# CLAUDE.md - DeepDrftPublic.Client

Guidance for working in the DeepDrftPublic.Client project (the Blazor WebAssembly assembly).

See the root `CLAUDE.md` for full architecture overview. This file covers what is specific to this project.

## One-line purpose

All interactive UI for the site. Blazor WebAssembly. Pages, controls, the streaming audio player stack, theme/dark-mode plumbing, HTTP clients for both backends.

## Actual structure

- `Pages/`: Routable components. `Home.razor` (hero/about), `SessionDetail.razor` (session detail — hero-dominant overlay composition rendered via `<ReleaseHeroOverlay>`: large background hero image with darkening gradient shim, cover thumbnail + title + play button overlaid near the hero's bottom, genre/date/share overlaid at the top; uses `MudContainer MaxWidth="Large"`; **does not compose `ReleaseDetailScaffold`** — `PlayTrack` is wired directly in its own `@code` block; mounts `<WaveformVisualizer>` ambient engine + `<WaveformVisualizerControlPopover>` directly; **Phase 20:** top action row carries `<TheaterModeToggle />` immediately left of the lava-lamp popover in a `.dd-detail-top-actions` cluster; release hero overlay and `<ReleaseDescription>` are gated `@if (!VisualizerControlState.TheaterMode)`; renders `<ReleaseDescription>` below the hero for the release's description blurb), `MixDetail.razor` (mix detail — composes `ReleaseDetailScaffold` with `TopRightAction` lava-lamp `<WaveformVisualizerControlPopover>`; hero+meta rendered via `<ReleaseHeroOverlay Class="mix-hero">` in the scaffold's `Hero` slot with `ShowHeader="false"` suppressing the duplicate masthead; square ~600px cover-as-background with metadata overlaid; full-bleed `<WaveformVisualizer>` is the mode-A centerpiece mounted by the page directly; renders `<ReleaseDescription>` below the hero for the release's description blurb; **Phase 20:** `TopRightAction` slot holds `<TheaterModeToggle />` + lava-lamp popover in a `.dd-detail-top-actions` cluster; hero overlay and description are gated `@if (!VisualizerControlState.TheaterMode)`), `CutDetail.razor` (album detail — composes `ReleaseDetailScaffold` with the `Ambient` slot carrying `<WaveformVisualizer>` + `<WaveformVisualizerControlPopover>` for mode-B ambient layer; renders `<ReleaseDescription>` below the hero for the release's description blurb; each track row carries a per-track `<SharePopover EntryKey="@track.EntryKey" />` aligned far-right as the last flex child of `.cut-detail-track-row`; **Phase 20:** `TopRightAction` slot holds `<TheaterModeToggle />` + lava-lamp popover in a `.dd-detail-top-actions` cluster; header and track-list body are gated `@if (!VisualizerControlState.TheaterMode)`), `FramePlayer.razor` (embeddable iframe player at `/FramePlayer`, uses `EmbedLayout`; two mutually-exclusive modes via query params: `TrackEntryKey` stages a single track as before; `ReleaseEntryKey` resolves the release's ordered tracks via `FramePlayerViewModel`, stages track 0 via `PlayerService.StageTrack`, and arms the queue via `Queue.Arm` — no JS interop in either path, so both run safely during prerender; the first play gesture in `AudioPlayerBar` routes through `Queue.Start()` which streams the current track and clears the armed state; release embeds expose queue skip-prev/next navigation in the player bar while single-track embeds show none; track-title links open in a new tab so the iframe keeps playing). **No demo pages** (`Counter.razor`, `Weather.razor` do not exist).
- `Layout/`: `MainLayout.razor` (root layout, wraps in `AudioPlayerProvider`, hosts theme switcher), `DeepDrftMenu.razor` (branded menu bar), `NavMenu.razor` (nav list), `Pages.cs` (centralised nav index — `MenuPages` for header, `AllPages` for exhaustive list), `DeepDrftFooter.razor` (site footer — logo, nav links, copyright; contains a "Privacy" button that opens a screen-centered tinted modal via `MudOverlay` (`DarkBackground="true"`, `Modal="true"`) carrying the anonymous-listener privacy note; trigger-button styling in the co-located `DeepDrftFooter.razor.css`, overlay chrome in the global `deepdrft-styles.css`; follows the `QueueOverlay`/`WaveformVisualizerControlPopover` `MudOverlay` idiom — scrim-click closes, panel stops propagation).
- `Controls/`: Reusable components.
  - `TrackCard.razor`: Individual track display (image, name, artist, album, genre, release date). Play/pause icon controlled via `IsPaused` parameter.
  - `TracksGallery.razor`: Responsive grid of `TrackCard` items (MudBlazor `MudGrid` with breakpoints). Fully controlled by parent; derives active-track state from cascaded player service.
  - `AppNavLink.razor`: Nav link with active-page highlight.
  - `AudioPlayerProvider.razor`: Cascading host for `IStreamingPlayerService`. Everything inside it gets the player via `[CascadingParameter]`.
  - `StreamNowButton.razor`: Reusable streaming-trigger button. Fetches a random track, warms the AudioContext (Safari gesture requirement), and starts streaming — routes through `IQueueService.PlayTrack` (deque PLAY semantics) when the queue cascade is present, falls back to `IStreamingPlayerService.SelectTrackStreaming` when absent. Accepts `ButtonClass` and `ButtonLabel` for distinct visual presentations; `OnStreamStarted` EventCallback for post-stream side effects (e.g., mobile menu close).
  - `AudioPlayerBar.razor`: Dock UI at the bottom (play/pause/seek/volume). In Fixed (embed) mode, renders an always-shown read-only queue panel below the controls when `ShowFixedPanel && _fixedPanelOpen` (release embeds only; single-track embeds stay panel-free). The Queue button in Fixed mode toggles `_fixedPanelOpen` and triggers a `postHeight` call via `embed-frame.ts` so the host page can resize the outer iframe. TypeScript counterpart for the resize handshake: `DeepDrftPublic/Interop/embed/embed-frame.ts` — reads `EmbedId` from `window.location.search`, exports `postHeight(element)` which measures the player element and posts `{type:"deepdrft-embed-resize", height, embedId?}` to `window.parent`; no-ops when not framed (compiled output gitignored). **Phase 20:** injects `WaveformVisualizerControlState` and subscribes to `Changed` (added alongside the existing `IPlayerService.StateChanged` subscription — same reference-guard + dispose pattern); mounts `<NowShowingPanel Release="CurrentTrack.Release" />` above the transport controls when `VisualizerControlState.TheaterMode && CurrentTrack?.Release is not null`.
  - `AudioPlayerBar/PlayerControls.razor`: Play/pause/stop buttons in the transport zone. Renders via `<PlayStateIcon>`. In embedded (`Fixed`) mode, skip-previous and skip-next render when `!Fixed || HasPrevious || HasNext` — so a release embed (which has a queue) shows forward/back navigation while a single-track embed (no queue) hides them; the Stop button is hidden in all embed contexts (`!Fixed` only).
