factcheck-guard

# FactCheck Guard — Runtime Claim Verification Prevents false claims about the codebase. Grep results are hypotheses, not proof. Every assertion about "what the code does" must be verified by reading the actual code. ## Why This Exists An 80% false claim rate was observed when agents trusted grep results without reading files. The pattern repeats: grep finds a string, agent asserts behavior, behavior is wrong. This skill converts the claim-verification guidelines into an actionable protocol. ## Confidence Markers (MANDATORY) Every factual claim about the codebase MUST carry one of these markers: | Marker | Meaning | Requirements | |--------|---------|-------------| | [VERIFIED] | Read the file, traced the logic | Must cite file:line | | [INFERRED] | Based on grep or file name | Must verify before asserting to others | | [UNCERTAIN] | Not yet checked | Must investigate before making the claim | Never promote an [INFERRED] claim to a statement of fact. Never let [UNCERTAIN] appear in a response to the user — investigate first. --- ## Verification Protocol ### Level 1: Existence Claims When asserting "X exists in the codebase": **Step 1 — Search (produces [INFERRED])** ``` Grep/Glob for the pattern. Result: "X appears at path/to/file.ts:42" [INFERRED] ``` **Step 2 — Read the file (required to reach [VERIFIED])** ``` Read path/to/file.ts, locate line 42. Confirm the match is actual code, not a comment or string literal. ``` **Step 3 — Check context** ``` Is the code...