## Step 7 Results: Error Handling Standardization and Operational Visibility

## Summary

Step 7 was implemented across the MVP runtime boundaries with a shared error taxonomy, actionable UI error surfacing, worker failure normalization, and API error envelope handling.

All required validation gates in `docs/step7.md` were executed and passed.

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## Scope Delivered

### Implemented
- Shared application error contract and taxonomy
- Service-layer error normalization (upload + transcription)
- UI error presentation helpers with suggested actions and error references
- Worker failure persistence format with category/suggestion/error_id markers
- API exception handlers for structured error responses
- Targeted tests for new error contract behavior

### Not implemented in this step
- External lane execution (`-m external`) was not required for Step 7 completion and was not run in this pass.

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## Files Added

- `src/transcription/errors.py`
- `src/transcription/api/errors.py`
- `src/transcription/ui/error_presenter.py`
- `tests/test_errors.py`
- `tests/api/test_error_responses.py`
- `docs/step7.md`

## Files Updated

- `src/transcription/app.py`
- `src/transcription/services/upload.py`
- `src/transcription/services/transcription.py`
- `src/transcription/ui/upload_page.py`
- `src/transcription/ui/jobs_page.py`
- `src/transcription/worker.py`
- `tests/services/test_upload.py`
- `tests/services/test_transcription.py`
- `tests/services/test_worker.py`
- `tests/integration/test_pipeline_flow.py`
- `uv.lock`

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## Implementation Notes by Phase

### Phase A/B (Foundation)
- Added `ErrorCategory` enum and `AppError` base type in `src/transcription/errors.py`.
- Added helper utilities:
  - `new_error_id()`
  - `build_error_envelope(...)`
  - `classify_unexpected_error(...)`
  - `format_error_detail(...)`

### Phase C (Service/Provider normalization)
- `UploadError` now extends `AppError` and includes category/suggestion/retriable metadata.
- `PromptLoadError` and `TranscriptionError` now extend `AppError`.
- Provider failures are mapped with deterministic category semantics (auth/payload/provider-failure cases).

### Phase D (UI visibility)
- Added `src/transcription/ui/error_presenter.py`.
- Upload and jobs pages now use centralized UI error rendering and summary helpers.
- UI error paths now include more visible/actionable guidance and reference IDs.

### Phase E (Worker failure handling)
- Worker now normalizes exception handling into structured persisted `error_detail` strings with:
  - category marker
  - suggestion marker
  - error_id marker
- Logging now includes category/error_id context in failure paths.

### Phase F (API envelope)
- Added `src/transcription/api/errors.py` and registered handlers in app factory.
- AppError and unexpected exceptions now serialize to stable API envelopes with mapped status codes.

---

## Validation Commands and Outcomes

All commands were executed with `uv run python -m pytest ...` and completed successfully.

1. `uv run python -m pytest tests/test_errors.py -q` ✅
2. `uv run python -m pytest tests/services/test_upload.py -q` ✅
3. `uv run python -m pytest tests/services/test_transcription.py -q` ✅
4. `uv run python -m pytest tests/providers/test_openrouter.py -q` ✅
5. `uv run python -m pytest tests/services/test_worker.py -q` ✅
6. `uv run python -m pytest tests/integration/test_pipeline_flow.py -q` ✅
7. `uv run python -m pytest tests/api/test_error_responses.py -q` ✅
8. `uv run python -m pytest tests/ui/test_upload_page.py -q` ✅
9. `uv run python -m pytest tests/ui/test_jobs_page.py -q` ✅
10. `uv run python -m pytest -m "not external" -q` ✅
11. `uv run python -m pytest --collect-only -q` ✅
12. `uv run python -m pytest -m unit -q` ✅
13. `uv run python -m pytest -m integration -q` ✅
14. `uv run python -m pytest tests/integration/test_pipeline_flow.py -q` ✅
15. `uv run python -m pytest tests/ui/test_upload_page.py -q` ✅
16. `uv run python -m pytest tests/ui/test_jobs_page.py -q` ✅
17. `uv run python -m pytest -q` ✅

Observed warning (non-blocking): Starlette/FastAPI TestClient deprecation warning related to `httpx` package naming.

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## Policy Alignment Check (`docs/error_handling.md`)

Aligned items:
- Stable taxonomy categories are implemented.
- Unexpected errors are normalized.
- User-facing UI paths include actionable guidance and references.
- Worker persistence includes trace-friendly failure detail.
- API error responses are structured and category-aware.

Follow-up candidates:
- Add richer UI tests that validate rendered suggested-action content end-to-end (current tests focus helper/service contracts).
- Consider typed storage fields for error metadata instead of packed `error_detail` strings in a future schema revision.

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## Step 7 Definition of Done Status

- [x] Shared error taxonomy implemented across MVP layers
- [x] GUI error paths upgraded for visibility/actionability
- [x] Worker failure persistence and log context standardized
- [x] API error envelope handling added and tested
- [x] Phase-level and full-suite validation gates passed
- [x] Results documented in this report

Step 7 is complete.