Port 3 community hooks from gsd-skill-creator, gated behind hooks.community config flag. All hooks are registered on install but are no-ops unless the project config has hooks: { community: true }.
gsd-session-state.sh (SessionStart): outputs STATE.md head for orientation. gsd-validate-commit.sh (PreToolUse/Bash): blocks non-Conventional-Commits messages. gsd-phase-boundary.sh (PostToolUse/Write|Edit): warns when .planning/ files are modified.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
