How do I install the Invalid Sidecar skill?

Run npx skillmds@latest add jacob-balslev/invalid-sidecar in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Invalid Sidecar safe to use?

This skill has not completed SkillMD's automated safety review yet. Capability flags: docs only. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Invalid Sidecar?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Invalid Sidecar free to use?

Yes. Installing skills from SkillMD is free. This skill is licensed under Apache-2.

Who published Invalid Sidecar?

jacob-balslev (@jacob-balslev) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Invalid Sidecar by jacob-balslev — Agent Skill

Name: Invalid Sidecar
Rating: 4.5 (4 reviews)
Author: jacob-balslev

Invalid Sidecar

Negative fixture for the gate-conformance suite: the SKILL.md frontmatter is fully valid, but the sibling audit-state.json sidecar is missing the required `owner` field. Activate only inside test-gate-conformance.js to prove the structural lint gate validates the sidecar against schemas/skill-audit-state.schema.json. Do NOT use as a production skill.

jacob-balslev 0ee84df 2 files · 2.2 KB Updated Sep 10, 2026

File contents

Invalid Sidecar (negative fixture)

This fixture is intentionally invalid at the SIDECAR layer: the SKILL.md frontmatter is valid, but audit-state.json omits the required owner field. The structural lint gate validates the sidecar against its schema and MUST reject this.

Concept of the skill

What it is: A deliberately broken capability skill used only by the conformance runner. Mental model: Keep the frontmatter valid but break the sibling audit-state.json so the sidecar-schema branch of the structural gate is the thing under test. Why it exists: To guard the sidecar-validation path — a regression that stopped validating audit-state.json against its schema would otherwise pass the suite. What it is NOT: It is not a production skill and never routes outside the test runner. Adjacent concepts: the other negative fixtures under this directory; the audit-state.json sidecar (ADR-0019); the skill-audit-state schema. One-line analogy: It is a form with the body filled in but a required field on the attached cover sheet left blank. Common misconception: That sidecar validity is the Behavior Gate's concern — it is structural (the Integrity Gate validates the sidecar shape before any eval runs).

Coverage

Valid frontmatter, invalid sidecar (missing required owner) → structural lint failure.

Philosophy of the skill

One broken layer per fixture keeps the failing assertion unambiguous.

Verification

Exercised by the gate-conformance runner; expected to fail structural lint with a sidecar required-field error.

Do NOT Use When

Always. This is a test fixture, not a usable skill.

---name: invalid-sidecardescription: Negative fixture for the gate-conformance suite: the SKILL.md frontmatter is fully valid, but the sibling audit-state.json sidecar is missing the required `owner` field. Activate only inside test-gate-conformance.js to prove the structural lint gate validates the sidecar against schemas/skill-audit-state.schema.json. Do NOT use as a production skill.license: Apache-2.0---# Invalid Sidecar (negative fixture)This fixture is intentionally invalid at the SIDECAR layer: the SKILL.md frontmatteris valid, but `audit-state.json` omits the required `owner` field. The structurallint gate validates the sidecar against its schema and MUST reject this.## Concept of the skill**What it is:** A deliberately broken capability skill used only by the conformance runner.**Mental model:** Keep the frontmatter valid but break the sibling audit-state.json so the sidecar-schema branch of the structural gate is the thing under test.**Why it exists:** To guard the sidecar-validation path — a regression that stopped validating audit-state.json against its schema would otherwise pass the suite.**What it is NOT:** It is not a production skill and never routes outside the test runner.**Adjacent concepts:** the other negative fixtures under this directory; the audit-state.json sidecar (ADR-0019); the skill-audit-state schema.**One-line analogy:** It is a form with the body filled in but a required field on the attached cover sheet left blank.**Common misconception:** That sidecar validity is the Behavior Gate's concern — it is structural (the Integrity Gate validates the sidecar shape before any eval runs).## CoverageValid frontmatter, invalid sidecar (missing required `owner`) → structural lint failure.## Philosophy of the skillOne broken layer per fixture keeps the failing assertion unambiguous.## VerificationExercised by the gate-conformance runner; expected to fail structural lint with a sidecar required-field error.## Do NOT Use When- Always. This is a test fixture, not a usable skill.

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