The track preview modal could hold a machine at 25% GPU. Three separate
causes, each measured in isolation with a kill-style ladder and, once the
GPU-engine counter proved to be clock-relative (a lighter workload read
HIGHER), with clock-immune process CPU-seconds.
Idle drain. The scrim's backdrop-filter is re-executed on every presented
frame -- a backdrop filter is never cached -- so its cost is presents/sec
times window area. Two infinite animations kept the modal presenting at the
display's refresh rate forever: the eq capsule's bars animated `height` (a
layout property, so style/layout/paint on the main thread every vsync) and
the cover glow's halo-breathe kept a blur(48px) copy recompositing. Either
one alone kept the pipeline hot, which is why killing one changed nothing.
The glow is deleted outright at Kyle's request; the eq bars now scale with
a stepped transform whose three delays are multiples of the step interval,
so all three jump on the same instants and one present serves them all.
Playing steady state: 7.2-10.5% of a core down to 1.4-2.2%. Paused: 0.2%.
Scrolling. The animations turned out to be innocent here -- reverting them
moved the number not at all. The cost was per-step work: re-decoding the
full artwork for the background wash, a main-thread accent scan, a new
cover mount, three times a second. The wash is now a 96x58 canvas with the
blur/saturate/brightness baked in at draw time and cached per artwork, and
an overlay preloader walks the manifest once at open -- nearest to the
active card first, capped at 60 -- filling the decoded-image, wash and
accent caches ahead of the user. A rapid-nav jump-cut was tried and
rejected on sight; the animations stay full at every rate.
Backend. preview_resolve swept the clip directory on every call, and any
landing outside the +/-1 prefetch window paid a full Deezer mint, download,
validate, write and loudness measure. The fetch-store-measure core is
factored out and a new preview_prewarm walks the session's track ids at
open, paced 250ms on top of the existing Deezer throttle and starting 1.5s
in so the first clip owns the network, halted by a generation guard on
dispose. A burst landing on a never-visited track is now audible in 154ms
off local disk. The sweep is throttled to ten minutes, and dispose deletes
prewarmed files instead of orphaning them until the hourly reap.
The debug overlay's GPU row was summing the counters machine-wide, so it
read roughly double the app's share with Discord and DWM folded in. It now
reports `app X% - sys Y%`, the app figure restricted to our process tree,
matching Task Manager's per-process rows.
The third action in the preview modal's control row has been a disabled
stub since the modal landed -- there was nowhere for it to go until the
album page existed. It goes there now.
The target is the item's own provider `albumId`, never a title match, so a
top-tracks preview lands on the exact record the modal's metadata line is
already naming: Elephant Gym's "Light" opens Angle, and AC/DC's "Highway
to Hell" the album rather than any of the compilations carrying it. The
manifest has carried `albumId` and an `actions.openAlbum` flag from the
start; all 20 rows of a Deezer top-track payload declare one.
The navigation lands on the previewed TRACK, not just the record -- the
album page's existing pending-track flash does the scrolling and the
highlight, the same landing the now-playing song link already gets.
Three details that are not obvious:
- The overlay must not import state.svelte.js (the module comment on
previewSession explains the cycle), so the navigator is injected by the
page exactly as `playFull` already is.
- Both ids are read out of previewUi and the snapshot BEFORE the close, not
after: closePreview() nulls the callback and drops the snapshot the
active item came from. And the close happens first, because the session
holds the audio focus and navigating under an open dialog would land the
new page behind the scrim.
- contracts.js freezes every manifest id as a String, while `catalog_album`
takes a u64 -- a JSON string fails to deserialize -- and the album page's
flash compares track ids with ===. Both cross back to numbers in
openAlbumFromPreviewItem, once, rather than at each call site.
An album session is already standing on the record it would open, so the
button greys out there with "You're already on this album" rather than
re-navigating to the page underneath. The decision is made from the
manifest's own contextKey, so it holds for any future surface that opens an
album-kind session. The album page still supplies the navigator, so a row
that ever declares a different album goes somewhere instead of being
silently dead.
Verified in the running app over CDP: artist top-tracks preview -> click ->
lands on Highway to Hell (id 9410086), pendingTrackId 92719900 as a Number,
matching track found on the page, .trow.flash present, modal gone, and the
glass bar trail reading Search -> AC/DC -> Highway to Hell. From an album
session the button is disabled and a click changes nothing. 85 JS tests
pass.
