Sprint 8 - Parallel Hook Optimization Success

Metadata

Implementation: Change V5.5.0 (Sprint 8)
Issues: #321, #322, #323, [Sprint 8] perf: Add cooldown to project-hygiene cleanup hook (#324)
Sprint: Sprint 8

Implementing RFC-Hook-Efficiency-Improvements Phase 1: Quick Wins. Four independent hook optimization tasks needed to be executed.

File Conflict Detection Validated: Pre-dispatch analysis confirmed no file overlap between tasks:
- #321 → plugins/viz-platform/hooks/hooks.json
- #322 → plugins/git-flow/hooks/branch-check.sh
- #323 → plugins/git-flow/hooks/commit-msg-check.sh
- #324 → plugins/project-hygiene/hooks/cleanup.sh
Parallel Execution Worked: All 4 executor agents ran simultaneously without conflicts.
Simple Changes, High Impact: Each change was XS/S effort but addresses real performance issues:
- Removed zero-value echo hook
- Added early exit for 90%+ of Bash commands
- Added cooldown to reduce filesystem scans

Hook optimization is low-hanging fruit: Most hooks can be optimized with simple early-exit checks.
Early grep before expensive operations: Pattern if ! grep -q 'pattern'; then exit 0; fi is extremely effective for PreToolUse hooks.
Session-scoped cooldowns via $PPID: Using /tmp/hook-name-${PPID}-last-run effectively limits hook frequency per session without affecting other sessions.