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songbird-orchestrator

Shared engine orchestration. Wires EngineController, StateStore, PluginRegistry, and session building into a single EngineBackend implementation used by both the Tauri desktop app (songbird-app) and the headless WebSocket server (songbird-headless). Before this crate, songbird-headless depended on songbird-app to reuse session build, device management, plugin swap, master-capture, and plugin-editor-hosting code. That dependency is gone — both binaries now depend on songbird-orchestrator instead, and the engine lifecycle has a single canonical owner.

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What lives here

  • RingBufferEngine — the EngineBackend implementation. Owns the engine controller, audio output, read pool, state store, transport, MIDI device manager, audio config, plugin registry, cached audio clips, and the rebuilding / restarting guards. Handles session builds, device open/close, plugin chain swaps, MIDI scheduler updates, and master-bus capture.
  • TerminalProvider — trait for desktop-only terminal sessions (the headless server passes None).
  • MasterCaptureState — global master-bus audio capture buffer used by the AI copilot to send audio context to Gemini.
  • plugins/ — plugin-editor lifecycle (plugin_editors.rs) and native editor windows (editor_windows.rs). Previously macOS-gated inside songbird-app; now cross-platform and shared.

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Swap modes

pub enum SwapMode {
    Full,   // rebuild entire session (project open, sample rate change)
    Graph,  // hot-swap graph only (plugin add/remove, connection edit)
}
Graph swaps are preferred on the hot path — they skip transport and scheduler re-init, and they don’t interrupt playback.

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Dependencies

  • songbird-engine — audio graph, transport, scheduler, ring buffer
  • songbird-state / songbird-sync — project state + dispatch bridge
  • songbird-plugin-registry — unified plugin registry
  • songbird-host-ffi — VST3/AU hosting (feature-gated: juce, vst3)
  • songbird-plugins — stock DSP plugins
  • songbird-session — session-build primitives
No UI or IPC dependencies. Safe to use from headless contexts.