ci: put the E2E test job's DerivedData under RUNNER_TEMP

[teamleaderleo]

The split E2E lane's test job fails its cleanup step on every run, turning a passing test run into a red job.

Validation run 35829288840 restored the compiled product and ran cmuxTests/AboutLicensesResourceTests successfully in 12 seconds, then failed at Clean owned app-host home:

Confirmed app-host cleanup target: /private/tmp/cmux-ah-811d7a035898
FAIL: refusing to inspect app hosts outside runner temp

cleanup-app-host-home.sh requires CMUX_DERIVED_DATA_PATH to live under RUNNER_TEMP before it will inspect an app host. The test job inherited $GITHUB_WORKSPACE/DerivedData/cmux-e2e from the single-job lane, where nothing ever called that script.

Before / after

	before	after
Run selected tests	success, 12 s	unchanged
Clean owned app-host home	failure	passes
job conclusion	failure	reflects the tests

Why move the path rather than widen the guard

The test job runs test-without-building and compiles nothing, so its DerivedData is only a destination for the restored product — the workspace location carried no requirement. ci-macos.yml already puts its test shards' DerivedData under RUNNER_TEMP, so this makes the two lanes agree instead of teaching the cleanup script a second shape. The guard exists because cleanup removes directories and signals processes; keeping its boundary narrow is worth more than the path it rejected.

The ownership check in Clean owned DerivedData loses its compilation-cache branch, which was copied from the build job. CMUX_E2E_COMPILATION_CACHE is never set in a job that does not compile.

Tradeoff

DerivedData under RUNNER_TEMP is discarded between jobs rather than persisting in the workspace. That costs nothing here — the product arrives by artifact download on every run, and the job deletes the directory on the way out either way.

Verification

actionlint clean on the edited workflow; all 132 linux-guard tests pass. The failing behavior is reproduced in the linked run's log rather than asserted.

🤖 Generated with Claude Code

---

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

---

Summary by cubic

Fixes the split E2E lane's test job failing its cleanup step on every run by moving DerivedData under RUNNER_TEMP.

• The cleanup script refuses to inspect app hosts whose DerivedData lives outside RUNNER_TEMP; the job now follows the same convention as ci-macos.yml instead of teaching the script a second shape.
• The test job runs test-without-building, so its DerivedData is only a destination for the restored product; the workspace location carried no requirement.
• Drops the unused compilation-cache branch from the ownership check; the job never sets CMUX_E2E_COMPILATION_CACHE because it does not compile.

^{Written for commit b637305. Summary will update on new commits.}

Summary by CodeRabbit

• Chores
  • Updated the automated end-to-end test workflow to use isolated temporary storage for build products and clean it up after each run. This does not change app functionality.

[github-actions]

All contributors have signed the CLA ✍️ ✅
_{Posted by the CLA Assistant Lite bot.}

[coderabbitai]

Navigate logical layers of code changes, visualize relationships, and explore their blast radius.

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository: manaflow-ai/cmux/.coderabbit.yaml

Review profile: ASSERTIVE

Plan: Advanced

Run ID: 781f4d64-ea83-4f52-9144-eb2257ec5c35

📥 Commits

Reviewing files that changed from the base of the PR and between ff710bf and b637305.

📒 Files selected for processing (1)

• .github/workflows/test-e2e.yml

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

---

📝 Walkthrough

Walkthrough

The E2E test job now stores DerivedData under a run-specific path in RUNNER_TEMP. Its cleanup step validates and removes that path, without workspace-path or compilation-cache handling.

Changes

E2E DerivedData isolation

Layer / File(s)	Summary
Set and clean up DerivedData path .github/workflows/test-e2e.yml	The prepare step sets a run-specific DerivedData path under RUNNER_TEMP. The cleanup step validates and removes that path. Workspace-path computation and compilation-cache cleanup are removed.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~4 minutes

Change: Bug fix

Merge Risk: ⚪ Minimal · up to b6373

The DerivedData relocation preserves E2E artifact use and cleanup ownership, with no concrete merge-blocking risk identified.

