# Component 24 Verification: Fleet-level Sentinel Link Coordination

## Status: Already Implemented

Component 24 (Fleet-level sentinel link coordination) was already fully implemented in `ratecontrol.go` at the time this bead was created.

## Verified Implementation

All requirements from the plan are present:

1. **Zone-level idle detection with sentinel designation**
   - Function: `designateSentinel()` (line 291)
   - Designates lexicographically smallest MAC as sentinel
   - Sentinel runs at 5 Hz (RateSentinel), others at 1 Hz (RateFleetIdle)
   - Test: `TestZoneIdleDetectionAndSentinelDesignation`

2. **Fleet-wide idle state tracking**
   - Field: `fleetIdle bool` (line 63)
   - Set when all zones are idle (line 285): `rc.fleetIdle = allZonesIdle && len(rc.zones) > 0`
   - Test: `TestFleetIdleDetection`

3. **Prediction engine preemptive zone ramping**
   - Method: `RampZone(zoneID string, rampAdjacent bool)` (line 189)
   - Ramps all nodes in zone to active rate (50 Hz)
   - Optionally ramps adjacent zones to sentinel (5 Hz)
   - Test: `TestRampZonePredictionEngine`

4. **1 Hz floor rate for fully-idle fleet**
   - Constant: `RateFleetIdle = 1` (line 19)
   - Applied to non-sentinel nodes in `designateSentinel()` (line 308)

## Tests Passing

All 15 ratecontrol tests pass, including:
- Zone-aware idle detection and sentinel designation
- Fleet idle state tracking
- Adjacent zone ramping on activation
- Prediction engine RampZone method
- Sentinel redesignation on node disconnect

## Implementation Date

The commit history shows this was implemented in commit `9c36b0d`:
```
feat(bf-28dv): implement zone-aware rate control (Component 24)
```

This bead serves as documentation that Component 24 is complete.