProcessStartTime } : {}),
diff --git a/src/main/runtime/structured-agent-session-codex-interrupt-order.test.ts b/src/main/runtime/structured-agent-session-codex-interrupt-order.test.ts
index a1095f28ccc..617ff88b0db 100644
--- a/src/main/runtime/structured-agent-session-codex-interrupt-order.test.ts
+++ b/src/main/runtime/structured-agent-session-codex-interrupt-order.test.ts
@@ -36,6 +36,7 @@ import {
   ensureStructuredAgentSessionHost,
   stopStructuredAgentSessionRuntime
 } from './structured-agent-session-runtime'
+import { scriptedCodexTransport } from './scripted-codex-transport.test-fixture'
 
 const CALLER = { callerKey: 'codex-interrupt-order-test' }
 const MODEL = {
@@ -220,8 +221,7 @@ beforeEach(async () => {
     resolveClaudeAuthPolicy: () => ({ account: 'managed' }),
     resolveCodexCommand: () => 'codex',
     resolveEnvironment: async () => ({ PATH: process.env.PATH }),
-    openCodexConnection: openConnection,
-    readProcessStartTime: async () => 1_700_000_000_000
+    ...scriptedCodexTransport(openConnection)
   })
   const attachParams = hostTestAttachParams(null, { providerHandle: undefined })
   attachParams.envelope.clientOperationId = operationId()
diff --git a/src/main/runtime/structured-agent-session-codex-opening-send-hold.test.ts b/src/main/runtime/structured-agent-session-codex-opening-send-hold.test.ts
index 6e3e94a3fa1..a49d89ddd5f 100644
--- a/src/main/runtime/structured-agent-session-codex-opening-send-hold.test.ts
+++ b/src/main/runtime/structured-agent-session-codex-opening-send-hold.test.ts
@@ -39,6 +39,7 @@ import {
   stopStructuredAgentSessionRuntime
 } from './structured-agent-session-runtime'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
+import { scriptedCodexTransport } from './scripted-codex-transport.test-fixture'
 
 // The turns a send or Stop is waiting on to open, so a test knows the wait began.
 const openWaits = vi.hoisted(() => {
@@ -237,8 +238,7 @@ beforeEach(async () => {
     resolveCodexCommand: () => 'codex',
     resolveLaunchArgs: () => [],
     resolveEnvironment: async () => ({ PATH: process.env.PATH }),
-    openCodexConnection: openConnection,
-    readProcessStartTime: async () => 1_700_000_000_000
+    ...scriptedCodexTransport(openConnection)
   })
   const attachParams = hostTestAttachParams(null, { providerHandle: undefined })
   attachParams.envelope.clientOperationId = operationId()
diff --git a/src/main/runtime/structured-agent-session-codex-settlement-order.test.ts b/src/main/runtime/structured-agent-session-codex-settlement-order.test.ts
index 7c07255edb3..f4fc4d54968 100644
--- a/src/main/runtime/structured-agent-session-codex-settlement-order.test.ts
+++ b/src/main/runtime/structured-agent-session-codex-settlement-order.test.ts
@@ -39,6 +39,7 @@ import {
   ensureStructuredAgentSessionHost,
   stopStructuredAgentSessionRuntime
 } from './structured-agent-session-runtime'
+import { scriptedCodexTransport } from './scripted-codex-transport.test-fixture'
 
 const CALLER = { callerKey: 'codex-settlement-order-test' }
 const MODEL = {
@@ -164,8 +165,7 @@ beforeEach(async () => {
     resolveClaudeAuthPolicy: () => ({ account: 'managed' }),
     resolveCodexCommand: () => 'codex',
     resolveEnvironment: async () => ({ PATH: process.env.PATH }),
-    openCodexConnection: openConnection,
-    readProcessStartTime: async () => 1_700_000_000_000
+    ...scriptedCodexTransport(openConnection)
   })
   const attachParams = hostTestAttachParams(null, { providerHandle: undefined })
   attachParams.envelope.clientOperationId = operationId()
diff --git a/src/main/runtime/structured-agent-session-codex-stopped-send-order.test.ts b/src/main/runtime/structured-agent-session-codex-stopped-send-order.test.ts
index 02c7ae282f2..a9633ae80dc 100644
--- a/src/main/runtime/structured-agent-session-codex-stopped-send-order.test.ts
+++ b/src/main/runtime/structured-agent-session-codex-stopped-send-order.test.ts
@@ -40,6 +40,7 @@ import {
   ensureStructuredAgentSessionHost,
   stopStructuredAgentSessionRuntime
 } from './structured-agent-session-runtime'
+import { scriptedCodexTransport } from './scripted-codex-transport.test-fixture'
 
 const CALLER = { callerKey: 'codex-stopped-send-resume-test' }
 const MODEL = {
@@ -177,8 +178,7 @@ async function startHost(): Promise<void> {
     resolveClaudeAuthPolicy: () => ({ account: 'managed' }),
     resolveCodexCommand: () => 'codex',
     resolveEnvironment: async () => ({ PATH: process.env.PATH }),
-    openCodexConnection: openConnection,
-    readProcessStartTime: async () => 1_700_000_000_000
+    ...scriptedCodexTransport(openConnection)
   })
 }
 
diff --git a/src/main/runtime/structured-agent-session-codex-turn-end-settlement.test.ts b/src/main/runtime/structured-agent-session-codex-turn-end-settlement.test.ts
index b57b6a3e1b5..f41061392fd 100644
--- a/src/main/runtime/structured-agent-session-codex-turn-end-settlement.test.ts
+++ b/src/main/runtime/structured-agent-session-codex-turn-end-settlement.test.ts
@@ -41,6 +41,7 @@ import {
 } from './structured-agent-session-runtime'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
 import { createCoordinatorMailObservationClock } from './structured-chat-coordinator-observation-clock.test-fixture'
+import { scriptedCodexTransport } from './scripted-codex-transport.test-fixture'
 