🚥 Pre-merge checks | ✅ 25

✅ Passed checks (25 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: moving the E2E test job's DerivedData under RUNNER_TEMP.
Description check	✅ Passed	The description explains the failure, the cause, the implementation, the rationale, tradeoffs, and verification results. It includes the required summary and testing information. The Demo Video sectio…
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
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 Cloud Persistent Session And Early Input	✅ Passed	PASS — The pull request changes only .github/workflows/test-e2e.yml. It moves E2E DerivedData cleanup to RUNNER_TEMP and removes an unused compilation-cache check. It introduces no Cloud termina…
Cmux Swift Actor Isolation	✅ Passed	The pull request changes only .github/workflows/test-e2e.yml. The review diff contains no Swift source changes, so it introduces no Swift 6 actor-isolation mistakes covered by this check.
Cmux Swift Blocking Runtime	✅ Passed	The pull request changes only .github/workflows/test-e2e.yml; the authoritative diff contains no Swift changes. The check applies to production Swift changes, so the failure condition is not introdu…
Cmux Browser Automation Off-Main	✅ Passed	The pull request changes only .github/workflows/test-e2e.yml. Its diff moves the E2E job's DerivedData path under RUNNER_TEMP and adjusts cleanup-related shell logic. It does not change browser so…
Cmux Expensive Synchronous Load	✅ Passed	PASS. The pull request changes only .github/workflows/test-e2e.yml. It adds or moves no production Swift code or synchronous agent-history load, so the custom check does not apply.
Cmux Cache Substitution Correctness	✅ Passed	The check applies to production Swift, TypeScript, and JavaScript changes. The authoritative diff changes only .github/workflows/test-e2e.yml; it contains no production-language changes or cache sub…
Cmux No Hacky Sleeps	✅ Passed	The PR changes only .github/workflows/test-e2e.yml. The runtime no-hacky-sleeps rule excludes GitHub Actions workflow YAML, and the changed lines only set and validate a DerivedData path. No covered…
Cmux Algorithmic Complexity	✅ Passed	The diff changes only .github/workflows/test-e2e.yml. Its changed shell commands set, create, validate, and remove a single DerivedData path. They add no collection scans, repeated per-target work, …
Cmux Swift Concurrency	✅ Passed	The pull request changes only .github/workflows/test-e2e.yml; the diff contains no Swift files or Swift concurrency patterns. The custom check applies to cmux-owned Swift code, so this workflow-only…
Cmux Swift @Concurrent	✅ Passed	The check applies to Swift changes. The reviewed diff changes only .github/workflows/test-e2e.yml; it contains no Swift source changes. Therefore, it introduces no violation of the Swift `@concurren…
Cmux Swift Package Boundaries	✅ Passed	The check applies to production Swift changes. The reviewed diff changes only .github/workflows/test-e2e.yml and contains no changed Swift files, so it does not alter Swift package boundaries.
Cmux Swiftpm Lockfiles	✅ Passed	The PR changes only .github/workflows/test-e2e.yml. The workflow diff moves DerivedData to RUNNER_TEMP and updates cleanup ownership checks. It does not change SwiftPM dependencies, package or Xco…
Cmux Swift Logging	✅ Passed	The diff changes only .github/workflows/test-e2e.yml; it contains no production Swift changes. The Swift logging check is not applicable.
Cmux User-Facing Error Privacy	✅ Passed	The diff changes only .github/workflows/test-e2e.yml. It moves the test job’s DerivedData path to RUNNER_TEMP and removes that job’s compilation-cache cleanup branch. The related cleanup diagnosti…
Cmux Full Internationalization	✅ Passed	The diff changes only .github/workflows/test-e2e.yml. It updates the E2E job’s DerivedData path and cleanup ownership check, and removes compilation-cache cleanup. These are CI operations, not user-…
Cmux Swiftui State Layout	✅ Passed	The changed-file inventory contains only .github/workflows/test-e2e.yml. The diff changes CI shell steps and introduces no SwiftUI views or state, layout measurements, lazy rows, or render-time muta…
Cmux Architecture Rethink	✅ Passed	The custom check applies to Swift architecture changes. The reviewed diff changes only .github/workflows/test-e2e.yml; it adds no Swift code or architecture behavior. The check is not applicable.
Cmux Swift Auxiliary Window Close Shortcuts	✅ Passed	PASS. The reviewed diff changes only .github/workflows/test-e2e.yml. It adds no Swift code or user-visible window declarations, so it does not trigger the auxiliary-window close-shortcut check.
Cmux Source Artifacts	✅ Passed	The PR changes only .github/workflows/test-e2e.yml, a workflow configuration file. Its diff changes the runtime DerivedData destination to a path under $RUNNER_TEMP and updates cleanup to remove t…
Cmux No Test Or Debug Seam In Production Source	✅ Passed	The PR changes only .github/workflows/test-e2e.yml. The authoritative diff contains no changed Swift files under a production Sources/ path, so this check does not apply.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Commit to this branch
• Create a new PR

---

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.}

[teamleaderleo]

Independent review — approving.

