The FastAPI backend kept one analysis session shared by every visitor and
spooled each upload to the server's /tmp, and the browser copied audio into
persistent OPFS storage. None of that fits a tool for unreleased masters, so
the web UI is now a static site that decodes and analyses in the tab:
- web/decode.js: WAV/AIFF PCM and float read directly with libsndfile's
scaling (bit-identical to librosa.load; Chromium's WAV decoder scales
positive int16 by 1/32767), other formats via decodeAudioData on an
OfflineAudioContext at the header-sniffed native rate. ID3 song names.
- web/dsp.js: ports of every Metric.compute with the same numerics
(pyloudnorm K-weighting via lfilter's DF2T recurrence, BS.1770 gating,
EBU LRA, resample_poly's Kaiser filter for true peak, librosa.stft and
amplitude_to_db), streaming passes with no signal-length intermediates.
- web/metrics.js: build_spec ports producing the existing plot payload.
- web/analysis-worker.js + app.js: per-tab track list and result cache, a
worker job queue where the visible metric jumps background prefetch, and
the renderer, which now also draws the metrics' own reference lines.
Deployment is nginx-unprivileged serving web/ read-only with
Content-Security-Policy connect-src 'none', so the page cannot make network
requests at all, and no access log. No secure context is needed, so plain
http on a LAN works. The Python web backend, its smoke test, the web extra
and the OPFS store are removed; the desktop app is unchanged.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015UXA39Sh9coAx4FhRkd8R2
