e2e/CI: dual-engine suites, per-engine screenshots, SwiftShader retired, prod web suite, CI-coverage gate

Squash of experiment/ff-big-modules vs main.

Big-module routing removed: native-EH shrank kicad_editor below
SpiderMonkey's x86-64 code budget (runs 29355049705/29356152413 green on
stock Firefox), so BIG_MODULE_SPECS routing and the baseline-only-JIT
crutch are gone — kicad-firefox and kicad-chromium both run the full
suite, with the module compiled the way real users' browsers compile it.

Per-engine screenshots end to end: stableShot/shotPath write
test-results/<engine>/<name>.png; baselines move to
baseline-screenshots/{chromium,firefox}/ and the whole tools/screenshots
pipeline (compare/promote/manifest/spec-map/changelog/Discord) keys on
<engine>/<name>. Previously Firefox and Chromium renders of one spec
overwrote each other and Firefox renders were never actually gated.
Seeded from CI run 29421380806 (92 new firefox baselines, +24 chromium
web-suite shots); manifest generated from the baseline tree.

One merged playwright.config.ts (kicad/asyncify/coroutine/perf as
projects); ~25 dead npm scripts dropped. The web suite is gated in CI for
the first time ever (4 rotted specs fixed, 5 broken lib-bridge specs
triaged as fixme in docs/features/web-e2e-rot/); cheap lint step after
npm ci; last 26 blind-sleep violations fixed.

SwiftShader retired: CI Chromium renders WebGL on ANGLE → Mesa llvmpipe
(--use-gl=angle --use-angle=gl --ignore-gpu-blocklist; the blocklist flag
is mandatory — llvmpipe is blocklisted and WebGL is silently unavailable
without it) in BOTH configs. Under WORKERS=4 congestion SwiftShader
transiently failed the first post-board-load draw and the recovery
cascade ended in a silent permanent Cairo fallback — that engine flip was
the "~1.2% changedRatio both directions" occ-export baseline flake.
Validated 160/160 across two 80-repeat rigs; full analysis in
docs/features/wx-parity-bugs/occ-export-context-eviction.md. Chromium
baselines shift slightly on llvmpipe — promote once from the first green
run. Deflakes the new coverage exposed: presence baselines settle before
capture; presence fixtures declare current file formats; perf gets its
own outputDir so CI evidence survives; occ-export settles the board paint
before the export dialog; menu-item waits (waitForRenderedByLabel before
clickMenuItem) in 4 specs + the TESTING.md rule.

Web suite runs the PROD build, in parallel: webServer becomes backend
`start` + the standalone's e2e:preview (build-preview.mjs: link-wasm →
stash the public/wasm symlink aside during vite build, build-demo.mjs's
move — then vite preview as the persistent server). The wasm middleware
serves /wasm/* in preview and emits COOP/COEP/CORP itself (a pthread
worker script's own response must carry COEP or Chrome kills it with
ERR_BLOCKED_BY_RESPONSE). VITE_* flags bake at build time;
VITE_ALLOW_USER_OVERRIDE joins turbo globalEnv. fullyParallel + default
workers: 5.2m → 1.4m. Determinism fixes the parallel run exposed:
shared-page specs become serial groups; locks.spec grabs alice's exact
item via the new kicadCollabTestSelectByUuid hook (cross-tab "first
footprint" order is not a ysync invariant); quit specs poll page.url()
(quit supersedes its own navigation — NS_BINDING_ABORTED on Firefox).
Suite: 51 passed / 12 skipped / 0 failed in 1.6m.

CI-coverage gate (lint:ci-coverage): every tests/**/*.spec.ts must be
reachable from the npm scripts the workflows invoke — scraped from
.github/workflows/, resolved through package.json, coverage asked from
playwright --list itself. Rules: uncovered-spec + orphan-project (with a
documented LOCAL_ONLY_PROJECTS allowlist). Gating next to
lint:determinism; 138 spec files / 13 projects accounted for.

Product fixes kept from the investigations (reachable on real GPUs too):
wx 7799fd1be5 — paint flags clear before dispatch + Invalidate always
propagates; kicad 3dcfea5e45 — SwiftShader pass-boundary flush +
per-instance font texture + first-frame GL-error drain (GAL recovery
recovers instead of falling back to Cairo) + the user-facing eeschema
switch navigates again under __EMSCRIPTEN__ (project-sync's
FaceRegistered gate had rerouted it into the hidden sync player; caught
by the newly-gated web suite).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018eUxiPApHgGiu9NFyQfhAq

tests/tools/screenshots/noise.ts

@@ -1,9 +1,10 @@
 /**
  * Calibration: measure the intra-CI noise floor.
  *
- * Render the suite twice on the same host (into two dirs), then:
+ * Render the suite twice on the same host (into two dirs, each with per-engine
+ * subdirs like test-results/), then:
  *   tsx tools/screenshots/noise.ts <run1-dir> <run2-dir>
- * prints, per engine (via the manifest) and globally, the max / p95 / mean
+ * prints, per engine (from the subdir) and globally, the max / p95 / mean
  * changed-pixel ratio between the two identical-input renders. Set
  * config.ts FLOORS.<engine>.changedRatio ≈ (max × 3) from this.
  *
@@ -13,17 +14,9 @@
  */
 import * as fs from 'fs';
 import * as path from 'path';
-import { MANIFEST_PATH, type Manifest } from './config';
+import { listEngineKeys, splitKey } from './config';
 import { diffImages, loadPng } from './image-ops';
 
-function listPngs(dir: string): string[] {
-    return fs.existsSync(dir) ? fs.readdirSync(dir).filter((f) => f.toLowerCase().endsWith('.png')) : [];
-}
-
-function engineOf(name: string, manifest?: Manifest): string {
-    return manifest?.screenshots.find((e) => e.name === name)?.engine ?? 'default';
-}
-
 function stats(values: number[]): { n: number; max: number; p95: number; mean: number } {
     if (!values.length) return { n: 0, max: 0, p95: 0, mean: 0 };
     const sorted = [...values].sort((a, b) => a - b);
@@ -43,20 +36,14 @@ function main(): void {
         process.exitCode = 2;
         return;
     }
-    const root = process.cwd();
-    const manifestPath = path.join(root, MANIFEST_PATH);
-    const manifest = fs.existsSync(manifestPath)
-        ? (JSON.parse(fs.readFileSync(manifestPath, 'utf8')) as Manifest)
-        : undefined;
-
-    const common = listPngs(dir1).filter((n) => fs.existsSync(path.join(dir2, n)));
+    const common = listEngineKeys(dir1).filter((k) => fs.existsSync(path.join(dir2, k)));
     const byEngine = new Map<string, number[]>();
     const all: number[] = [];
-    for (const name of common) {
-        const d = diffImages(loadPng(path.join(dir1, name)), loadPng(path.join(dir2, name)));
+    for (const key of common) {
+        const d = diffImages(loadPng(path.join(dir1, key)), loadPng(path.join(dir2, key)));
         const ratio = d.dimsMatch ? d.changedRatio : 1;
         all.push(ratio);
-        const eng = engineOf(name, manifest);
+        const eng = splitKey(key).engine;
         (byEngine.get(eng) ?? byEngine.set(eng, []).get(eng)!).push(ratio);
     }