pass optional input to validate fn

Author: aashka-trivedi

mellea/stdlib/session.py

@@ -300,9 +300,11 @@ def act(
         else:
             # Default validation strategy just validates all of the provided requirements.
             if strategy.validate is None:
-                strategy.validate = lambda reqs, val_ctx, output: self.validate(
-                    reqs, output=output
-                )
+                strategy.validate = (
+                    lambda reqs, val_ctx, output, input=None: self.validate(  # type: ignore
+                        reqs, output=output, input=input
+                    )
+                )  # type: ignore
 
             # Default generation strategy just generates from context.
             if strategy.generate is None:
@@ -483,6 +485,7 @@ def validate(
         format: type[BaseModelSubclass] | None = None,
         model_options: dict | None = None,
         generate_logs: list[GenerateLog] | None = None,
+        input: CBlock | None = None,
     ) -> list[ValidationResult]:
         """Validates a set of requirements over the output (if provided) or the current context (if the output is not provided)."""
         # Turn a solitary requirement in to a list of requirements, and then reqify if needed.
@@ -492,7 +495,17 @@ def validate(
             validation_target_ctx = self.ctx
         else:
             validation_target_ctx = SimpleContext()
-            validation_target_ctx.insert(output)
+            if input is not None:
+                # some validators may need input as well as output
+                validation_target_ctx.insert_turn(
+                    ContextTurn(
+                        input,
+                        output,  # type: ignore
+                    ),  # type: ignore
+                    generate_logs=generate_logs,
+                )
+            else:
+                validation_target_ctx.insert(output)
         rvs = []
         for requirement in reqs:
             val_result = requirement.validate(