The release-blocking `terminal rendering golden mac` job was failing ~40%
of Cut Release runs with `Expected e2e repo to be loaded`, leaving the RC
stuck as a draft (publish-release depends on this job).
Root cause: the sharedPage fixture did a single-shot fetchRepos() + find()
+ throw. window.api.repos.add() fires a repos:changed echo that triggers a
concurrent fetchRepos() in the renderer; the store's reposFetchGeneration
guard then drops the fixture's own awaited fetch result, leaving `repos`
briefly stale, so find() returns undefined and throws. The repo lands a few
ms later (the failure screenshot's sidebar actually shows it).
Wrap the repo load in expect.poll (matching the seeded-worktree poll right
below it) so it retries fetchRepos until the repo lands, then runs the
idempotent updateRepo. Also harden the single-shot hasWebgl/cursorHidden
diagnostics reads in the golden spec: WebGL reattaches asynchronously after
a worktree switch, so poll those eventually-consistent fields until they
settle before the golden asserts. Regression detection is preserved: a real
WebGL/cursor regression times out the poll and still fails the test; the
geometry/wrap/overpaint golden checks stay single-shot.
0ebfc989cb