This PR implements several critical improvements to repository health monitoring and automated triage workflows.
### Summary of Changes
1. **Backlog Age Metric**: Added `tools/gemini-cli-bot/metrics/scripts/backlog_age.ts` to measure the median and P90 age of open issues and PRs. This addresses the "Survivorship Bias" in current latency metrics, which only sample recently closed items.
2. **Metrics Persistence**: Fixed a bug in `tools/gemini-cli-bot/metrics/index.ts` that limited the timeseries history to 100 lines (effectively ~2 runs). Increased to 5000 lines to preserve historical trends.
3. **Robust Stale Closer**: Upgraded `.github/workflows/gemini-scheduled-stale-issue-closer.yml` to a 2-phase system (Mark as Stale -> Close). This centralized logic replaces the throttled default stale action and includes robust human activity detection.
4. **Triage Bug Fix**: Fixed a critical bug in `.github/workflows/unassign-inactive-assignees.yml` where a missing `for` loop caused the script to fail.
5. **Policy Consolidation**: Disabled issue staleness in `.github/workflows/stale.yml` to avoid conflicts with the new custom 2-phase closer.
### Why this is recommended
- **Data-Driven Triage**: Without backlog age metrics, we were blind to the "Slow Path" backlog that is growing despite fast "recently closed" latency.
- **Automated Hygiene**: The broken and throttled triage workflows were allowing the backlog to grow unchecked (now at 2351 issues). These fixes restore automated pruning.
- **Metrics Reliability**: Expanding the timeseries window ensures that deltas and trends are calculated against stable historical data.
### Impact
- **Backlog Visibility**: New metrics will show the real age of open items.
- **Throughput**: Increased stale closer throughput will begin reducing the 2300+ issue backlog.
- **Reliability**: Automated unassignment of inactive contributors will keep "help wanted" items moving.
gemini-cli[bot]