Fix Metrics History Retention & Accuracy
This PR addresses several issues identified in the repository's metrics collection and analysis pipeline:
1. **Increased History Retention**: Increased the rolling window in `metrics/index.ts` from 100 rows to 5000 rows. The previous limit was too small (holding only ~1.5 runs of data), which prevented meaningful delta calculations.
2. **Restored Backlog Age Metric**: Re-introduced `backlog_age.ts` to calculate the average age of the oldest 100 open issues. This provides visibility into backlog stagnation.
3. **Enhanced Throughput Accuracy**: Updated `throughput.ts` to distinguish between items **authored** by maintainers and items **processed** (merged/closed) by maintainers. This gives a more accurate measure of maintainer velocity.
4. **Added Bottleneck Analysis**: Introduced `bottlenecks.ts` to sample open PRs and identify if they are likely waiting on a maintainer review or an author's response.
These changes will significantly improve the "Brain's" ability to identify trends and bottlenecks in the repository workflow.
# Impact
- More accurate 7-day and 30-day deltas for all metrics.
- Better visibility into maintainer workload and backlog health.
- Data-driven identification of whether bottlenecks are due to maintainer capacity or author responsiveness.
gemini-cli[bot]