List files in an indexed dependency. First choice for file/path enumeration tasks such as files under a directory; use `path_prefix` for directory prefixes (e.g. `lib/`) and optional `extensions` for language filtering. Use this to discover paths before `code_read` (when `code_read` returns `FILE_NOT_FOUND` or you don't yet know the path) and to scope `code_grep`. Address via `target.registry` + `target.package_name` (package scope) or `target.repo_url` + optional `target.git_ref` (repo scope), mutually exclusive. Narrow with `path`, `path_prefix`, `globs`, `extensions`, `file_types`, `languages`, or file-intent filters. JSON envelope shape: `{total, hasMore, files: [{path, name, language, fileType, byteSize}], resolution, indexedVersion}`. When fresh data is not ready within the wait window, responses may include `targetResolution` provenance, `indexingEstimate`, and immediately-queryable alternatives. `availableVersions` and `availableRefs` are already indexed/queryable; `suggestedRefs` are fuzzy ref hints and may need indexing first. On an `INDEXING` error envelope, retry with a longer `wait_timeout_ms` or use a version/ref from `details.availableVersions` / `details.availableRefs`.