State and lifecycle

State ownership

The VST3 component stores processor state, while the controller mirrors host-visible parameter and UI state. Keep serialized data versioned and deterministic. Do not serialize transient DSP buffers or WebView objects.

Kernel lifecycle

Hook	Use it for
prepare	Sample-rate setup and preallocation
reset	Clear algorithm history after processing configuration changes
suspend	Pause background algorithm state when processing stops
resume	Resume after the host restarts processing

setupProcessing() and active-state changes trigger reset behavior. setProcessing(false/true) maps to suspend/resume.

Web UI state

The bridge snapshot separates parameter, configuration, and UI revisions. Configuration and UI state updates use optimistic revision checks so stale editors receive a state conflict instead of overwriting newer data.

TypeScript
1const snapshot = await bridge.getSnapshot();23await bridge.setUiState({4  expectedRevision: snapshot.uiRevision,5  value: { selectedTab: 'meters' }6});

Treat UI state as optional presentation state. Audio output must remain valid when no editor has ever opened.

Test the full sequence

Cover save, destroy, restore, activate, prepare, process, suspend, resume, reopen editor, and reload editor. Real DAWs differ in ordering, so unit tests should accept valid host sequences without assuming one application.