Proposal: bidirectional SkillSpector ↔ ATR category crosswalk (SARIF interop)

Summary

Propose a bidirectional crosswalk between SkillSpector's category/rule IDs and ATR (Agent Threat Rules), a separate open MIT detection ruleset for AI-agent attacks. Both tools emit SARIF 2.1.0 with ruleId and target the same SKILL.md threat surface (prompt injection, MCP tool poisoning, data exfiltration, privilege escalation, supply chain), so a category↔category mapping lets a user who runs one tool reason about the other's output, and — more usefully — surfaces coverage gaps in both directions.

This is interop, not a request to import or depend on anything. SkillSpector stays the engine; the crosswalk is a static reference artifact.

Why this is distinct from #221

#221 maps SkillSpector rules to an OWASP framework (AST10) — a checklist taxonomy. This is a different axis: a peer detection engine's categories, where each side has concrete rules and the diff is informative. A SkillSpector category with no ATR counterpart (or vice versa) is a real, actionable gap signal rather than a framework-coverage box.

Shape

1. A docs/ mapping table: each SkillSpector category (P1-P8, TP1-TP4, E1-E4, MCP LP1-LP4, AST*, SC*, etc.) ↔ ATR category, with full / partial / gap noted per direction.
2. Gaps called out explicitly on both sides — that is the point, not coverage bragging.
3. Optional, only if you want it: a non-normative atr field alongside the existing rule metadata so a SARIF consumer can pivot. I would not push this unless you see value; the standalone doc is the low-friction version.

I am happy to draft the table against the current category set and open a DCO-signed PR if the direction is welcome. If you would rather keep external-scanner crosswalks out of the repo, a HOLD is completely fine and I will not push it.

Disclosure: ATR maintainer.

Start by reviewing the current SkillSpector category and rule IDs, the existing docs/ structure, and its SARIF 2.1.0 metadata. Compare those categories with ATR's current rules and record full, partial, and missing coverage in a bidirectional mapping table, including explicit gaps. Done means the crosswalk is complete and reviewable; add the optional atr metadata only if maintainers approve it.