 // The turns a send or Stop is waiting on to open, so a test knows the wait began.
 const openWaits = vi.hoisted(() => {
@@ -280,8 +281,7 @@ beforeEach(async () => {
     resolveClaudeAuthPolicy: () => ({ account: 'managed' }),
     resolveCodexCommand: () => 'codex',
     resolveEnvironment: async () => ({ PATH: process.env.PATH }),
-    openCodexConnection: openConnection,
-    readProcessStartTime: async () => 1_700_000_000_000
+    ...scriptedCodexTransport(openConnection)
   })
   const attachParams = hostTestAttachParams(null, { providerHandle: undefined })
   attachParams.envelope.clientOperationId = operationId()
diff --git a/src/main/runtime/structured-agent-session-integration.test.ts b/src/main/runtime/structured-agent-session-integration.test.ts
index 7232960bfa9..deaee6763c3 100644
--- a/src/main/runtime/structured-agent-session-integration.test.ts
+++ b/src/main/runtime/structured-agent-session-integration.test.ts
@@ -46,6 +46,7 @@ import {
 } from './structured-agent-session-runtime'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
 import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
+import { scriptedCodexTransport } from './scripted-codex-transport.test-fixture'
 
 const journals = createTrackedJournalOpener()
 
@@ -364,8 +365,7 @@ beforeEach(async () => {
           codexOverrideReads += 1
           return { CODEX_PROFILE: configuredCodexProfile }
         },
-        openCodexConnection: codex.openConnection,
-        readProcessStartTime: async () => 1_700_000_000_000
+        ...scriptedCodexTransport(codex.openConnection)
       }).then(() => undefined),
     registerOwnedSubscriptionCleanup: vi.fn((_id: string, dispose: () => void) => ({
       releaseIfCurrent: dispose
diff --git a/src/main/runtime/structured-agent-session-runtime-exit.test.ts b/src/main/runtime/structured-agent-session-runtime-exit.test.ts
index f5ed248e736..36e1e514d75 100644
--- a/src/main/runtime/structured-agent-session-runtime-exit.test.ts
+++ b/src/main/runtime/structured-agent-session-runtime-exit.test.ts
@@ -19,6 +19,7 @@ import {
 } from './structured-agent-session-runtime'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
 import { codexProviderHandle } from '../../shared/agent-session-provider-handle-encoding'
+import { scriptedCodexTransport } from './scripted-codex-transport.test-fixture'
 
 describe('structured session runtime provider-exit wiring', () => {
   let root: string | null = null
@@ -91,8 +92,7 @@ describe('structured session runtime provider-exit wiring', () => {
       resolveClaudeAuthPolicy: () => ({ account: 'managed' }),
       resolveCodexCommand: () => 'codex',
       resolveEnvironment: async () => ({ PATH: process.env.PATH }),
-      openCodexConnection: openConnection,
-      readProcessStartTime: async () => 1_700_000_000_000
+      ...scriptedCodexTransport(openConnection)
     })
     const attachParams = hostTestAttachParams(null, { providerHandle: undefined })
     attachParams.envelope.clientOperationId = operationId()
@@ -197,8 +197,7 @@ describe('structured session runtime provider-exit wiring', () => {
       resolveClaudeAuthPolicy: () => ({ account: 'managed' }),
       resolveCodexCommand: () => 'codex',
       resolveEnvironment: async () => ({ PATH: process.env.PATH }),
-      openCodexConnection: openConnection,
-      readProcessStartTime: async () => 1_700_000_000_000
+      ...scriptedCodexTransport(openConnection)
     })
     const attachParams = hostTestAttachParams(null, { providerHandle: undefined })
     attachParams.envelope.clientOperationId = operationId()
@@ -229,8 +228,7 @@ describe('structured session runtime provider-exit wiring', () => {
       resolveClaudeAuthPolicy: () => ({ account: 'managed' }),
       resolveCodexCommand: () => 'codex',
       resolveEnvironment: async () => ({ PATH: process.env.PATH }),
-      openCodexConnection: openConnection,
-      readProcessStartTime: async () => 1_700_000_000_000
+      ...scriptedCodexTransport(openConnection)
     })
     await restarted.restoreReadableSessions()
     const history = await restarted.history({ sessionId: SESSION, direction: 'tail' })
@@ -304,8 +302,7 @@ describe('structured session runtime provider-exit wiring', () => {
       resolveClaudeAuthPolicy: () => ({ account: 'managed' }),
       resolveCodexCommand: () => 'codex',
       resolveEnvironment: async () => ({ PATH: process.env.PATH }),
-      openCodexConnection: openConnection,
-      readProcessStartTime: async () => 1_700_000_000_000
+      ...scriptedCodexTransport(openConnection)
     })
     const attachParams = hostTestAttachParams(null, { providerHandle: undefined })
     attachParams.envelope.clientOperationId = operationId()
@@ -412,8 +409,7 @@ describe('structured session runtime provider-exit wiring', () => {
       resolveClaudeAuthPolicy: () => ({ account: 'managed' }),
       resolveCodexCommand: () => 'codex',
       resolveEnvironment: async () => ({ PATH: process.env.PATH }),
-      openCodexConnection: openConnection,
-      readProcessStartTime: async () => 1_700_000_000_000
+      ...scriptedCodexTransport(openConnection)
     })
     const attachParams = hostTestAttachParams(null, { providerHandle: undefined })
     attachParams.envelope.clientOperationId = operationId()
diff --git a/src/main/runtime/structured-agent-session-runtime.ts b/src/main/runtime/structured-agent-session-runtime.ts
index 64e44ab74c5..637cc61aaf2 100644
--- a/src/main/runtime/structured-agent-session-runtime.ts
+++ b/src/main/runtime/structured-agent-session-runtime.ts
@@ -26,6 +26,7 @@ import { AgentSessionRecoveryCapsule } from './agent-session-recovery-capsule'
 import type { CodexStructuredPermissionPolicy } from '../codex/codex-structured-permission-policy'
 import type { StructuredAgentCommandSettings } from '../native-chat/structured-agent-command-resolution'
 import type { CodexStructuredSessionAdapterDeps } from '../codex/codex-structured-session-adapter'
+import type { readCodexCliInstallation } from '../preflight/codex-cli-installation'
 import type { ClaudeStructuredSessionAdapterDeps } from '../claude/claude-structured-session-adapter'
 import {
   StructuredAgentSessionHost,
@@ -113,6 +114,8 @@ export type StructuredAgentSessionRuntimeDeps = {
   }
   /** Provider transports are overridden only to drive the runtime against scripted children. */
   openCodexConnection?: CodexStructuredSessionAdapterDeps['openConnection']
+  /** Scripted transports must also replace the real host's version probe. */
+  readCodexInstallation?: typeof readCodexCliInstallation
   openClaudeConnection?: ClaudeStructuredSessionAdapterDeps['openConnection']
   /** Scripted app-servers carry fake pids the real start-time read cannot answer for. */
   readProcessStartTime?: CodexStructuredSessionAdapterDeps['readProcessStartTime']
diff --git a/src/main/runtime/structured-chat-coordinator-mail-rig.test-fixture.ts b/src/main/runtime/structured-chat-coordinator-mail-rig.test-fixture.ts
index 8155b889b37..bd74bdd1b75 100644
--- a/src/main/runtime/structured-chat-coordinator-mail-rig.test-fixture.ts
+++ b/src/main/runtime/structured-chat-coordinator-mail-rig.test-fixture.ts
@@ -35,6 +35,7 @@ import {
   type FakeConnection
 } from './structured-chat-coordinator-fake-codex-fixture'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
+import { scriptedCodexTransport } from './scripted-codex-transport.test-fixture'
 
