feat(car-sharing): EventBus broadcast / fan-out on trip completion (Phase 3)

[intech]

⚠️ BLOCKED — merge only AFTER @connectum/events 1.1.0 is published

This example uses EventBusOptions.publishes (framework PR #166), which ships in 1.1.0 — not yet on npm (it's in the open Version Packages PR connectum#165). The example pins ^1.0.0, which resolves to 1.1.0 once published; until then a plain pnpm install pulls 1.0.0 (no publishes) and the example fails to typecheck/run. Opened as a draft on purpose. Un-draft and merge after the events 1.1.0 release.

What

Phase 3 adds the third orthogonal interaction mechanism to car-sharing: a fire-and-forget EventBus broadcast / fan-out. When the Phase-2 Temporal saga settles a trip, TripCompleted is published once and consumed independently by 3 reactors (pricing/analytics, audit-log, notifications). EventBus is for broadcast only — orchestration stays Temporal's job.

Phase	Mechanism	Shape
1	ctx.call	sync typed RPC
2	Temporal saga	durable orchestration + compensation
3	EventBus broadcast	fire-and-forget 1 → N independent reactors

How

• proto/trips/v1/trip_events.proto — TripCompleted + TripEventHandlers, topic trips.completed via the (connectum.events.v1.event).topic option.
• publishes (PR #166) — the publisher resolves the declared topic from the proto option with no raw topic string (the clean replacement for the old hand-passed-topic workaround). Verified: no {topic} passed to any publish().
• Fan-out = 3 separate reactor buses, each a distinct consumer group — forced by the per-bus duplicate-topic guard, and giving real-broker fan-out (distinct durable consumers). Reactors are idempotent by tripId.
• Publish site = a new terminal saga activity publishTripCompleted in the worker. Failure semantics: a success-only try/catch tail outside the saga try/catch (reached only when SETTLED; its catch does not rethrow) — a failed broadcast can never roll back a settled, paid trip. Separate proxyActivities retry block for the publish.

Tests (dockerless)

One publish drives all 3 reactors over a shared MemoryAdapter (full TripCompleted shape asserted), the topic resolves to trips.completed from the proto option, topic isolation, and a guard test (broadcast failure leaves the trip SETTLED). buf generate/lint + typecheck exit 0; pnpm test 41/41 (all Phase-2 suites still green). docker-compose nats (JetStream) + 3 reactor processes on the saga profile are config-only.

🤖 Generated with Claude Code

https://claude.ai/code/session_01MdeH7fExPmiRHRirGuvGk3

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 1c349d7c-c0da-49af-a13d-83e07ef54ebc

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/car-sharing-eventbus-broadcast

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[intech]

Verified the publishes dependency against the #165 pkg.pr.new 1.1.0 snapshots (published-shape, not local tarballs): overrode the whole @connectum/* set to https://pkg.pr.new/@connectum/<pkg>@165 and ran buf generate + typecheck + pnpm test — all green, 41/41, @connectum/events dist carries publishes. So Risk #1 is purely release timing, not a code defect: this example builds/runs against the real published-shape 1.1.0 package. Still draft — un-draft + merge once @connectum/events 1.1.0 is on npm (#165), at which point the ^1.0.0 pin resolves to it automatically.