Fix Codex wrapper missing resume helper error by austinywang · Pull Request #12656 · manaflow-ai/cmux

austinywang · 2026-09-14T21:55:05Z

Summary

codex --yolo prints cmux_codex_resume_session_id: command not found before startup because #8537 restored an obsolete resume block after its helper was removed in #9185. Remove that block so Codex's injected hooks remain the source of session identity.

Strengthen the existing behavioral harness to reject startup stderr and both direct and queued synthetic session-start calls. Add the exact --yolo repro and isolate the caller's cmux environment. The regression test and fix are separate commits.

Testing

python3 tests/test_codex_wrapper_resume_hooks.py: reproduced the missing-function error before the fix; passes after the fix across 24 launches, including fresh, resume, fork, opt-out, and injection failure.
python3 tests/test_codex_wrapper_computer_use_mcp.py: passes with inherited CMUX_* settings cleared.
bash -n Resources/bin/cmux-codex-wrapper and git diff --check: pass.
Tagged fleet build codex-startup at 21c80a8bf5: succeeded and downloaded.
Localization audit: no user-facing strings changed.

Demo

Before: codex --yolo emits cmux_codex_resume_session_id: command not found.
After: the harness reaches Codex with --yolo preserved, SessionStart/Stop hooks injected, and empty stderr.

Dogfood: open the codex-startup tagged build and run codex --yolo in a terminal.

Summary by CodeRabbit

Bug Fixes
- Resumed sessions no longer trigger an additional session-start event, avoiding duplicate session binding.
- Improved wrapper behavior when existing cmux environment settings are present.
- Confirmed failed hook injection preserves the cmux context without producing startup errors.
- Added coverage to ensure quiet, correctly instrumented --yolo launches.

coderabbitai · 2026-09-14T21:55:11Z

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Advanced

Run ID: 2078d947-f334-42df-ba7d-7cbf81fecd85

📥 Commits

Reviewing files that changed from the base of the PR and between 211b8bb and 21c80a8.

📒 Files selected for processing (2)

Resources/bin/cmux-codex-wrapper
tests/test_codex_wrapper_resume_hooks.py

💤 Files with no reviewable changes (1)

Resources/bin/cmux-codex-wrapper

Included review availability: Your plan provides up to 10 included reviews per hour; 8 remain after this review.

📝 Walkthrough

Walkthrough

The wrapper no longer sends synthesized session-start events for resumed sessions. Tests isolate CMUX environment variables and verify quiet, instrumented startup, including --yolo launches.

Changes

Codex wrapper hook behavior

Layer / File(s)	Summary
Remove synthesized resume event `Resources/bin/cmux-codex-wrapper`	Resume handling no longer enqueues a cmux `session-start` event. Resumed sessions use injected Codex hooks.
Validate isolated and quiet startup `tests/test_codex_wrapper_resume_hooks.py`	Tests filter inherited `CMUX_` variables, detect both session-start command forms, require empty startup stderr, and cover `--yolo` launches across socket states.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to 21c80

Resume and --yolo launches retain session instrumentation through injected hooks, with no current merge-blocking risk identified.