 export const COORDINATOR = '4a1f6c2e-8b3d-4e7a-9c15-0d2b6e8f1a37'
 export const PEER_CHAT = '7e3b9d15-2c4a-4f86-a0b1-5c9e2d7f3b64'
@@ -257,8 +258,7 @@ beforeEach(async () => {
     resolveLaunchArgs: () => [],
     resolveClaudeAuthPolicy: () => ({ account: 'managed' }),
     resolveEnvironment: async () => ({ PATH: '/usr/bin' }),
-    openCodexConnection: codex.openConnection,
-    readProcessStartTime: async () => 1_700_000_000_000,
+    ...scriptedCodexTransport(codex.openConnection),
     // The same calls the runtime's own host install makes.
     onSessionStatusChanged: (summary) => runtime.onStructuredSessionStatusForMail(summary),
     onSessionTabHidden: (sessionId) => runtime.onStructuredSessionTabHidden(sessionId)
diff --git a/src/main/runtime/structured-child-records-switch.test.ts b/src/main/runtime/structured-child-records-switch.test.ts
index d826b2f1b2f..949afdb89dc 100644
--- a/src/main/runtime/structured-child-records-switch.test.ts
+++ b/src/main/runtime/structured-child-records-switch.test.ts
@@ -34,6 +34,7 @@ import {
   stopStructuredAgentSessionRuntime
 } from './structured-agent-session-runtime'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
+import { scriptedCodexTransport } from './scripted-codex-transport.test-fixture'
 import { createScriptedClaudeRuntime } from './structured-claude-scripted-runtime-test-support'
 
 vi.mock('../telemetry/client', () => ({ track: vi.fn() }))
@@ -128,8 +129,7 @@ describe('the chat strip and the session list read the same host child records',
       resolveClaudeAuthPolicy: () => ({ account: 'managed' }),
       resolveCodexCommand: () => 'codex',
       resolveEnvironment: async () => ({ PATH: process.env.PATH }),
-      openCodexConnection: openConnection,
-      readProcessStartTime: async () => 1_700_000_000_000,
+      ...scriptedCodexTransport(openConnection),
       statusSink
     })
     const attachParams = hostTestAttachParams(null, { providerHandle: undefined })
diff --git a/src/main/runtime/structured-codex-child-work-runtime.test.ts b/src/main/runtime/structured-codex-child-work-runtime.test.ts
index 3fc2599c3eb..bd29562320e 100644
--- a/src/main/runtime/structured-codex-child-work-runtime.test.ts
+++ b/src/main/runtime/structured-codex-child-work-runtime.test.ts
@@ -20,6 +20,7 @@ import {
   stopStructuredAgentSessionRuntime
 } from './structured-agent-session-runtime'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
+import { scriptedCodexTransport } from './scripted-codex-transport.test-fixture'
 import { AgentHookServer } from '../agent-hooks/server'
 import { makeStructuredAgentStatusSubject } from '../../shared/agent-status-subject'
 import { AgentSessionRecoveryCapsule } from './agent-session-recovery-capsule'
@@ -88,8 +89,7 @@ describe('structured Codex child work through the production runtime', () => {
       resolveClaudeAuthPolicy: () => ({ account: 'managed' }),
       resolveCodexCommand: () => 'codex',
       resolveEnvironment: async () => ({ PATH: process.env.PATH }),
-      openCodexConnection: openConnection,
-      readProcessStartTime: async () => 1_700_000_000_000,
+      ...scriptedCodexTransport(openConnection),
       statusSink: {
         publish: () => {},
         forget: () => {},
diff --git a/src/main/runtime/structured-codex-session-rpc-test-harness.ts b/src/main/runtime/structured-codex-session-rpc-test-harness.ts
index ebb54a15061..67ff1574b75 100644
--- a/src/main/runtime/structured-codex-session-rpc-test-harness.ts
+++ b/src/main/runtime/structured-codex-session-rpc-test-harness.ts
@@ -29,6 +29,7 @@ import {
   stopStructuredAgentSessionRuntime
 } from './structured-agent-session-runtime'
 import { createStructuredAgentSessionLogger } from '../native-chat/agent-session-wire/structured-agent-session-logger'
+import { scriptedCodexTransport } from './scripted-codex-transport.test-fixture'
 
 export const SESSION = 'session-integration-1'
 export const THREAD = 'thread-integration'
@@ -229,8 +230,7 @@ export async function openStructuredCodexRpcHarness(
     }),
     resolveAgentLaunchEnv: (agent): Record<string, string> =>
       agent === 'codex' ? { CODEX_PROFILE: 'configured' } : {},
-    openCodexConnection: codex.openConnection,
-    readProcessStartTime: async () => 1_700_000_000_000
+    ...scriptedCodexTransport(codex.openConnection)
   })
   const runtime = {
     getRuntimeId: () => 'runtime-1',
diff --git a/src/main/runtime/structured-foreground-command-strip.test.ts b/src/main/runtime/structured-foreground-command-strip.test.ts
index 3d9bd0060c0..2e819f4daf4 100644
--- a/src/main/runtime/structured-foreground-command-strip.test.ts
+++ b/src/main/runtime/structured-foreground-command-strip.test.ts
@@ -15,6 +15,7 @@ import {
   ensureStructuredAgentSessionHost,
   stopStructuredAgentSessionRuntime
 } from './structured-agent-session-runtime'
+import { scriptedCodexTransport } from './scripted-codex-transport.test-fixture'
 