  - `AudioPlayerBar/TrackMetaLabel.razor`: Now-playing track-title + artist row. Takes `[Parameter] bool Fixed` (passed from `AudioPlayerBar.razor`). When `Fixed` (embedded iframe), the track-title anchor renders with `target="_blank" rel="noopener noreferrer"` so clicking it opens the release detail page in a new tab; the docked (non-embedded) player keeps same-tab nav. When no release is attached the title renders unlinked in both modes.
  - `AudioPlayerBar/NowShowingPanel.razor`: Phase 20 "now showing" presentational band rendered by `AudioPlayerBar` **only when** `VisualizerControlState.TheaterMode && CurrentTrack?.Release is not null`. Carries the release identity the hidden detail page would otherwise show: cover art thumbnail (`deepdrft-track-detail-cover-art` / `deepdrft-gradient-soft-secondary` placeholder), release title linked via `ReleaseRoutes.DetailHref(Release)`, and a release-mode `SharePopover` (`ReleaseEntryKey` + `ReleaseMedium`) wrapped in `.dd-accent-icon`. `[Parameter, EditorRequired] ReleaseDto Release` — non-null by the bar's mount gate. Purely presentational: owns no player logic, no Theater state, and no data fetch. Layout CSS lives in `AudioPlayerBar.razor.css` (`.now-showing` / `.now-showing-cover` / `.now-showing-cover-art` / `.now-showing-cover-placeholder` / `.now-showing-title-link` / `.now-showing-title` / `.now-showing-share`); all surface/text binds `--deepdrft-page-*` theme-aware aliases — no new dark overrides.
  - `AudioPlayerBar/PlayStateIcon.razor`: Icon button encapsulating service subscription + transport-state icon selection. Injects `IPlayerService`, subscribes to `StateChanged`, calls `PlaybackIcons.Resolve()` to determine icon and active state.
  - `AudioPlayerBar/LevelMeterFab.razor`: Floating-action button replacing the static FAB in the minimized dock. Renders a continuous vertical fill inside the music-note silhouette that tracks live audio level (0–100%), with fixed three-zone gradient (green 0–60%, yellow 60–85%, orange 85–100%). Note silhouette always visible at 25% opacity; idle when paused/stopped. Reuses spectrum-callback infrastructure.
  - `SpectrumVisualizer.razor`: Bar-graph spectrum display, driven by `getSpectrumData` JS callback.
  - `ReleaseHeroOverlay.razor`: Shared presentational overlay shell consumed by both `SessionDetail` and `MixDetail`. Renders a background-image hero region with genre/date/share overlaid at the top and title/artist/play at the bottom. Parameters: `HeroImageKey`, `PlaceholderIcon`, `CoverThumbKey` (optional cover thumb in bottom row), `Title`, `Artist`, `Genre`, `ReleaseDate`, `ShareContent` (slot), `PlayContent` (slot), `Class` (per-page aspect/sizing override). Owns no player logic or data fetch; each consuming page passes its own play and share slots. Overlay shell is plain `<div>`s; background-image surface is a `<div class="release-hero-img">` (no `MudPaper`).
  - `ReleaseDescription.razor`: Shared presentational blurb block for release detail pages. Renders a header row (mono uppercase eyebrow label "Notes" in `.deepdrft-release-description-label` + thin horizontal divider in `.deepdrft-release-description-rule`, inside `.deepdrft-release-description-header`) above the release's short `Description` paragraph (`.deepdrft-release-description-text`, display-serif weight 300), all wrapped in `.deepdrft-release-description`, placed just below the hero/header. The header row mirrors the home page's `.section-label`/`.divider-line` motif. Purely presentational — owns no data fetch or player wiring. A null/whitespace `Description` renders nothing at all (no block, no divider, no whitespace artifact; the guard lives here so every consumer gets it for free). Parameter: `Description` (`string?`).
  - `WaveformVisualizer.razor`: The single WebGL2 lava-lamp visualizer engine. Hosts the waveform of whatever track is currently playing/selected. Three hosting modes: mode A (Mix detail — full-bleed centerpiece), mode B (Cut/Session detail — ambient layer behind hero+content via `ReleaseDetailScaffold`'s `Ambient` slot), mode C (NowPlaying hero panel — full-bleed background for the home hero's right side, mounted by `NowPlaying.razor` inside `.np-visualizer-bg`). `[Parameter] bool Fill` switches from fixed-viewport positioning to container-relative sizing (CSS-only; the renderer is identical in both modes). The bridge resolves the current track's `EntryKey` and re-fetches the high-res datum on track change. Subscribes to `WaveformVisualizerControlState.Changed` and pushes each updated dial to the WebGL module via JS interop. Follows the live playing track (keys on host `TrackId` match OR shared host `ReleaseEntryKey`).
  - `WaveformVisualizerControls.razor`: The waveform visualizer control panel (content hosted by `WaveformVisualizerControlPopover`). Phase 15 re-layout: a deterministic **three-row sectioned layout** encoding the visualizer's two subsystems. Row 1 (MODE, always visible): two iconographic lamp toggles (lava on/off, waveform on/off) left-aligned + collisions knob (conditional — only when both subsystems on) + color knob pinned far-right. Row 2 (LAVA, visible only when `LavaEnabled`): "LAVA:" section label + Gravity / Heat / FluidAmount / FluidViscosity knobs. Row 3 (WAVE, visible only when `WaveformEnabled`): "WAVE:" section label + scroll-speed `MudSlider` (not a knob) + width knob pinned far-right. Total: two lamp toggles, seven `RadialKnob`s, one `MudSlider`. Colour principle: lamp toggles / knob arcs / slider are green (`Color.Primary` — interactive); section labels / knob caption icons are light (static). Each control has a playful `MudTooltip`. `[Parameter] bool PanelChrome` scopes panel chrome (NowPlayingCard look — square corners, lighter-navy, thin border) to the popover mount; chrome classes live in the global `deepdrft-styles.css` (CSS isolation cannot reach portaled overlay content). `[Parameter] bool Visible` gates the rows via `@if` while the container holds reserved min-height. Owns no JS interop: mutates the injected `WaveformVisualizerControlState` and raises `Changed`. No control is a seek surface (read-only contract).
