The MCP server read one line, ran it and answered it before reading the next,
so notifications/cancelled was never seen during a call and every request
(even ping) waited behind a running export.
- vectorcraft_doc::cancel: a thread-local cancel token and progress sink that
long work polls. Checkpoints: PDF pages, PDF flattening, geometry bake,
raster-effect flattening, drawing objects, raster artboards, and before any
file is written. A cancelled command returns EngineError::Cancelled and
changes nothing.
- Server::serve reads on its own thread: notifications/cancelled drops a
queued request or stops the running one (no reply, as the MCP spec says),
engine-free requests (ping, the list methods, prompts/get) are answered at
once, a request that would wait behind a call running for 2 s is refused
with -32003 naming that call, and _meta.progressToken gets
notifications/progress (page n of m). Queue and output are bounded.
- The remote backend stops waiting for the app when the call is cancelled.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