 vi.mock('../telemetry/client', () => ({ track: vi.fn() }))
 vi.mock('../telemetry/cohort-classifier', () => ({ getCohortAtEmit: vi.fn() }))
@@ -61,8 +62,7 @@ describe('foreground commands in the background-task channel', () => {
       resolveClaudeAuthPolicy: () => ({ account: 'managed' }),
       resolveCodexCommand: () => 'codex',
       resolveEnvironment: async () => ({ PATH: process.env.PATH }),
-      openCodexConnection: codex.openConnection,
-      readProcessStartTime: async () => 1_700_000_000_000,
+      ...scriptedCodexTransport(codex.openConnection),
       statusSink: {
         publish: (summary, subject) => server.ingestStructuredStatus(summary, subject),
         forget: (subject) => server.dropStructuredStatus(subject),
diff --git a/src/renderer/src/components/native-chat/NativeChatNoticeRow.test.tsx b/src/renderer/src/components/native-chat/NativeChatNoticeRow.test.tsx
index 777936a1c93..5843947753b 100644
--- a/src/renderer/src/components/native-chat/NativeChatNoticeRow.test.tsx
+++ b/src/renderer/src/components/native-chat/NativeChatNoticeRow.test.tsx
@@ -3,6 +3,7 @@ import '@testing-library/jest-dom/vitest'
 import { act, cleanup, fireEvent, render, screen } from '@testing-library/react'
 import { afterEach, describe, expect, it, vi } from 'vitest'
 import { projectStructuredItemsToNativeChat } from '../../../../shared/structured-agent-session-projection'
+import type { AgentSessionFailureFact } from '../../../../shared/agent-session-failure'
 import type { AgentJournalStatusItem } from '../../../../shared/agent-session-journal-types'
 import { TooltipProvider } from '@/components/ui/tooltip'
 import { MessageRow } from './NativeChatMessageRow'
@@ -419,3 +420,41 @@ describe('notice rows', () => {
     expect(screen.queryByText('Words an older host wrote')).toBeNull()
   })
 })
+
+describe('Codex installation in notice rows', () => {
+  it.each([null, '0.135.0'])(
+    'shows the plain host failure through the ordinary notice row: %s',
+    (installedVersion) => {
+      const failure: AgentSessionFailureFact = {
+        kind: installedVersion === null ? 'cliMissing' : 'startFailed',
+        ...(installedVersion === null
+          ? {}
+          : {
+              refusal: {
+                code: 'agent_session_operation_invalid',
+                details: {
+                  reason: 'attachFailed',
+                  codexInstallation: { installedVersion, minimumVersion: '0.136.0' }
+                }
+              }
+            })
+      }
+      const text = installedVersion
+        ? 'Codex 0.135.0 is too old for chats. Update to 0.136.0 or newer.'
+        : "Codex wasn't found on the computer running this chat. Install it, or check its Command in Settings → Agents."
+      renderStatus(
+        {
+          kind: 'status',
+          tone: 'error',
+          ...agentSessionFailureWords(failure, { agentName: 'Codex', surface: 'row' })
+        },
+        null,
+        false,
+        false,
+        'Codex'
+      )
+      expect(screen.getByText(text)).toBeInTheDocument()
+      expect(screen.queryByRole('button')).toBeNull()
+    }
+  )
+})
diff --git a/src/renderer/src/components/native-chat/NativeChatStructuredSession.approval-and-start-failure.test.tsx b/src/renderer/src/components/native-chat/NativeChatStructuredSession.approval-and-start-failure.test.tsx
index 3dc83d883e8..757f5576c4b 100644
--- a/src/renderer/src/components/native-chat/NativeChatStructuredSession.approval-and-start-failure.test.tsx
+++ b/src/renderer/src/components/native-chat/NativeChatStructuredSession.approval-and-start-failure.test.tsx
@@ -197,7 +197,10 @@ afterEach(() => {
   }
 
   // The notices are the host's rows'; a copy an earlier session left in the outbox gives way to them.
-  function renderPane(messages: ReturnType<typeof rejected>[]): void {
+  function renderPane(
+    messages: ReturnType<typeof rejected>[],
+    agent: 'claude' | 'codex' = 'claude'
+  ): void {
     mocks.submissions = messages.map((message) => message.submission)
     localStorage.setItem(
       `orca:desktopStructuredAgentSessionOutbox:v1:${encodeURIComponent(SESSION_ID)}`,
@@ -210,7 +213,7 @@ afterEach(() => {
         tabId="start-failure-tab"
         sessionId={SESSION_ID}
         target={{ kind: 'local' }}
-        agent="claude"
+        agent={agent}
       />
     )
   }
@@ -268,4 +271,37 @@ afterEach(() => {
 
     expect(within(await notice('first')).getByText(START_FAILED_REASON)).toBeTruthy()
   })
+
+  it.each([null, '0.100.0', '0.135.0'])(
+    'states a missing or too-old Codex (installed version %s) in the existing failure notice',
+    async (installedVersion) => {
+      const failure: AgentSessionFailureFact = {
+        kind: installedVersion === null ? 'cliMissing' : 'startFailed',
+        ...(installedVersion === null
+          ? {}
+          : {
+              refusal: {
+                code: 'agent_session_operation_invalid',
+                details: {
+                  reason: 'attachFailed',
+                  codexInstallation: { installedVersion, minimumVersion: '0.136.0' }
+                }
+              }
+            })
+      }
+      const { text } = agentSessionFailureWords(failure, { agentName: 'Codex', surface: 'row' })
+      renderPane([rejected('codex-message', text, failure)], 'codex')
+      const row = await notice('codex-message')
+      expect(within(row).getByText(text)).toBeTruthy()
+      expect(text).toContain(
+        installedVersion === null
+          ? "Codex wasn't found on the computer running this chat. Install it, or check its Command in Settings → Agents."
+          : `Codex ${installedVersion} is too old for chats. Update to 0.136.0 or newer.`
+      )
+      if (installedVersion !== null) {
+        expect(text).not.toContain('Settings → Agents')
+      }
+      expect(text).not.toContain('codex update')
+    }
+  )
 }
diff --git a/src/renderer/src/components/native-chat/agent-session-availability-words-text.ts b/src/renderer/src/components/native-chat/agent-session-availability-words-text.ts
index a1ab8d3fe33..3e6250afda6 100644
--- a/src/renderer/src/components/native-chat/agent-session-availability-words-text.ts
+++ b/src/renderer/src/components/native-chat/agent-session-availability-words-text.ts
@@ -18,6 +18,7 @@ type AvailabilityCopyId = Extract<
   | 'agentNotSignedIn'
   | 'thenSendAgain'
   | 'cliMissing'
+  | 'codexCliTooOld'
 >
 