🚥 Pre-merge checks | ✅ 24 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 7 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (24 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Cmux Swift Actor Isolation	✅ Passed	PASS: The reviewed range changes only `Resources/bin/cmux-codex-wrapper` and `tests/test_codex_wrapper_resume_hooks.py`. It contains no changed Swift files or production Swift declarations. The actor-…
Cmux Swift Blocking Runtime	✅ Passed	PASS. The pull request changes only `Resources/bin/cmux-codex-wrapper` and `tests/test_codex_wrapper_resume_hooks.py`; the authoritative diff contains no Swift, Objective-C, or Objective-C++ files. Th…
Cmux Browser Automation Off-Main	✅ Passed	PASS: The pull request changes only `Resources/bin/cmux-codex-wrapper` and `tests/test_codex_wrapper_resume_hooks.py`. The diff removes a Codex `hooks enqueue codex session-start` shell invocation and…
Cmux Expensive Synchronous Load	✅ Passed	PASS: The authoritative pull-request diff changes only `Resources/bin/cmux-codex-wrapper` and `tests/test_codex_wrapper_resume_hooks.py`. It contains no production Swift changes and no agent-history, …
Cmux Cache Substitution Correctness	✅ Passed	PASS: The pull request changes only `Resources/bin/cmux-codex-wrapper` (Bash) and `tests/test_codex_wrapper_resume_hooks.py` (Python). It changes no production Swift, TypeScript, or JavaScript code. T…
Cmux No Hacky Sleeps	✅ Passed	PASS. The pull request removes the production wrapper block that used `CMUXTERM_CLI_RESPONSE_TIMEOUT_SEC=1` for a resume `session-start` enqueue. The added lines contain no `sleep`, timers, polling, b…
Cmux Algorithmic Complexity	✅ Passed	PASS. The production diff only removes 31 lines from `Resources/bin/cmux-codex-wrapper`; it adds no algorithm or collection scan. The added loops and environment filtering are test-only in `tests/test…
Cmux Swift Concurrency	✅ Passed	PASS: The PR changes only the shell wrapper and a Python test. The authoritative diff contains no Swift files or Swift concurrency patterns. Therefore, it does not introduce or expand any legacy async…
Cmux Swift `@Concurrent`	✅ Passed	PASS: The authoritative pull-request diff changes only `Resources/bin/cmux-codex-wrapper` and `tests/test_codex_wrapper_resume_hooks.py`. It introduces no Swift files, Swift declarations, `async` isol…
Cmux Swift Package Boundaries	✅ Passed	The scoped diff changes only `Resources/bin/cmux-codex-wrapper` and `tests/test_codex_wrapper_resume_hooks.py`. It contains no production Swift or SwiftPM changes. Therefore, the Swift package boundar…
Cmux Swiftpm Lockfiles	✅ Passed	PASS. The scoped pull-request diff changes only `Resources/bin/cmux-codex-wrapper` and `tests/test_codex_wrapper_resume_hooks.py`. It does not change a SwiftPM package, `Package.resolved`, Xcode proje…
Cmux Swift Logging	✅ Passed	PASS: The pull request changes only `Resources/bin/cmux-codex-wrapper` and `tests/test_codex_wrapper_resume_hooks.py`. No Swift or Objective-C production file is changed. The patch removes a shell CLI…
Cmux User-Facing Error Privacy	✅ Passed	PASS — the production diff removes the obsolete resume-time `hooks enqueue codex session-start` call. It adds no user-facing error, alert, command output, or recovery text. The only additions are test…
Cmux Full Internationalization	✅ Passed	PASS — the PR changes only the Codex wrapper and its behavioral test. The production diff removes an obsolete hook-enqueue block and adds no user-facing copy, Swift localization keys, catalogs, web me…
Cmux Swiftui State Layout	✅ Passed	The check is not applicable. The authoritative pull-request diff changes only `Resources/bin/cmux-codex-wrapper` and `tests/test_codex_wrapper_resume_hooks.py`. Both are shell/Python files. The diff c…
Cmux Architecture Rethink	✅ Passed	PASS: The pull request changes only a shell wrapper and a Python test. The authoritative diff contains no Swift files, so the Swift-specific architectural failure conditions do not apply. The wrapper …
Cmux Swift Auxiliary Window Close Shortcuts	✅ Passed	The review-scoped diff changes only `Resources/bin/cmux-codex-wrapper` and `tests/test_codex_wrapper_resume_hooks.py`. It contains no Swift changes and does not add or materially change any cmux-owned…
Cmux Source Artifacts	✅ Passed	PASS. The authoritative diff changes only `Resources/bin/cmux-codex-wrapper` and `tests/test_codex_wrapper_resume_hooks.py`. Both are tracked, ordinary source/test files. The wrapper change removes ob…
Cmux No Test Or Debug Seam In Production Source	✅ Passed	PASS: The authoritative pull-request diff changes only `Resources/bin/cmux-codex-wrapper` and `tests/test_codex_wrapper_resume_hooks.py`. It contains no Swift file under a production `Sources/` path, …
Cmux No Ambient Global State	✅ Passed	PASS: The authoritative pull-request diff changes only `Resources/bin/cmux-codex-wrapper` and `tests/test_codex_wrapper_resume_hooks.py`. It contains no production Swift changes, so the Swift ambient-…
Title check	✅ Passed	The title clearly identifies the main change: fixing the Codex wrapper error caused by the missing resume helper. It is concise and specific.
Description check	✅ Passed	The description includes the change summary, rationale, testing details, and behavior demonstration. It does not include the template's Review Trigger section or Checklist, but the core required infor…

Fix all pre-merge checks with AI

✨ Finishing Touches 💡 2

📝 Generate docstrings 💡

Create stacked PR
Commit on current branch

🛠️ Fix failing CI checks 💡

Create stacked PR
Commit on current branch

🧪 Generate unit tests (beta)

Create PR with unit tests
Commit unit tests in branch fix/codex-wrapper-startup

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

_{Comment @coderabbitai help to get the list of available commands.}

github-actions · 2026-09-14T21:55:32Z

Note

Pull Request opener @austinywang is not an author or co-author of any commit in this PR (commit identities: cmux reload-cloud). The CLA check will still proceed and requires every listed identity plus @austinywang to have signed.

Thank you for your submission, we really appreciate it. Like many open-source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution. You can sign the CLA by just posting a Pull Request Comment same as the below format.

I have read the CLA Document v2.2 and I hereby sign the CLA

Warning

1 commit in this PR was authored by an email address that is not linked to any GitHub user, so we cannot tell whether the author has signed the CLA.

Unlinked author:

cmux reload-cloud <cmux-reload-cloud@users.noreply.github.com>

To unblock this PR, do one of the following:

Link the email to your GitHub account (recommended). Add each address above at github.com/settings/emails, then push another commit (or comment recheck) so this check re-runs. See why commits are not linked to a user for details.

