bug(events): LoggingEventBus.emit() handler exception block missing exc_info=True — no traceback logged #1311

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opened 2026-04-02 11:04:16 +00:00 by CoreRasurae · 0 comments

CoreRasurae commented

2026-04-02 11:04:16 +00:00

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Metadata

Commit Message: fix(events): add exc_info=True to LoggingEventBus.emit() handler exception block
Branch: bugfix/m5-logging-bus-exception-swallow

Background

Discovered during code review of PR #1174 (fix for #988). Issue #988 fixed the identical omission in ReactiveEventBus.emit() — this issue tracks the same pattern in the sibling EventBus protocol implementation.

LoggingEventBus is the other EventBus protocol implementation in the infrastructure/events/ package. While ReactiveEventBus is the production DI registrant (registered as Singleton in the container), LoggingEventBus is used in test contexts and is a protocol-compliant implementation that should behave consistently.

Current Behavior

logging_bus.py:76-83: The handler exception block in LoggingEventBus.emit() logs error_type=type(exc).__name__ and error=str(exc) but does not include exc_info=True. When a subscriber handler fails, the log contains the exception type and message text but no traceback. This is the same class of bug that #988 identified and fixed in ReactiveEventBus.

except Exception as exc:
    _logger.warning(
        "logging_event_handler_failed",
        event_type=event.event_type.value,
        handler=getattr(handler, "__qualname__", repr(handler)),
        error_type=type(exc).__name__,
        error=str(exc),
        # ← no exc_info=True — traceback is lost
    )

Expected Behavior

The handler exception block should include exc_info=True so that structlog forwards the full traceback to the configured log output, consistent with the fix applied to ReactiveEventBus in PR #1174.

Acceptance Criteria

LoggingEventBus.emit() handler exception block includes exc_info=True
Behavior is consistent with ReactiveEventBus.emit() exception handling (both protocol implementations forward tracebacks)
Unit test verifies exc_info appears in the log entry when a handler raises
nox passes with coverage >= 97%

Subtasks

Add exc_info=True to the _logger.warning() call in LoggingEventBus.emit() handler exception block (src/cleveragents/infrastructure/events/logging_bus.py:77-83)
Remove @tdd_expected_fail tag from the corresponding TDD test once fix is applied
Update CHANGELOG.md with fix entry
Run nox (all default sessions), fix any errors

References

Sibling fix: PR #1174 / Issue #988 (ReactiveEventBus)
File: src/cleveragents/infrastructure/events/logging_bus.py:76-83
Specification: docs/specification.md §Event System — EventBus protocol

Definition of Done

This issue is complete when:

All subtasks above are completed and checked off.
A Git commit is created where the first line of the commit message matches the Commit Message in Metadata exactly, followed by a blank line, then additional lines providing relevant details about the implementation.
The commit is pushed to the remote on the branch matching the Branch in Metadata exactly.
The commit is submitted as a pull request to master, reviewed, and merged before this issue is marked done.

## Metadata - **Commit Message**: `fix(events): add exc_info=True to LoggingEventBus.emit() handler exception block` - **Branch**: `bugfix/m5-logging-bus-exception-swallow` ## Background Discovered during code review of PR #1174 (fix for #988). Issue #988 fixed the identical omission in `ReactiveEventBus.emit()` — this issue tracks the same pattern in the sibling `EventBus` protocol implementation. `LoggingEventBus` is the other `EventBus` protocol implementation in the `infrastructure/events/` package. While `ReactiveEventBus` is the production DI registrant (registered as Singleton in the container), `LoggingEventBus` is used in test contexts and is a protocol-compliant implementation that should behave consistently. ## Current Behavior `logging_bus.py:76-83`: The handler exception block in `LoggingEventBus.emit()` logs `error_type=type(exc).__name__` and `error=str(exc)` but does **not** include `exc_info=True`. When a subscriber handler fails, the log contains the exception type and message text but no traceback. This is the same class of bug that #988 identified and fixed in `ReactiveEventBus`. ```python except Exception as exc: _logger.warning( "logging_event_handler_failed", event_type=event.event_type.value, handler=getattr(handler, "__qualname__", repr(handler)), error_type=type(exc).__name__, error=str(exc), # ← no exc_info=True — traceback is lost ) ``` ## Expected Behavior The handler exception block should include `exc_info=True` so that structlog forwards the full traceback to the configured log output, consistent with the fix applied to `ReactiveEventBus` in PR #1174. ## Acceptance Criteria - [ ] `LoggingEventBus.emit()` handler exception block includes `exc_info=True` - [ ] Behavior is consistent with `ReactiveEventBus.emit()` exception handling (both protocol implementations forward tracebacks) - [ ] Unit test verifies `exc_info` appears in the log entry when a handler raises - [ ] `nox` passes with coverage >= 97% ## Subtasks - [ ] Add `exc_info=True` to the `_logger.warning()` call in `LoggingEventBus.emit()` handler exception block (`src/cleveragents/infrastructure/events/logging_bus.py:77-83`) - [ ] Remove `@tdd_expected_fail` tag from the corresponding TDD test once fix is applied - [ ] Update CHANGELOG.md with fix entry - [ ] Run `nox` (all default sessions), fix any errors ## References - Sibling fix: PR #1174 / Issue #988 (`ReactiveEventBus`) - File: `src/cleveragents/infrastructure/events/logging_bus.py:76-83` - Specification: `docs/specification.md` §Event System — `EventBus` protocol ## Definition of Done This issue is complete when: - All subtasks above are completed and checked off. - A Git commit is created where the **first line** of the commit message matches the Commit Message in Metadata exactly, followed by a blank line, then additional lines providing relevant details about the implementation. - The commit is pushed to the remote on the branch matching the **Branch** in Metadata exactly. - The commit is submitted as a **pull request** to `master`, reviewed, and **merged** before this issue is marked done.

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2026-04-02 11:04:32 +00:00