Initial release: 8-bit sound synthesizer with LLM/MCP integration

Soundgen is a Rust workspace for generating 8-bit/chiptune sound effects,
UI sounds, and ambient textures for game audio assets. It features JSON-first
sound specs, an MCP server for LLM tool-use, an egui GUI editor, and a
runtime library with NES-authentic DAC emulation.

Features:
- 6 voice types: pulse, triangle, noise, DPCM, wavetable, FM
- Effects: ADSR envelope, frequency sweep, biquad filter, vibrato
- 13 built-in presets (SFX/UI/ambient) as JSON data files
- MCP server: list_presets, generate_sfx, render_sound tools
- Pattern-based sequencer (JSON song format)
- egui GUI: virtual keyboard, preset browser, channel editor, undo/redo
- Runtime: NES nonlinear DAC + SoundBank for game embedding
- 90 tests, 0 warnings

Crates:
- soundgen-core: synthesis engine (no I/O)
- soundgen-fmt: SoundSpec JSON schema + PresetRegistry
- soundgen-io: WAV writer + audio playback
- soundgen-seq: sequencer (patterns, songs)
- soundgen-cli: gen/render/render-song/list-presets
- soundgen-mcp: MCP server for LLM integration
- soundgen-gui: egui editor
- soundgen-runtime: NES DAC + SoundBank

README.md

@@ -0,0 +1,140 @@
+# Soundgen
+
+8-bit sound synthesizer in Rust for game audio assets, with LLM integration via MCP.
+
+## Features
+
+- **6 voice types**: pulse (NES duty cycles), triangle, noise (LFSR), DPCM samples, wavetable (Game Boy wave), FM (2-operator)
+- **Effects**: ADSR envelope, frequency sweep (linear/exponential), biquad filter (lowpass/highpass), vibrato
+- **JSON-first**: every sound is a `SoundSpec` JSON object — LLMs generate JSON, CLI/MCP render to WAV
+- **Presets as data**: 13 built-in presets in `presets/{sfx,ui,ambient}/` — extend without recompilation
+- **MCP server**: LLMs can call `list_presets`, `generate_sfx`, `render_sound` as tools
+- **Sequencer**: pattern-based song playback (JSON format)
+- **GUI**: egui editor with virtual keyboard, preset browser, channel controls, sequencer
+- **Runtime library**: NES-authentic nonlinear DAC + SoundBank for game embedding
+- **No allocations in audio hot path**: `tick() -> f32`, `&mut self`
+
+## Quick Start
+
+```bash
+# List available presets
+cargo run --bin soundgen -- list-presets
+
+# Generate a sound from a preset
+cargo run --bin soundgen -- gen jump --out assets/jump.wav
+
+# Generate with parameter override
+cargo run --bin soundgen -- gen explosion --out assets/explosion.wav --param volume=0.95
+
+# Render from a custom JSON spec
+cargo run --bin soundgen -- render presets/sfx/laser.json --out laser.wav
+
+# Render a song (sequencer)
+cargo run --bin soundgen -- render-song song.json --out music.wav
+
+# Launch the GUI editor
+cargo run -p soundgen-gui
+```
+
+## MCP Server (for LLM integration)
+
+Run the MCP server on stdio:
+
+```bash
+cargo run -p soundgen-mcp -- --presets-dir presets
+```
+
+Configure in Claude Desktop / MCP client:
+
+```json
+{
+  "mcpServers": {
+    "soundgen": {
+      "command": "/path/to/soundgen-mcp",
+      "args": ["--presets-dir", "/path/to/presets"]
+    }
+  }
+}
+```
+
+LLM workflow:
+1. `list_presets` → see available sounds
+2. `generate_sfx { preset: "jump", out_path: "assets/jump.wav" }` → WAV created
+3. `render_sound { spec: {...}, out_path: "assets/custom.wav" }` → custom sound
+
+## SoundSpec JSON Format
+
+```json
+{
+  "name": "jump",
+  "duration": 0.3,
+  "sample_rate": 44100,
+  "channels": [
+    {
+      "type": "pulse",
+      "duty": 50,
+      "frequency": { "start": 200, "end": 800, "curve": "exponential" },
+      "envelope": { "attack": 0.01, "decay": 0.15, "sustain": 0.0, "release": 0.14 },
+      "volume": 0.7
+    }
+  ]
+}
+```
+
+Channel types: `pulse`, `triangle`, `noise`
+
+## Song JSON Format (Sequencer)
+
+```json
+{
+  "bpm": 120,
+  "rows_per_beat": 4,
+  "tracks": [
+    { "type": "pulse", "duty": 50, "volume": 0.4 }
+  ],
+  "patterns": [
+    { "rows": [ { "notes": [{"frequency": 440}] }, {"notes": [null]} ] }
+  ],
+  "pattern_order": [0]
+}
+```
+
+## Architecture
+
+Cargo workspace:
+
+| Crate | Purpose |
+|---|---|
+| `soundgen-core` | Synthesis engine (generators, effects, mixer). No I/O. |
+| `soundgen-fmt` | `SoundSpec` JSON schema + `PresetRegistry` |
+| `soundgen-io` | WAV writer (`hound`) + playback (subprocess) |
+| `soundgen-seq` | Sequencer: patterns, songs |
+| `soundgen-cli` | `gen`, `render`, `render-song`, `list-presets` |
+| `soundgen-mcp` | MCP server for LLM tool-use |
+| `soundgen-gui` | egui GUI editor |
+| `soundgen-runtime` | NES-authentic DAC + `SoundBank` for game embedding |
+
+## Runtime Library (for game integration)
+
+```rust
+use soundgen_runtime::SoundBank;
+
+// Load all presets at init time
+let bank = SoundBank::load_dir(std::path::Path::new("presets"))?;
+
+// Play by name (zero-allocation, returns pre-rendered buffer)
+let (samples, sample_rate) = bank.get("jump").unwrap();
+
+// Pitch-shifted variant
+let (pitched, sr) = bank.get_pitched("jump", 1.5)?;
+```
+
+## Built-in Presets
+
+**SFX**: jump, explosion, coin, laser, hit, powerup
+**UI**: click, hover, confirm, error
+**Ambient**: wind, rain, drone
+
+## License
+
+MIT