Measure complete CSS updates and fully cached warm reloads

perf/README.md

@@ -311,3 +311,27 @@ plus the source frontend build tag. WebKit does not expose the long-task API.
 Migration supports `--out` to preserve earlier phase evidence. Existing lazy
 harness results are copied to `phase4-lazy-2026-10-08.json` after each Phase 4 run
 and the Phase 3 result is restored. No production requests or deploys are needed.
+
+## Phase 5 complete measurements
+
+```bash
+node --test perf/measurement.test.mjs
+node perf/baseline.mjs --runs 5 --browser all --profile all --scenario all \
+  --out perf/results/final-2026-10-08.json \
+  --compare perf/results/baseline-2026-10-07.json
+node perf/lazy.mjs --browser all --out perf/results/phase5-lazy-2026-10-08.json
+```
+
+Warm reloads now wait for verified idle asset caching before counters reset and
+assert that no application asset body transfers. CSS update totals now include
+activation and the changed inactive stylesheet's verified background cache fill,
+matching the feature-update boundary. `readyWireBytes`/`readyDuration` retain the
+blocking readiness snapshot separately. Core updates stop at blocking readiness
+because app.js is blocking. Every update asserts that the only application asset
+payload is the edited file; worker script checks/imports and index/manifest count
+as overhead in the total. Historical Phase 3/4 CSS numbers were readiness only.
+No product behavior changes are involved in these measurement corrections.
+
+Keep browser/build/test processes idle during full timing measurements. WebKit's
+zero long-task field means unavailable, not zero work. Autoplay-blocked/media-ready
+null results do not establish playback performance or iPhone audio continuity.