  - `WaveformVisualizerControlPopover.razor`: Pairs the lava-lamp icon button with `WaveformVisualizerControls` as a **screen-centered tinted modal** (Phase 15). The primitive is `MudOverlay` (`DarkBackground="true"`, `Modal="true"`) — **not** `MudPopover`; `AnchorOrigin`/`TransformOrigin` parameters do not exist (a centered modal has no anchor). Clicking the lava-lamp icon opens the overlay; clicking the scrim closes it (knob-drag-safe: `RadialKnob`'s `position:fixed` capture div sits above the scrim during a drag, so releasing outside the panel never fires the close handler). The panel stops click propagation so an inside click is not a dismissal. `[Parameter] Size IconSize` controls the trigger-icon size (default `Large`). This is the unit every host places — one icon anywhere gives the full control panel centered on screen, regardless of where the icon sits. Placed identically on Mix, Cut, Session, and the NowPlaying hero panel (full parity; in NowPlaying it sits in `.np-visualizer-controls` at the panel's top-right corner, not inside `NowPlayingCard`).
  - `TheaterModeToggle.razor`: Phase 20 Theater-Mode toggle button. Visible only when `State.LavaEnabled || State.WaveformEnabled` (no visualizer subsystem active → no theater to enter). Disabled until interactive (`!RendererInfo.IsInteractive`), same guard as Play and the lava-lamp trigger. On click: flips `WaveformVisualizerControlState.TheaterMode` and calls `NotifyChanged()`. Shows an on/off `aria-pressed` active state. Glyph: Material `Theaters`. `.dd-accent-icon` container gives the green-accent glyph in both themes with zero new CSS — same treatment as `WaveformVisualizerControlPopover`. Subscribes to `State.Changed` in `OnInitialized` and unsubscribes on `Dispose` to re-render when another observer (e.g. `CoerceTheaterMode()`) flips the state. `[Parameter] Size IconSize` (default `Large`) matches the adjacent lava-lamp trigger. Placed **immediately left** of the lava-lamp popover on all three detail pages inside a `.dd-detail-top-actions` cluster.
  - `WaveformZoomMapping.cs`: Maps the `WaveformVisualizerControlState.Resolution` fraction to an integer zoom level for the WebGL renderer.
  - `NowPlayingCard.razor`: Home-page text panel showing the currently playing track (label, title, sub-line). Renders label/"Now Playing" dot, track name, and artist·release sub-line from the cascaded `IStreamingPlayerService`. Subscribes to `IPlayerService.StateChanged` in `OnParametersSet` (reference-guarded, idempotent) and unsubscribes on dispose to re-render on track/state change. No visualizer or popover; those moved to `NowPlaying.razor`.
  - `NowPlayingStats.razor`: Home hero stat row. Three cards: Studio Cuts (total Cut-medium track count + zero-suppressed per-`ReleaseType` Cut release breakdown), Mixes (`MixReleaseCount` labelled "Sets" + `hh:mm` total mix runtime via `RuntimeFormat`), and Plays (live `TotalPlays` odometer in `.hero-stat-odometer` + `UniqueListeners` "N listeners" secondary line via `.hero-stat-sub` — Phase 16 wave 16.5). All three cards read from the same `HomeStatsDto` round-trip; no extra fetch path. Fetches via `IStatsDataService` on init; bridges the prerender fetch across the WASM seam with `PersistentComponentState` (persists only on a successful load, matching the medium-browse bridge pattern). Implements `IDisposable` to release the `PersistingComponentStateSubscription`.
  - `NowPlaying.razor`: Owns the home hero's right-side panel (`.now-playing-panel` — the outer wrapper formerly called `.hero-right` in `Home.razor`). Mounts `<WaveformVisualizer Fill="true">` as a full-bleed background inside `.np-visualizer-bg`, `<WaveformVisualizerControlPopover>` in `.np-visualizer-controls` (top-right corner), the three pulsing `.circle-deco` rings, and the content layer (hosts `<NowPlayingCard>` + `<NowPlayingStats>`). `Home.razor`'s `MudItem` renders `<NowPlaying />` directly with no wrapper. Subscribes to `IPlayerService.StateChanged` in `OnParametersSet` (reference-guarded, idempotent) and unsubscribes on dispose — needed because the player cascade is `IsFixed` (the provider's own re-render does not reach `NowPlaying`), so the subscription is the only way to re-render and re-propagate `ReleaseEntryKey`/`TrackId`/`TrackEntryKey` into `<WaveformVisualizer>` when the playing track changes.
  - `QueueList.razor`: Shared presentational queue-list component (Phase 17 wave 17.1). Renders `Items` as an ordered list with the current track marked; `Editable` flag gates drag-reorder handles (drag handle icon + `MudDropContainer`/`MudDropZone` for reorder) and per-row remove controls. The remove (×) control is suppressed on the currently-playing row (`Editable && !isCurrent`) — the current track cannot be removed via the UI (wave 17.2; reorder of the current row is still permitted). When not editable, renders a plain `<div>` — the read-only state for the embed's fixed-order shared queue. Reorder, remove, and row-jump are surfaced to the parent as `EventCallback<(int FromIndex, int ToIndex)> OnReorder`, `EventCallback<int> OnRemove`, and `EventCallback<int> OnJump`; the component calls no `IQueueService` method itself (purely presentational, no data fetch, no player wiring). Both view modes (docked overlay 17.2, embedded panel 17.3) consume this single component differing only in hosting context and the `Editable` flag. Runs during prerender without JS interop (drag work is client-only and inert when no drag occurs).
  - `QueueOverlay.razor`: Screen-centered tinted modal hosting the docked-player editable queue (Phase 17 wave 17.2). Borrows the `WaveformVisualizerControlPopover` `MudOverlay` idiom (`DarkBackground="true"`, `Modal="true"`): the panel stops click propagation; scrim-click closes the overlay; drag-safe (the panel's capture div sits above the scrim during a drag so releasing outside the panel never fires the close handler). Auto-closes when a removal empties the queue. Hosts `QueueList` in `Editable="true"` mode. Opened/closed by the Queue toggle button in `PlayerTransportZone` (shown only when `!Fixed && Items.Count > 0`; `QueueMusic` glyph, active state when open).
  - `AddToQueueButton.razor`: Append-only Add-to-Queue button shared across detail-page play sites (Phase 17 wave 17.4). Two modes: track mode (calls `IQueueService.Enqueue` with a single `TrackDto`) and release mode (calls `IQueueService.EnqueueRange` with an ordered track list). Material `PlaylistAdd` glyph; tooltip "Add to queue" (track mode) / "Add release to queue" (release mode). Reads the cascaded `IQueueService`; disabled until interactive or when the cascade is absent. Append-only — does not play, does not navigate. Placed at: `CutDetail` header (release mode, `TrackNumber`-ordered list), `CutDetail` track rows (track mode), `SessionDetail` hero play (track mode), `MixDetail` hero play (track mode). Excluded from `StreamNowButton` (OQ9) and `ReleaseGallery` cards (OQ10, deferred).
