Coherent 5-edit Wave 1 GREEN landing per Plan 04-02 Task 2; RED gate from
Task 1 (`tests/build/no-new-function-in-sw-chunk.test.ts` 1-hit assertion)
flips GREEN with 0 hits of `new Function` in any SW chunk
(`dist/assets/index.ts-*.js` glob).
## Threat T-04-02-01 mitigation (Elevation of Privilege — `new Function` literal)
Three layered mechanisms cooperate to drop the CSP-unsafe `new Function`
literal from the SW chunk while preserving JSZip's zip-assembly correctness
end-to-end (REVISION iter-2 WARNING 1 empirically pinned at UAT harness 33/33):
1. **Runtime polyfill prelude** at top-of-module of `src/background/index.ts`
(BEFORE the first `import`): an inline `queueMicrotask`-based polyfill
installs `globalThis.setImmediate` at SW boot. JSZip's pre-bundled
`dist/jszip.min.js` IIFE guards its internal setimmediate polyfill behind
`if(!s.setImmediate){...}`, so the upstream offending body never executes
at runtime once our prelude has installed the safe fast-path.
2. **`vite-plugin-node-polyfills` `exclude: ['setimmediate']`** in vite.config.ts:
prevents the plugin from injecting its node-stdlib-browser-aliased
setimmediate polyfill into the chunk. NOTE: this alone is insufficient
because JSZip's `dist/jszip.min.js` ships its OWN bundled-in setimmediate
(via the package.json `"browser"` field that maps `./lib/index` →
`./dist/jszip.min.js`); the plugin's `exclude` only filters the plugin's
own contributions.
3. **`resolve.alias.setimmediate`** redirects bare-specifier `setimmediate`
requires to `src/shared/setimmediate-stub.ts` (a 22-LOC TS module that
installs the same `queueMicrotask`-based polyfill via side-effect import).
This catches any future direct `import 'setimmediate'` consumer that
bypasses the prelude.
4. **`stripSetimmediateNewFunction()` Rollup post-transform plugin** in
vite.config.ts: surgically replaces the single occurrence of
`(I=new Function(""+I))` with `(I=function(){})` in any output chunk
that contains the JSZip-bundled setimmediate IIFE. The replacement is
observably equivalent in our codepath (the parent `typeof I!="function"&&`
guard means the body never runs when I is already a function — which is
the only form JSZip ever uses — AND the runtime prelude makes the entire
IIFE body unreachable regardless). Without this plugin, JSZip's
pre-bundled distribution embeds the upstream setimmediate package's
`setImmediate.js` verbatim inside its internal CJS module registry
(slot 54), unreachable by Vite's resolve.alias or the polyfill plugin's
exclude.
## Architecture decision log
**Option α (force JSZip unbundled `lib/index.js` via `resolve.alias.jszip`)
was attempted and reverted 2026-05-21** (between commits 630d40c and this).
Empirically broke UAT harness A30+ because the unbundled entry's transitive
readable-stream-browser browser-field mapping did not propagate correctly
through Vite's resolver — the async zip-write pipeline silently produced
an empty events.json. The post-transform plugin (Option β) is the
minimum-surface fix that preserves JSZip's runtime behavior verbatim while
satisfying the textual `new Function` count = 0 invariant.
## Verification
**Build / static gates:**
- `npm run build` exits 0; SW chunk `dist/assets/index.ts-DfBxWCT9.js`
(378.92 kB) contains 0 occurrences of `new Function` (was 1 in pre-fix
`index.ts-8LkXuqac.js`).
- `npx tsc --noEmit` exits 0.
- `grep -rn 'permissions.request' src/` returns 0 hits (Plan 04-02 ROADMAP
SC #4 regression pin GREEN).
- `node generate-icons.cjs` exits 0; old `generate-icons.js` no longer
exists (rename via `git mv` preserves history).
- `grep -c "exclude: \\['setimmediate'\\]" vite.config.ts` returns 1.
- `grep -c "queueMicrotask" src/background/index.ts` returns ≥1.
- `grep -c "Resolved in Phase 4 Plan 04-02" .planning/phases/01-stabilize-video-pipeline/deferred-items.md` returns ≥1.
**Test gates:**
- Focused: `npm test -- tests/build/no-new-function-in-sw-chunk.test.ts tests/build/dead-code-grep.test.ts --run` → 3/3 GREEN (Task 1's RED gate flipped GREEN).
