Record cache reuse probes and reset each benchmark configuration

plans/phase6-investigation.md

@@ -51,3 +51,28 @@ FCP is 909 ms; the first classic request reaches the proxy at 250 ms and complet
 at 423 ms. Lazy still applies only the saved layout, in the original cascade order.
 Other selected layouts may speculatively download the small classic stylesheet;
 it never applies or blocks their rendering. No inline script or CSP change.
+
+
+The page-to-worker prototype successfully delivered bodies, but still transferred
+app.js twice. `phase6-handoff-mode.json` records the two requests: identical URL,
+`Accept-Encoding: gzip, deflate`, no-cors mode and immutable response, but script
+versus empty request destinations. Force-cache in the page did not reuse the
+script body's cache either. This prototype was discarded, not shipped.
+
+A fetch preload plus a later fetch also failed the one-body assertion. The
+shipping fix instead starts one cache-first fetch promise in the head loader.
+The final eager app-bootstrap consumes that response, verifies header AND SHA-256,
+and caches it before executing unchanged app.js as a classic script. A specific
+server-generated CSP hash authorizes only those exact bytes; unsafe-inline remains
+absent. DOMContentLoaded boot runs exactly once; the temporary script node and
+response promise are released. Native, insecure HTTP and rollback modes retain
+external classic execution. Only server asset-manifest rendering changed; no
+frontend imports, worker sync algorithm, update flow or playback source changed.
+
+The initial owned-response trial passed with one app.js body, FCP 1040 ms and
+981468 wire bytes (one fresh sample; not a final median). Five-run acceptance and
+regression results will be recorded separately. Historical diagnostics retained
+all samples. Full-harness configurations now reset to the base tree before each
+browser/profile, preventing a preceding synthetic update from contaminating the
+next cold build. The historical invalid media fixture remains unchanged: home
+launch only, not autoplay/audio latency.