External Skill Fixture Builder

External Skill Fixture Builder

Use this skill when a third-party ecosystem pattern should be tested by skill-harness but should not become a live dependency.

Process

• Choose the fixture lane by install posture, not by brand:
  • pure SKILL.md pack
  • plugin manifest
  • Cursor .mdc rules
  • Codex/Claude/Cursor subagents
  • MCP/tool config
  • generated record/replay skill
  • Beads or task-memory repo
  • multi-agent workspace layout
• Use minimal synthetic fixtures when possible.
• Use pinned external snapshots only when real structure matters and license/provenance allows it.
• Keep fixtures out of global user directories and live install caches.
• Make the fixture assert one behavior: parse, classify, trust recommendation, drift detection, render target, or installer opt-in.
• Add a command or check that proves the fixture is exercised.

Output

Fixture Lane

Source Or Synthetic Basis

Files Included

Expected Classification

Risk Flags Expected

Check Command

Follow-Up Adoption Question

Avoid

• making fixtures large mirrors of public repos
• using fixtures as a back door for third-party adoption
• mixing fixture coverage with default installer behavior
• storing credentials, real traces, browser recordings, or private task state in fixtures