Document-processing tests

Use these suites when changing upload, status, processing, or edit-history behavior.

Key suites

api/tests/test_document_edit_audit.py — edit diff computation, one-time patch restriction, status gating, and audit creation.
api/tests/test_edit_history.py — persistence and response shaping for edit_history.
tests/integration/test_document_processing.py — upload and status path integration.
tests/integration/test_async_document_processing.py — Celery-backed polling flow.
tests/unit/processing/test_upload_validation.py — upload validation rules.
tests/unit/processing/test_document_classification_toggle.py — classification behavior switch.

edit_history is saved and accumulated correctly
edited_by is derived from the authenticated user rather than the client payload
completed documents cannot be patched arbitrarily
task polling reads the persisted processing row
upload validation rejects malformed requests early

Prefer the smallest test slice that matches the code path:

request validation only → tests/unit/processing/test_upload_validation.py
edit history or audit semantics → api/tests/test_document_edit_audit.py and api/tests/test_edit_history.py
queue/poll behavior → tests/integration/test_async_document_processing.py