  - `ReleaseDetailScaffold.razor`: Shared scaffold for release detail pages. Gained an optional `Ambient` `RenderFragment` slot (Phase 12) — a full-bleed layer rendered behind the main content. Absent slot = no regression. Cut mounts `<WaveformVisualizer>` + `<WaveformVisualizerControlPopover>` here; Mix uses its own full-bleed mount outside the scaffold. The scaffold's default masthead PLAY (`PlayTrack`) routes through `IQueueService.PlayTrack` (deque PLAY semantics — prepends the track to the queue front) when the queue cascade is present, falling back to `IStreamingPlayerService.SelectTrackStreaming` when absent; toggle-pause is handled directly via `IStreamingPlayerService.TogglePlayPause` when this track is already active.
  - `SharePopover.razor`: Share affordance serving both track and release surfaces from one clipboard/popover-chrome source. **Track mode** (`EntryKey` set): copies the track's canonical URL and offers an iframe embed snippet pointing at `FramePlayer?TrackEntryKey=…`. **Release mode** (`ReleaseEntryKey` + `ReleaseMedium` set): copies the release's canonical detail URL (via `ReleaseRoutes.DetailHref`) and offers an iframe embed snippet pointing at `FramePlayer?ReleaseEntryKey=…`, which queues and auto-advances through the release's tracks on first play. Both modes offer the embed affordance — release mode no longer suppresses it. The iframe snippet is built by `EmbedSnippetBuilder`. A transient "Copied!" confirmation resets after a short delay.
- `Helpers/`: Utilities and mapper functions.
  - `PlaybackIcons.cs`: Static `Resolve(isPlaying, isPaused, trackId, currentTrackId)` method — the sole glyph-mapping source for transport icons across all surfaces. Returns `(Icon, IsActive, IsPaused)` tuple.
  - `RuntimeFormat.cs`: Static `ToHoursMinutes(double totalSeconds)` helper. Formats a seconds value as `h:mm` (hours not zero-padded, minutes always two digits). Negative / non-finite inputs return `"0:00"`. Used by `NowPlayingStats` for the mix runtime figure.
  - `EmbedSnippetBuilder.cs`: Static helper that builds the iframe embed snippet the share popover copies. Two targets diverge in height and content (Phase 17 wave 17.3): `ForTrack(baseUri, trackEntryKey)` → compact `<iframe>` at 196 px (no queue panel, no script, unchanged from before 17.3). `ForRelease(baseUri, releaseEntryKey)` → taller `<iframe>` at 384 px plus a host-side `<script>` resize listener; mints a fresh random token per call (8 hex chars from `Guid.NewGuid().ToString("N")[..8]`) used as the iframe id (`deepdrft-embed-{token}`) and threaded into the iframe src as `&EmbedId={token}` — the in-iframe `embed-frame.ts` reads this token and includes it in `postMessage` payloads so the host listener can route resize messages to the correct iframe when multiple release embeds share a host page. The script matches on `embedId` and applies `iframe.style.height`; degrades safely (panel still works inside the iframe) if the host strips the script. Pure string composition — unit-testable without rendering. TypeScript counterpart: `DeepDrftPublic/Interop/embed/embed-frame.ts` (compiled output gitignored).
- `Services/`: Audio player + dark-mode services.
  - `IPlayerService` / `IStreamingPlayerService`: Contracts exposed to UI.
  - `AudioPlayerService`: Abstract base (lifecycle, initialise, select track, play/pause/stop/seek/volume).
  - `StreamingAudioPlayerService`: Production implementation. Chunked stream from `TrackMediaClient`, adaptive 16–64 KB buffer, early-playback, **seek-beyond-buffer** via offset request to the content API.
  - `AudioInteropService`: JS interop wrapper over `window.DeepDrftAudio`. Manages `DotNetObjectReference` lifetimes for progress, end-of-playback, spectrum callbacks.
  - Dark-mode services: `DarkModeServiceBase` (cookie name constant), `DarkModeCookieService` (JS cookie read/write).
  - `WaveformVisualizerControlState`: Scoped session-persistent holder for the visualizer's **eight** continuous control positions, **two subsystem on/off toggles** (Phase 15), and one **Theater-Mode flag** (Phase 20): `ScrollSpeed`, `GradientRotationSpeed`, `LavaGravity`, `LavaHeat`, `FluidAmount` (wax count/volume), `FluidViscosity` (cohesion — the second half of the Phase 10 "bubbles" split; `BlobDensity` is gone), `CollisionStrength`, `WaveformWidth`, `LavaEnabled` (bool, default `true`), `WaveformEnabled` (bool, default `true`), `TheaterMode` (bool, default `false` — `DefaultTheaterMode`). Each has a matching `Default*` const. `Changed` event is the decoupling seam — controls mutate state + raise `Changed`; the bridge (`WaveformVisualizer`) subscribes and pushes the affected uniform or subsystem-enable; the Theater observers (the three detail pages and `AudioPlayerBar`) subscribe to react to `TheaterMode`. **`CoerceTheaterMode()`**: enforces the invariant that Theater Mode cannot remain on when both subsystems are off — called from `WaveformVisualizerControls.ToggleLava`/`ToggleWaveform` **before** `NotifyChanged()` so all observers see a consistent, coerced state in the same `Changed` cycle. `TheaterMode` is a page-chrome presentation flag; the visualizer bridge ignores it. Scoped DI so state survives SPA nav within a session and resets on fresh page load.
  - `PlayTracker`: Per-session play-session tracker (Phase 16 wave 16.1). Opens on playback start, advances a high-water position on each progress tick (from `StreamingAudioPlayerService` — not the HTTP layer, so seek-beyond-buffer re-fetches are the same play), closes on track-switch / stop / organic-end / page-unload. Engagement floor: ≥3 s OR ≥5% of duration. Three-bucket classification (`partial`/`sampled`/`complete`). Emits at most one event per session via `IPlayEventSink`. No player or JS dependency — testable against a fake sink.
  - `ShareTracker`: Per-session share tracker (Phase 16 wave 16.1). Called by `SharePopover` after a successful clipboard write; applies a 60-second per-(target, channel) debounce. Sends via `BeaconInterop`. Scoped so debounce memory resets on fresh page load. **Wave 16.3:** injects `IAnonIdProvider`; attaches `_anonId.Current` to `ShareEventDto.AnonId` (omitted when null).
  - `BeaconInterop`: `navigator.sendBeacon` JS interop wrapper (Phase 16 wave 16.1). Fires JSON payloads to `api/event/{play,share}` fire-and-forget. Also wires a page-unload handler that flushes any pending play event when the page is torn down.
  - `BeaconPlayEventSink`: Production `IPlayEventSink` (Phase 16 wave 16.1). Serializes the play classification and fires it via `BeaconInterop` to `api/event/play`. Synchronous (`EmitPlay` cannot await — it is called from the player close path and the page-unload handler). **Wave 16.3:** injects `IAnonIdProvider`; reads `_anonId.Current` synchronously at emit time and sets `PlayEventDto.AnonId` (omitted when null via `WhenWritingNull`).