The preview backend never received a volume — clips played at the crate
default (0.7) regardless of the slider, even muted. The session now sets
the preview volume from the app store (mute → 0) before the first load and
mirrors it live while the modal is open; the debug overlay's PREVIEW row
exposes the backend's resting volume as proof.
The player-bar volume (and fallback seek) fill is now always the accent
color — matching the waveform scrubber's played region — stepping up to
the hover shade on hover instead of white-until-hover.
Also syncs package-lock to the soulstream name + alpha version.
Preview modal audio, five rounds:
- True track-change crossfade: scheduleSettle no longer silences the
outgoing clip at t=0; preview_load's equal-power fade owns both ramps,
gated on the incoming voice's first Playing event (audible_marks), with
failure/overstay fallbacks. CROSSFADE_MS = 340 — locked to the reel's
card-slide so audio and visuals land together.
- Two-neighbour lease prefetch + a 15-min on-disk clip byte-cache
(recent_clips): steps in BOTH directions crossfade in ~15 ms; revisits
never re-download.
- Adaptive settle (isolated steps fire immediately, bursts coalesce) and
anticipatory auto-advance (step at clip end minus 400 ms) so auto-play
crossfades over the tail instead of gapping.
- Session resume memory: revisited tracks continue where they left off
(decoder-level start offset via play_local_from/resume_at); finished
tracks restart from the top.
- Open/close crossfades with the MAIN player: fade-pause with the
desired-paused latch landing at ramp end, fade-resume from the paused
position; MAIN_FADE_GEN guards; focus handshake relaxation documented
in focusBridge.
Volume normalization (Settings > Playback, default on):
- Dependency-free BS.1770/EBU R128 meter in the player crate (K-weighting,
400 ms gated blocks, incremental) + analyzer that reads the same growing
file playback streams from — first plays are measured at download speed.
- Gain layered under user volume; audible start GATED on a preliminary
measurement (10 s of audio or 800 ms budget) so the level is right from
the first sample and never changes mid-track; prelim boosts capped 3 dB,
peak-aware clipping guard, persistent loudness-cache.json.
- Gapless boundaries get their own sample-accurate gain via
SetNextNormGainDb, fed by preload analysis.
Debug overlay (Ctrl+Shift+D): process-tree CPU / PDH GPU / working-set +
private-commit RAM / network rates / FPS / current-track download progress
read from the backend's own StreamProgress / live normalization state /
preview session phase. Polls only while visible.
131 JS + player + app tests green; every path verified live over CDP.
The transitioned track translateY collapsed to 0 in Chromium (percent-
translated zero-height track), leaving the active cover one stride low
per step. The track is now a fixed anchor at the reel centre; each card
positions itself at (index - activeIndex) * stride and animates its own
small `top`, so no coordinate ever exceeds +/-RENDER_RADIUS * stride.
Verified with the transition ON: centre offset 0 at every index in the
12- and 500-item fixtures, 5 cards in the DOM at scale, wheel gates,
dialog semantics, Tab containment, focus restore, and polite announce
all pass. Dev window.__preview*/__ui handles removed from App.svelte.
Working:
- PreviewOverlay.svelte mounted at app root; opens over a fixture manifest
(window.__previewFixture(n) in dev), inert background, player bar hidden,
focus trap, keyboard nav, F3 rail, T3 swaps, R1b capsule, accent extraction.
- previewSession.svelte.js: store + service wiring (production + fixture).
- Root integration in App.svelte; revision-gateway bumps + notePlaybackGeneration
threaded through state.svelte.js player entry points; api.win guarded so plain
vite browser mounts.
- Launcher on the artist page builds a real artist manifest and opens the modal
with a play-full starter.
- 70 JS tests still green.
Two bugs found and fixed during bring-up:
- effect_update_depth_exceeded: bleed-crossfade and bump effects read AND wrote
the same $state; wrapped writes in untrack(). This loop was breaking Svelte's
scheduler globally (even ui.* stopped reacting).
- accentFromImage now sets crossOrigin for remote covers.
KNOWN BROKEN (handoff): reel vertical centering. The active card stays centred
at index 0 but drifts by one stride per step. Root cause isolated — see
TODO-Feature-Docs/scrollable-track-previews/HANDOFF-PHASE2C.md.
KeelrLeek