 export const AVAILABILITY_PIECES: Record<
@@ -69,5 +70,7 @@ export const AVAILABILITY_PIECES: Record<
       values
     ),
   cliMissing: (values) =>
-    translate('components.native-chat.failureWords.cliMissing', COPY.cliMissing, values)
+    translate('components.native-chat.failureWords.cliMissing', COPY.cliMissing, values),
+  codexCliTooOld: (values) =>
+    translate('components.native-chat.failureWords.codexCliTooOld', COPY.codexCliTooOld, values)
 }
diff --git a/src/renderer/src/components/native-chat/use-structured-agent-session-start-failure-facts.test.ts b/src/renderer/src/components/native-chat/use-structured-agent-session-start-failure-facts.test.ts
index 97ef023dffb..4d7f65ab071 100644
--- a/src/renderer/src/components/native-chat/use-structured-agent-session-start-failure-facts.test.ts
+++ b/src/renderer/src/components/native-chat/use-structured-agent-session-start-failure-facts.test.ts
@@ -40,3 +40,26 @@ it('holds the same facts while the start rows state nothing new', () => {
   rerender({ items: [row, startFailureRow('other-start', { kind: 'providerStartFailed' })] })
   expect(result.current).toBe(second)
 })
+
+it('re-derives a changed Codex installation refusal instead of retaining its old facts', () => {
+  function failure(installedVersion: string | null): AgentSessionFailureFact {
+    return {
+      kind: 'startFailed',
+      refusal: {
+        code: 'agent_session_operation_invalid',
+        details: {
+          reason: 'attachFailed',
+          codexInstallation: { installedVersion, minimumVersion: '0.136.0' }
+        }
+      }
+    }
+  }
+  const { result, rerender } = renderHook(
+    ({ items }) => useStructuredAgentSessionStartFailureFacts(items, true),
+    { initialProps: { items: [startFailureRow('gen-1', failure(null))] } }
+  )
+  const initial = result.current
+  rerender({ items: [startFailureRow('gen-1', failure('0.135.0'))] })
+  expect(result.current).not.toBe(initial)
+  expect(result.current).toEqual([failure('0.135.0')])
+})
diff --git a/src/renderer/src/i18n/en-runtime-required.json b/src/renderer/src/i18n/en-runtime-required.json
index 2f4af488fdc..d000a602d4b 100644
--- a/src/renderer/src/i18n/en-runtime-required.json
+++ b/src/renderer/src/i18n/en-runtime-required.json
@@ -2864,6 +2864,7 @@
         "claudeManagedNotSignedIn": "This Claude account isn't signed in. Sign in again in Claude Accounts settings.",
         "claudeSystemNotSignedIn": "Claude isn't signed in. Run `{{loginCommand}}`, or choose an account in Claude Accounts settings.",
         "cliMissing": "{{agent}} wasn't found on the computer running this chat. Install it, or check its Command in Settings → Agents.",
+        "codexCliTooOld": "Codex {{installedVersion}} is too old for chats. Update to {{minimumVersion}} or newer.",
         "codexManagedNotSignedIn": "This Codex account isn't signed in. Sign in again in Codex Accounts settings.",
         "codexSystemNotSignedIn": "Codex isn't signed in. Run `{{loginCommand}}`.",
         "commandAfterAnswer": "Answer the agent's question or approval, then run /{{command}}.",
diff --git a/src/renderer/src/i18n/locales/en.json b/src/renderer/src/i18n/locales/en.json
index c7413042f03..e7798c8734d 100644
--- a/src/renderer/src/i18n/locales/en.json
+++ b/src/renderer/src/i18n/locales/en.json
@@ -18054,6 +18054,7 @@
         "sendAgainToTryOnceMore": "Send your message again to try once more.",
         "couldNotStart": "{{agent}} couldn't start.",
         "couldNotRestart": "{{agent}} couldn't restart.",
+        "codexCliTooOld": "Codex {{installedVersion}} is too old for chats. Update to {{minimumVersion}} or newer.",
         "notSignedIn": "{{agent}} is not signed in.",
         "claudeSystemNotSignedIn": "Claude isn't signed in. Run `{{loginCommand}}`, or choose an account in Claude Accounts settings.",
         "claudeManagedNotSignedIn": "This Claude account isn't signed in. Sign in again in Claude Accounts settings.",
diff --git a/src/renderer/src/i18n/locales/es.json b/src/renderer/src/i18n/locales/es.json
index a76edbcff12..8906f2d8380 100644
--- a/src/renderer/src/i18n/locales/es.json
+++ b/src/renderer/src/i18n/locales/es.json
@@ -17754,6 +17754,7 @@
         "couldNotStart": "{{agent}} no pudo iniciarse.",
         "editSavedArguments": "Edítalos en Ajustes > Agentes > Argumentos.",
         "couldNotRestart": "{{agent}} no pudo reiniciarse.",
+        "codexCliTooOld": "Codex {{installedVersion}} es demasiado antiguo para los chats. Actualiza a {{minimumVersion}} o una versión posterior.",
         "notSignedIn": "{{agent}} no ha iniciado sesión.",
         "claudeSystemNotSignedIn": "Claude no ha iniciado sesión. Ejecuta `{{loginCommand}}` o elige una cuenta en los ajustes de Cuentas de Claude.",
         "claudeManagedNotSignedIn": "Esta cuenta de Claude no ha iniciado sesión. Vuelve a iniciar sesión en la configuración de Cuentas de Claude.",
diff --git a/src/renderer/src/i18n/locales/fr.json b/src/renderer/src/i18n/locales/fr.json
index 0b3486d1f7b..b3b4b2fafdd 100644
--- a/src/renderer/src/i18n/locales/fr.json
+++ b/src/renderer/src/i18n/locales/fr.json
@@ -17856,6 +17856,7 @@
         "couldNotStart": "{{agent}} n'a pas pu démarrer.",
         "editSavedArguments": "Modifiez-les dans Paramètres > Agents > Arguments.",
         "couldNotRestart": "{{agent}} n'a pas pu redémarrer.",
+        "codexCliTooOld": "Codex {{installedVersion}} est trop ancien pour les conversations. Mettez-le à jour vers {{minimumVersion}} ou une version ultérieure.",
         "notSignedIn": "{{agent}} n’est pas connecté.",
         "claudeSystemNotSignedIn": "Claude n’est pas connecté. Exécutez `{{loginCommand}}`, ou choisissez un compte dans les paramètres des Comptes Claude.",
         "claudeManagedNotSignedIn": "Ce compte Claude n’est pas connecté. Reconnectez-vous dans les paramètres des Comptes Claude.",
diff --git a/src/renderer/src/i18n/locales/ja.json b/src/renderer/src/i18n/locales/ja.json
index a555dd5f7bd..a852837556d 100644
--- a/src/renderer/src/i18n/locales/ja.json
+++ b/src/renderer/src/i18n/locales/ja.json
@@ -17789,6 +17789,7 @@
         "couldNotStart": "{{agent}} を起動できませんでした。",
         "editSavedArguments": "設定 > Agent > 引数で編集してください。",
         "couldNotRestart": "{{agent}} を再起動できませんでした。",
+        "codexCliTooOld": "Codex {{installedVersion}} はチャットには古すぎます。{{minimumVersion}} 以降に更新してください。",
         "notSignedIn": "{{agent}} にサインインしていません。",
         "claudeSystemNotSignedIn": "Claude にサインインしていません。`{{loginCommand}}` を実行するか、Claude アカウント設定でアカウントを選択してください。",
         "claudeManagedNotSignedIn": "この Claude アカウントにサインインしていません。設定の Claude アカウントで再度サインインしてください。",
diff --git a/src/renderer/src/i18n/locales/ko.json b/src/renderer/src/i18n/locales/ko.json
index 834e4c442db..0e8217e2245 100644
--- a/src/renderer/src/i18n/locales/ko.json
+++ b/src/renderer/src/i18n/locales/ko.json
@@ -17789,6 +17789,7 @@
         "couldNotStart": "{{agent}}을(를) 시작하지 못했습니다.",
         "editSavedArguments": "설정 > 에이전트 > 인수에서 수정하세요.",
         "couldNotRestart": "{{agent}}을(를) 다시 시작하지 못했습니다.",
+        "codexCliTooOld": "Codex {{installedVersion}}은 채팅에 사용하기에는 너무 오래된 버전입니다. {{minimumVersion}} 이상으로 업데이트하세요.",
         "notSignedIn": "{{agent}}에 로그인되어 있지 않습니다.",
         "claudeSystemNotSignedIn": "Claude에 로그인되어 있지 않습니다. `{{loginCommand}}`을 실행하거나 Claude 계정 설정에서 계정을 선택하세요.",
         "claudeManagedNotSignedIn": "이 Claude 계정에 로그인하지 않았습니다. Claude 계정 설정에서 다시 로그인하세요.",
diff --git a/src/renderer/src/i18n/locales/zh.json b/src/renderer/src/i18n/locales/zh.json
index bec53737a97..edfaed1a3b6 100644
--- a/src/renderer/src/i18n/locales/zh.json
+++ b/src/renderer/src/i18n/locales/zh.json
@@ -17768,6 +17768,7 @@
         "couldNotStart": "{{agent}} 无法启动。",
         "editSavedArguments": "请在设置 > 智能体 > 参数中编辑。",
         "couldNotRestart": "{{agent}} 无法重新启动。",
+        "codexCliTooOld": "Codex {{installedVersion}} 版本过旧，无法用于聊天。请更新到 {{minimumVersion}} 或更高版本。",
         "notSignedIn": "{{agent}} 尚未登录。",
         "claudeSystemNotSignedIn": "Claude 尚未登录。请运行 `{{loginCommand}}`，或在 Claude 账户设置中选择账户。",
         "claudeManagedNotSignedIn": "此 Claude 账户尚未登录。请在 Claude 账户设置中重新登录。",
diff --git a/src/shared/agent-session-failure-copy.ts b/src/shared/agent-session-failure-copy.ts
index 47c5cde1e3f..48ba20afa52 100644
--- a/src/shared/agent-session-failure-copy.ts
+++ b/src/shared/agent-session-failure-copy.ts
@@ -5,6 +5,7 @@ import {
   CLAUDE_PROFILE_MISSING_MESSAGE,
   CLAUDE_PROFILE_SETUP_FAILED_MESSAGE
 } from './claude-profile-routing'
+import type { AgentSessionRefusalReference } from './agent-session-wire-refusals'
 