  - `IAnonIdProvider` / `AnonIdProvider`: Wave 16.3 anonymous-listener id seam. `IAnonIdProvider` exposes `string? Current` (synchronous cached read, safe on the unload path) and `ValueTask EnsureLoadedAsync()` (warms the cache from `localStorage` via `window.DeepDrftAnonId.get` JS interop — idempotent, never throws). `AnonIdProvider` is the production implementation; degrades to null when `localStorage` is unavailable (private mode / blocked storage). The token itself outlives the session in `localStorage`; the in-process cache is scoped (resets on fresh page load). Callers warm the cache when going interactive, then read `Current` synchronously on the close/unload path with no extra JS hop. TypeScript interop: `DeepDrftPublic/Interop/telemetry/anonid.ts` (mints GUID on first visit, returns null without throwing when storage is unavailable).
  - `IQueueService` / `QueueService`: **Two-level deque** orchestrator above the single-slot player. The deque has two entry ends. **PLAY (manual)** enters the FRONT: `PlayTrack(track)` and `PlayRelease(tracks, startIndex)` prepend the played track/release in order, **remove the previously-current track**, make the new front current, start streaming it, and leave whatever sat after the old current intact behind the prepend (a whole release prepends in order in one op). The detail pages (Cut header/row, Session/Mix hero) and `StreamNowButton` route their PLAY through these. **Add-to-queue** enters the BACK: `Enqueue`/`EnqueueRange` append to the end without interrupting the current track (`AddToQueueButton`). `Next`/`Previous` advance or step back, walking `CurrentIndex` and leaving played tracks behind so `Previous` can reach them; `JumpTo(index)` moves the pointer to a queued row and streams it once (the playlist panel's row-jump — it does NOT prepend or stream the intervening rows). **End-of-track:** auto-advance (`TrackEnded`) advances when there is a next track; when the **last** track ends naturally the queue **empties** and goes dormant (bug #2) rather than stranding the finished track. `Clear` empties the queue. **Bug #3 (dormant-seed):** the first `Enqueue`/`EnqueueRange` into a dormant queue while a track is already playing externally (via the attached player, not through the queue) seeds the head with that now-playing track and then appends — yielding `[now-playing, added]` (even when adding the same track). The queue learns the externally-playing track through the existing `Attach(player)` seam (`_player.CurrentTrack`) — no new dependency, no `IServiceProvider`. **Armed-idle state** (prerender-safe release embeds): `Arm(tracks)` replaces the queue at index 0 with no JS interop; `IsArmed` signals armed-but-not-streaming; `Start()` streams the current track and clears `IsArmed`. `AudioPlayerBar` reads `IsArmed` to route the embed's first play gesture through `Start()`. `QueueChanged` fires on all list/position changes; cascaded via `AudioPlayerProvider`. `Move`/`RemoveAt` are interop-free reorder/remove mutations that adjust `CurrentIndex` and never re-stream. `ClearUpcoming()` keeps the current track and drops the up-next. **Bug #4 (reactivity):** `AudioPlayerBar.QueueItems` caches `QueueService.Items` as a `_queueItemsCache` snapshot (the service exposes its backing list by reference); the cache is invalidated and set to `null` in `OnQueueChanged`, so every real mutation hands `QueueList` a new list reference while frequent progress-tick re-renders reuse the cached one without allocating. `QueueList.OnParametersSet` calls `_dropContainer?.Refresh()` so the `MudDropContainer` re-reads the new list and the open panel re-flows immediately. **Bug #1 (label):** the docked `QueueOverlay` panel header reads **"Playlist"** (the current track stays listed). `PlayRelease` materializes `tracks.ToList()` before mutating so it can never alias the service's own `Items` list.
- `Clients/`: HTTP API clients (both target DeepDrftAPI).
  - `TrackClient`: SQL metadata API. Uses named `IHttpClientFactory` client `"DeepDrft.API"`. Sends `page` param (not `pageNumber`). Deserializes response as bare `PagedResult<TrackDto>` (not wrapped in ApiResultDto envelope).
  - `TrackMediaClient`: Content API. Uses named `IHttpClientFactory` client `"DeepDrft.Content"`. Methods like `GetAudioStreamAsync(trackId, byteOffset?)` → `Stream` with optional Range header support for seek-beyond-buffer.
  - `StatsClient`: Home stats API. Uses named `IHttpClientFactory` client `"DeepDrft.API"`. Single method `GetHomeStats()` → `ApiResult<HomeStatsDto>` (calls `GET api/stats/home`; response is a bare DTO, no `ApiResultDto` envelope). Registered scoped; consumed via `IStatsDataService`.
- `Services/ITrackDataService`: Contract used by the visualizer bridge and other consumers. Includes `GetTrackWaveform(entryKey)` → high-res `WaveformProfileDto` (calls `GET api/track/{entryKey}/waveform/high-res`); used by `WaveformVisualizer` to re-fetch the datum on track change.
- `Services/IStatsDataService` / `StatsClientDataService`: Home-stats read abstraction. `IStatsDataService.GetHomeStats()` → `ApiResult<HomeStatsDto>`. `StatsClientDataService` is the single implementation (delegates to `StatsClient`); registered scoped. Components inject `IStatsDataService` so they do not branch on render mode — mirrors `IReleaseDataService`.
- `ViewModels/`: Component state.
  - `TracksViewModel`: Scoped. Holds current page, page size, sort column, descending flag. `SetPage(pageNumber)` calls `TrackClient.GetPageAsync` and updates. Registered in `Startup.ConfigureDomainServices`.
  - `TrackDetailViewModel`: Scoped. Holds loaded track, loading flag, not-found flag. `Load(entryKey)` fetches via `ITrackDataService` and resets all flags per call (prevents cross-navigation bleed). Registered in `Startup.ConfigureDomainServices`.
  - `FramePlayerViewModel`: Scoped. Resolves the ordered track list for a release embed (`FramePlayer?ReleaseEntryKey=…`). `Load(releaseEntryKey)` calls `IReleaseDataService.GetByEntryKey` → `release.Id` → `ITrackDataService.GetPage(sortColumn:"TrackNumber", releaseId:…)`, mirroring `CutDetailViewModel.Load` exactly so an embedded release queues the same ordered list the Cut detail page plays. Owns no playback or staging — `FramePlayer.razor` uses the loaded `Tracks` to stage and arm. Registered scoped in `Startup.ConfigureDomainServices`.
- `Common/`: Shared utilities.
  - `DarkModeSettings.cs`: `[PersistentState]`-annotated class (single source of truth for dark mode in the client). Registered scoped.
  - `ReleaseRoutes.cs`: Static helper. `DetailHref(long id, ReleaseMedium)` returns the canonical public detail route for a release; consumed by Archive, AlbumsView, player bar, and TrackRedirect (11.B).
- `Program.cs`: WASM entry point. Calls `Startup.ConfigureApiHttpClient`, `ConfigureContentServices`, `ConfigureDomainServices`.
- `_Imports.razor`: Global using statements and component imports.

