# Track Specification: Performance Dashboard (performance_dashboard_20260306)

## Overview
Expand performance metrics panel with CPU/RAM graphs, frame time histogram. Uses existing `performance_monitor.py`.

## 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
- 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
- [ ] 1-space indentation