docs(bf-53q6): note that feature was already complete

notes/bf-53q6.md

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+# bf-53q6: System Cgroup Memory Panel - Already Complete
+
+## Task
+Add system cgroup memory panel to web dashboard (real-time utilization + OOM event counter)
+
+## Status
+**ALREADY COMPLETE** - This bead was implemented in prior commits.
+
+## Implementation Details
+
+### Backend (src/systemCgroupMonitor.ts + src/web/server.ts)
+- `systemCgroupMonitor.ts` reads cgroup memory stats from `/sys/fs/cgroup/user.slice/user-1001.slice/`
+  - memory.current (usage)
+  - memory.high (soft limit)
+  - memory.max (hard limit)
+  - memory.events (oom_kill counter)
+  - memory.swap.current (swap usage)
+- Background sampler runs every 10s, maintaining 30-sample history (5 minutes)
+- API endpoints:
+  - `GET /api/system/memory` - current status
+  - `GET /api/system/memory/history` - sparkline data
+  - `GET /api/system/memory/summary` - formatted summary
+
+### Frontend Components
+- `SystemMemoryIndicator.tsx` (7.5KB)
+  - Compact progress bar (green <70%, yellow 70-90%, red >90%)
+  - 5-minute sparkline (30 bars, sampled every 10s)
+  - OOM kill counter badge
+  - Swap indicator
+  - Updates every 10s via polling
+
+- `SystemMemoryPanel.tsx` (23KB)
+  - Full detail modal with all cgroup stats
+  - System memory section (total, available)
+  - Swap section (total, free, used bar)
+  - FABRIC process RSS
+  - OOM risk legend
+  - Refresh button
+
+### Integration (App.tsx)
+- SystemMemoryIndicator in fleet header (line 928)
+- SystemMemoryPanel as modal (lines 1122-1125)
+- Toggle button in header (lines 872-877)
+
+## Related Commits
+- `81b57e6` refactor(bf-53q6): add SystemMemoryIndicator to fleet header and clean up cgroup monitor
+- `83baf06` feat(bf-53q6): integrate SystemMemoryPanel into FABRIC web dashboard
+- `820e509` feat(bf-53q6): integrate SystemMemoryPanel into FABRIC web dashboard
+
+## Verification
+- ✅ Web build successful (`npm run build:web`)
+- ✅ Type check passes (`tsc --noEmit`, excluding unrelated OTLP test errors)
+- ✅ All files committed and pushed