Scan a repository and build a lightweight chunk index at /.context-index/chunks.json. Run this once before search_code (and re-run after significant code changes).

Search the previously built chunk index with a BM25-style keyword score and return a compact evidence packet (FILE / LINES / SCORE + snippet) instead of full files. Call index_repo first if no index exists.

Read an explicit line range from a single file inside root. Use this only after search_code narrows down a location and the returned snippet isn't enough context. Capped at 300 lines per call.

Run one of a fixed allowlist of test commands (no arbitrary shell) and return only the filtered failure-relevant output: command, exit code, and lines matching error/failed/assert/expected/traceback/test-file-path, tail-capped at 120 lines (falls back to last 80 raw lines if nothing matches).