[teamleaderleo]

Fixes a flaky red in the cmux NEXT swift test job (CmuxNextAppTests). It fails only in the full run and passes when its suite runs alone:

✘ Test aStripDividerUnderADockIsNotHoveredOrDrawnThere(_:) recorded an issue with 1 argument mode → .docked at DividerCursorUnderDockTests.swift:91:13: Expectation failed: !((lines → []).isEmpty → true → true)
(same for mode → .overlay)

(CI jobs 122247588853, 122242789085.)

Cause. This is test isolation, not #26100. A diagnostic build printed the handle's state at the failure: line color clear, showsActiveLine false, model.style.paneSeparation == .none. The fixture's LayoutModel follows the process-wide DesignSettings. A fresh process has chromeStyle default, which uses dividers or borders, and that draws a hover line. But settings tests that run earlier in the same process (PaneChromeEvenGapTests' load(nil), PaneChromeEvenInsetTests' reset) apply a cmux.json without appearance.chromeStyle. That leaves the app default flat-sidebar-line, whose separation is none, and none draws no divider hover line (PaneSeparation.drawsDividerFeedback). So the result depended on test order.

Change. The fixture pins its style with model.followsDesignMetrics = false (base LayoutStyle, .borders), as other layout tests already do. All of the test's assertions are unchanged.

Fleet proof (full CmuxNextAppTests runs):

• base: red in 2 of 7 full runs (base plus test-only changes in other files)
• head 6699ad3: green in 5/5 full runs

No capture: test fixture only; nothing on screen changes.

Risk: none for the product. One test fixture line changes.

Independent review: Codex (gpt-6-astra, xhigh) SHIP.

Agent session: agent session

🤖 Generated with Claude Code

[teamleaderleo]

Owned by an agent session · session

[teamleaderleo]

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

[teamleaderleo]

Review (codex gpt-6-astra xhigh, next-review): SHIP at 6699ad3

No blocking findings.

The fixture change preserves all assertions and isolates the test from shared design settings. Review was limited to the supplied files; repository reads required unavailable approval. Tests were not run.

[github-actions]

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

Review 6699ad3: 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=pr26338 -f ref=ib/wintab-divider-line -f platform=macos -f backend_mode=local

[blacksmith-sh]

Found 4 test failures on Blacksmith runners:

Failures

Test	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

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

[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]

The feat-cmux-next push run https://github.com/manaflow-ai/cmux/actions/runs/40619334537 at 0c83363 failed: cmux-next checks (god files, concurrency, crash safety, l10n).
Those jobs last passed at cfe2fa2. This pull request is one of 4 merged since: #26338, #26502, #26511, #26507.
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]

The feat-cmux-next push run https://github.com/manaflow-ai/cmux/actions/runs/40619221614 at fc4458f failed: cmux-next checks (god files, concurrency, crash safety, l10n).
Those jobs last passed at cfe2fa2. This pull request is one of 2 merged since: #26338, #26502.
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)