static/js/player-state.js — one exported object, two fields. app.js's 70 reference
sites rewritten. Provably a no-op; nothing shrinks.
WHY NOW. Every slice carved out of app.js so far only ever READ the state it shared
(loopA/loopB, _audioSeekGen, currentFilename), so a read-only getter hook was enough
and no container was needed — twice I checked and twice I got away with it. That
runs out at count-in: it genuinely WRITES `isPlaying` (it starts and stops playback,
4 sites) and `lastAudioTime` (2). `import { isPlaying }` then `isPlaying = true`
THROWS — an imported binding cannot be assigned to. So the state has to live on an
object: `S.isPlaying = true` is a property write, and works from any module holding
the same S. Same shape stems, studio, and editor all converged on.
DELIBERATELY SMALL. app.js has ~104 top-level `let` scalars; lifting all of them is
a ~977-site rewrite for no benefit, because most are private to one cluster and
travel with it. Only what a carved module must WRITE goes here. Add on demand.
THE REWRITE IS AST-DRIVEN, NOT TEXTUAL — and that is not fussiness. Of 100 textual
occurrences of these two names, only 70 resolve to the module binding:
* 22 are member accesses (`someObj.isPlaying`, `window.feedBack.isPlaying`)
* 4 are the LOCAL PARAMETER of `function setPlayButtonState(isPlaying)` — a blind
replace yields `function setPlayButtonState(S.isPlaying)`
* 1 is an object key
* 2 are shorthand properties `{ isPlaying }`, which must become
`{ isPlaying: S.isPlaying }` — and acorn gives a shorthand's key and value the
SAME range, so rewriting both produced `isPlaying: S.isPlaying: S.isPlaying`
until I deduped by range
A find-and-replace corrupts all 29. The rewrite walks the AST, skips shadows, member
properties and keys, and replaces identifier RANGES.
`window.feedBack.isPlaying` — the PUBLIC mirror — is a different thing and is
untouched. Two test sandboxes stub it; those were left alone deliberately.
VERIFIED WITH REAL PLAYBACK. A/B against origin/main in two browsers, real song:
togglePlay -> the public mirror goes true -> false -> true across two toggles, the
audio element's paused state follows, seekBy works — IDENTICAL, zero page errors.
Harnesses: 8 vm-sandbox suites slice playback code out of app.js and now see
S.isPlaying — juce_engine_reroute, loop_restart, play_button_reroute_guard,
playback_app_adapter, song_restart, song_seek, speed_reset, and the python
idempotence source-assert. Each gets the same container in its sandbox; every
assertion is unchanged.
pytest 2396, node 1040/1040, ESLint 0, tailwind clean, Codex 0.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
On the first song after a fresh load on desktop, the audio engine is often
still starting when the song loads, so the song begins on the HTML5 <audio>
element and the engine-reroute watcher then migrates it to the JUCE backing
transport. The reroute's first step is a deliberate audio.pause(), which
rejects autoplay's in-flight togglePlay() audio.play() with an AbortError —
even though playback continues on JUCE.
togglePlay()'s catch then reset isPlaying=false and the button to "Play"
while the song kept playing: the button showed Play during playback, so it
took two clicks to actually pause (one to resync the flag, one to pause).
The reroute already guards the <audio> 'play'/'pause' DOM listeners with
window._juceRerouteInProgress; this extends the same guard to togglePlay()'s
catch and the count-in catch, so a play() rejection caused by the reroute's
own pause doesn't clobber the button. A genuine failure (outside a reroute)
still resets correctly.
Adds a regression test that drives togglePlay() through a reroute-aborted
play() and asserts the button stays Pause; it fails without the guard.
Claude-Session: https://claude.ai/code/session_01QbexxfTt8q2tAn436MqGWF
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
