What problem does it solve? Claims that a Lean proof "typechecks" often travel without the checker output that would prove it, making verified results indistinguishable from bare assertions. This Skill runs a proof through a local Lean checker and reports the verdict with the full evidence chain intact. ## Core Features & Use Cases - Evidence-backed verdicts: Every pass/fail is quoted against raw checker output, with the checker version and dependency set recorded so the context of the check is never ambiguous. - Two-proof comparison: Check two proofs side by side while keeping each proof's chain of statement, dependencies, and result strictly separate. - Gap labeling: Unchecked spans, assumed lemmas, sorry placeholders, and version mismatches are labeled UNKNOWN rather than smoothed over. - Use Case: Before relying on a formal claim in a paper or codebase, freeze the proof file, run it through the checker in a fixed context, and receive a report with the raw verdict, diagnostics excerpt, and the single most consequential gap. ## Quick Start Check the attached Lean proof file and report whether it passes, including the checker version, dependencies, and any gaps.
