Event Bus Publish Guardrails + API i18n Cleanup

• Status: Accepted

• Date: 2025-12-28

• Context:

  • Event publishing failures were silently ignored, violating the no-error-suppression rule.
  • Several API error strings were missing i18n keys, breaking the localized error contract.
  • A few runtime logs still interpolated context into messages and needed structured fields.

• Decision:

  • Introduce EventBusError and make EventBus::publish return Result so failures are handled explicitly.
  • Add publish helpers in runtime services (API state, fsops, libtorrent worker, app bootstrap) that log publish failures with structured fields.
  • Expand the API i18n bundle to include new error keys used by settings and auth flows.
  • Move anyhow to dev-dependencies for revaer-api and remove the remaining debug assert/log interpolation in production paths.

• Consequences:

  • Positive outcomes: event publishing is no longer silently ignored; API error messages are consistently localizable; log output stays structured.
  • Risks or trade-offs: event publish errors are now surfaced via warnings, which may be noisy if the bus is misconfigured.

• Follow-up:

  • Implementation tasks: ensure downstream callers handle EventBusError where needed; keep i18n bundles in sync with new error keys.
  • Review checkpoints: confirm just ci passes and that SSE/event flows still deliver updates without regressions.

• Motivation:

  • Align runtime error handling with AGENT.md guardrails and remove hidden failure paths.

• Design notes:

  • Event bus publish errors expose event_id + event_kind for structured logging without embedding context in messages.
  • API error strings added to en.json match the exact keys emitted by handlers.

• Test coverage summary:

  • Not run in this change set; run just ci before release.

• Observability updates:

  • Added structured warning logs when event publishing fails.

• Risk & rollback plan:

  • Low risk; revert to prior publish semantics if event logging proves too noisy.

• Dependency rationale:

  • No new dependencies added.