refinement of upcoming tracks

conductor/tracks/performance_dashboard_20260306/spec.md

@@ -1,21 +1,39 @@
 # Track Specification: Performance Dashboard (performance_dashboard_20260306)
 
 ## Overview
-Expand performance metrics panel with CPU/RAM usage, frame time, input lag with historical graphs. Uses existing performance_monitor.py which has basic metrics but no visualization.
+Expand performance metrics panel with CPU/RAM graphs, frame time histogram. Uses existing `performance_monitor.py`.
 
-## Architectural Constraints
-- **60fps Constraint**: Metrics collection MUST NOT impact frame rate.
-- **Thread Safety**: Cross-thread metrics MUST use proper synchronization.
+## Current State Audit
+
+### Already Implemented
+- **`src/performance_monitor.py`**: `PerformanceMonitor` class
+- **`get_metrics()`**: Returns FPS, frame time, CPU, input lag
+- **Basic display in GUI diagnostics**
+
+### Gaps to Fill
+- No historical graphs
+- No rolling window storage
+- No frame time histogram
 
 ## Functional Requirements
-- **CPU/RAM Graphs**: Display rolling CPU and RAM usage over time.
-- **Frame Time**: Show frame time histogram.
-- **Input Lag**: Track and display input-to-response latency.
-- **Historical Data**: Maintain rolling window of metrics history.
+- Rolling window of metrics (deque with maxlen)
+- Line graphs for CPU/RAM over time
+- Frame time histogram
+- Uses existing `PerformanceMonitor.get_metrics()`
+
+## Key Integration Points
+| File | Purpose |
+|-----|---------|
+| `src/performance_monitor.py` | Add history storage |
+| `src/gui_2.py` | Graph rendering |
+
+## Architectural Constraints
+- 60fps during graph rendering
+- Memory bounded (max 100 data points)
 
 ## Acceptance Criteria
-- [ ] CPU graph shows rolling history.
-- [ ] RAM graph shows rolling history.
-- [ ] Frame time histogram displays.
-- [ ] Input lag metrics tracked.
-- [ ] Uses existing performance_monitor.py.
+- [ ] CPU graph shows rolling history
+- [ ] RAM graph shows rolling history
+- [ ] Frame time histogram displays
+- [ ] Input lag metrics tracked
+- [ ] 1-space indentation