## Two HTTP clients pattern

Both clients are configured in `Startup.cs` (static methods called from **both** server and WASM `Program.cs`):

- `TrackClient` uses `"DeepDrft.API"` (base address from `appsettings.json` `ApiUrls:SqlApi`, points to DeepDrftAPI). Fetches paginated metadata.
- `TrackMediaClient` uses `"DeepDrft.Content"` (base address from `appsettings.json` `ApiUrls:ContentApi`, points to DeepDrftAPI). Streams audio bytes, optionally with offset.

Both are configured with JSON serializer settings (case-insensitive property matching). The dual-client pattern keeps concerns separated: one for structured data, one for binary streaming. Both target DeepDrftAPI (they may share the same host URL in production).

## Audio player stack (deepest part of the codebase)

### Contracts
- `IPlayerService`: Initialize, SelectTrack, Play, Pause, Stop, Seek, SetVolume. Sync interface. Owns `EventCallback? OnStateChanged` (single, provider-owned) and `event Action? StateChanged` (multicast, for cascade consumers).
- `IStreamingPlayerService`: Extends above. SelectTrackStreaming(track) starts the chunked stream flow.

### Implementation
- `AudioPlayerService` (abstract base): Lifecycle. Stores current track, playback state, volume. `SelectTrack` throws `NotSupportedException` (buffered path is dead); derived classes override `SelectTrackStreaming`.
- `StreamingAudioPlayerService` (production): Constructor takes `TrackMediaClient`, `AudioInteropService`, logger. `SelectTrackStreaming`:
  1. Calls `TrackMediaClient.GetAudioStreamAsync(trackId)`, which returns a response object including `ContentType` (e.g., `audio/wav`, `audio/mpeg`, `audio/flac`).
  2. `StreamingAudioPlayerService.StreamAudioAsync` reads chunks (16–64 KB adaptive), pushes each via `AudioInteropService.ProcessStreamingChunkAsync(contentType, chunk)` (JS interop call with format hint).
  3. TypeScript `StreamDecoder` is format-agnostic; delegates format-specific header parsing and chunked decoding to the appropriate `IFormatDecoder` implementation (e.g., `WavFormatDecoder` for WAV, TBD MP3/FLAC decoders for other formats). Decoder parses header (first chunk), decodes subsequent chunks to `AudioBuffer`s.
  4. `PlaybackScheduler` schedules buffers on Web Audio `AudioContext`.
  5. Playback starts as soon as a configurable min buffer count is queued.
  6. **Seek beyond buffer**: if seek target is past the decoded range, `Seek(position)` calls `TrackMediaClient.GetAudioStreamAsync(trackId, byteOffset)` with a file-absolute byte offset. Client sends `Range: bytes={offset}-`; server responds 206 with raw bytes (same format as original file); decoder retains the parsed header and feeds the continuation directly into the decode pipeline.

