feat(builder): add subscribe flag for write-only pathways#78
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Adds optional `subscribe?: boolean` (default `true`) to PathwaysBuilder.register(). When `false`, .write() works but the in-process pump does not subscribe to that pathway's flow type. Use for analytical / write-only events that have no in-service consumer, avoiding back-pressure on the shared pump queue. Provisioning still creates the flow type and event type for write-only pathways so .write() targets exist in flowcore. Only the pump.start() registrations are filtered via the new private buildSubscribedRegistrations() helper. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
Adds optional
subscribe?: boolean(defaulttrue) toPathwaysBuilder.register(). When set tofalse,.write()still works but the in-process pump does NOT subscribe to that pathway's flow type, so events are not pulled and.handle()will never fire.Use for analytical / write-only events that have no in-service consumer, avoiding back-pressure on the shared pump queue.
Why
Without this option, registering a pathway with
writable: trueand no.handle()causes the in-process pump to subscribe and queue events that are never acknowledged, eventually wedging the shared pump and timing out every othersessionPathway.writeviawaitForPathwayToBeProcessed. We hit this in production forpump-pulse.0in data-pathways CP — that fix lands in a follow-up PR once this version is on npm.Behavior
subscribe: true(default): unchanged — pump subscribes, handler fires.subscribe: false: pump skips subscription..write()works..handle()registered for the pathway will not fire (no events are delivered).Test plan
tests/pathway-subscribe-flag.test.ts(6 steps)deno test -A --ignore=tests/postgres-pathway-state.test.ts— 14 files / 127 steps green