Fix compound SSH PTY attach startup scripts

[austinywang]

Summary

• Export the no-progress retry environment on standalone shell lines before executing attach source.
• Keep noProgressRetryLoopLines(command:) valid for simple, compound, and multi-line POSIX shell commands.
• Add a behavior regression that executes a generated compound attach script under /bin/sh.

Closes #9423

Root cause

noProgressRetryLoopLines(command:) accepted arbitrary shell source but interpolated it after NAME=value prefixes. The foreground-auth CLI path passed a command beginning with if, and POSIX shells only permit assignment prefixes before a simple command. The generated startup script therefore failed during parsing before SSH could start.

Moving the two per-attempt values into standalone export commands removes that hidden command-shape restriction. Future callers cannot recreate the same syntax error by supplying compound or multi-line shell source.

Testing

• Red baseline: https://github.com/manaflow-ai/cmux/actions/runs/30783465527
  • 8 tests executed on test-only commit b0b5270cbe.
  • The new regression failed alone with status 2 and the expected unexpected token then parse error.
• Local /bin/sh -n syntax check passed with the fixed shape.
• Local /bin/sh execution verified both retry values are exported to child processes.
• Swift parser checks passed for the changed source and test files.
• git diff --check origin/main...HEAD passed.

Demo Video

Not applicable. This changes generated CLI shell source and has no visual UI.

---

^{Need help on this PR? Tag @codesmith-bot with what you need. Autofix is disabled.}

---

Summary by cubic

Fixes SSH PTY attach startup scripts so compound or multi-line POSIX shell commands don’t fail to parse. Exports retry env vars on their own lines to avoid if-prefix syntax errors and preserve the retry policy (addresses #9423).

• Bug Fixes
  • Export CMUX_SSH_PTY_ATTACH_NO_PROGRESS_RETRY and CMUX_SSH_PTY_ATTACH_NO_PROGRESS_LIMIT before running the attach command; no assignment prefixes.
  • Keep noProgressRetryLoopLines(command:) valid for simple, compound, and multi-line commands.
  • Add a regression test that runs a compound if-based attach under /bin/sh and verifies env propagation.

^{Written for commit 1c4e8ac. Summary will update on new commits.}

Summary by CodeRabbit

• Bug Fixes

  • Improved SSH terminal attachment reliability by ensuring no-progress retry settings are preserved through nested shell commands.
  • Reduced the risk of attachment timeouts and incorrect exit statuses during stalled or slow connections.

• Tests

  • Added coverage for nested-shell attachment scenarios, including retry configuration propagation and successful completion.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: e20167c7-ae3a-4283-a7d1-338058a7ece6

📥 Commits

Reviewing files that changed from the base of the PR and between 84f5755 and 1c4e8ac.

📒 Files selected for processing (2)

• Packages/macOS/CmuxFoundation/Sources/CmuxFoundation/SSHPTYAttachExitCode.swift
• cmuxTests/SSHPTYAttachNoProgressRetryTests.swift

---

📝 Walkthrough

Walkthrough

The SSH PTY retry loop now exports no-progress variables before executing attach commands. An integration test verifies propagation through compound shell commands and successful completion.

Changes

SSH PTY retry handling

Layer / File(s)	Summary
Export retry environment before attach attempts Packages/macOS/CmuxFoundation/Sources/CmuxFoundation/SSHPTYAttachExitCode.swift, cmuxTests/SSHPTYAttachNoProgressRetryTests.swift	noProgressRetryLoopLines uses shell exports instead of command prefixes. The integration test verifies retry-variable propagation, completion, and exit status.

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

Possibly related issues

• Issue 7695 in manaflow-ai/cmux-dev-artifacts: It addresses exporting SSH PTY retry variables before compound attach commands and adding integration coverage.

Possibly related PRs

• manaflow-ai/cmux#9111: It introduced and tested the SSH PTY attach retry mechanism modified here.
• manaflow-ai/cmux#9213: It also changes no-progress retry handling for SSH PTY attach scripts.
• manaflow-ai/cmux#9425: It adds related environment-export changes and compound-command regression coverage.

