[teamleaderleo]

swift-test-summary.test.sh failed once on #21185's CI (cmux-next checks, job 119061489846), in the "crashed run" case:

a crashed run does not name crashesHere()
awk: fatal: cannot open file `/tmp/swift-test-log.8ynCVu' for reading: No such file or directory
sed: can't read /tmp/swift-test-log.8ynCVu: No such file or directory

The wrapper's temp log in /tmp disappeared before the wrapper reported, so the report could not name the unfinished test. The wrapper only deletes its own log, on EXIT, and no script in the repo sweeps /tmp/swift-test-log.*, so the delete probably came from outside the run, most likely one of the ~32 script tests the checks job runs at once (run-checks-concurrently.sh). I did not find the deleter. This is a flake, not a steady base red: the six later feat-cmux-next runs of cmux-next checks all print swift-test-summary.test.sh: ok.

Fix:

• The wrapper keeps its log in $RUNNER_TEMP (the job's own temp dir) when it's set, falling back to $TMPDIR or /tmp as before. The wrapper's crash reports already go to $RUNNER_TEMP. This helps if the deleter targets /tmp, which is likely but unproven.
• Found in review: if mktemp failed, $log was empty and the EXIT trap ran rm -f "" .*, deleting every dotfile in the working directory. The wrapper now stops with an ::error instead.

This is separate from #23129, which fixes a different flake in the same test (the crash-report mtime in the signal case).

Observed (macOS):

• bash scripts/cmux-next/tests/swift-test-summary.test.sh passes with RUNNER_TEMP unset and with it set to a fresh directory.
• With RUNNER_TEMP=/nonexistent/x, the wrapper exits 1 with the ::error and leaves the working directory's dotfiles alone.

The cmux-next CI guard group red fails the same set of workflow-guard tests on base; it is not this PR's.

🤖 Generated with Claude Code

Agent session: cosmic-gray

[github-actions]

cmux status _{(one comment, edited in place; each line is updated by the job that owns it)}

Review 52b1cdf: HQ feed card · gallery before/after runs · checks

App of this head (app.zip, kept 1 day)

gh workflow run reload-build.yml -R manaflow-ai/cmux --ref feat-cmux-next -f tag=pr23143 -f ref=chief-sidebar-2/swift-test-log-runner-temp -f platform=macos -f backend_mode=local

[teamleaderleo]

Owned by projects-ee on cosmic-gray · session

[blacksmith-sh]

Found 27 test failures on Blacksmith runners:

Failures

Test	View Logs
.github/workflows/ nightly-next-tick.yml: triggers on the display names ['cmux-next', 'cmux-tui artifacts' ] and declares no SOURCE_WORKFLOW_PATHS, so renaming any of those workflows stops this one from ever triggering and nothing reports it	View Logs
main.IOSWiring.test_test_ios_macos_jobs_take_the_runner_jobs_pool/ test_test_ios_macos_jobs_take_the_runner_jobs_pool	View Logs
main.SideLanes.test_a_completed_failed_blacksmith_retry_is_not_watched_again/ test_a_completed_failed_blacksmith_retry_is_not_watched_again	View Logs
main.SideLanes.test_a_real_failure_on_cmux_next_attempt_two_is_not_rescued/ test_a_real_failure_on_cmux_next_attempt_two_is_not_rescued	View Logs
cmux-next.yml job swift-canary step 'Report the build fleet compile verdict' uses the t oolchain (swift) before scripts/select-ci-xcode.sh runs	View Logs
debug info {'CMUX_SWIFT_SANITIZE': 'address', 'CMUX_SWIFT_TEST_DEBUG_INFO': 'none'}: 's wift --version' lacks '-debug-info-format none'/ debug info {'CMUX_SWIFT_SANITIZE': 'address', 'CMUX_SWIFT_TEST_DEBUG_INFO': 'none'}: 's wift --version' lacks '-debug-info-format none'	View Logs
debug info {'CMUX_SWIFT_SANITIZE': 'address', 'CMUX_SWIFT_TEST_DEBUG_INFO': 'none'}: 's wift package resolve --package-path Packages/macOS/Pkg --scratch-path Packages/macOS/ Pkg/.build-sanitize-address' lacks '-debug-info-format none'	View Logs
debug info {'CMUX_SWIFT_SANITIZE': 'address', 'CMUX_SWIFT_TEST_DEBUG_INFO': 'none'}: wa nt one build and two suites: ['swift package resolve --package-path Packages/macOS/ Pkg --scratch-path Packages/macOS/Pkg/ .build-sanitize-address', 'swift --version', 'swift build --build-tests -c debug -debug -info-format none --sanitize=address --scratch-path Packages/macOS/Pkg/ .build-sanitize-address -Xlinker -no_compact_unwind --package-path Packages/macOS/ Pkg', 'swift test -c debug -debug-info-format none --sanitize=address --scratch-path Pa ckages/macOS/Pkg/ .build-sanitize-address -Xlinker -no_compact_unwind --package-path Packages/macOS/ Pkg --skip-build --filter ATests', 'swift test -c debug -debug-info-format none --sanit ize=address --scratch-path Packages/macOS/Pkg/ .build-sanitize-address -Xlinker -no_compact_unwind --package-path Packages/macOS/ Pkg --skip-build --filter BTests']	View Logs
debug info {'CMUX_SWIFT_SANITIZE': 'address'}: want one build and two suites: ['swift p ackage resolve --package-path Packages/macOS/Pkg --scratch-path Packages/macOS/Pkg/ .build-sanitize-address', 'swift --version', 'swift build --build-tests -c debug --sani tize=address --scratch-path Packages/macOS/Pkg/ .build-sanitize-address -Xlinker -no_compact_unwind --package-path Packages/macOS/ Pkg', 'swift test -c debug --sanitize=address --scratch-path Packages/macOS/Pkg/ .build-sanitize-address -Xlinker -no_compact_unwind --package-path Packages/macOS/ Pkg --skip-build --filter ATests', 'swift test -c debug --sanitize=address --scratch-pa th Packages/macOS/Pkg/ .build-sanitize-address -Xlinker -no_compact_unwind --package-path Packages/macOS/ Pkg --skip-build --filter BTests']	View Logs
debug info {'CMUX_SWIFT_TEST_DEBUG_INFO': 'dwarf'}: want one build and two suites: ['sw ift package resolve --package-path Packages/macOS/ Pkg', 'swift --version', 'swift build --build-tests -c debug --package-path Packages/ macOS/Pkg', 'swift test -c debug --package-path Packages/macOS/ Pkg --skip-build --filter ATests', 'swift test -c debug --package-path Packages/macOS/ Pkg --skip-build --filter BTests']	View Logs

...and 17 more test failures. View all on Blacksmith

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

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[teamleaderleo]

Bead cx-piva0 created for this PR by the cmux coordinator.

[teamleaderleo]

merge-audit: #23143 merged at 024a53b without no SHIP review receipt on the head; no risk tier label. #23292 reverts it. To keep this change, add the missing evidence for 024a53b here; the next audit pass then closes #23292. Otherwise review and land #23292.

[github-actions]

Shipped in:

• cmux NEXT nightly 1.0.0-nightly.3958372135301 (bc661dae0e)

[teamleaderleo]

Review (subagent, correctness first): SHIP at 024a53b

This is a post-hoc independent review of the merged change (merge commit cc347e0). It was read-only and nothing was run. risk:low (CI wrapper script only).

Nothing blocks. Notes:

• The comment blamed /tmp, but the real cause was the watcher subshell inheriting the EXIT trap. Fixed on base by cmux-next: swift test wrapper sets its cleanup trap after it forks (swift-test-summary flake) #23290. The bash 3.2 wait $tee_pid race predates this PR and was fixed by ci(cmux-next): the swift test wrapper reads its log only once tee has written it (bash 3.2) #23402.

The merge-audit revert of this PR is handled separately. See leo-workspace briefs/2026-10-20-gui-push/revert-triage.md.