[jonahgabriel]

Summary

• Adds topic_router: dict[str, str] | None param to DispatchResultApplier.__init__
• Each output event is published to its per-type declared Kafka topic instead of the single output_topic fallback
• Events not in the router map fall back to output_topic (backward-compatible — no existing callers broken)
• Router is built from contract.yaml published_events via build_topic_router_from_contract() (wired in OMN-4883)

Test plan

• 3 new unit tests: routes known type, falls back for unknown type, no router uses output_topic
• All 15 tests pass (12 existing + 3 new)
• mypy --strict clean
• All pre-commit hooks pass

Tickets

• Fixes: OMN-4881
• Epic: OMN-4880

Summary by CodeRabbit

Release Notes

• New Features

  • Enabled per-event-type Kafka topic routing, allowing different event types to be published to distinct topics with automatic fallback to the default output topic for unmapped types.

• Tests

  • Added comprehensive test coverage for topic routing functionality, including proper routing behavior, fallback handling, and default behavior when no custom routing is configured.

[coderabbitai]

📝 Walkthrough

Walkthrough

The DispatchResultApplier class gains optional per-event-type Kafka topic routing. A new topic_router parameter accepts event class name to topic mappings, enabling selective topic assignment during event publishing with automatic fallback to the default output topic.

Changes

Cohort / File(s)	Summary
Core Feature Implementation src/omnibase_infra/runtime/service_dispatch_result_applier.py	Added optional topic_router parameter to constructor to map event type names to Kafka topics. Resolves publish topic per event during distribution with fallback to default output_topic. Updated logging and docstrings accordingly.
Test Coverage tests/unit/runtime/test_service_dispatch_result_applier.py	Added helper builders _make_accepted_event and _make_result_with to construct test fixtures. Introduced three new tests validating topic router behavior: known event routing, unknown event fallback, and default behavior without router.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Poem

🐰 A rabbit hops through event streams so fine,
With topic routers that align,
Each event type now finds its place,
On Kafka topics at perfect grace!
🐇✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The pull request title accurately describes the main change: adding a topic_router parameter to DispatchResultApplier for per-event-type topic routing, which aligns directly with the primary modifications shown in both the implementation and test files.
Docstring Coverage	✅ Passed	Docstring coverage is 80.00% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch jonahgabriel/omn-4881-task-1-tdd-add-topic_router-param-to-dispatchresultapplier

📝 Coding Plan

• Generate coding plan for human review comments

---

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[coderabbitai]

🧹 Nitpick comments (3)

src/omnibase_infra/runtime/service_dispatch_result_applier.py (1)

136-166: Defensively copy topic_router in __init__.

Storing the passed dict directly allows external mutation after construction, which can change routing behavior at runtime unexpectedly.

Suggested patch

-        self._topic_router: dict[str, str] = topic_router or {}
+        self._topic_router: dict[str, str] = (
+            dict(topic_router) if topic_router is not None else {}
+        )

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@src/omnibase_infra/runtime/service_dispatch_result_applier.py` around lines
136 - 166, The constructor stores the passed topic_router reference directly
(topic_router -> self._topic_router), which allows external mutation to affect
routing; defensively copy the mapping in __init__ so self._topic_router is an
independent dict (e.g., use a shallow copy when topic_router is not None) and
keep the existing fallback to an empty dict when topic_router is None; update
the assignment that sets self._topic_router in
ServiceDispatchResultApplier.__init__ to create that copy.

tests/unit/runtime/test_service_dispatch_result_applier.py (2)

423-468: Strengthen topic-router tests with single-call assertions.

Each test currently inspects only the last publish call; asserting exactly one publish call will catch accidental duplicate publishes.

