streaming-remount background-restore test is flaky on macOS #3061

Problem

apps/desktop/e2e/streaming-remount.spec.ts:67 ("returning to a live conversation settles output accumulated while away") fails roughly one run in six on macOS, and only when the whole file runs — the test passes consistently on its own.

The failing assertion is that no intermediate paint shows partially accumulated background output:

expect(backgroundRestoreObserved?.texts.some((text) =>
  text.includes('background output') && !text.includes(backgroundSteering)
)).toBe(false);

The observer watches document.body with subtree: true and samples .maka-bubble-streaming's textContent on every mutation, so its sampling rate depends on how much unrelated DOM churns during the restore. That makes it sensitive to changes elsewhere in the shell, which is a fragile way to assert "no intermediate paint".

Measured before and after #3033's row rebuild: about 1 failure in 7 and 1 in 6 respectively, so the rate is not obviously changed by that work. CI (Linux) has not reproduced it.

Either the intermediate paint is real and rare — in which case the test is finding a genuine bug and should be made deterministic enough to prove it — or the observation method is too coarse. Worth resolving before it gets muted.

Context

Observed while verifying #3033.