shared-live-scenarios.js publishes the ordered behavioral scenario IDs used by both runtimes. The runtime adapters bind the selected runtime, version, and exact generated live-build ID into the existing live driver while retaining runtime-specific ratio-bar, tooltip, credential-store, transport, and Shorts-control capabilities.

hermetic-artifact-smoke.js makes three shared scenarios executable against both generated artifacts and one extension-specific stale-response race executable against the generated MV3 artifact:

watch-render verifies the first rendered count and visible ratio bar.
watch-spa-side-panel clicks the related-video link from A to B using non-proportional 90/10 and 35/65 fixtures. It retains hidden copies of A's initialized controls both before and inside the new current root, replaces B's action container during settling, and then requires exactly one B-owned count/bar/tooltip with no RYD bars left in any retained tree. Readiness must remain valid for 300 ms, after which the exact invariant is sampled continuously for another second. The result includes first-valid latency and sample counts.
watch-spa-dislike-activation reuses that exact A-to-B replacement setup, clicks the one visible B-owned Dislike button once, and requires one ordered /interact/vote plus /interact/confirmVote chain for B with value -1 and the same confirmed 36-character user ID. Confirmation must return HTTP 200 with the literal JSON value true, and the exact one-vote/one-confirmation invariant must remain stable for another second so a duplicated listener fails. The userscript chain is observed through its routed fake backend; the extension chain is observed at the loopback MV3 background server. Both paths reject unexpected or escaped traffic and page errors, unhandled rejections, and console errors.
extension-watch-spa-delayed-outgoing-failure holds A's /votes response, navigates to B, releases A as malformed, and requires B to initialize exactly once without ever showing A's error or data. This proves that navigation queued during an in-flight initialization is not swallowed and that stale failures are as harmless as stale successes.
extension-startup-resilience.e2e.js leaves /configs/selectors pending forever and requires the manifest-injected content script to initialize Watch from its bundled selectors within the startup budget. This prevents an optional remote selector refresh from blocking every listener, count, and ratio bar in the extension.

node Extensions/e2e/hermetic-artifact-smoke.js

The userscript is injected into an isolated context with GM shims. The extension is loaded as a real unpacked MV3 artifact in an isolated persistent Chromium profile, and the smoke requires its service worker to start. The mobile extension coverage launches that profile with an Android user agent, mobile metrics, and touch enabled; its Shorts vote uses a real touchscreen tap and holds the exact one-vote/one-confirmation invariant after both touch and synthetic click events have fired.

Extension API safety

The extension background eagerly registers as soon as its service worker starts. That can happen before Playwright can install a context route, so routing the production origin after launchPersistentContext() is not a safe hermetic strategy.

The adapter therefore starts a loopback fake API first, copies the current dist/chrome artifact into an owned OS temporary directory, replaces the exact production origin in the background bundle, and adds only the corresponding loopback host permission. It refuses non-loopback origins or a missing replacement point. The content-script bundle is left byte-for-byte intact: Chromium blocks HTTPS-page content scripts from reaching loopback under Private Network Access, so a BrowserContext route fulfills its normal API-origin requests instead. That route is installed before any YouTube page is created or navigated. The temporary background bundle also replaces the exact first-install changelog listener with a no-op so a fresh profile cannot open the changelog and request its remote font before the catch-all is ready. A launch-time host resolver rule also denies every non-loopback hostname, closing the worker-startup window before Playwright routing exists. A missing exact listener fails preparation. The tracked build output is never modified. Both the derived artifact and its browser profile are removed after the run.

The derived background bundle begins with a test-only runtime probe before any production bundle code. It records worker exceptions, unhandled rejections, failed console assertions, errors, and warnings both in the worker and at the loopback server. Every extension scenario checks this shared page-and-worker signal collector, including startup signals that a listener attached after service-worker discovery would miss. A negative-control browser test rejects a Promise inside the real MV3 worker and requires the guard to detect it. Both fake API transports validate CORS preflights against the declared endpoint/method contract; an OPTIONS request to any other path is recorded and failed.

The extension build emits a root-only receipt with its mode and a deterministic hash of production inputs. The artifact verifier requires a fresh production receipt, rejects inline development source maps, and SHA-256 compares each browser bundle mirror with Webpack's root output. The direct extension Playwright command runs this verifier first, preventing the suite from silently exercising a stale or watch-generated dist/chrome artifact.

Setting RYD_EXTENSION_ARTIFACT to another directory is rejected by the Playwright global setup unless RYD_E2E_ALLOW_CUSTOM_EXTENSION_ARTIFACT=1 is also set. Use that explicit bypass only for an intentional custom or negative-control fixture; the selected directory still has to pass standalone production MV3 validation.

A future dedicated Webpack test build can replace this derivation with the following equivalent hook:

Define an API-base compile constant only when a hermetic-build flag is enabled.
Reject a hermetic API base whose parsed hostname is not 127.0.0.1, ::1, or localhost.
Use that constant from Extensions/combined/src/config.js for both background and content-script bundles.
Add the loopback host match to the generated test manifest only; never to release manifests.
Start the fake server before building so its allocated origin is compiled into the artifact, then launch the persistent context.

The artifact smoke is part of npm run test:e2e:systematic and npm run test:all. Its colocated Jest tests cover the shared catalog, runtime binding, capability validation, loopback guard, derived-artifact transformation, signal collection, and cleanup behavior. The browser run rejects stale/current ownership mistakes, missed initialization, duplicate activation, unexpected traffic, console errors, page errors, unhandled rejections, and a missing auxiliary extension script. Both Playwright runtime suites also include a negative render oracle that substitutes a no-op runtime artifact and requires the owned Dislike count and ratio bar assertions to fail, preventing the fixtures themselves from creating a false green when either generated runtime stops executing.

Authenticated live-build identity

The authenticated Chromium suite is intentionally separate from this hermetic runner. build:live:userscript and build:live:extension generate a fresh 32-character build ID, compile it into the page marker, and write the same ID to the runtime's live-build.json. The live suite reads that file and requires an exact marker match before every shared scenario. Rebuilding without reinstalling or reloading the runtime therefore fails even when the semantic version did not change. Its approved reaction phase additionally proves that a real playlist SPA transition from A to B produces no interaction request by itself, then requires the reaction and cleanup handshakes to target B exactly, return 2xx, confirm with literal true, and restore the initial reaction. See Extensions/UserScript/e2e/live/README.md for the complete preparation and safety contract.

Firefox changelog lifecycle

After a production build, run the native temporary-addon regression with the pinned Node runtime:

$env:RYD_FIREFOX_CHANGELOG_LIFECYCLE = "1"
$env:RYD_FIREFOX_CHANGELOG_EXPECT_IMMEDIATE = "1"
node Extensions/e2e/firefox-consent-smoke.js

This uses an owned Firefox profile and a loopback API. A probe added only to the derived test extension records actual runtime.onInstalled events and background restarts. The regression checks fresh installation, removal/reinstallation, temporary reload with an unseen or pending changelog, and suppression after the changelog has been shown. It preserves the production artifact and writes event, storage, and tab evidence to test-results/firefox-consent-*/result.json.

Unset both environment variables before running the packaged-install matrix. Omit only RYD_FIREFOX_CHANGELOG_EXPECT_IMMEDIATE when recording the behavior of an older artifact: that mode records the lifecycle outcome and does not require the temporary-reload fix. ryd.background-changelog.spec.js also covers normal update deferral until browser startup and retry after tab creation fails.