### Interop bridge
- `AudioInteropService.CreatePlayerAsync` polls `DeepDrftAudio.isReady()` before proceeding; `index.ts` sets `ready = true` after attaching the API to `window`. This guards against slow WASM boot / cache misses.
- `AudioInteropService.ProcessStreamingChunkAsync(contentType, chunk)` calls JS `window.DeepDrftAudio.processStreamingChunk(contentType, chunk)` and awaits the Promise. The `contentType` parameter is passed through to the format-decoder factory.
- `AudioInteropService` also manages callback registrations for progress (fired by `PlaybackScheduler`), end-of-playback (fired by `PlaybackScheduler`), and spectrum data (fired by `SpectrumAnalyzer`). Each callback is a `DotNetObjectReference` to a delegate.

### Format decoders (TypeScript)
New modules in `DeepDrftPublic/Interop/audio/`:

- `IFormatDecoder.ts`: Interface. Defines contract for format-specific decoders: `parseHeader(chunk, offset)` → header metadata; `decodeChunk(chunk, offset)` → `AudioBuffer`; `getAlignedSegmentSize(chunk, offset, rawData?)` → frame-aligned segment boundary (optional `rawData` parameter for format-specific frame-boundary scanning).
- `WavFormatDecoder.ts`: Concrete WAV implementation (active). Parses RIFF/WAVE structure, fmt and data chunks. All WAV-specific byte-parsing logic lives here. Exported as the default WAV decoder.
- `Mp3FormatDecoder.ts`: Concrete MP3 implementation (implemented, not yet wired). Implements `IFormatDecoder` for MP3: ID3v2 skip, MPEG Layer III frame-sync + header decode (MPEG1/2/2.5), Xing/Info/VBRI VBR-header detection (frame count + 100-entry TOC for seek), CBR frame-aligned segment sizing, VBR TOC-interpolation seek (`calculateByteOffset`), zero-copy `wrapSegment` (raw MP3 frames are self-contained). CBR sub-frame tail guard prevents over-read.
- `FlacFormatDecoder.ts`: Concrete FLAC implementation (implemented, not yet wired). Implements `IFormatDecoder` for FLAC: scans all metadata blocks (STREAMINFO mandatory, SEEKTABLE optional), extracts 20-bit sample rate / 3-bit channels / 5-bit bitsPerSample / 36-bit total-samples from bit-packed STREAMINFO, builds 38-byte synthetic STREAMINFO block for per-segment wrapping, binary-search SEEKTABLE for seek. `wrapSegment` prepends `fLaC + STREAMINFO` to each audio segment so `decodeAudioData` sees a valid FLAC stream. `getAlignedSegmentSize` scans backward through peek bytes for the `0xFF/(0xF8|0xF9)` FLAC frame sync so each segment ends on a real frame boundary.

`StreamDecoder.ts` remains the orchestrator — it accepts the first chunk, selects the right format decoder via factory (based on `contentType`), peeks candidate bytes before calling `getAlignedSegmentSize` (non-destructive read), passes them as `rawData`, and uses zero-copy `subarray` for the actual segment. It delegates all format-specific work to the decoder and chains subsequent chunks through the same decoder instance. `Mp3FormatDecoder` and `FlacFormatDecoder` are implemented modules but not yet wired into `AudioPlayer.createFormatDecoder` factory (Wave 3 pending).

### Component integration
- `AudioPlayerProvider.razor` is the cascading host. It injects `IStreamingPlayerService` (resolved to `StreamingAudioPlayerService` in DI), stores it in a cascade with `IsFixed="true"`, and keeps it alive across navigation.
- `AudioPlayerBar.razor` is the dock UI. It cascades the player, binds buttons to `Play()` / `Pause()` / `Seek()` / `SetVolume()`, and displays current time / duration / progress bar. Minimize-state mutations (`Expand`, `ToggleMinimized`, `Close`) all route through a private `SetMinimized(bool value)` mutator, which guards no-ops, fires the `OnMinimized` callback, and calls `StateHasChanged()`. Subscribes to `IPlayerService.StateChanged` in `OnParametersSet` (reference-guarded, idempotent) and unsubscribes on dispose to re-render itself when the cascade updates.
- `SpectrumVisualizer.razor` calls `AudioInteropService.GetSpectrumData()` on a timer, receives bar heights, renders via MudBlazor `MudChart` or custom canvas.
- `TracksView.razor` injects `TracksViewModel` + cascaded `IStreamingPlayerService`. `PlayTrack(track)` calls `PlayerService.SelectTrackStreaming(track)`. Subscribes to `IPlayerService.StateChanged` in `OnParametersSet` and calls `StateHasChanged()` unconditionally on any state change, ensuring the gallery correctly reflects play/pause/track-change transitions. Active-track state is derived from `PlayerService.CurrentTrack` and `PlayerService.IsPlaying` (no local `_selectedTrack` field).

## Dark-mode plumbing

- `DarkModeSettings` (`Common/`): `[PersistentState]`-annotated class with `IsDarkMode` property. Registered scoped in `Startup.ConfigureDomainServices`. Single source of truth in the client.
- `DarkModeServiceBase`: Holds the cookie name constant (`"darkMode"`).
- `DarkModeCookieService`: Reads/writes the cookie via JS (`document.cookie` interop). Calls `DarkModeSettings.IsDarkMode = value` when the cookie changes or user toggles the button.
- Server-side `DarkModeService` (in `DeepDrftPublic`, **not here**): Reads the cookie during prerender, seeds the `DarkModeSettings` instance, rounds it through `PersistentComponentState` to the client.
- `MainLayout.razor`: Wraps entire layout in `CascadingValue` of `DarkModeSettings`, so all children see the current dark-mode state. The dark-mode toggle button (hand-rolled lit/unlit gas-lamp icon from `DeepDrftShared.Client/Common/DDIcons.cs`) calls `DarkModeCookieService.ToggleDarkModeAsync()`.

The flow ensures the first paint uses the correct theme (no flash), and toggling the button persists the setting to a 365-day cookie.

## MVVM convention

Component state lives in ViewModels (registered scoped in DI). Components render and dispatch only.

