feat: add matplotlib requirement factory

mellea/stdlib/requirements/__init__.py

@@ -6,6 +6,7 @@
     MatplotlibHeadlessBackend,
     PlotDependenciesAvailable,
     PlotFileSaved,
+    python_plotting_requirements,
 )
 from .python_reqs import PythonExecutionReq
 from .python_tools import (
@@ -49,6 +50,7 @@
     "is_markdown_list",
     "is_markdown_table",
     "python_code_generation_requirements",
+    "python_plotting_requirements",
     "req",
     "reqify",
     "requirement_check_to_bool",

mellea/stdlib/requirements/plotting/__init__.py

@@ -11,6 +11,12 @@
     MatplotlibHeadlessBackend,
     PlotDependenciesAvailable,
     PlotFileSaved,
+    python_plotting_requirements,
 )
 
-__all__ = ["MatplotlibHeadlessBackend", "PlotDependenciesAvailable", "PlotFileSaved"]
+__all__ = [
+    "MatplotlibHeadlessBackend",
+    "PlotDependenciesAvailable",
+    "PlotFileSaved",
+    "python_plotting_requirements",
+]

mellea/stdlib/requirements/plotting/matplotlib.py

@@ -8,6 +8,7 @@
 
 from mellea.core import Context, Requirement, ValidationResult
 from mellea.stdlib.requirements.python_reqs import _has_python_code_listing
+from mellea.stdlib.requirements.python_tools import python_code_generation_requirements
 
 # Matplotlib backends suitable for headless (non-interactive) execution.
 # Includes standard raster (Agg, Cairo), vector (pdf, svg, pgf),
@@ -334,3 +335,81 @@ def _validate_dependencies(self, ctx: Context) -> ValidationResult:
         return ValidationResult(
             result=True, reason="All dependencies available (matplotlib, numpy)."
         )
+
+
+def python_plotting_requirements(
+    output_path: str,
+    allowed_imports: list[str] | None = None,
+    output_limit_chars: int = 10_000,
+    timeout_seconds: int = 5,
+    use_sandbox: bool = False,
+) -> list[Requirement]:
+    """Bundle matplotlib-specific requirements for plotting code validation.
+
+    Factory function that creates a complete set of requirements for validating
+    matplotlib plotting code, composing general Python code generation requirements
+    with plotting-specific constraints for headless backend configuration, file
+    output, and dependency availability.
+
+    Args:
+        output_path: File path where the plot should be saved (e.g., '/tmp/plot.png').
+            This path must match the savefig() call in the generated code.
+        allowed_imports: Whitelist of importable top-level modules. None allows all.
+            Default None.
+        output_limit_chars: Maximum allowed characters of captured stdout.
+            Default 10,000.
+        timeout_seconds: Maximum execution time in seconds. Default 5.
+        use_sandbox: Use llm-sandbox for Docker-isolated execution. Default False.
+
+    Returns:
+        list[Requirement]: Seven requirements in validation order:
+            1-4. PythonCodeExtraction, PythonSyntaxValid, PythonExecutionReq,
+                 ImportRestrictions/NoImportRestrictions (from python_code_generation_requirements)
+            5. MatplotlibHeadlessBackend — validates headless backend configuration
+            6. PlotFileSaved — validates plot is saved to the specified output_path
+            7. PlotDependenciesAvailable — validates matplotlib and numpy are available
+
+    Raises:
+        TypeError: If output_path is not a string.
+        ValueError: If output_path is empty.
+
+    Examples:
+        >>> output_path = "/tmp/plot.png"
+        >>> reqs = python_plotting_requirements(output_path=output_path)
+        >>> len(reqs)
+        7
+        >>> isinstance(reqs[4], MatplotlibHeadlessBackend)
+        True
+        >>> isinstance(reqs[5], PlotFileSaved)
+        True
+        >>> isinstance(reqs[6], PlotDependenciesAvailable)
+        True
+        >>> reqs_restricted = python_plotting_requirements(
+        ...     output_path=output_path,
+        ...     allowed_imports=["matplotlib", "numpy"]
+        ... )
+        >>> len(reqs_restricted)
+        7
+    """
+    if not isinstance(output_path, str):
+        raise TypeError(
+            f"output_path must be a string, got {type(output_path).__name__}"
+        )
+
+    if not output_path.strip():
+        raise ValueError("output_path cannot be empty")
+
+    requirements = python_code_generation_requirements(
+        allowed_imports=allowed_imports,
+        output_limit_chars=output_limit_chars,
+        timeout_seconds=timeout_seconds,
+        use_sandbox=use_sandbox,
+    )
+    requirements.extend(
+        [
+            MatplotlibHeadlessBackend(),
+            PlotFileSaved(output_path=output_path),
+            PlotDependenciesAvailable(),
+        ]
+    )
+    return requirements

test/stdlib/requirements/plotting/test_matplotlib.py

@@ -2,12 +2,20 @@
 
 import pytest
 
-from mellea.core import Context, ModelOutputThunk
+from mellea.core import Context, ModelOutputThunk, Requirement
 from mellea.stdlib.context import ChatContext
 from mellea.stdlib.requirements.plotting import (
     MatplotlibHeadlessBackend,
     PlotDependenciesAvailable,
     PlotFileSaved,
+    python_plotting_requirements,
+)
+from mellea.stdlib.requirements.python_tools import (
+    ImportRestrictions,
+    NoImportRestrictions,
+    PythonCodeExtraction,
+    PythonExecutionReq,
+    PythonSyntaxValid,
 )
 
