diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 7b072d5..230146c 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -19,7 +19,7 @@ repos:
     - id: trailing-whitespace
 
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.14.9
+    rev: v0.14.11
     hooks:
     - id: ruff
       args: [--fix]
diff --git a/AGENTS.md b/AGENTS.md
new file mode 100644
index 0000000..1080e77
--- /dev/null
+++ b/AGENTS.md
@@ -0,0 +1,325 @@
+# AGENTS.md
+
+This file provides guidance for AI coding agents working on the **sphinx-design** repository.
+
+## Project Overview
+
+sphinx-design is a Sphinx extension for designing beautiful, view size responsive web components. It provides:
+
+- Grids, cards, dropdowns, tabs, badges, buttons, and icons
+- Responsive design inspired by [Bootstrap](https://getbootstrap.com/) (v5), [Material Design](https://material.io), and [Material-UI](https://material-ui.com/)
+- Support for both reStructuredText and [MyST Markdown](https://myst-parser.readthedocs.io/) (via integration with myst-parser)
+
+The extension works with multiple Sphinx themes including alabaster, sphinx-rtd-theme, pydata-sphinx-theme, sphinx-book-theme, furo, and sphinx-immaterial.
+
+## Repository Structure
+
+```
+pyproject.toml          # Project configuration and dependencies
+tox.ini                 # Tox test environment configuration
+package.json            # Node.js config for SASS compilation
+
+sphinx_design/          # Main source code
+├── __init__.py         # Package init with setup() entry point
+├── _compat.py          # Compatibility utilities
+├── extension.py        # Main Sphinx extension setup
+├── shared.py           # Shared constants and base classes
+├── badges_buttons.py   # Badge and button directives
+├── cards.py            # Card directives
+├── dropdown.py         # Dropdown directive
+├── grids.py            # Grid directives
+├── tabs.py             # Tab directives
+├── icons.py            # Icon roles (Material, FontAwesome, Octicons)
+├── article_info.py     # Article info directive
+└── compiled/           # Compiled static assets (CSS, JS)
+
+style/                  # SASS source files
+├── index.scss          # Main SCSS entry point
+├── _variables.scss     # SCSS variables
+├── _grids.scss         # Grid styles
+├── _cards.scss         # Card styles
+├── _tabs.scss          # Tab styles
+├── _dropdown.scss      # Dropdown styles
+└── ...                 # Other component styles
+
+tests/                  # Test suite
+├── conftest.py         # Pytest fixtures
+├── test_snippets.py    # Snippet-based tests
+├── test_misc.py        # Miscellaneous tests
+├── test_snippets/      # Test fixture files for snippets
+└── test_misc/          # Test fixture files for misc tests
+
+docs/                   # Documentation source (MyST Markdown)
+├── conf.py             # Sphinx configuration
+├── index.md            # Documentation index
+├── get_started.md      # Getting started guide
+├── grids.md            # Grid documentation
+├── cards.md            # Card documentation
+├── tabs.md             # Tab documentation
+├── dropdowns.md        # Dropdown documentation
+├── badges_buttons.md   # Badge and button documentation
+└── snippets/           # Code snippets for docs (myst/, rst/)
+```
+
+## Development Commands
+
+All commands should be run via [`tox`](https://tox.wiki) for consistency. The project uses `tox-uv` for faster environment creation.
+
+### Testing
+
+```bash
+# Run all tests (default Python version)
+tox
+
+# Run tests with a specific Python version
+tox -e py311
+tox -e py312
+
+# Run a specific test file
+tox -- tests/test_snippets.py
+
+# Run a specific test function
+tox -- tests/test_snippets.py::test_function_name
+
+# Run tests without myst-parser dependency
+tox -e py311-no-myst
+
+# Run with coverage
+tox -- --cov=sphinx_design
+
+# Update regression test fixtures
+tox -- --force-regen
+```
+
+### Documentation
+
+```bash
+# Build docs with different themes
+tox -e docs-alabaster
+tox -e docs-rtd
+tox -e docs-pydata
+tox -e docs-sbt
+tox -e docs-furo
+tox -e docs-im
+
+# Clean build (set CLEAN env var)
+CLEAN=1 tox -e docs-furo
+
+# Build with a different builder (e.g., linkcheck)
+BUILDER=linkcheck tox -e docs-furo
+```
+
+### Code Quality
+
+```bash
+# Type checking with mypy
+tox -e mypy
+
+# Linting with ruff (auto-fix enabled)
+tox -e ruff-check -- --fix
+
+# Formatting with ruff
+tox -e ruff-fmt
+
+# Run pre-commit hooks on all files
+pre-commit run --all-files
+
+# Compile SASS to CSS
+npm run css
+# or via pre-commit
+pre-commit run --all css
+```
+
+## Code Style Guidelines
+
+- **Formatter/Linter**: Ruff (configured in `pyproject.toml`)
+- **Type Checking**: Mypy (configured in `pyproject.toml`)
+- **Pre-commit**: Use pre-commit hooks for consistent code style
+
+### Best Practices
+
+- **Type annotations**: Use complete type annotations for all function signatures.