- `TracksViewModel`: Holds page number, page size, sort column, descending flag. `SetPage(pageNumber)` is the command. `TracksView.razor` injects it and calls `SetPage`.
- New VMs go in `ViewModels/` and register in `Startup.ConfigureDomainServices`.

## Theming convention

- Bespoke `PaletteLight` / `PaletteDark` defined inline in `MainLayout.razor` (MudBlazor theme objects).
- CSS classes prefixed `deepdrft-` live in `DeepDrftPublic/wwwroot/styles/deepdrft-styles.css` (shared across server and client).
- Custom SVG icons: `DeepDrftShared.Client/Common/DDIcons.cs` (hand-rolled gas-lamp, lava-lamp, etc. — shared across public and CMS surfaces).

### Interactive-accent icons (`.dd-accent-icon` / `.dd-accent-fill`)

Green-accent interactive icon affordances (Play / Share / Add-to-Queue / lava-lamp trigger, etc.) use a **single reusable treatment** in `deepdrft-styles.css`, not per-site dark overrides. Wrap the affordance(s) in a container carrying `.dd-accent-icon`; the rule colours the inner `.mud-icon-root` glyph green-accent (`--deepdrft-green-accent`, the brand constant — same value in both palettes) in **both** themes. Add `.dd-accent-fill` to the same container when it also holds a filled `Color.Secondary` `MudButton` whose fill must go green-accent in **dark** (dark-only — light already renders green fill + white text).

Two reasons this is needed and why it's a class, not a palette colour: (1) no MudBlazor `Color` enum is green in both themes (`Dark.Secondary` is off-white), so palette-only solutions can't express "green in both"; (2) MudBlazor stamps the standalone rule `.mud-secondary-text { color: …secondary !important }` (0,1,0) on the glyph `<svg>`, so wrapper-level overrides never reach it — the reusable rule targets `.dd-accent-icon .mud-icon-button .mud-icon-root` (0,3,0) `!important`, which beats it on specificity alone; source order is not load-bearing for the glyph clause. The Session/Mix release-detail hero Share/Play glyphs use this class too: they were already green-accent in light (via `Color.Secondary` → `Light.Secondary`), so folding them in keeps light pixel-identical while fixing the dark over-image glyphs — they are not actually theme-divergent. **Add new green-accent icon affordances by applying this class, not by spawning a new dark override.**

**Self-themed components are authoritative over `.dd-accent-icon`.** `PlayStateIcon` owns its glyph colour inside `.icon-container` and must beat a surrounding `.dd-accent-icon` in dark — its scoped CSS rule targets `.mud-icon-root` at (0,5,0) `!important` (after Blazor's scope attribute is applied), which outranks the consolidation rule's (0,3,0) `!important`. Do not wrap a `PlayStateIcon` in `.dd-accent-icon` expecting to recolor its play-chip glyph — the play chip always shows navy (`--deepdrft-play-glyph`) against the moss-green chip in dark.

**Layout-only cluster class: `.dd-detail-top-actions`.** When two or more icon affordances sit together in a top-action row (e.g. the Theater toggle + lava-lamp popover on the three detail pages), wrap them in `.dd-detail-top-actions` — a layout-only `display:flex; align-items:center; gap:0.25rem` class in `deepdrft-styles.css`. No colour; prevents the `SpaceBetween` row from spreading the icons apart. Each affordance inside still carries its own `.dd-accent-icon` wrapper independently.

**Gas-lamp toggle is self-colored in its SVG.** `DDIcons.GasLampLit` (dark-mode icon) carries `fill="#2A5C4F"` directly on its frame path — no CSS colour override is needed. The former dark nav rule (`.deepdrft-theme-dark .dd-nav-actions .mud-icon-button`) has been removed as dead. `DDIcons.GasLamp` (light-mode icon) continues to use `currentColor` and inherits nav text colour in light (the unlit toggle is theme-divergent by design).

## Development commands

```bash
# The client runs as part of the DeepDrftPublic host:
dotnet run --project DeepDrftPublic

# Watch during development (rebuilds WASM as you change .cs/.razor/.ts files):
dotnet watch run --project DeepDrftPublic

# Build just the client (for verification):
dotnet build DeepDrftPublic.Client

# Run client-specific tests (if any; currently none exist):
dotnet test DeepDrftTests/
```

## Configuration

- `Program.cs`: Entry point. Calls `Startup.ConfigureApiHttpClient` (registers named clients), `ConfigureContentServices` (same), `ConfigureDomainServices` (registers services like `TracksViewModel`, `DarkModeSettings`, `AudioPlayerService`).
- Both `Startup` methods are static and called from **both** the server `DeepDrftPublic/Program.cs` and the client `Program.cs`, ensuring prerender and runtime DI are identical.
- No `appsettings.json` in the WASM assembly — config comes from the server `appsettings.json` via HTTP or is hardcoded.

## Important patterns

- **Cascading parameters**: `AudioPlayerProvider` cascades `IStreamingPlayerService`. All children (including `MainLayout` and pages) access it via `[CascadingParameter] IStreamingPlayerService Player { get; set; }`.
- **Result types**: Clients return `ApiResult<T>` from NetBlocks. UI checks `Success` before using `Value`.
- **Async/await**: All operations are async.
- **Stream consumption**: `TrackMediaClient.GetAudioStreamAsync` returns a `Stream` (not fully buffered). `StreamingAudioPlayerService` reads it in chunks to avoid memory pressure on large files.
- **Detail pages under InteractiveAuto must load in `OnParametersSetAsync`, not `OnInitializedAsync`**: Blazor reuses a scoped component instance across same-template navigations (e.g. `/mixes/5` → `/mixes/8`), firing `OnParametersSet`/`OnParametersSetAsync` rather than re-running `OnInitialized`. If load logic is in `OnInitialized` only, the ViewModel retains the prior track and Play will stream the wrong item. Capture the route parameter (id/key) synchronously at the top of `OnParametersSetAsync` before any await — after an await the route state may have advanced. Guard `PersistentComponentState` restores on id/key equality to prevent cross-item bleed when the prerender and WASM-boot passes disagree on which item is current.

When working with this project, maintain the separation between presentation (Razor components) and logic (ViewModels/Clients), follow the established audio player architecture, and respect the dark-mode round-trip (cookie → DarkModeSettings → PersistentComponentState → client).
