Status: Implemented — shipped in #602, closing #601.

Summary

The GL replay harness drives recorded .rnr sessions through the real EditorShell::runFrame() loop while the editor renders on a background AsyncRenderer worker thread. Because a worker render lands relative to wall-clock, tests that compared specific replay frames were chronically flaky (the two #601-disabled subtests plus later accumulations). This design added a deterministic replay framework: replay-only worker scheduling modes (DrainEachFrame, HoldFramesBehind) that make render landing a function of frame index, a content-only capture mode that excludes editor chrome, and a worker-delay injection hook used to validate determinism. All of it is test-only and defaults to production behavior. The #601-disabled gl_rnr_replay_tests / editor_layer_stress_tests subtests were re-enabled (or retired in favor of narrower coverage) as deterministic tests.

The shipped mechanism — API, scheduling modes, content-only capture, worker-state hooks, and where the tests live — is documented in Deterministic Replay Testing.

The original full design (goals, adversarial premortem, per-milestone plan, and the disabled-test inventory) is recoverable from git history.