+- **Docstrings**: Use Sphinx-style docstrings (`:param:`, `:return:`, `:raises:`).
+- **Directive classes**: Extend `SdDirective` (from `shared.py`) for new directives.
+- **Warning messages**: Use `WARNING_TYPE = "design"` for consistent warning categorization.
+- **Testing**: Write tests for all new functionality. Use `pytest-regressions` for output comparison.
+
+### Docstring Example
+
+```python
+def create_component(
+    name: str,
+    rawtext: str,
+    *,
+    classes: Sequence[str] = (),
+) -> nodes.container:
+    """Create a component container node.
+
+    :param name: The component name.
+    :param rawtext: The raw text content.
+    :param classes: Additional CSS classes to apply.
+    :return: A container node with the component.
+    """
+    ...
+```
+
+## Testing Guidelines
+
+### Test Structure
+
+- Tests use `pytest` with fixtures from `conftest.py`
+- Regression testing uses `pytest-regressions` for output comparison
+- The `sphinx_builder` fixture creates temporary Sphinx projects for testing
+
+### Writing Tests
+
+1. Use the `sphinx_builder` fixture to create test Sphinx applications
+2. Add test content as `.txt` files in `tests/test_snippets/` or `tests/test_misc/`
+3. Use `file_regression` or `data_regression` fixtures for comparing output
+
+### Example Test Pattern
+
+`````python
+def test_grid_basic(sphinx_builder, file_regression):
+    builder = sphinx_builder()
+    builder.src_path.joinpath("index.md").write_text(
+        """
+# Test
+
+````{grid} 2
+:gutter: 1
+
+```{grid-item}
+Item 1
+```
+
+```{grid-item}
+Item 2
+```
+````
+""",
+        encoding="utf8",
+    )
+    builder.build()
+    doctree = builder.get_doctree("index")
+    file_regression.check(doctree.pformat(), extension=".xml")
+`````
+
+## Pull Request Requirements
+
+When submitting changes:
+
+1. **Description**: Include a meaningful description or link explaining the change
+2. **Tests**: Include test cases for new functionality or bug fixes
+3. **Documentation**: Update docs if behavior changes or new features are added
+4. **Changelog**: Update `CHANGELOG.md` under the appropriate section
+5. **Code Quality**: Ensure `pre-commit run --all-files` passes
+
+## Architecture Overview
+
+### Extension Setup
+
+The extension follows a modular architecture where each component type has its own module:
+
+```
+setup() in __init__.py
+    └── setup_extension() in extension.py
+            ├── setup_badges_and_buttons()
+            ├── setup_cards()
+            ├── setup_grids()
+            ├── setup_dropdown()
+            ├── setup_icons()
+            ├── setup_tabs()
+            └── setup_article_info()
+```
+
+### Key Components
+
+#### Base Classes (`sphinx_design/shared.py`)
+
+- `SdDirective`: Base class for sphinx-design directives (extends `SphinxDirective`)
+- `create_component()`: Factory function for creating component nodes
+- `WARNING_TYPE`: Constant for warning categorization
+
+#### Directives
+
+Each component type has its own module with directives:
+
+- **Grids** (`grids.py`): `grid`, `grid-item`, `grid-item-card` directives
+- **Cards** (`cards.py`): `card`, `card-header`, `card-footer`, `card-carousel` directives
+- **Tabs** (`tabs.py`): `tab-set`, `tab-item` directives
+- **Dropdowns** (`dropdown.py`): `dropdown` directive
+- **Badges/Buttons** (`badges_buttons.py`): `button-link`, `button-ref` directives and `bdg-*` roles
+- **Icons** (`icons.py`): Icon roles for Material, FontAwesome, and Octicons
+
+#### Static Assets
+
+Compiled CSS and JS are stored in `sphinx_design/compiled/`:
+
+- CSS is compiled from SASS sources in `style/`
+- JavaScript for tab functionality
+
+### Styling
+
+The extension uses SASS for styling:
+
+1. SASS source files are in `style/`
+2. Compiled using `npm run css` (requires Node.js)
+3. Output goes to `sphinx_design/compiled/style.min.css`
+4. CSS is automatically copied to build output during Sphinx builds
+
+## Key Files
+
+- `pyproject.toml` - Project configuration, dependencies, and tool settings
+- `sphinx_design/__init__.py` - Package entry point with `setup()` for Sphinx