🚥 Pre-merge checks | ✅ 25

✅ Passed checks (25 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main fix for compound SSH PTY attach startup scripts.
Description check	✅ Passed	The description explains the root cause, fix, testing, and why a demo video is not applicable.
Linked Issues check	✅ Passed	The changes directly resolve issue #9423 by removing invalid environment prefixes before compound shell commands and preserving retry behavior.
Out of Scope Changes check	✅ Passed	The changes are limited to the SSH PTY attach fix and its regression test, with no unrelated code changes identified.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Cmux Swift Actor Isolation	✅ Passed	The Swift 6 production diff only changes shell-source strings and documentation; it adds no actor, Sendable, protocol, UI-store, or shared mutable reference declaration. The other changes are test-...
Cmux Swift Blocking Runtime	✅ Passed	The production diff only replaces shell variable prefixes with exports; it adds no blocking or timing primitive. Semaphore waits remain in the pre-existing test-only helper.
Cmux Browser Automation Off-Main	✅ Passed	The diff only changes SSH PTY retry generation and its tests; it does not modify browser socket commands, WebKit/AppKit routing, worker policy, or browser policy tests.
Cmux Expensive Synchronous Load	✅ Passed	The production diff only changes generated shell exports in SSHPTYAttachExitCode.swift; it adds no agent-history loader, large-file parse, directory scan, syscall loop, or interactive/main-actor path.
Cmux Cache Substitution Correctness	✅ Passed	The diff only changes generated POSIX shell exports and command execution; it does not replace an authoritative read with a cache or affect persistence, history, undo, or snapshot paths.
Cmux No Hacky Sleeps	✅ Passed	The PR changes only Swift files, adds standalone exports and a test, and introduces no sleep, timer, polling, or wall-clock wait; the existing shell sleep is unchanged.
Cmux Algorithmic Complexity	✅ Passed	The production diff only replaces one shell prefix with two export lines; it adds no collection scan, sort, join, or nested traversal. The new 23-line regression is test-only.
Cmux Swift Concurrency	✅ Passed	The PR changes shell-generation strings and adds a test call; it introduces no runtime Dispatch, Combine, completion-handler, or fire-and-forget Task pattern. Existing test synchronization is uncha...
Cmux Swift @Concurrent	✅ Passed	The diff changes only synchronous Swift functions and adds a synchronous test; it introduces no nonisolated async work, @concurrent annotation, actor-isolated access, or UI-bound heavy async call.
Cmux Swift Package Boundaries	✅ Passed	The only production Swift diff is in the existing CmuxFoundation SwiftPM target; the regression test is test code, so no app-target package-boundary violation exists.
Cmux Swiftpm Lockfiles	✅ Passed	The PR changes only SSHPTYAttachExitCode.swift and its test; no Package.swift, Package.resolved, .gitignore, workflow, or Xcode package-reference paths changed.
Cmux Swift Logging	✅ Passed	The diff adds only standalone shell exports and a regression test; it adds no production print, Logger, NSLog, file, or stdout/stderr diagnostic logging.
Cmux User-Facing Error Privacy	✅ Passed	The production diff only moves existing retry environment variables into internal shell exports; the user-visible retry diagnostic remains generic, and added variable references are test-only or in...
Cmux Full Internationalization	✅ Passed	The PR changes only shell environment-generation code and a regression test; it adds no user-facing copy, localization keys, catalogs, web messages, metadata, or changelog entries.
Cmux Swiftui State Layout	✅ Passed	The diff changes only SSH shell retry logic and its test; no SwiftUI import, state wrapper, layout API, store reference, or render-time mutation was added.
Cmux Architecture Rethink	✅ Passed	The full PR diff is a small shell correctness fix: it exports existing retry state before arbitrary command source. No new production timing, polling, locks, observers, flags, or lifecycle owners w...
Cmux Swift Auxiliary Window Close Shortcuts	✅ Passed	The diff changes shell-generation logic and a test-only /bin/sh Process fixture; it adds no NSWindow, NSPanel, SwiftUI window, identifier, or close-shortcut routing.
Cmux Source Artifacts	✅ Passed	Both changed paths are tracked Swift source/test files; scans found no forbidden artifact directories, binary content, or generated-output markers.
Cmux No Test Or Debug Seam In Production Source	✅ Passed	The PR production diff only changes shell exports and a comment in SSHPTYAttachExitCode.swift; it adds no DEBUG guard, test/debug seam, visibility widening, or production accessor.
Cmux No Ambient Global State	✅ Passed	The PR only changes statements inside existing SSHPTYAttachExitCode.noProgressRetryLoopLines; the public enum and static API predate the PR, with no new global function, mutable var, namespace, or...

✨ Finishing Touches 💡 1

⚔️ Resolve merge conflicts 💡

• Resolve merge conflict in branch issue-9423-ssh-startup-env-prefix-if

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch issue-9423-ssh-startup-env-prefix-if

---

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

• X
• Mastodon
• Reddit
• LinkedIn

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

[austinywang]

Superseded by #9425, which merged while this PR's red and green suite runs were in progress. #9425 contains the same generator-level standalone export fix and a stronger behavior test that runs both /bin/sh -n and the generated script. No unique change remains in this PR.