fix(chatgpt): build the bundled app-server path with posix.join on every host

[lidge-jun]

Summary

The full Cross-platform CI run on dev (36891940246) fails windows 3/9 on tests/clients/desktop-app-server-shim-launcher.test.ts:60, a test #6361 added: "the bundled binary is derived from the discovered bundle root". resolveChatgptCodexBinary builds the candidate with node:path join, which uses backslashes on Windows. The test then receives null where it expects the POSIX bundle path.

A ChatGPT.app bundle path is a macOS path, so this PR builds the candidate with posix.join on every host. On macOS nothing changes. On Windows, the resolver now returns the same path the test, and the rest of the shim, expect.

Verification

• I did not run local suites, on the project owner's instruction. Hosted CI on this PR, including the Windows legs, is the evidence.
• The failing assertion is visible in job 110469799162 of run 36891940246. The change touches one line and adds none, so the file-size ratchet is unaffected.

Checklist

• Scope stays focused and avoids unrelated cleanup.
• Docs or release notes were updated when needed. No user-facing change.
• Security-sensitive changes were reviewed for secrets, auth, and unsafe defaults. Path construction only; it adds no new filesystem access.

Summary by CodeRabbit

• Bug Fixes
  • Fixed an issue that could prevent the app from locating its macOS executable when paths were resolved on a different operating system. macOS bundle paths are now handled consistently across host platforms, improving startup reliability in cross-platform environments. This change affects path resolution only; it does not alter the app’s behavior or features once launched.
• Tests
  • Added coverage to verify that macOS executable paths use consistent separators and remain within the expected app bundle.

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-01T16:38:39.219891Z	e906c01	PR opened

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between e906c01 and 5e73284.

📒 Files selected for processing (1)

• tests/clients/desktop-app-server-shim-launcher.test.ts

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📝 Walkthrough

Walkthrough

The launcher now uses POSIX path construction for candidate macOS bundle paths. A test checks that the probed paths use / and remain under the expected bundle’s Contents/ directory.

Changes

Bundle path resolution

Layer / File(s)	Summary
Use POSIX separators for bundle paths src/chatgpt/app-server-shim/launcher.ts, tests/clients/desktop-app-server-shim-launcher.test.ts	The launcher imports posix and uses posix.join to construct candidate macOS bundle paths. The test checks that probed paths use / and begin with the expected bundle root’s Contents/ path.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to 5e732

The change addresses host-dependent separators for macOS bundle candidates, and the supplied context reports hosted CI coverage. No actionable merge-blocking regression is established.

Architecture Summary

Architecture risk: 🔵 Low · up to 5e732

The change affects 2 systems.

Changed systems: src, tests

Architecture concerns
No architecture-level concerns identified.

Review details

Systems and components

• observed — src (service) was modified; 1 changed file maps to changed impact.
• observed — tests (service) was modified; 1 changed file maps to changed impact.

Before / after behavior

• observed — Modified behavior in src/chatgpt/app-server-shim/launcher.ts: The path import now includes posix for POSIX-specific path construction.
• observed — Modified behavior in src/chatgpt/app-server-shim/launcher.ts: resolveChatgptCodexBinary now uses posix.join instead of host-dependent join when constructing candidate macOS bundle paths.
• observed — Modified behavior in tests/clients/desktop-app-server-shim-launcher.test.ts: Added coverage asserting that all probed bundle paths use / rather than \ and begin with the expected bundle root’s Contents/ path.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: using posix.join to construct the bundled app-server path on every host.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 2 files.
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.

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[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: e906c019fa

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[chatgpt-codex-connector]

Update the owned ChatGPT architecture document

This changes the path-construction invariant in the owned src/chatgpt/ area, but the commit does not update its mapped document, structure/clients/chatgpt-desktop.md. Document that bundle candidates must retain POSIX semantics even on non-macOS test hosts so the Windows-safe behavior remains part of the subsystem contract; repository ownership rules require an owned source change and its document update to land together.

AGENTS.md reference: AGENTS.md:L42-L43

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[github-actions]

✅ Deterministic PR hygiene checks passed.

[lidge-jun]

Maintainer integration record (MAINTAINERS.md, dev-only)

• Actor: @lidge-jun (admin), stabilizing dev for the next release as authorized by the project owner.

• Exact head: 5e732845748e5e76daef111f5f5113e66f213cbd. Cause: the full dev Cross-platform run 36891940246 failed windows 3/9 on tests/clients/desktop-app-server-shim-launcher.test.ts:60, from feat(chatgpt): experimental macOS app-server quota-gate shim (split from #5947) #6361. The fix builds the ChatGPT.app bundle candidate with posix.join, and a regression asserts that every probed candidate stays POSIX.

• Hosted CI at this head: Cross-platform CI 36897666599 success (the PR lane skips the Windows shards; the next full dev run proves the Windows fix).

• Local suites: not run, by explicit owner instruction.

• Not a security-boundary change.

• Enforce PR target branch is fail, stuck in the flooded Actions queue (it never executes head code). I checked its conditions by hand: base is dev, and the Summary, Verification and Checklist sections are present. PR hygiene passed at this head.