chord recognition improvements

2026-03-08 01:38:09 +00:00
parent e3e4554d1f
commit 22b8f1fe04
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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Commands
+
+```bash
+# Development (Vite dev server + Electron window with hot reload)
+npm run electron:dev
+
+# Browser-only dev (no Electron)
+npm run dev
+
+# Build installers
+npm run electron:build:win    # Windows NSIS installer → releases/
+npm run electron:build:mac    # macOS DMG → releases/
+npm run electron:build:linux  # Linux AppImage → releases/
+```
+
+No test suite exists. There is no lint script — no ESLint config is present.
+
+## Architecture
+
+**Electron shell** (`electron/main.cjs`) loads `dist/index.html` in production or `localhost:5173` in dev. The renderer process has full Web Audio API access (`sandbox: false`). `preload.cjs` uses `contextIsolation: true` with no exposed IPC — Electron is purely a window host; all logic lives in the renderer.
+
+**Two audio pipelines run in parallel** inside `AudioCapture.jsx`:
+
+| Path | FFT | Purpose |
+|---|---|---|
+| Pitch | 4096 samples (~90ms, `smoothingTimeConstant=0.0`) | McLeod pitch detection via `pitchy` → feeds key detection |
+| Chord | 16384 samples (~370ms, `smoothingTimeConstant=0.5`) | Harmonic summation chroma → feeds chord detection |
+
+The 16384 FFT gives 2.7 Hz/bin resolution, which is necessary to separate adjacent semitones on low guitar strings (~5-6 Hz apart). The chord analyser uses `computeChroma()` — a harmonic summation that folds each FFT bin back through 5 harmonics to cancel overtone contamination (prevents minor chords from reading as major).
+
+**State and detection logic lives entirely in `App.jsx`:**
+
+- `handleNote` (pitch callback) → accumulates `noteHistoryRef`, runs Krumhansl-Schmuckler key detection every 5 notes, votes in `keyVotesRef` (rolling window, requires strong consensus before committing)
+- `handleChroma` (chord callback) → averages a ring buffer of `chromaSmooth` frames, runs a **chroma stability gate** (per-bin variance check — bails if still in transition), then matches against chord templates via `matchChordFromChroma`, votes in `chordVotesRef`
+- `handleOnset` (onset callback from RMS spike detection) → builds a **tempo histogram** from pairwise inter-onset intervals, folding all intervals into 55–220 BPM range; the histogram peak drives BPM display
+
+Both `handleNote` and `handleChroma` use `useCallback(fn, [])` (empty deps). All values they need from render scope are kept in refs synced via `useEffect` — this prevents `AudioCapture`'s `start` from recreating on every render.
+
+**All music theory is in `src/lib/theory.js`:**
+
+- `detectKey` / `detectTopKeys` — Krumhansl-Schmuckler correlation against major/minor profiles only (K-S cannot distinguish modes — Dorian vs natural minor look the same; user manually picks mode)
+- `matchChordFromChroma` — weighted coverage score (inEnergy / (inEnergy + outEnergy×0.7)), requires root presence (`chroma[r] >= 0.08`), margin over second-best, diatonic/bass bonuses
+- `MATCH_CHORD_TYPES` — the subset of chord types used in real-time detection (not all of `CHORD_TYPES`)
+- `detectRepeatingProgression` — non-overlapping pattern match over last 20 chords, length 2–6
+
+**`src/services/audioService.js`** is a self-contained tuner hook (`useAudioTuner`) used only by `Tuner.jsx`. It uses its own separate `AudioContext` with simple autocorrelation — independent from the main pitch/chord pipeline.
+
+## Design tokens (Tailwind)
+
+Defined in `tailwind.config.js`: `bg-surface` (#0f0f0f), `bg-panel` (#1a1a1a), `border-border` (#2a2a2a), `text-accent` / `bg-accent` (#a855f7 purple). Use these rather than raw hex in components.
+
+## Key configuration (`DEFAULTS` in `App.jsx`)
+
+| Key | Purpose |
+|---|---|
+| `chromaSmooth` | Ring buffer size (frames averaged before chord check) |
+| `chordVoteThreshold` | Consecutive matching chord frames required to commit |
+| `chordMinScore` | Minimum coverage score from `matchChordFromChroma` |
+| `keyVoteWindow` / `keyVoteThreshold` | Rolling window size and consensus count for key lock |
+| `noteHistorySize` | Max pitch-class history kept for K-S key detection |
+
+These are exposed in `Settings.jsx` as sliders. `configRef` keeps a ref in sync so stable callbacks can read current values.
+
+## Instrument views
+
+`Fretboard.jsx` and `Piano.jsx` are SVG-rendered visualisers. Both accept `keyInfo`, `currentChord`, and `monoColor`. They call `getPentatonicScale`, `getFullScale`, `getChordTones` from `theory.js` and colour notes by tier: chord tone (purple `#a855f7`) > pentatonic (amber or light purple in mono) > scale (dark gray or lightest purple in mono).
+
+## GitHub Actions
+
+`.github/workflows/release.yml` builds Windows and macOS installers on tagged pushes (`v*`) using `softprops/action-gh-release@v2`. Build scripts use `--publish never` to prevent electron-builder's own publish step.