git:20260809.78a4943 to git:20260810.b3e14d0

+ - **`uv sync --frozen` alone does not install `pytest` or `mutmut`** — they live in the `dev` optional-dependency group (`pyproject.toml`'s `[project.optional-dependencies] dev`), and a bare `--frozen` sync skips every extra. Always run `uv sync --frozen --extra dev` in a fresh worktree/clone before testing.

+ - **Symptom, not just the fix**: this fails *silently*, not loudly. `uv run pytest` still runs — it just falls through PATH to a system `pytest` (e.g. `/opt/homebrew/bin/pytest`, a different Python than `.venv`'s) instead of erroring "pytest not found". The tell is `uv run which pytest` resolving outside `.venv/bin/`, or DB-backed test modules (`test_memory_read.py`, `test_no_db_mode.py`, ...) failing collection with `ModuleNotFoundError: No module named 'psycopg'` even though `uv run python -c "import psycopg"` succeeds — the module-level import works fine standalone; only the wrong pytest interpreter can't see it. A scoped run against a couple of test files can look completely green while the full suite silently loses its collection of every DB-touching module — the whole point of `--frozen` (a reproducible, verifiable environment) is defeated by exactly the case it's meant to prevent.