Write run_agent: find the module that defines a function

Code search is lookup with decoys: every caller of a function mentions its name.

Your task

Write run_agent. It names the module that defines a function, using two tools.

• search(query) returns the ids of files containing that text, shortest first
• fetch(doc_id) returns that file, or None when the id does not exist
• answer with the module name from the file's "# module:" header, or not found
• a file that imports or calls the function does not define it
• each scenario carries a token budget; going over it fails that scenario

At submit the suite runs your agent against codebases you have not seen, each with its own files.