# Todo 52.7 Benchmark Output Reservation and Cardinality Plan

**Status:** done

## Goal

Eliminate remaining report publication races and prevent an incomplete benchmark execution from being reported as successful.

## Scope

- Reserve both final report paths with exclusive file creation before writing temporary content; never overwrite a path created by another process.
- Remove lock/reservation sidecar files entirely; clean only placeholders/temporary/published files owned by the current attempt after failure.
- Replace argparse error details with a generic safe message so malformed values cannot be echoed to stderr.
- Require `len(results) == len(cases) * len(modes) * runs_per_case`; mismatches become redacted system errors in the report and exit code 2.

## Files

- Modify: `src/agent_lab/infrastructure/benchmark_reporting.py`
- Modify: `src/agent_lab/presentation/benchmark_cli.py`
- Modify: `tests/test_benchmark_reporting.py`
- Modify: `tests/test_benchmark_cli.py`

## Verification

- `uv run pytest tests/test_benchmark_reporting.py tests/test_benchmark_cli.py -q`
- concurrent reservation stress test
- `uv run pytest`
- `git diff --check`