This PR focuses strictly on reducing GitHub Actions costs by optimizing the CI matrix, as requested.
### Summary of Changes
1. **CI Matrix Optimization**:
- **Linux**: Retained the full matrix of Node.js versions (20.x, 22.x, 24.x) with sharding (`cli`, `others`) to ensure robust coverage on the primary platform.
- **macOS**: Reduced to a single job running Node.js 20.x (the recommended version). This eliminates the matrix and sharding for Mac, significantly reducing the usage of expensive Mac runners.
- **Impact**: Expected to reduce Mac runner usage by approximately 83% (from 6 jobs per run to 1 job per run) while maintaining core cross-platform compatibility checks.
2. **Scope Refinement**:
- Reverted unrelated changes to policy engines, documentation, and tests that were inadvertently included in previous iterations of this branch.
- Confirmed that optimizations in `gemini-cli-bot-pulse.yml` and `gemini-cli-bot-brain.yml` have been fully reverted to their baseline state.
### Data-Driven Justification
- **Mac Runner Cost**: macOS runners are significantly more expensive than Linux runners. By consolidating Mac testing into a single job for the recommended Node.js version, we maintain essential platform verification while minimizing cost.
- **Linux Matrix**: Moving the heavier matrix testing (multiple Node versions) to Linux leverages more cost-effective runners without sacrificing compatibility verification.
This PR implements several measures to reduce the cost of GitHub Actions usage, focusing on the highest-impact areas identified through real per-workflow minutes consumption analysis.
### Summary of Changes
1. **CI Matrix Optimization**: Reduced the `test_mac` matrix in `Testing: CI` to only run on Node.js 20.x.
- **Reason**: macOS runners (especially `macos-latest-large`) are significantly more expensive than Linux runners. Node.js 22.x and 24.x are still covered by the `test_linux` matrix, ensuring core compatibility. OS-specific issues are likely to be caught on the recommended Node.js version (20.x).
- **Impact**: Expected to reduce Mac runner usage by approximately 66% in the CI pipeline.
2. **Pulse Workflow Optimization**:
- Added a check to skip `npm ci` and subsequent steps if no reflex scripts are present in `tools/gemini-cli-bot/reflexes/scripts`.
- Reduced `fetch-depth` from 0 (full clone) to 1 (shallow clone).
- **Reason**: The Pulse workflow runs every 30 minutes. Installing dependencies when there is nothing to run is a waste of resources.
- **Impact**: Eliminates unnecessary dependency installation and reduces clone time for the Pulse workflow.
3. **Brain Workflow Optimization**:
- Reduced `fetch-depth` from 0 to 1.
- **Reason**: The Brain workflow does not require full repository history for its reasoning or metrics collection phases.
- **Impact**: Reduces clone time for the daily Brain workflow runs.
### Data-Driven Justification
Analysis of the last 7 days of metrics (`actions_spend_minutes`) showed:
- **Testing: CI**: 4074 minutes (approx. 64% of total spend).
- **macOS Runners**: The primary driver of CI cost due to high per-minute rates on large runners.
- **Pulse Workflow**: While frequent, it was not in the top list of spenders, but still represents low-hanging fruit for optimization.
These changes prioritize high-impact reductions in expensive runner minutes while maintaining robust cross-platform testing on the primary supported Node.js version.
gemini-cli[bot]