 
@@ -449,3 +457,123 @@ def test_path_as_keyword_with_different_names(self):
         result = req.validation_fn(ctx)
         # fname= is the correct keyword; savefig has no 'filename' parameter
         assert result.as_bool() is True
+
+
+class TestPythonPlottingRequirementsFactory:
+    """Tests for python_plotting_requirements factory function."""
+
+    def test_factory_returns_list_of_requirements(self):
+        """Test that factory returns a list of seven Requirement instances."""
+        output_path = "/tmp/plot.png"
+        reqs = python_plotting_requirements(output_path=output_path)
+
+        assert isinstance(reqs, list)
+        assert len(reqs) == 7
+        assert all(isinstance(r, Requirement) for r in reqs)
+
+    def test_factory_returns_correct_requirement_order(self):
+        """Test requirements are in expected order (python tools + plotting)."""
+        output_path = "/tmp/plot.png"
+        reqs = python_plotting_requirements(output_path=output_path)
+
+        # First 4 from python_code_generation_requirements
+        assert isinstance(reqs[0], PythonCodeExtraction)
+        assert isinstance(reqs[1], PythonSyntaxValid)
+        assert isinstance(reqs[2], PythonExecutionReq)
+        assert isinstance(
+            reqs[3], NoImportRestrictions
+        )  # No allowed_imports, so NoImportRestrictions
+
+        # Last 3 plotting-specific
+        assert isinstance(reqs[4], MatplotlibHeadlessBackend)
+        assert isinstance(reqs[5], PlotFileSaved)
+        assert isinstance(reqs[6], PlotDependenciesAvailable)
+
+    def test_factory_with_allowed_imports(self):
+        """Test that allowed_imports parameter creates ImportRestrictions."""
+        output_path = "/tmp/plot.png"
+        allowed_imports = ["matplotlib", "numpy"]
+        reqs = python_plotting_requirements(
+            output_path=output_path, allowed_imports=allowed_imports
+        )
+
+        assert len(reqs) == 7
+        assert isinstance(reqs[3], ImportRestrictions)
+        assert reqs[3].allowed_imports == allowed_imports
+
+    def test_factory_propagates_output_path(self):
+        """Test that output_path is correctly passed to PlotFileSaved."""
+        output_path = "/output/my_plot.png"
+        reqs = python_plotting_requirements(output_path=output_path)
+
+        plot_saved_req = reqs[5]
+        assert isinstance(plot_saved_req, PlotFileSaved)
+        assert plot_saved_req.output_path == output_path
+        assert output_path in plot_saved_req.description
+
+    def test_factory_with_different_paths(self):
+        """Test factory works with various output path formats."""
+        test_paths = [
+            "/tmp/plot.png",
+            "/output/figures/chart.svg",
+            "plot.pdf",
+            "/var/tmp/matplotlib_output.jpg",
+        ]
+
+        for path in test_paths:
+            reqs = python_plotting_requirements(output_path=path)
+            assert len(reqs) == 7
+            assert reqs[5].output_path == path
+
+    def test_factory_raises_on_non_string_path(self):
+        """Test that factory raises TypeError for non-string output_path."""
+        with pytest.raises(TypeError):
+            python_plotting_requirements(output_path=123)
+
+        with pytest.raises(TypeError):
+            python_plotting_requirements(output_path=None)
+
+        with pytest.raises(TypeError):
+            python_plotting_requirements(output_path=["/tmp/plot.png"])
+
+    def test_factory_raises_on_empty_path(self):
+        """Test that factory raises ValueError for empty output_path."""
+        with pytest.raises(ValueError):
+            python_plotting_requirements(output_path="")
+
+        with pytest.raises(ValueError):
+            python_plotting_requirements(output_path="   ")
+
+    def test_factory_can_be_unpacked(self):
+        """Test that factory result can be unpacked like in usage examples."""
+        output_path = "/tmp/plot.png"
+        reqs = python_plotting_requirements(output_path=output_path)
+
+        # Verify unpacking pattern works
+        unpacked = [*reqs]
+        assert len(unpacked) == 7
+        assert unpacked == reqs
+
+    def test_factory_requirements_are_independent_instances(self):
+        """Test that multiple factory calls create independent requirement instances."""
+        reqs1 = python_plotting_requirements(output_path="/tmp/plot1.png")
+        reqs2 = python_plotting_requirements(output_path="/tmp/plot2.png")
+
+        # Different instances
+        assert reqs1[5] is not reqs2[5]
+        # But different output paths
+        assert reqs1[5].output_path != reqs2[5].output_path
+
+    def test_factory_with_custom_execution_parameters(self):
+        """Test that custom execution parameters can be passed through."""
+        output_path = "/tmp/plot.png"
+        reqs = python_plotting_requirements(
+            output_path=output_path,
+            output_limit_chars=5000,
+            timeout_seconds=10,
+            use_sandbox=True,
+        )
+
+        assert len(reqs) == 7
+        execution_req = reqs[2]
+        assert isinstance(execution_req, PythonExecutionReq)