Workers

The canonical document stays on the main thread. Workers maintain derived state for parsing, highlighting, minimap drawing, spellcheck and TypeScript language analysis.

Synchronization

The document integration can transfer immutable source chunks and versioned edit information to a worker. The worker keeps the source it needs and updates its own derived state. A new version identifies which document a response describes.

This keeps expensive parsing and analysis away from the immediate input path. Communication, source retention and result application still have costs. Measure those costs with your integration.

Owners and lifetime

A worker owner starts its worker, tracks requests and state, and disposes it. Host integrations that supply an owner or shared service must retain it while its consumers need it.

Worker failure handling differs by system. Tree-sitter and Shiki owners can start a fresh generation on the next request after a crash; failed requests are not automatically replayed. Minimap and TypeScript integrations require recreating their affected contribution or transport after failure. See the worker topology for each owner.

Platform dependencies

Module workers need valid emitted URLs. Tree-sitter also loads WebAssembly. Minimap drawing uses OffscreenCanvas. SharedArrayBuffer cancellation is optional and used only when the page is cross-origin isolated.

The Bundling and workers guide covers production asset requests and Content Security Policy checks.