docs(07-01): complete config history UI timeline plan

- SUMMARY.md with plan execution results
- STATE.md updated to phase 7 complete
- ROADMAP.md and REQUIREMENTS.md updated

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

.planning/phases/07-config-history-ui/07-01-SUMMARY.md

@@ -0,0 +1,89 @@
+---
+phase: 07-config-history-ui
+plan: 01
+subsystem: ui
+tags: [react, tanstack-query, timeline, config-history]
+
+requires:
+  - phase: 06-history-api
+    provides: GET /api/tenants/{tid}/devices/{did}/config-history endpoint
+provides:
+  - ConfigHistorySection component with timeline rendering
+  - configHistoryApi.list() API client function
+  - Configuration history visible on device detail overview tab
+affects: [07-config-history-ui]
+
+tech-stack:
+  added: []
+  patterns: [timeline component pattern matching BackupTimeline.tsx]
+
+key-files:
+  created:
+    - frontend/src/components/config/ConfigHistorySection.tsx
+  modified:
+    - frontend/src/lib/api.ts
+    - frontend/src/routes/_authenticated/tenants/$tenantId/devices/$deviceId.tsx
+
+key-decisions:
+  - "Reimplemented formatRelativeTime locally rather than extracting shared util (matches BackupTimeline pattern)"
+  - "Poll interval 60s via refetchInterval for near-real-time change visibility"
+
+patterns-established:
+  - "Config history timeline: vertical dot timeline with component badge, summary, line delta, relative time"
+
+requirements-completed: [UI-01, UI-02]
+
+duration: 3min
+completed: 2026-03-13
+---
+
+# Phase 7 Plan 1: Config History UI Summary
+
+**ConfigHistorySection timeline component on device detail page, fetching change entries via TanStack Query with 60s polling**
+
+## Performance
+
+- **Duration:** 3 min
+- **Started:** 2026-03-13T04:11:08Z
+- **Completed:** 2026-03-13T04:14:00Z
+- **Tasks:** 2
+- **Files modified:** 3
+
+## Accomplishments
+- Added configHistoryApi.list() and ConfigChangeEntry interface to api.ts
+- Created ConfigHistorySection with vertical timeline, loading skeleton, and empty state
+- Wired component into device detail overview tab below Interface Utilization
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: API client and ConfigHistorySection component** - `6bd2451` (feat)
+2. **Task 2: Wire ConfigHistorySection into device detail page** - `36861ff` (feat)
+
+## Files Created/Modified
+- `frontend/src/lib/api.ts` - Added ConfigChangeEntry interface and configHistoryApi.list()
+- `frontend/src/components/config/ConfigHistorySection.tsx` - Timeline component with loading/empty/data states
+- `frontend/src/routes/_authenticated/tenants/$tenantId/devices/$deviceId.tsx` - Import and render ConfigHistorySection
+
+## Decisions Made
+- Reimplemented formatRelativeTime locally (same pattern as BackupTimeline.tsx) rather than extracting to shared util -- keeps components self-contained
+- Used 60s refetchInterval for polling new config changes
+
+## 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 renders on device overview tab
+- Ready for any future detail/drill-down views on individual changes
+
+---
+*Phase: 07-config-history-ui*
+*Completed: 2026-03-13*