sem-integration

# sem Integration Foundation patterns for using [sem](https://github.com/Ataraxy-Labs/sem) semantic diffs in night-market skills. ## When To Use Consult this skill when building or modifying skills that consume git diff output. It provides the detection, installation, and fallback patterns. ## When NOT To Use - Direct sem CLI usage (just run `sem diff` yourself) - Skills that don't consume diff output ## Detection Pattern Check sem availability once per session: ```bash # Detection (cache per session) _sem_check() { local cache="${CLAUDE_CODE_TMPDIR:-/tmp}/sem-available" if [ -f "$cache" ]; then cat "$cache" return fi if command -v sem &>/dev/null; then echo "1" | tee "$cache" else echo "0" | tee "$cache" fi } ``` When `_sem_check` returns `0`, offer installation. See `modules/detection.md` for install-on-first-use logic and platform-specific commands. ## Semantic Diff Pattern Primary path (sem available): ```bash sem diff --format json <baseline> ``` Fallback path (sem unavailable): ```bash git diff --name-only --diff-filter=A <baseline> git diff --name-only --diff-filter=M <baseline> git diff --name-only --diff-filter=D <baseline> git diff --name-only --diff-filter=R <baseline> ``` See `modules/fallback.md` for output normalization that produces the same entity schema from both paths. ## Impact Analysis Pattern Primary path (sem available): ```bash sem impact --json <file-or-entity> ``` Fallback path (sem unavailable): use rg/g...