HelloThisWorld 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 for
the machine-readable contract and 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
- Identify the key symbols/keywords in the question.
- Use
repo_searchto locate candidate evidence. - Use
read_fileto confirm the strongest candidate. - Produce a structured answer where every claim cites a real
file:line. - If the evidence is missing or ambiguous, return
insufficient_evidencewith an emptyclaimsarray. Never invent an answer or a citation.
Output contract
The skill must return JSON with:
status:answered|insufficient_evidence|refusedanswer: a short natural-language answerclaims: array of{ text, citations: [{ file, line }] }toolCalls: array of{ tool, arguments }confidence(optional):low|medium|high
See examples.md for concrete input/output pairs.
Design note: contract vs. model
This SKILL.md and the contract are model-independent — they describe what a
correct answer looks like. How reliably a given model satisfies the contract
(pass rate, latency, cost, failure modes) is measured separately by the eval
harness and will differ per model. The offline mock adapter is a reference
implementation that satisfies the contract deterministically.