Add repo agent guidelines

AGENTS.md

@@ -0,0 +1,26 @@
+# Root AGENT instructions
+
+This repository uses Python and expects all development tasks to use `uv` for environment and package management.
+
+## Development workflow
+
+1. Use `uv` to create a virtual environment and sync dependencies:
+   ```bash
+   uv venv
+   uv sync
+   ```
+2. When adding or updating dependencies, edit `pyproject.toml` and run `uv pip install <package>` followed by `uv pip freeze > uv.lock`.
+3. Run tests with `uv`:
+   ```bash
+   uv run pytest
+   ```
+   Run coverage with:
+   ```bash
+   uv run coverage run -m pytest
+   uv run coverage xml
+   ```
+4. Follow PEP8 guidelines. Format code with `black` and lint with `ruff` if available.
+5. Provide docstrings for all public functions and classes.
+6. Commit messages should be concise but descriptive.
+7. After making changes, ensure all tests pass before committing.
+