PR #30888 - manaflow-ai/cmux

Summary

Review follow-ups to #30826 (Home's dock takes tabs once the tree reports its ids). This PR changes tests and one comment only, with no behavior change.

From the independent review of #30826 (https://github.com/manaflow-ai/cmux/pull/30826#issuecomment-6557423419):

Continuation: HomeDockAllowTabsTests no longer loops 2000 Task.yield calls (REVIEW.md section 6). The recorded request resumes a continuation (Sent.next(after:)), and the test also awaits the wait task itself. The suite's time limit bounds a request that never comes.
UserDefaults cleanup: each test removes its UserDefaults suite (removePersistentDomain), so no plist is left on the test host.
Two new tests:
- aLaterStepReplacesTheWait: two steps with no ids, then the ids. Exactly one column.update goes, and the first wait ends with none.
- theWaitEndsWhenHomesPageIsGone: the wait ends when Home's page leaves the tree, and the ids arriving later send nothing.
HomeDock:
- A comment says why the wait keeps the HomeDock across its await. A window Home makes a HomeDock per connect and keeps none, so a later "fix" to a weak capture would break it.
- allowTabsWait is private(set) so the tests can await it.

Changelog

none

Testing

These are new and changed tests. They cover behavior #30826 already added, so there is no red commit. They pass at the base of this change: the HomeDock behavior is #30826's, unchanged here.

Compile: cmux-ci compile-check --app --package CmuxNext --recipe-version 2 job 6c98bb17a942958e881d7ac8 passed at 43924e7e552 (before the merge of feat). Job bf17cd1e372f688d77a98f09 runs at the head f842b961924.
Display worker, CMUX_TEST_REQUIRE_GUI=1, HomeDockAllowTabsTests: GREEN_RESULT

Observed / Not run

Observed: the compile-check above and prepush-gate.py with no new violations.
Not run: the full CmuxNextHomeEngineTests suite.

perf claim: none

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Summary by cubic

Review follow-ups to #30826; tests and one comment only, with no behavior change.

HomeDockAllowTabsTests no longer loops 2000 Task.yield calls — a recorded request resumes a continuation, and each test awaits the wait task itself.
Each test removes its UserDefaults suite, so no plist is left on the test host.
Two new tests: a later step replaces the wait (exactly one allow_tabs request when the ids come), and the wait ends when Home's page leaves the tree.
HomeDock.allowTabsWait is now private(set) for the tests, and a comment explains why the wait holds the HomeDock across its await.