Browser QA scripts

Synthetic-microphone end-to-end checks for Phrase Mode (puppeteer-core + system Chrome). They stub getUserMedia with a tunable oscillator feeding a MediaStreamDestination, so note detection is exercised through the real detection pipeline — not only through virtual taps.

Run:

npm i --no-save puppeteer-core   # does not modify package.json
npm run build
npx vite preview --port 4199 &    # serve dist
node scripts/phrase_e2e.cjs       # matcher basics (first-note match)
node scripts/phrase_e2e2.cjs      # repeated notes, release re-attack,
                                  # timeout re-arm, tempo count-in/misses

In-app debug state is available with localStorage.phraseDebug = '1' (window.__phraseDebug() returns phase, cursor, statuses, summary, pool, frame count, mic-gate state). Only ever a QA aid, not part of the UI.