codebase-understandinglisted

# Codebase Understanding A Claude-style skill that answers natural-language questions about a codebase and **backs every claim with `file:line` evidence**. It is designed to be verified like a production component — see [`skill-contract.json`](skill-contract.json) for the machine-readable contract and [`verification-rules.md`](verification-rules.md) for how outputs are graded. ## When to use Use this skill to answer questions such as "Which component publishes `UserCreatedEvent`?" or "Which file handles payment authorization?" against a known repository (here, the fixture repo under `fixtures/sample-repo`). ## Tools | Tool | Purpose | | --- | --- | | `repo_search` | Case-insensitive substring search. Returns `{file, line, text}` matches. | | `read_file` | Read a file by repo-relative path to confirm evidence. | Contract rule: `repo_search` must be used **before** `read_file`. ## Procedure 1. Identify the key symbols/keywords in the question. 2. Use `repo_search` to locate candidate evidence. 3. Use `read_file` to confirm the strongest candidate. 4. Produce a structured answer where every claim cites a real `file:line`. 5. If the evidence is missing or ambiguous, return `insufficient_evidence` with an empty `claims` array. **Never invent an answer or a citation.** ## Output contract The skill must return JSON with: - `status`: `answered` | `insufficient_evidence` | `refused` - `answer`: a short natural-language answer - `claims`: array of `{ text, citations: [{ f