+- `sphinx_design/extension.py` - Main extension setup, CSS/JS handling
+- `sphinx_design/shared.py` - Base classes and shared utilities
+- `sphinx_design/grids.py` - Grid layout directives
+- `sphinx_design/cards.py` - Card component directives
+- `sphinx_design/tabs.py` - Tab component directives
+
+## Debugging
+
+- Build docs with `-v` flag for verbose output
+- Check `docs/_build/html/<theme>/` for build outputs
+- Use `tox -- -v --tb=long` for verbose test output with full tracebacks
+- Inspect generated HTML to debug styling issues
+
+## Common Patterns
+
+### Adding a New Component
+
+1. Create a new module in `sphinx_design/` (e.g., `my_component.py`)
+2. Define directive class(es) extending `SdDirective`
+3. Create a `setup_my_component(app: Sphinx)` function
+4. Call the setup function from `setup_extension()` in `extension.py`
+5. Add SASS styles in `style/_my_component.scss`
+6. Import the SASS file in `style/index.scss`
+7. Document in `docs/`
+8. Add tests in `tests/`
+
+### Adding a New Directive Option
+
+1. Add the option to the directive's `option_spec` dictionary
+2. Handle the option in the directive's `run()` method
+3. Add appropriate CSS classes or attributes to the output node
+4. Document the new option
+5. Add tests for the new option
+
+### Working with SASS
+
+1. Edit SASS files in `style/`
+2. Run `npm run css` to compile (or `pre-commit run --all css`)
+3. Compiled output goes to `sphinx_design/compiled/style.min.css`
+4. Test with different themes to ensure compatibility
+
+## Reference Documentation
+
+- [Docutils Repository](https://github.com/live-clones/docutils)
+- [Docutils Documentation](https://docutils.sourceforge.io/)
+- [Docutils Nodes](https://docutils.sourceforge.io/docs/ref/doctree.html)
+- [Docutils release log](https://docutils.sourceforge.io/RELEASE-NOTES.html)
+- [Sphinx Repository](https://github.com/sphinx-doc/sphinx)
+- [Sphinx Extension Development](https://www.sphinx-doc.org/en/master/extdev/index.html)
+- [Bootstrap Documentation](https://getbootstrap.com/docs/5.0/)
+- [SASS Documentation](https://sass-lang.com/documentation)
diff --git a/PR_DESCRIPTION.md b/PR_DESCRIPTION.md
new file mode 100644
index 0000000..c594d1b
--- /dev/null
+++ b/PR_DESCRIPTION.md
@@ -0,0 +1,14 @@
+## Add AGENTS.md and tox environments for code quality
+
+This PR adds developer tooling and documentation for AI coding agents.
+
+### Changes
+
+- **Add `AGENTS.md`**: Comprehensive guide for AI agents working on this repository, including project overview, repository structure, development commands, code style guidelines, testing patterns, and architecture documentation.
+
+- **Add tox environments for code quality**:
+  - `tox -e mypy` — Type checking
+  - `tox -e ruff-check` — Linting (auto-fix by default)
+  - `tox -e ruff-fmt` — Formatting
+
+- **Add `[dependency-groups]` to `pyproject.toml`**: Pinned versions for mypy and ruff matching `.pre-commit-config.yaml` for consistency between CI and local development.
diff --git a/pyproject.toml b/pyproject.toml
index 6f3c60d..de8a36f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -56,6 +56,10 @@ theme-rtd = ["sphinx-rtd-theme~=2.0"]
 theme-sbt = ["sphinx-book-theme~=1.1"]
 theme-im = ["sphinx-immaterial~=0.12.2"]
 
+[dependency-groups]
+mypy = ["mypy==1.19.1"]
+ruff = ["ruff==0.14.11"]
+
 [tool.flit.sdist]
 exclude = [
     "docs/",
diff --git a/tox.ini b/tox.ini
index 805c762..98a94bf 100644
--- a/tox.ini
+++ b/tox.ini
@@ -47,3 +47,18 @@ commands_pre =
 commands =
     sphinx-build -nW --keep-going {posargs} -b {env:BUILDER:html} docs/ docs/_build/{env:BUILDER:html}/{env:SPHINX_THEME:}
 commands_post = echo "open docs/_build//{env:BUILDER:html}/{env:SPHINX_THEME:}/index.html"
+
+[testenv:mypy]
+description = Run type checking with mypy
+dependency_groups = mypy
+commands = mypy {posargs:sphinx_design}
+
+[testenv:ruff-check]
+description = Run linting with ruff (use --fix to auto-fix)
+dependency_groups = ruff
+commands = ruff check {posargs:--fix}
+
+[testenv:ruff-fmt]
+description = Run formatting with ruff
+dependency_groups = ruff
+commands = ruff format {posargs}