docs(06-01): complete config history timeline plan

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.planning/phases/06-history-api/06-01-SUMMARY.md

@@ -0,0 +1,95 @@
+---
+phase: 06-history-api
+plan: 01
+subsystem: api
+tags: [fastapi, sqlalchemy, pagination, timeline, rbac]
+
+# Dependency graph
+requires:
+  - phase: 05-diff-engine
+    provides: router_config_changes and router_config_diffs tables with parsed change data
+provides:
+  - GET /api/tenants/{tid}/devices/{did}/config-history endpoint
+  - get_config_history service function with pagination
+affects: [06-02, frontend-config-history]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns: [raw SQL text() joins for timeline queries, same RBAC pattern as config_backups]
+
+key-files:
+  created:
+    - backend/app/services/config_history_service.py
+    - backend/app/routers/config_history.py
+    - backend/tests/test_config_history_service.py
+  modified:
+    - backend/app/main.py
+
+key-decisions:
+  - "Raw SQL text() for JOIN query consistent with config_diff_service.py pattern"
+  - "Pagination defaults: limit=50, offset=0 with validation (ge=1, le=200 for limit)"
+
+patterns-established:
+  - "Config history queries use JOIN between changes and diffs tables for timeline view"
+
+requirements-completed: [API-01, API-04]
+
+# Metrics
+duration: 2min
+completed: 2026-03-13
+---
+
+# Phase 6 Plan 1: Config History Timeline Summary
+
+**GET /config-history endpoint returning paginated change timeline with component, summary, timestamp, and diff metadata via JOIN query**
+
+## Performance
+
+- **Duration:** 2 min
+- **Started:** 2026-03-13T03:58:03Z
+- **Completed:** 2026-03-13T04:00:00Z
+- **Tasks:** 2
+- **Files modified:** 4
+
+## Accomplishments
+- Config history service querying router_config_changes JOIN router_config_diffs for timeline entries
+- REST endpoint with viewer+ RBAC and config:read scope enforcement
+- 4 unit tests covering formatting, empty results, pagination, and ordering
+- Router registered in main.py alongside existing config routers
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Config history service and tests (TDD)** - `f7d5aec` (feat)
+2. **Task 2: Config history router and main.py registration** - `5c56344` (feat)
+
+## Files Created/Modified
+- `backend/app/services/config_history_service.py` - Query function for paginated config change timeline
+- `backend/app/routers/config_history.py` - REST endpoint with RBAC, pagination query params
+- `backend/tests/test_config_history_service.py` - 4 unit tests with AsyncMock sessions
+- `backend/app/main.py` - Router import and registration
+
+## Decisions Made
+- Used raw SQL text() for the JOIN query, consistent with config_diff_service.py pattern
+- Pagination limit constrained to 1-200 via FastAPI Query validation
+- Copied _check_tenant_access helper (same pattern as config_backups.py)
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+None
+
+## User Setup Required
+None - no external service configuration required.
+
+## Next Phase Readiness
+- Config history timeline endpoint ready for frontend consumption
+- Plan 06-02 can build on this for detailed diff view endpoints
+
+---
+*Phase: 06-history-api*
+*Completed: 2026-03-13*