Suggested patch

 async def test_topic_router_routes_known_event_to_declared_topic() -> None:
@@
     result = _make_result_with([_make_accepted_event()])
     await applier.apply(result)
+    bus.publish_envelope.assert_awaited_once()
     published_topic = bus.publish_envelope.call_args.kwargs["topic"]
     assert published_topic == "onex.evt.platform.node-registration-accepted.v1"
@@
 async def test_topic_router_falls_back_for_unknown_event_type() -> None:
@@
     result = _make_result_with([_make_accepted_event()])
     await applier.apply(result)
+    bus.publish_envelope.assert_awaited_once()
     published_topic = bus.publish_envelope.call_args.kwargs["topic"]
     assert published_topic == "responses"
@@
 async def test_no_topic_router_uses_output_topic() -> None:
@@
     result = _make_result_with([_make_accepted_event()])
     await applier.apply(result)
+    bus.publish_envelope.assert_awaited_once()
     published_topic = bus.publish_envelope.call_args.kwargs["topic"]
     assert published_topic == "responses"

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@tests/unit/runtime/test_service_dispatch_result_applier.py` around lines 423
- 468, Add an assertion that the mock publish method was called exactly once in
each of the three tests (test_topic_router_routes_known_event_to_declared_topic,
test_topic_router_falls_back_for_unknown_event_type,
test_no_topic_router_uses_output_topic) to catch unexpected duplicate publishes:
after awaiting applier.apply(result) assert the AsyncMock for
event_bus.publish_envelope was called exactly once (use
bus.publish_envelope.assert_awaited_once() or
bus.publish_envelope.assert_called_once() depending on whether publish_envelope
is awaited) before inspecting call_args.kwargs["topic"].

---

412-413: Remove type: ignore[type-arg] by typing the events parameter as list[BaseModel].

The events parameter can be precisely typed to match the ModelDispatchResult.output_events field annotation (list[BaseModel]), eliminating the need for the ignore comment. BaseModel is already imported in this file.

Change:

def _make_result_with(events: list) -> ModelDispatchResult:  # type: ignore[type-arg]

to:

def _make_result_with(events: list[BaseModel]) -> ModelDispatchResult:

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@tests/unit/runtime/test_service_dispatch_result_applier.py` around lines 412
- 413, The helper function _make_result_with currently uses a broad events
parameter and silences a typing error with "type: ignore[type-arg]"; change the
signature to type events as list[BaseModel] to match
ModelDispatchResult.output_events and remove the ignore. Update the function
definition for _make_result_with(events: list[BaseModel]) -> ModelDispatchResult
so callers and the ModelDispatchResult construction use the correct typed list
of BaseModel.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@src/omnibase_infra/runtime/service_dispatch_result_applier.py`:
- Around line 136-166: The constructor stores the passed topic_router reference
directly (topic_router -> self._topic_router), which allows external mutation to
affect routing; defensively copy the mapping in __init__ so self._topic_router
is an independent dict (e.g., use a shallow copy when topic_router is not None)
and keep the existing fallback to an empty dict when topic_router is None;
update the assignment that sets self._topic_router in
ServiceDispatchResultApplier.__init__ to create that copy.

In `@tests/unit/runtime/test_service_dispatch_result_applier.py`:
- Around line 423-468: Add an assertion that the mock publish method was called
exactly once in each of the three tests
(test_topic_router_routes_known_event_to_declared_topic,
test_topic_router_falls_back_for_unknown_event_type,
test_no_topic_router_uses_output_topic) to catch unexpected duplicate publishes:
after awaiting applier.apply(result) assert the AsyncMock for
event_bus.publish_envelope was called exactly once (use
bus.publish_envelope.assert_awaited_once() or
bus.publish_envelope.assert_called_once() depending on whether publish_envelope
is awaited) before inspecting call_args.kwargs["topic"].
- Around line 412-413: The helper function _make_result_with currently uses a
broad events parameter and silences a typing error with "type:
ignore[type-arg]"; change the signature to type events as list[BaseModel] to
match ModelDispatchResult.output_events and remove the ignore. Update the
function definition for _make_result_with(events: list[BaseModel]) ->
ModelDispatchResult so callers and the ModelDispatchResult construction use the
correct typed list of BaseModel.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 66ad1cfe-d8ae-4b5b-be84-b6e3f57ceff9

📥 Commits

Reviewing files that changed from the base of the PR and between e8fc8c3 and 5e9e8fc.

📒 Files selected for processing (2)

• src/omnibase_infra/runtime/service_dispatch_result_applier.py
• tests/unit/runtime/test_service_dispatch_result_applier.py