 /** Sentences a refusal notice shows too, so a chat says them one way. */
 export const TERMINAL_AGENT_HOLDS_CHAT = 'This chat is still open in a terminal agent.'
@@ -27,6 +28,8 @@ export const AGENT_SESSION_FAILURE_COPY = {
   sendAgainToTryOnceMore: 'Send your message again to try once more.',
   couldNotStart: "{{agent}} couldn't start.",
   couldNotRestart: "{{agent}} couldn't restart.",
+  codexCliTooOld:
+    'Codex {{installedVersion}} is too old for chats. Update to {{minimumVersion}} or newer.',
   argumentsUnsupportedOption: 'Saved Arguments contain an unsupported option ({{option}}).',
   argumentsMissingValue: 'Saved Arguments need a value for {{option}}.',
   argumentsMultipleValues: 'Saved Arguments give {{option}} more than one value.',
@@ -140,6 +143,8 @@ export type AgentSessionFailureCopyId = keyof typeof AGENT_SESSION_FAILURE_COPY
 
 /** What a piece's `{{name}}` placeholders stand for. */
 export type AgentSessionFailureCopyValues = {
+  installedVersion?: string
+  minimumVersion?: string
   agent?: string
   command?: string
   loginCommand?: string
@@ -158,6 +163,23 @@ export type AgentSessionFailureSay = (
   values?: AgentSessionFailureCopyValues
 ) => string
 