- Full vitest: 183/183 GREEN on the clean run (180 baseline + 3 net new
from Plan 04-02 Task 1's two new files). Pre-existing intermittent flakes
per 04-01-SUMMARY Issues Encountered (blob-url-download / webm-remux /
webm-playback ffmpeg dry-run) persist across SUMMARY runs and are owned
by Plan 04-03.
**Pre-checkpoint bundle gates (per saved memory feedback-pre-checkpoint-bundle-gates.md):**
1. Tier-1 FORBIDDEN_HOOK_STRINGS: 13/13 tests GREEN; inventory unchanged at
12 strings (Plan 04-02 added no harness hooks).
2. SW CSP-safety grep: `grep -rn 'new Function\\|eval(' dist/assets/` returns
0 hits — polarity flipped from the pre-existing 1 documented exception
(the setimmediate literal). T-04-02-01 mitigation pin lands.
3. Node-globals: `Buffer.copy / .isView / .length / .push / .shift / .slice
/ .write` in SW chunk (pre-existing JSZip internals; unchanged from
04-01-SUMMARY).
4. DOM-globals: `document.createElement / .createTextNode / .documentElement
/ .F` + `window.Math / .console / .localStorage / .process` (pre-existing
JSZip text encoder fallback paths; unchanged from 04-01-SUMMARY).
5. manifest.json: present, MV3, `name: __MSG_extName__` (chrome.i18n intact).
**Empirical UAT harness (REVISION iter-2 WARNING 1):**
- `HEADLESS=1 SKIP_PROD_REBUILD=0 npm run test:uat` → 33/33 assertions
passed (verbatim `UAT harness: 33/33 assertions passed` in stdout).
Confirms JSZip's full SAVE → zip pipeline (A24-A32 inclusive, exercising
the in-memory MediaRecorder segments + base64 port wire + remux + zip
assembly + chrome.downloads + events.json + meta.json + screenshot)
operates correctly under the new bundle. The setimmediate polyfill
replacement preserves zip-write behavior end-to-end at the empirical
layer.
## Files
- **vite.config.ts**: imports `node:url` (fileURLToPath/URL) + `Plugin`
type from vite; adds `nodePolyfills.exclude: ['setimmediate']`;
adds `resolve.alias.setimmediate` → `src/shared/setimmediate-stub.ts`;
adds `stripSetimmediateNewFunction()` Rollup post-transform plugin
with full rationale comment.
- **src/background/index.ts**: 17-line top-of-module prelude inserted
BEFORE the first `import { Logger } ...` line. Inline `queueMicrotask`-based
setimmediate polyfill with typed widening cast (no `as any` per
CLAUDE.md). Reversible by `git revert`.
- **src/shared/setimmediate-stub.ts** (NEW): 50-LOC TS module providing
the same `queueMicrotask`-based polyfill via side-effect import.
Documented as the resolve.alias target.
- **generate-icons.js → generate-icons.cjs**: `git mv` preserving history.
Node 14+ treats `.cjs` as CJS regardless of `package.json` "type":
"module" per https://nodejs.org/api/packages.html#determining-module-system.
No code change; `require('fs')` + `require('path')` resolve cleanly.
No other references to the old `.js` path elsewhere in the codebase
outside the `.planning/` audit trail.
- **.planning/phases/01-stabilize-video-pipeline/deferred-items.md**:
appended "Resolved in Phase 4 Plan 04-02" closure block citing this
commit; details the 4-mechanism layered mitigation; documents the
Option α attempt + reversion.
References:
- .planning/phases/04-harden-clean-up-optional/04-RESEARCH.md §Q1
- .planning/phases/04-harden-clean-up-optional/04-PATTERNS.md
§vite.config.ts + §src/background/index.ts
- Plan 04-02 threat model T-04-02-01 (Elevation of Privilege) +
T-04-02-02 (DoS — JSZip fallback compatibility; verified by UAT 33/33)
- node_modules/jszip/lib/utils.js:7 (upstream `require("setimmediate")`)
- node_modules/setimmediate/setImmediate.js (upstream polyfill source)
- Plan 01-12 Wave 7 deferred-items.md disclosure (Phase 5 → Phase 4 target)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Mark
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