# Track Specification: Cost & Token Analytics Panel (cost_token_analytics_20260306)

## Overview
Real-time cost tracking panel displaying cost per model, session totals, and breakdown by tier. Uses existing cost_tracker.py which is implemented but has no GUI.

## Architectural Constraints
- **Non-Blocking**: Cost calculations MUST NOT block UI thread.
- **Efficient Updates**: Updates SHOULD be throttled to <10ms latency.

## Functional Requirements
- **Cost Display**: Show real-time cost for current session.
- **Per-Model Breakdown**: Display cost grouped by model (Gemini, Anthropic, DeepSeek).
- **Tier Breakdown**: Show cost grouped by tier (Tier 1-4).
- **Session Totals**: Accumulate and display total session cost.

## Acceptance Criteria
- [ ] Cost panel displays in GUI.
- [ ] Per-model cost shown correctly.
- [ ] Tier breakdown accurate.
- [ ] Total accumulates correctly.
- [ ] Uses existing cost_tracker.py functions.