/sem-integration

name: sem-integration
description: Provides sem semantic-diff detection, install-on-first-use, and fallback patterns. Use when building skills that consume git diff output.
alwaysApply: false
category: infrastructure
tags:
- sem
- semantic-diff
- git
- foundation
provides:
  infrastructure:
  - sem-detection
  - sem-fallback
  patterns:
  - install-on-first-use
  - graceful-degradation
estimated_tokens: 400
progressive_loading: true
module_strategy: reference-based
modules:
- modules/detection.md
- modules/fallback.md

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:

# 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):

sem diff --format json <baseline>

Fallback path (sem unavailable):

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):

sem impact --json <file-or-entity>

Fallback path (sem unavailable): use rg/grep to trace callers by filename. See `modules/fallback.md`.

Exit Criteria

• [ ] `_sem_check` result cached per session at

`${CLAUDE_CODE_TMPDIR:-/tmp}/sem-available`; detection command runs at most once per session regardless of how many skills invoke it

• [ ] When sem is unavailable, install offer presented and fallback

path used automatically (`git diff --name-only --diff-filter=` variants); no silent failure

• [ ] Fallback output normalized to the same entity schema as sem

JSON output per `modules/fallback.md`; consumers downstream see the same structure from both paths

• [ ] Skills consuming this integration declare

`dependencies: [leyline:sem-integration]` in frontmatter rather than reimplementing the detection pattern