Add a bounded per-chunk center-tile selector to the real-event replay prototype and retain the paired timing, mixed-boundary, CPU, HIP, and sandbox-failure evidence.
Capture prepared events through a test-only producer consumer and measure serial and indexed parallel generation independently. Compare the production atomic kernel with bounded pixel-owned tile reductions while preserving double HDR, cache support, and direct fallback ordering.
Validate captured inputs, edge and multichunk fixtures, CPU/HIP renderer regressions, and 45 isolated final replays. Keep the production HIP algorithm unchanged because gains depend on event distribution.
wyj