Observability

import { SqliteTracer } from '@polymatx/weave';

const tracer = new SqliteTracer('./weave.sqlite');

await flow.run({
  initialState,
  onEvent: (e) => tracer.record(e),
});

Every emitted TraceEvent is written to the SQLite file. The trace UI reads from the same file:

npx @polymatx/weave-ui --db ./weave.sqlite --port 4321
# open http://localhost:4321

Event types

Event	When it fires
run.start	Graph run begins
node.start	Node entered
node.end	Node returned a patch
agent.call	An LLM call completed (carries token usage, cost USD)
tool.call	An agent tool was invoked
token.delta	A streaming agent emitted a chunk
run.end	Graph reached END
run.error	Run aborted or threw

Querying programmatically

const runs = tracer.listRuns(50);
const events = tracer.getEvents(runId);

Useful for building custom dashboards or wiring weave traces into your own ETL.