The fix matches the failure. cleanup-app-host-home.sh refuses to inspect an app host whose CMUX_DERIVED_DATA_PATH is outside RUNNER_TEMP, and the split lane's test job inherited $GITHUB_WORKSPACE/DerivedData/cmux-e2e from the single-job lane, where that script was never called. Moving it under $RUNNER_TEMP satisfies the guard rather than weakening it, and aligns the lane with where ci-macos.yml already puts its test shards.

The part worth checking is the second half of the diff, which deletes the compilation-cache guard and its rm -rf. That reads like a safety check being dropped, but it is dead code in this job:

• Every CMUX_E2E_COMPILATION_CACHE assignment and use is in the build job (lines 272-469 of the post-change file).
• GITHUB_ENV does not cross jobs, so in test that variable is always unset. The guard's "" case matched unconditionally and if [ -n "$cache_path" ] never fired.
• The build job keeps its own Clean owned DerivedData step with the guard and the cache removal intact (line 472 onward), so nothing loses protection.

Removing a check that can only ever pass, in a job that has no cache to remove, is the right call over carrying it as decoration.

Adding ${GITHUB_RUN_ID}-${GITHUB_RUN_ATTEMPT} to the path also makes the directory unique per attempt, which matters more under RUNNER_TEMP on a reused self-hosted workspace than it did under the old workspace path. The cleanup case reconstructs the identical expression, so the owned-path comparison still matches exactly.

Validation in the description is the right shape: it names the run, the test that passed, and the specific step that went from failure to pass, rather than asserting the lane is green.

— Rockall g1 🪙
Run: run_cmux_land_ready_prs_20260923_A

[teamleaderleo]

Independent review

Reviewed by a separate agent against the files rather than the diff description. No blocking findings.

The one question worth answering, since it decides whether this is safe: the .xctestrun manifests are produced by the build job with paths rooted at its DerivedData, so moving the test job's DerivedData looks like it should break test-without-building. It doesn't. scripts/ci/app_host_test_products.py stamp records the producer's path into the receipt, and restore rewrites every manifest string to the consumer's resolved path, then re-runs validate_manifest — which requires TestHostPath, TestBundlePath and UITargetAppPath to resolve to files inside the new Build/Products. A bad relocation fails the restore step loudly instead of mis-running the tests. ci-macos.yml has always depended on this: its compile-admission job builds at /private/tmp/cmux-ci/derived-data-compile-admission and its shards consume from $RUNNER_TEMP/..., a pair that never matched.

Also checked: nothing embeds the build DerivedData path in the binaries (LD_RUNPATH_SEARCH_PATHS is @executable_path-relative plus one machine-fixed absolute), parallel_artifact_download.py was already RUNNER_TEMP-relative, run-app-host-xcodebuild.sh's stale-host scan covers both old and new paths, and the product contract in reuse_app_host_products.py does not hash the DerivedData location. The case patterns are fully quoted, so a glob metacharacter or space in RUNNER_TEMP is matched literally, and set -euo pipefail means a partial prepare leaves the variable unset, hitting the "" arm rather than a wrong one.

The review's most useful finding was that the guard which should have caught this still didn't, so the PR now carries it. check_every_app_host_home_is_identified_and_cleaned already enumerates every job that prepares an app-host home, but asserted only what prepare needs — not the boundary cleanup enforces at runtime. It now also requires each such job to publish CMUX_DERIVED_DATA_PATH under RUNNER_TEMP. Mutation-tested three ways: reverting this workflow to the pre-fix path fails it, as does moving ci-macos.yml's shard DerivedData out of RUNNER_TEMP or dropping the publishing step — so it checks both callers, not just the one that broke.

Second gap closed: step() resolves an ambiguous step name to the build job, so the test job's Clean owned DerivedData arm had no coverage at all. A typo in its ownership pattern would ship green and fail only on a runner, under if: always(), after the tests passed — the exact failure shape here. A typo mutation now fails the suite.

Verification: actionlint clean, all 132 linux-guard tests pass, and run 35844665006 is green end to end on b637305919 — build 14.4 min, test 2.8 min, with Prepare isolated app-host home, Clean owned app-host home and Clean owned DerivedData all executed rather than skipped.

Non-blocking, not taken here: the new path uses $RUNNER_TEMP verbatim while the build job resolves its own through pwd -P. cmux_validate_app_host_derived_data would reject an unresolved path, so a runner with a symlinked component in RUNNER_TEMP would fail — but ci-macos.yml has used the raw form in the same place for a long time, and matching it is worth more than pre-empting a pool that doesn't exist.

— Coppervane g1 🔆
run=run_cmux-e2e-cost-20260923 · repairing the E2E build/test split landed in #13908