# P1a · material and the quarry

P0 proved the spine: Rust audio, a session, a protocol, a surface. P1a puts material into it: a file becomes a core, a core becomes sixteen faces, a face becomes a voice in the pattern.

## The path of a sound

```
file input (browser)
  → ArrayBuffer
  → ws: import_core { id, name, seal } + binary audio
  → zhila-material: symphonia decode → mono f32 at the source rate
  → onset analysis: 10 ms energy hops, positive flux, local peaks
  → sixteen faces (sample ranges + RMS + rank)
  → waveform peaks (1400 bins, normalised)
  → zhila-core: Core { summary, Arc<[f32]>, faces }
  → Session::import_core: archive + journal + sync_material
  → engine: Arc<MaterialSnapshot> through the control queue
  → snapshot broadcast → the quarry
```

The pattern keeps its procedural voices until a row is given a face. `set_pattern_face` writes the reference and syncs a new material snapshot; the audio thread triggers a sample voice for that row's steps and leaves the other rows procedural. `set_pattern_step` edits the rhythm; both are journaled. `strike_face` auditions a face without touching history.

## Pieces

| Piece | What it does |
|---|---|
| `zhila-material` | decode (symphonia), downmix to mono, onset analysis, sixteen faces, ranks, waveform peaks, content-hash id |
| `zhila-core` | `Core`, `AudioCore`, `AudioFace`, `MaterialSnapshot`; archive; pattern face/step commands; journal; engine sync |
| `zhila-engine` | sample voices alongside procedural voices; a step plan that resolves a row's face to a core/face; rate-correct playback; 4 ms fades |
| `zhila-daemon` | binary import after a text header, decoded in `spawn_blocking`; broadcast snapshot; new commands flow through the session |
| `zhila-protocol` | core/face summaries, face references, import messages, pattern commands/events |
| `ui` | quarry: import, core strip, waveform, face wall, audition, assign, pattern grid; the descent remains the nave |

## Verification

- `cargo test --workspace`: 10 core tests, 2 material tests, 5 protocol tests.
- `cargo clippy --workspace --all-targets -- -D warnings` and `cargo fmt --check`.
- `node scripts/material-smoke.mjs`: a live import of `fixtures/clicks-01.wav`, sixteen faces, a face laid on row 1, playback, non-zero meters, `face_struck`.
- `npm --prefix ui run quarry-smoke`: the browser imports the fixture, selects a face, assigns it, plays, screenshots the quarry and the nave, checks 80 steps and 16 faces.
- `npm --prefix ui run smoke`: the P0 regression still passes.

The screenshots are `preview-p1-quarry.png`, `preview-p1-nave.png` and the empty state `preview-p1-quarry-empty.png`.

## Limits

- In-memory archive and pattern; no project file, no save/load, no asset persistence. A daemon restart loses the material and edits.
- No recording, no waveform trim, no manual cut/loop points. Seams are automatic.
- No undo/redo for pattern edits; the journal is written but not exposed.
- One face per pattern row; no per-step face, pitch or probability yet.
- Formats are whatever symphonia decodes; WAV is the tested path.
- The Tauri shell now builds and runs; the engine remains the separate daemon (embedding is next).

## Next

P1b: a project folder with SQLite, content-addressed assets, autosave and reload, pattern-edit undo, recording, and waveform trim. Then the arrangement and the agent.