# Todo 52.1 Benchmark URL Control Characters Plan

**Status:** done

## Goal

Keep malformed benchmark targets inside the configuration error boundary instead of leaking an `httpx.InvalidURL` during live client construction.

## Scope

- Reject ASCII and Unicode characters whose category is control/format, including NUL, CR, LF, and tab.
- Retain the existing HTTP(S), no-userinfo, no-query, and no-fragment requirements.
- Add focused valid/invalid URL regression tests.

## Files

- Modify: `src/agent_lab/application/benchmark.py`
- Modify: `tests/test_benchmark_config.py`

## Verification

- `uv run pytest tests/test_benchmark_config.py tests/test_tool_invocation_comparison.py -q`
- `uv run pytest`
- `git diff --check`

## Observe / Update

- Control-category characters are rejected before transport construction while printable internationalized URLs remain covered.
- Focused tests passed (`67 passed`) and the full suite passed at this checkpoint (`472 passed`).