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+---
+plan: 06-03
+phase: 06-performance-production-hardening
+status: complete
+completed_at: 2026-06-03
+commits:
+  - fb35f0e
+  - 5a93257
+self_check: PASSED
+---
+
+# Plan 06-03: Locust Load Test Implementation
+
+## What was built
+
+Full Locust load test for Phase 6 SLA verification (D-04, D-05, D-06).
+
+### Files created
+
+| File | Purpose |
+|------|---------|
+| `backend/requirements-dev.txt` | Dev-only deps with `locust>=2.34.0`; includes `-r requirements.txt` |
+| `backend/load_tests/locustfile.py` | Full DocuVaultUser implementation (121 lines) |
+| `backend/load_tests/README.md` | Operator guide: install, run command, env vars, SLA semantics, cleanup |
+
+### Key decisions
+
+**Credential strategy: Option A (self-bootstrapping)**
+`on_start()` calls `POST /api/auth/register` (409 silently ignored), then `POST /api/auth/login`. Zero out-of-band setup; works against a clean DB.
+
+**Upload endpoint: direct `/api/documents/upload`**
+Confirmed against `backend/api/documents.py`: accepts `UploadFile file` + `Form target_backend="minio"`. Used over the presigned-URL flow (upload-url → MinIO PUT → confirm) because it is a single HTTP call from the Locust process perspective, simpler to implement correctly, and exercises the same code path for performance measurement.
+
+**Task weights (D-05 realistic session)**
+| Task | Weight | Endpoint |
+|------|--------|----------|
+| list_documents | 5 | GET /api/documents/ |
+| get_document | 3 | GET /api/documents/{id} |
+| upload_document | 2 | POST /api/documents/upload |
+| refresh_token | 1 | POST /api/auth/refresh |
+
+**SLA listener (D-06)**
+`@events.quitting.add_listener check_sla` reads `stats.total.get_response_time_percentile(0.95/0.99)` and `fail_ratio`. Sets `environment.process_exit_code = 1` if: fail_ratio > 1%, p95 > 200ms, or p99 > 500ms.
+
+## Acceptance criteria verification
+
+- `locust` in requirements-dev.txt only (not requirements.txt): ✓
+- Syntax valid (`ast.parse`): ✓
+- `class DocuVaultUser`: 1 ✓
+- No `raise NotImplementedError` stubs: 0 ✓
+- `events.quitting.add_listener`: 1 ✓
+- `@task` decorators: 4 ✓
+- p95 and p99 references: present ✓
+- No application code imports: 0 ✓
+- README.md with LOAD_TEST_EMAIL documentation: ✓
+
+## Notes for downstream plans
+
+- Plan 06-06 should reference this file in the RUNBOOK.md under the "Load Testing" section
+- The load test user (`loadtest@example.com`) will persist in the DB after a run — operator cleanup documented in README.md
+- Locust is intentionally excluded from the production Dockerfile; the production requirements.txt is unchanged