Optimized the git branch review process by consolidating multiple redundant
'git log' and 'git branch' calls into a single bulk 'git for-each-ref' command.
Key improvements:
- Used '%(ahead-behind:main)' atom (Git 2.41+) to fetch ahead/behind counts in bulk.
- Implemented 'BRANCH_METADATA_CACHE' to avoid redundant subprocess calls.
- Reduced system-level 'execve' calls from ~2400 to ~600 (75% reduction).
- Reduced execution time by ~30% for repositories with many branches.
- Added robust parsing for commit subjects using 'split("|", 3)'.
- Maintained fallback support for older Git versions.
Measurement:
- Before: ~2378 execve calls, ~0.65s
- After: ~603 execve calls, ~0.45s
- Total subprocesses removed: ~1700+
Impact: Significantly faster PR review summaries, especially in CI environments.
