The original Layer 1 gate (74400ae) verified module-init under
SW-simulated globals. It did not exercise remuxSegments — the
actual runtime code path the SW reaches on SAVE_ARCHIVE.
Layer 2 imports webm-remux.ts as SOURCE in a spawned Node child
under SW-simulated globals, invokes remuxSegments with a synthetic
single-segment EBML payload, and classifies the outcome:
- `ok` (returned a Blob) or `domain_error` (e.g. invalid EBML
header — proves runtime path is structurally reachable) → PASS
- `sw_incompat` (ReferenceError for Node globals, EvalError /
unsafe-eval for CSP) → FAIL with the specific error surfaced
This is the gate that empirically caught the ts-ebml Buffer issue
addressed by the preceding polyfill commit; it closes the loop
between "bundle loads" (Layer 1) and "bundle works at runtime"
(Layer 2).
Polyfill-aware design: Layer 2 leaves `Buffer` AVAILABLE in the
child env (split strip list: SW_SOURCE_STRIP_GLOBALS omits
'Buffer'). The vite-plugin-node-polyfills rewrite is BUNDLER-LEVEL
(Buffer → imported polyfill chunk) and does not apply when source
is loaded outside Vite. Leaving Buffer available faithfully
models what the polyfilled bundle provides at SW runtime, while
keeping the classifier ready to flag Buffer regressions if the
polyfill ever gets removed. `process`/`window`/`document` remain
stripped (polyfill is configured globals.process: false; SW
genuinely lacks DOM).
Node 24 native TS transform (`--experimental-transform-types`)
is used for source loading; a tiny inline resolution hook
appends `.ts` to extensionless relative specifiers, mimicking
vite/rollup's extension policy. Hook is base64-encoded as a
data: URL so the test stays self-contained (no on-disk hook file).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Mark
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