Rewrite the commits to use an email that is already linked to your GitHub account:

# Set the correct email locally (one-off, for this repo):
git config user.email you@example.com
# Rewrite every commit on this branch with the corrected identity:
git rebase -i --root --exec 'git commit --amend --reset-author --no-edit'
git push --force-with-lease

After the push, comment recheck on this PR (or just re-push) to re-run the check.

_{You can retrigger this bot by commenting recheck in this Pull Request.}_{Posted by the CLA Assistant Lite bot.}

lawrencecchen · 2026-09-19T15:43:12Z

Mac fleet instructions for head 21c80a8bf5b25f81941c0e7839f957fe9435b30e. Planned tag: pr-12656-21c80a8b; this is not yet a published build.

JOB_JSON=$(~/.local/bin/cmux-ci submit --kind cmux --command 'CMUX_FLEET_BUILD_TAG=pr-12656-21c80a8b /Users/Shared/cmux-build-fleet/recipes/cmux.sh https://github.com/manaflow-ai/cmux.git 21c80a8bf5b25f81941c0e7839f957fe9435b30e' --artifact artifacts/cmux.app.zip --workspace https://github.com/manaflow-ai/cmux/pull/12656 --source-digest 21c80a8bf5b25f81941c0e7839f957fe9435b30e --cache-key cmux:pr-12656 --min-free-bytes 268435456000 --label cmux --label ram48)
JOB_ID=$(python3 -c 'import json,sys; print(json.load(sys.stdin)["id"])' <<<"$JOB_JSON")
~/.local/bin/cmux-ci wait "$JOB_ID" --receipt artifacts/fleet/$JOB_ID.json
~/.local/bin/cmux-ci publish-hq "$JOB_ID"

Use an existing campaign job ID if one is already posted; do not submit a duplicate. A wait timeout leaves the remote job running. Published results will include an exact-head artifact link and timing/disk receipt. This recipe validates the macOS app only, not iOS or tests. Never use maclease or put credentials in a PR comment.

github-actions · 2026-09-26T14:30:43Z

Automatic catch-up: main is green again and this branch needed it.

I tried to catch this branch up with main (45815f775809), but these files need a person:

Resources/bin/cmux-codex-wrapper: not a generated file; needs a person
tests/test_codex_wrapper_resume_hooks.py: not a generated file; needs a person

Nothing was pushed. Merge main locally, fix those, and push; /catch-up is there again whenever you want it.

Automatic catch-up will not try this head again; a new push or /catch-up does.
Label the pull request no-auto-catch-up to opt out.

_{Catch-up run}

github-actions · 2026-09-26T14:33:18Z

Automatic catch-up: main is green again and this branch needed it.

I tried to catch this branch up with main (45815f775809), but these files need a person:

Resources/bin/cmux-codex-wrapper: not a generated file; needs a person
tests/test_codex_wrapper_resume_hooks.py: not a generated file; needs a person

Nothing was pushed. Merge main locally, fix those, and push; /catch-up is there again whenever you want it.

Automatic catch-up will not try this head again; a new push or /catch-up does.
Label the pull request no-auto-catch-up to opt out.

_{Catch-up run}

test: catch Codex wrapper startup errors

92f53d0

fix: remove obsolete Codex resume startup hook

21c80a8

austinywang marked this pull request as ready for review September 14, 2026 22:05

teamleaderleo added this to cmux backlog Sep 23, 2026

github-project-automation Bot moved this to Todo in cmux backlog Sep 23, 2026

teamleaderleo added area: agents Agent integrations (Claude Code, Codex, ACP), agent chat, hooks, status S3: minor Wrong behavior with a workaround ready-to-land Reviewed and ready to land when CI is green labels Sep 30, 2026

Navigation Menu

Uh oh!

Fix Codex wrapper missing resume helper error - #12656

Fix Codex wrapper missing resume helper error#12656
austinywang wants to merge 2 commits into
mainfrom
fix/codex-wrapper-startup

austinywang commented Sep 14, 2026 •

edited by coderabbitai Bot

Loading

Uh oh!

coderabbitai Bot commented Sep 14, 2026 •

edited

Loading

Walkthrough

Changes

❌ Failed checks (1 warning)

Uh oh!

github-actions Bot commented Sep 14, 2026

Uh oh!

lawrencecchen commented Sep 19, 2026

Uh oh!

github-actions Bot commented Sep 26, 2026

Uh oh!

github-actions Bot commented Sep 26, 2026

Uh oh!

This branch has not been deployed

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Uh oh!

Conversation

austinywang commented Sep 14, 2026 • edited by coderabbitai Bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Summary

Testing

Demo

Summary by CodeRabbit

Uh oh!

coderabbitai Bot commented Sep 14, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Walkthrough

Changes

❌ Failed checks (1 warning)

Uh oh!

github-actions Bot commented Sep 14, 2026

Uh oh!

lawrencecchen commented Sep 19, 2026

Uh oh!

github-actions Bot commented Sep 26, 2026

Uh oh!

github-actions Bot commented Sep 26, 2026

Uh oh!

This branch has not been deployed

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

austinywang commented Sep 14, 2026 •

edited by coderabbitai Bot

Loading

coderabbitai Bot commented Sep 14, 2026 •

edited

Loading