Fix OpenEnv grader detection - Add __all__ exports to tasks.py and grader.py

- Add explicit __all__ exports to grader.py for grade_task_1-5 functions
- Add explicit __all__ exports to tasks.py for task configurations
- Resolves 'Not enough tasks with graders' validation error
- Ensures all 5 tasks and graders are properly detectable by OpenEnv evaluation system

grader.py

@@ -27,6 +27,16 @@ import numpy as np
 from environment import BusRoutingEnv
 from tasks import TASKS, TaskConfig
 
+# Explicitly export grader functions for OpenEnv detection
+__all__ = [
+    "grade_task_1",
+    "grade_task_2", 
+    "grade_task_3",
+    "grade_task_4",
+    "grade_task_5",
+    "grade_all_tasks",
+]
+
 
 # ---------------------------------------------------------------------------
 # Heuristic baselines

tasks.py

@@ -14,6 +14,21 @@ from typing import Any, Dict
 
 from environment import BusRoutingEnv
 
+# Explicitly export task configurations for OpenEnv detection
+__all__ = [
+    "TaskConfig",
+    "task_1",
+    "task_2", 
+    "task_3",
+    "task_4",
+    "task_5",
+    "TASKS",
+    "TASK_EASY",
+    "TASK_MEDIUM", 
+    "TASK_HARD",
+    "get_task",
+]
+
 
 @dataclass
 class TaskConfig: