build(deps): drop unused runtime dependencies

dependency-license-policy.toml

@@ -27,11 +27,6 @@ reports = [{ version = "2026.2.25", license = "Mozilla Public License 2.0 (MPL 2
 reason = "Unmodified character-detection library installed as a separate transitive dependency, imported rather than incorporated."
 reports = [{ version = "5.2.0", license = "GNU Lesser General Public License v2 or later (LGPLv2+)" }]
 
-[exceptions.matplotlib]
-reason = "Plot rendering for the reporting layer. PSF-2.0 is the Python Software Foundation licence, ASF Category A."
-reports = [{ version = "3.10.8", license = "Python Software Foundation License" }]
-
-
 [exceptions.numpy]
 reason = "Core numerical dependency, BSD-3-Clause overall. The additional identifiers cover vendored components and are each permissive or public-domain-equivalent. Python 3.10 resolves 2.2.6, which reports the same licence as the generic BSD classifier."
 reports = [

pyproject.toml

@@ -41,14 +41,12 @@ dependencies = [
     "PyYAML>=6.0",
     # The engine's config models are Pydantic; core/preview.py renders with
     # Rich. Every third-party import must be declared here so the package
-    # installs standalone; tests/test_packaging_contract.py enforces it.
+    # installs standalone, and everything declared here must be imported;
+    # tests/test_packaging_contract.py enforces both.
     "pydantic>=2.0",
     "rich",
     "pandas",
     "pyarrow",
-    "seaborn",
-    "matplotlib",
-    "langdetect",
     # NOTE: ipykernel is deliberately NOT a runtime dependency. The only
     # IPython use in shipped code is a guarded `from IPython import
     # get_ipython` probe in core/manifest.py, so requiring a Jupyter kernel

tests/test_packaging_contract.py

@@ -85,14 +85,23 @@ def test_registry_discovers_both_plugins(self) -> None:
 
 
 class TestDeclaredDependencies:
-    """Every third-party import must be declared by the distribution that
-    contains it. Undeclared imports resolve fine in the monorepo, where a
-    sibling package happens to pull them in, and fail on a standalone install."""
+    """Third-party imports and declared dependencies match in both directions.
+    An undeclared import resolves fine in the monorepo, where a sibling package
+    happens to pull it in, and fails on a standalone install. A declared
+    dependency nothing imports still installs, with everything it depends on,
+    for every user."""
 
     #: Imported behind try/except ImportError on purpose; must stay optional.
     #: Undeclared on purpose: a guarded notebook probe, not a dependency.
     _OPTIONAL = {"IPython"}
 
+    #: Distribution names differ from import names for a few packages.
+    _IMPORT_TO_DISTRIBUTION = {
+        "yaml": "pyyaml",
+        "lingua": "lingua_language_detector",
+        "dotenv": "python_dotenv",
+    }
+
     @staticmethod
     def _imports(src_root: Path, own_package: str) -> set[str]:
         found: set[str] = set()
@@ -122,21 +131,23 @@ def test_plugin_declares_everything_it_imports(self) -> None:
         imported = self._imports(root / "src", "usersim")
         declared = self._declared(root / "pyproject.toml")
 
-        # Distribution names differ from import names for a few packages.
-        aliases = {
-            "yaml": "pyyaml",
-            "lingua": "lingua_language_detector",
-            "dotenv": "python_dotenv",
-        }
         # Packages this distribution ships; they are not dependencies.
         first_party = {"usersim"}
         missing = {
             mod
             for mod in imported - self._OPTIONAL - first_party
-            if aliases.get(mod, mod).lower().replace("-", "_") not in declared
+            if self._IMPORT_TO_DISTRIBUTION.get(mod, mod).lower().replace("-", "_") not in declared
         }
         assert not missing, f"the distribution imports but does not declare: {sorted(missing)}"
 
+    def test_plugin_imports_everything_it_declares(self) -> None:
+        imported = {
+            self._IMPORT_TO_DISTRIBUTION.get(mod, mod).lower().replace("-", "_")
+            for mod in self._imports(_REPO_ROOT / "src", "usersim")
+        }
+        unused = self._declared(_REPO_ROOT / "pyproject.toml") - imported
+        assert not unused, f"the distribution declares but never imports: {sorted(unused)}"
+
     def test_optional_imports_stay_guarded(self) -> None:
         """An undeclared import is only acceptable behind try/except."""
         src = _REPO_ROOT / "src"