[teamleaderleo]

Fixes a flake in the cmux-next swift test job (seen in job 122287803089, the full parallel CmuxNextAppTests run):

✘ Test theCatalogIsBuiltOnceAndRebuiltOnlyWhenAFolderChanges() recorded an issue at BackdropCatalogStoreTests.swift:28:6: Time limit was exceeded: 60.000 seconds
✘ Test theCatalogIsBuiltOnceAndRebuiltOnlyWhenAFolderChanges() recorded an issue at BackdropCatalogStoreTests.swift:46:9: Expectation failed: store.catalog.choices.contains { $0.id.contains("mine.png") }

Cause: FolderChanges.events() returned its stream and armed the folder watches (the DispatchSource file-system sources) later, inside a .utility detached task. BackdropCatalogStore calls events(), builds the catalog and bumps builds. The test waits for that build and then adds mine.png. Under a loaded parallel run, the utility task could start only after the file was added. That change was never seen, so the wait for a second build never ended and the 60 s limit fired. The test already waits on a condition (an observed build counter) and not on a sleep. The missing event was the bug, so the time limit stays as it is.

Change: events() now arms the watches before it returns, and the loop task takes them over. So any change made after events() returns is buffered and seen. FolderChangesTests drops the 100 ms head start it gave the loop to arm, which this makes unnecessary.

Proof (fleet suite gate): at head 90b418c, BackdropCatalogStoreTests passed 5/5 and FolderChangesTests passed 5/5 (no head-start sleep). The suite gate runs one suite per process, so the load that starved the utility task in the full parallel run does not happen there. The base red is only in CI's parallel run, and at base 68f7028 the gate passes 5/5 too. The fix rests on the ordering argument above, not on a reproduction.

No capture: nothing visible changes. This is the timing of a folder watch, and the wallpaper list looks the same before and after.

Review: Codex (gpt-6-astra, xhigh) gave SHIP at head 90b418c. It checked that the non-Sendable FolderWatch moves into Task.detached under region isolation.

Risk: low. The watch opens a few microseconds earlier, on the caller's thread rather than the loop's. Cancellation and re-arming are unchanged. The only other user is BackdropCatalogStore.

Agent session: agent session

🤖 Generated with Claude Code

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[teamleaderleo]

Owned by an agent session · session

[github-actions]

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

Review f6e6430: 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=pr26320 -f ref=ib/backdrop-catalog -f platform=macos -f backend_mode=local

[blacksmith-sh]

Found 6 test failures on Blacksmith runners:

Failures

Test	View Logs
main.WiringTests.test_both_deferrals_ask_the_script/ test_both_deferrals_ask_the_script	View Logs
main.WiringTests.test_the_pool_matches_the_daemon_test_job/ test_the_pool_matches_the_daemon_test_job	View Logs
build_only must be a conjunctive exclusion on the helper, signing, and publication jobs , and must not gate the unsigned app build/ build_only must be a conjunctive exclusion on the helper, signing, and publication jobs , and must not gate the unsigned app build	View Logs
nightly.yml must derive the embedded key and sign every appcast through the helper/ nightly.yml must derive the embedded key and sign every appcast through the helper	View Logs
test_the_nightly_is_covered (main.NightlyStepCoverageTests.test_the_nightly_is_cove red)/ test_the_nightly_is_covered (main.NightlyStepCoverageTests.test_the_nightly_is_cove red)	View Logs
test_the_repository_highlights_validate (main.DigestTests.test_the_repository_highl ights_validate)/ test_the_repository_highlights_validate (main.DigestTests.test_the_repository_highl ights_validate)	View Logs

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[teamleaderleo]

Bead cx-2p0oi1 created for this PR by the cmux coordinator.

[teamleaderleo]

Review (codex gpt-6-astra xhigh, next-review): SHIP at 90b418c

No blocking findings.

[github-actions]

The feat-cmux-next push run https://github.com/manaflow-ai/cmux/actions/runs/40618800354 at 46f5779 failed: cmux-next checks (god files, concurrency, crash safety, l10n), cmux-next generated files.
Those jobs last passed at af80466. This pull request is one of 3 merged since: #26320, #26071, #26338.
If the failure is in your change, fix forward on feat-cmux-next. Pull requests run only the tiers their paths reach (docs/ci/cmux-next-tiers.md); label a batch PR full-ci to run them all before merging.

[github-actions]

Shipped in:

• cmux NEXT nightly 1.0.0-nightly.4062181672501 (f2500c8ab0)
• cmux NEXT nightly 1.0.0-nightly.4062224162001 (0c8336391b)