+export function codexInstallationFailureWords(
+  refusal: AgentSessionRefusalReference | undefined,
+  say: AgentSessionFailureSay
+): string | null {
+  const installation =
+    refusal?.code === 'agent_session_operation_invalid'
+      ? refusal.details?.codexInstallation
+      : undefined
+  return installation
+    ? say(installation.installedVersion === null ? 'cliMissing' : 'codexCliTooOld', {
+        agent: 'Codex',
+        installedVersion: installation.installedVersion ?? '',
+        minimumVersion: installation.minimumVersion
+      })
+    : null
+}
+
 /** The host's words, and any surface without translations. */
 export const sayAgentSessionFailureEnglish: AgentSessionFailureSay = (id, values = {}) => {
   const filled = new Map(Object.entries(values))
diff --git a/src/shared/agent-session-failure-words.ts b/src/shared/agent-session-failure-words.ts
index f73d3536cf2..9a0cbea46de 100644
--- a/src/shared/agent-session-failure-words.ts
+++ b/src/shared/agent-session-failure-words.ts
@@ -20,6 +20,7 @@ import {
 import type { AgentSessionConversationCommand } from './agent-session-conversation-command'
 import { cliMissingSentence, notSignedInSentence } from './agent-session-availability-sentences'
 import {
+  codexInstallationFailureWords,
   sayAgentSessionFailureEnglish,
   type AgentSessionFailureCopyId,
   type AgentSessionFailureCopyValues,
@@ -145,6 +146,10 @@ function startRetry(
 
 function couldNot(verb: 'couldNotStart' | 'couldNotRestart'): Sentence {
   return (context, fact, _surface, say) => {
+    const installationFailure = codexInstallationFailureWords(fact.refusal, say)
+    if (installationFailure) {
+      return installationFailure
+    }
     const failed = say(verb, agent(say, context))
     if (fact.argumentProblem) {
       const problemCopy = {
diff --git a/src/shared/agent-session-refusal-details.ts b/src/shared/agent-session-refusal-details.ts
index ae52282631a..747757b0b00 100644
--- a/src/shared/agent-session-refusal-details.ts
+++ b/src/shared/agent-session-refusal-details.ts
@@ -8,6 +8,10 @@
 
 import type { AgentSessionAccountKind } from './agent-session-availability'
 import type { AgentJournalResolution } from './agent-session-journal-types'
+import {
+  readCodexInstallationProblem,
+  type CodexInstallationProblem
+} from './codex-cli-installation'
 import {
   readAgentSessionArgumentProblem,
   type AgentSessionArgumentProblem
@@ -158,6 +162,7 @@ type AgentSessionRefusalFactsByCode = {
   agent_session_operation_invalid: RewindFacts & {
     account?: AgentSessionAccountKind
     argumentProblem?: AgentSessionArgumentProblem
+    codexInstallation?: CodexInstallationProblem
   }
   agent_session_operation_unknown: RewindFacts
   agent_session_checkpoint_stale: {
@@ -279,6 +284,10 @@ export function readAgentSessionRefusalDetails<C extends AgentSessionWireRefusal
     code === 'agent_session_operation_invalid'
       ? readAgentSessionArgumentProblem(value.argumentProblem)
       : undefined
+  const codexInstallation =
+    code === 'agent_session_operation_invalid'
+      ? readCodexInstallationProblem(value.codexInstallation)
+      : undefined
   const read = {
     ...(isAgentSessionRefusalReason(code, value.reason) ? { reason: value.reason } : {}),
     ...facts,
@@ -287,7 +296,8 @@ export function readAgentSessionRefusalDetails<C extends AgentSessionWireRefusal
     (value.account === 'managed' || value.account === 'system')
       ? { account: value.account }
       : {}),
-    ...(argumentProblem ? { argumentProblem } : {})
+    ...(argumentProblem ? { argumentProblem } : {}),
+    ...(codexInstallation ? { codexInstallation } : {})
   }
   // oxlint-disable-next-line typescript/consistent-type-assertions -- SAFETY: the reason was checked against `code`'s list and only the facts `code` lists (plus the verdict every code may carry) were kept.
   return Object.keys(read).length > 0 ? (read as AgentSessionRefusalDetails<C>) : undefined
diff --git a/src/shared/agent-session-refusal-notice.ts b/src/shared/agent-session-refusal-notice.ts
index f81e1b51a90..ea124b0b74c 100644
--- a/src/shared/agent-session-refusal-notice.ts
+++ b/src/shared/agent-session-refusal-notice.ts
@@ -98,6 +98,16 @@ function reasonParts(
   write: AgentSessionWriteKind,
   context: AgentSessionFailureWordsContext
 ): AgentSessionWriteNoticePart[] | undefined {
+  if (
+    failure.code === 'agent_session_operation_invalid' &&
+    failure.details?.codexInstallation &&
+    (write === 'send' || write === 'composer-send')
+  ) {
+    return [
+      NOT_DONE[write],
+      { failure: { kind: 'startFailed', refusal: failure }, surface: 'rejection', context }
+    ]
+  }
   if (
     failure.code === 'agent_session_operation_invalid' &&
     failure.details?.argumentProblem &&
diff --git a/src/shared/agent-session-visible-failures.ts b/src/shared/agent-session-visible-failures.ts
index 32a9cbce25f..ae00d1c083e 100644
--- a/src/shared/agent-session-visible-failures.ts
+++ b/src/shared/agent-session-visible-failures.ts
@@ -36,6 +36,12 @@ export function sameAgentSessionFailureFact(
     a.detail?.audience === b.detail?.audience &&
     a.refusal?.code === b.refusal?.code &&
     a.refusal?.details?.reason === b.refusal?.details?.reason &&
+    (a.refusal?.code !== 'agent_session_operation_invalid' ||
+      b.refusal?.code !== 'agent_session_operation_invalid' ||
+      (a.refusal.details?.codexInstallation?.installedVersion ===
+        b.refusal.details?.codexInstallation?.installedVersion &&
+        a.refusal.details?.codexInstallation?.minimumVersion ===
+          b.refusal.details?.codexInstallation?.minimumVersion)) &&
     a.attachment?.reason === b.attachment?.reason &&
     a.attachment?.limit === b.attachment?.limit &&
     a.retry?.error === b.retry?.error &&
diff --git a/src/shared/agent-session-write-failure.ts b/src/shared/agent-session-write-failure.ts
index 20dc9856390..cc35fd969ee 100644
--- a/src/shared/agent-session-write-failure.ts
+++ b/src/shared/agent-session-write-failure.ts
@@ -9,6 +9,7 @@ import {
 } from './agent-session-refusal-details'
 import type { AgentSessionRewindReason } from './agent-session-rewind'
 import type { AgentSessionArgumentProblem } from './agent-session-argument-problem'
+import type { CodexInstallationProblem } from './codex-cli-installation'
 import {
   isAgentSessionWireRefusalCode,
   readAgentSessionRefusalReference,
@@ -76,6 +77,7 @@ type DurableRefusalFacts = {
     rewindReason?: AgentSessionRewindReason
     account?: AgentSessionAccountKind
     argumentProblem?: AgentSessionArgumentProblem
+    codexInstallation?: CodexInstallationProblem
   }
   agent_session_operation_unknown: { rewindReason?: AgentSessionRewindReason }
   /** A snapshot from when it was refused; see `agentSessionOwnerVerdictAllowsFreshOperationId`. */
@@ -83,7 +85,12 @@ type DurableRefusalFacts = {
 }
 
