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@@ -6,6 +6,68 @@ Newest entries at the top. Group by phase/wave header (mirroring `PLAN.md` / `CM
 
 ---
 
+## WaveformSeeker Wave 1 — Loudness profile + layout refactor
+
+**Status:** W1-T1 (backend loudness computation) and W1-T3 (player layout refactor) landed on 2026-06-05.
+
+### W1-T1 — Backend waveform loudness profiling
+
+**Landed 2026-06-05.**
+
+Implemented Phase 1 of the WaveformSeeker feature (`product-notes/spectrum-seeker.md`): loudness-profile computation and storage for preprocessed waveform data.
+
+**Backend changes (`DeepDrftContent`):**
+- Added `ILoudnessAlgorithm` strategy interface for swappable loudness computation.
+- Implemented `RmsLoudnessAlgorithm` — first loudness algorithm using root-mean-square; future LUFS implementation swaps in via the same interface without touching service, wire format, or storage.
+- `WaveformProfileService` — computes peak-normalized loudness profile from PCM WAV (one linear buffer pass), buckets by time slice, normalizes to `[0,1]`, stores as byte-quantized sidecar in new `profiles` vault (FileDatabase `MediaFileVault`).
+- `WaveformProfileOptions` — config-bound options object carrying `BucketCount` (default 512) and future algorithm-selection knobs.
+
+**Integration changes (`DeepDrftAPI`):**
+- Wired `WaveformProfileService` into `UnifiedTrackService.UploadAsync` — profile computed on upload, stored immediately, failure silently swallowed (consistent with FileDatabase philosophy in `CLAUDE.md`).
+
+**Models (`DeepDrftModels`):**
+- `WaveformProfileDto` — carries quantized profile data; format independent of algorithm or bucket count.
+
+**Testing (`DeepDrftTests`):**
+- 4 new unit tests: RMS algorithm correctness against known-good PCM samples, swappable-algorithm contract (two strategies swap cleanly), and integration with `WaveformProfileService`.
+
+**Architecture notes:**
+- Profile is derived binary content; stored in FileDatabase vault sidecar per `CLAUDE.md` principle ("binary content lives in the vault").
+- Loudness measure is an abstraction (not hardwired RMS) — RMS→LUFS future change requires only a new `ILoudnessAlgorithm` implementation, no refactoring of service, component, or wire format.
+- No external audio-processing dependency pulled in for RMS — reuses existing PCM parser from `AudioProcessor`.
+- Cost: one linear pass over PCM buffer at upload (few hundred ms for typical WAV); never on playback path.
+
+### W1-T3 — Player layout refactor (SpectrumVisualizer relocation + VolumeZone rename)
+
+**Landed 2026-06-05.**
+
+Implemented Phase 3 of the WaveformSeeker feature: architectural layout move separating live-spectrum visualization from loudness-over-time seeking.
+
+**Conceptual split:**
+- Live-spectrum (FFT frequency bars, `SpectrumVisualizer`) moved from `PlayerSeekZone` → stacked above the volume slider in new `VolumeZone`. Conceptually with the output level.
+- Static loudness-over-time (future `WaveformSeeker`) takes over the seek zone. Conceptually with transport position.
+
+**Component changes (`DeepDrftPublic.Client/Controls/AudioPlayerBar`):**
+- `VolumeControls.razor` → renamed **`VolumeZone.razor`** for symmetry with transport and seek zones; now a vertical stack hosting `SpectrumVisualizer` above the volume slider.
+- `SpectrumVisualizer` — `BucketCount` parameter defaulted to 24 buckets (down from 32) to fit the narrow volume cluster; set `flex-shrink: 0` to pin the spectrum to a fixed footprint above the volume control.
+- `PlayerSeekZone.razor` — `SpectrumVisualizer` block removed; placeholder for future `WaveformSeeker` component.
+
+**CSS changes (`AudioPlayerBar.razor.css`):**
+- Adjusted volume cluster width constraints to accommodate the 24-bucket spectrum stacked above.
+- Responsive layout unchanged at 600px breakpoint (single-row transport/volume with full-width seek below on narrow; same 3-zone layout on wide).
+
+**Scope:**
+- Pure layout move; zero change to spectrum animation lifecycle, player logic, or seek gesture handling.
+- Both `AudioPlayerBar` and `SpectrumVisualizer` components affected.
+- Build clean: 0 errors, 0 new warnings.
+
+**Notes for future work:**
+- `PlayerSeekZone` is now ready for the `WaveformSeeker` component (W1-T4/Phase 4 onwards).
+- Volume cluster can comfortably accommodate 24 FFT bars; 32 would cause visual cramping (why the override exists).
+- Spectrum visualization lifecycle (subscription to `StateChanged`, animation via `AudioInteropService.StartSpectrumAnimationAsync`) unchanged — only position in the DOM tree changed.
+
+---
+
 ## Phase 2 — Product surface: player and theming
 
 **Status:** Track card glass theming landed on 2026-06-05. AudioPlayerBar responsive unification and SpectrumVisualizer fix landed on 2026-06-05.