Harden OpenEnv grader entrypoints

tasks/airline_seat_upsell_gauntlet/grader.py

@@ -4,6 +4,7 @@ from guardian_openenv.task_graders import grade_airline_seat_upsell_gauntlet
 def grade(*args: Any, **kwargs: Any):
     """Grader function mapped for the OpenEnv Phase 2 validator."""
     try:
-        return grade_airline_seat_upsell_gauntlet(*args, **kwargs)
+        result = grade_airline_seat_upsell_gauntlet(*args, **kwargs)
+        return float(result)
     except Exception:
         return 0.001

tasks/marketplace_ghost_checkout/grader.py

@@ -4,6 +4,7 @@ from guardian_openenv.task_graders import grade_marketplace_ghost_checkout
 def grade(*args: Any, **kwargs: Any):
     """Grader function mapped for the OpenEnv Phase 2 validator."""
     try:
-        return grade_marketplace_ghost_checkout(*args, **kwargs)
+        result = grade_marketplace_ghost_checkout(*args, **kwargs)
+        return float(result)
     except Exception:
         return 0.001

tasks/value_hotel_budget_guard/grader.py

@@ -4,7 +4,8 @@ from guardian_openenv.task_graders import grade_value_hotel_budget_guard
 def grade(*args: Any, **kwargs: Any):
     """Grader function mapped for the OpenEnv Phase 2 validator."""
     try:
-        return grade_value_hotel_budget_guard(*args, **kwargs)
+        result = grade_value_hotel_budget_guard(*args, **kwargs)
+        return float(result)
     except Exception:
         # Fallback to a valid score if evaluation throws to avoid full crash
         return 0.001

validate_submission.py

@@ -1,7 +1,10 @@
 from __future__ import annotations
 
+import importlib
 from pathlib import Path
 
+import yaml
+
 from guardian_openenv.environment import GuardianReviewEnvironment
 from guardian_openenv.models import ActionType, GuardianAction
 from guardian_openenv.tasks import TASKS
@@ -19,11 +22,34 @@ def main() -> None:
     if missing:
         raise SystemExit(f"Missing required files: {', '.join(missing)}")
 
+    manifest = yaml.safe_load(Path("openenv.yaml").read_text(encoding="utf-8")) or {}
+    manifest_graders = {
+        str(task.get("id")): str(task.get("grader"))
+        for task in manifest.get("tasks", [])
+        if task.get("id") and task.get("grader")
+    }
+
     env = GuardianReviewEnvironment()
     if len(TASKS) < 3:
         raise SystemExit("At least 3 tasks are required.")
 
     for task in TASKS:
+        grader_path = manifest_graders.get(task.task_id)
+        if not grader_path:
+            raise SystemExit(f"Task {task.task_id} is missing a grader in openenv.yaml")
+        module_name, function_name = grader_path.rsplit(":", 1)
+        grader_fn = getattr(importlib.import_module(module_name), function_name)
+        manifest_score = grader_fn()
+        if not isinstance(manifest_score, (int, float)):
+            raise SystemExit(
+                f"Manifest grader for {task.task_id} must return a plain numeric score, got {type(manifest_score).__name__}"
+            )
+        if not (0.0 < float(manifest_score) < 1.0):
+            raise SystemExit(
+                f"Manifest grader score out of range for {task.task_id}: {manifest_score} "
+                "(must be strictly between 0 and 1)"
+            )
+
         observation = env.reset(task.task_id)
         if observation.task_id != task.task_id:
             raise SystemExit(f"reset() returned wrong task for {task.task_id}")