 const DURABLE_FACT_KEYS: Partial<Record<AgentSessionWireRefusalCode, readonly string[]>> = {
-  agent_session_operation_invalid: ['rewindReason', 'account', 'argumentProblem'],
+  agent_session_operation_invalid: [
+    'rewindReason',
+    'account',
+    'argumentProblem',
+    'codexInstallation'
+  ],
   agent_session_operation_unknown: ['rewindReason'],
   agent_session_ownership_unknown: ['ownerVerdict']
 } satisfies { [C in keyof DurableRefusalFacts]: readonly (keyof DurableRefusalFacts[C])[] }
diff --git a/src/shared/codex-cli-installation.test.ts b/src/shared/codex-cli-installation.test.ts
new file mode 100644
index 00000000000..0cebc319be3
--- /dev/null
+++ b/src/shared/codex-cli-installation.test.ts
@@ -0,0 +1,49 @@
+import { describe, expect, it } from 'vitest'
+import {
+  CODEX_MINIMUM_SUPPORTED_VERSION,
+  codexCliInstallation,
+  readCodexInstallationProblem
+} from './codex-cli-installation'
+
+describe('Codex structured chat version floor', () => {
+  it.each([
+    ['codex-cli 0.135.0', 'unsupported'],
+    ['codex-cli 0.136.0', 'ready'],
+    ['codex-cli v0.136.0', 'ready'],
+    ['0.136.0-alpha.2', 'unsupported'],
+    ['0.136.0+build.2', 'ready'],
+    ['0.137.0-alpha.2', 'ready'],
+    ['codex-cli 0.153.4\n', 'ready'],
+    ['codex-cli 1.0.0', 'ready'],
+    ['codex-cli unknown', 'unknown'],
+    ['company-wrapper 0.1.0\ncodex-cli 0.136.0', 'ready'],
+    ['company-wrapper 9.0.0\ncodex-cli 0.135.0', 'unsupported'],
+    ['codex-cli 0.135.0\ncodex-cli 0.136.0', 'unknown'],
+    ['wrapper 0.135.0', 'unknown'],
+    ['0.135.0\n0.136.0', 'unknown'],
+    ['', 'unknown']
+  ])('%s is %s', (output, status) => {
+    expect(codexCliInstallation(true, output)).toMatchObject({
+      status,
+      minimumVersion: CODEX_MINIMUM_SUPPORTED_VERSION
+    })
+  })
+
+  it('distinguishes an absent binary from an unverifiable version', () => {
+    expect(codexCliInstallation(false, null)).toMatchObject({ status: 'missing', version: null })
+    expect(codexCliInstallation(true, null)).toMatchObject({ status: 'unknown', version: null })
+  })
+
+  it('admits only version facts that can safely be put in the refusal sentence', () => {
+    const problem = { installedVersion: '0.135.0', minimumVersion: '0.136.0' }
+    expect(readCodexInstallationProblem(problem)).toEqual(problem)
+    expect(readCodexInstallationProblem({ ...problem, installedVersion: null })).toEqual({
+      ...problem,
+      installedVersion: null
+    })
+    expect(
+      readCodexInstallationProblem({ ...problem, installedVersion: '<script>' })
+    ).toBeUndefined()
+    expect(readCodexInstallationProblem({ ...problem, minimumVersion: '' })).toBeUndefined()
+  })
+})
diff --git a/src/shared/codex-cli-installation.ts b/src/shared/codex-cli-installation.ts
new file mode 100644
index 00000000000..e388a78e76e
--- /dev/null
+++ b/src/shared/codex-cli-installation.ts
@@ -0,0 +1,61 @@
+import { compareAppVersions, isValidAppVersion, parseCliVersion } from './app-version'
+
+export const CODEX_MINIMUM_SUPPORTED_VERSION = '0.136.0'
+
+export type CodexCliInstallation = {
+  status: 'missing' | 'unsupported' | 'ready' | 'unknown'
+  version: string | null
+  minimumVersion: string
+}
+
+export type CodexInstallationProblem = {
+  installedVersion: string | null
+  minimumVersion: string
+}
+
+export function parseCodexCliVersion(output: string | null | undefined): string | null {
+  const lines = output?.split(/\r?\n/).map((line) => line.trim()) ?? []
+  const identified = lines.filter((line) => /^codex(?:-cli)?\s/i.test(line))
+  const candidates = identified.length ? identified : lines.filter(Boolean)
+  const versions = candidates.map((line) => {
+    const value = line.replace(/^codex(?:-cli)?\s+/i, '').replace(/^v/i, '')
+    return isValidAppVersion(value) ? parseCliVersion(value) : null
+  })
+  return versions.length && versions.every((version) => version !== null && version === versions[0])
+    ? versions[0]
+    : null
+}
+
+export function codexCliInstallation(
+  installed: boolean,
+  output: string | null
+): CodexCliInstallation {
+  const version = parseCodexCliVersion(output)
+  return {
+    status: !installed
+      ? 'missing'
+      : version === null
+        ? 'unknown'
+        : compareAppVersions(version, CODEX_MINIMUM_SUPPORTED_VERSION) < 0
+          ? 'unsupported'
+          : 'ready',
+    version,
+    minimumVersion: CODEX_MINIMUM_SUPPORTED_VERSION
+  }
+}
+
+export function readCodexInstallationProblem(value: unknown): CodexInstallationProblem | undefined {
+  if (
+    typeof value !== 'object' ||
+    value === null ||
+    !('installedVersion' in value) ||
+    !('minimumVersion' in value) ||
+    (value.installedVersion !== null &&
+      (typeof value.installedVersion !== 'string' || !isValidAppVersion(value.installedVersion))) ||
+    typeof value.minimumVersion !== 'string' ||
+    !isValidAppVersion(value.minimumVersion)
+  ) {
+    return undefined
+  }
+  return { installedVersion: value.installedVersion, minimumVersion: value.minimumVersion }
+}