RuleProbe reads the same instruction file your AI coding agent reads (CLAUDE.md, AGENTS.md, .cursorrules) and checks whether the agent's output actually followed the rules. AST analysis, filesystem checks, regex pattern matching. 53 matchers across 9 categories. Every failure includes file, line number, and what was found. No LLM in the verification pipeline. Deterministic, reproducible, ships as CLI and GitHub Action.