fix: validate ParameterDef.bounds are comparable at construction

packages/gds-framework/gds/parameters.py

@@ -11,9 +11,9 @@
 
 from __future__ import annotations
 
-from typing import Any
+from typing import Any, Self
 
-from pydantic import BaseModel, ConfigDict, Field
+from pydantic import BaseModel, ConfigDict, Field, model_validator
 
 from gds.types.typedef import TypeDef  # noqa: TC001
 
@@ -32,6 +32,26 @@ class ParameterDef(BaseModel):
     description: str = ""
     bounds: tuple[Any, Any] | None = None
 
+    @model_validator(mode="after")
+    def _validate_bounds(self) -> Self:
+        """Validate that bounds are comparable and correctly ordered."""
+        if self.bounds is None:
+            return self
+        low, high = self.bounds
+        try:
+            result = low <= high
+        except TypeError as e:
+            raise ValueError(
+                f"ParameterDef '{self.name}': bounds ({low!r}, {high!r}) "
+                f"are not comparable: {e}"
+            ) from None
+        if not result:
+            raise ValueError(
+                f"ParameterDef '{self.name}': lower bound {low!r} "
+                f"exceeds upper bound {high!r}"
+            )
+        return self
+
     def check_value(self, value: Any) -> bool:
         """Check if a value satisfies this parameter's type and constraints."""
         if not self.typedef.check_value(value):

packages/gds-framework/tests/test_v02_features.py

@@ -123,6 +123,26 @@ def test_check_value_no_bounds(self, float_type):
         p = ParameterDef(name="rate", typedef=float_type)
         assert p.check_value(999.0) is True
 
+    def test_bounds_inverted_raises(self, float_type):
+        """Inverted bounds (low > high) should fail at construction."""
+        with pytest.raises(ValidationError, match="exceeds upper bound"):
+            ParameterDef(name="rate", typedef=float_type, bounds=(1.0, 0.0))
+
+    def test_bounds_non_comparable_raises(self, float_type):
+        """Non-comparable bounds should fail at construction."""
+        with pytest.raises(ValidationError, match="not comparable"):
+            ParameterDef(name="rate", typedef=float_type, bounds=("a", 1))
+
+    def test_bounds_equal_is_valid(self, float_type):
+        """Equal bounds (low == high) should be allowed."""
+        p = ParameterDef(name="rate", typedef=float_type, bounds=(0.5, 0.5))
+        assert p.bounds == (0.5, 0.5)
+
+    def test_bounds_none_is_valid(self, float_type):
+        """None bounds should be allowed (no validation)."""
+        p = ParameterDef(name="rate", typedef=float_type, bounds=None)
+        assert p.bounds is None
+
 
 class TestParameterSchema:
     def test_empty_schema(self):