feat(mma): Implement ExecutionEngine with auto-queue and step-mode support

dag_engine.py

@@ -76,3 +76,50 @@ class TrackDAG:
             visit(ticket.id)
 
         return stack
+
+class ExecutionEngine:
+    def __init__(self, dag: TrackDAG, auto_queue: bool = False):
+        self.dag = dag
+        self.auto_queue = auto_queue
+
+    def tick(self) -> List[Ticket]:
+        """
+        Returns a list of tasks that are currently 'ready' to be executed.
+        A task is ready if its status is 'todo' and all its dependencies are 'completed'.
+        If auto_queue=True, it will automatically mark 'ready' tasks as 'in-progress',
+        unless step_mode=True is set on the task.
+        """
+        ready = self.dag.get_ready_tasks()
+        
+        if self.auto_queue:
+            for ticket in ready:
+                if not ticket.step_mode:
+                    ticket.status = "in_progress"
+        
+        return ready
+
+    def approve_task(self, task_id: str):
+        """
+        Manually approves a task to move it to 'in_progress'.
+        Typically used for tasks with step_mode=True or when auto_queue is False.
+        """
+        ticket = self.dag.ticket_map.get(task_id)
+        if ticket and ticket.status == "todo":
+            # Check if dependencies are met first
+            all_done = True
+            for dep_id in ticket.depends_on:
+                dep = self.dag.ticket_map.get(dep_id)
+                if not dep or dep.status != "completed":
+                    all_done = False
+                    break
+            
+            if all_done:
+                ticket.status = "in_progress"
+
+    def update_task_status(self, task_id: str, status: str):
+        """
+        Updates the status of a specific task within the DAG.
+        """
+        ticket = self.dag.ticket_map.get(task_id)
+        if ticket:
+            ticket.status = status

tests/test_execution_engine.py

@@ -0,0 +1,123 @@
+import pytest
+from models import Ticket
+from dag_engine import TrackDAG, ExecutionEngine
+
+def test_execution_engine_basic_flow():
+    # Setup tickets with dependencies
+    t1 = Ticket(id="T1", description="Task 1", status="todo", assigned_to="worker")
+    t2 = Ticket(id="T2", description="Task 2", status="todo", assigned_to="worker", depends_on=["T1"])
+    t3 = Ticket(id="T3", description="Task 3", status="todo", assigned_to="worker", depends_on=["T1"])
+    t4 = Ticket(id="T4", description="Task 4", status="todo", assigned_to="worker", depends_on=["T2", "T3"])
+
+    dag = TrackDAG([t1, t2, t3, t4])
+    engine = ExecutionEngine(dag)
+
+    # Tick 1: Only T1 should be ready
+    ready = engine.tick()
+    assert len(ready) == 1
+    assert ready[0].id == "T1"
+
+    # Complete T1
+    engine.update_task_status("T1", "completed")
+
+    # Tick 2: T2 and T3 should be ready
+    ready = engine.tick()
+    assert len(ready) == 2
+    ids = {t.id for t in ready}
+    assert ids == {"T2", "T3"}
+
+    # Complete T2
+    engine.update_task_status("T2", "completed")
+
+    # Tick 3: Only T3 should be ready (T4 depends on T2 AND T3)
+    ready = engine.tick()
+    assert len(ready) == 1
+    assert ready[0].id == "T3"
+
+    # Complete T3
+    engine.update_task_status("T3", "completed")
+
+    # Tick 4: T4 should be ready
+    ready = engine.tick()
+    assert len(ready) == 1
+    assert ready[0].id == "T4"
+
+    # Complete T4
+    engine.update_task_status("T4", "completed")
+
+    # Tick 5: Nothing ready
+    ready = engine.tick()
+    assert len(ready) == 0
+
+def test_execution_engine_update_nonexistent_task():
+    dag = TrackDAG([])
+    engine = ExecutionEngine(dag)
+    # Should not raise error, or handle gracefully
+    engine.update_task_status("NONEXISTENT", "completed")
+
+def test_execution_engine_status_persistence():
+    t1 = Ticket(id="T1", description="Task 1", status="todo", assigned_to="worker")
+    dag = TrackDAG([t1])
+    engine = ExecutionEngine(dag)
+    
+    engine.update_task_status("T1", "in_progress")
+    assert t1.status == "in_progress"
+    
+    ready = engine.tick()
+    assert len(ready) == 0 # Only 'todo' tasks should be returned by tick() if they are ready
+
+def test_execution_engine_auto_queue():
+    t1 = Ticket(id="T1", description="Task 1", status="todo", assigned_to="worker")
+    t2 = Ticket(id="T2", description="Task 2", status="todo", assigned_to="worker", depends_on=["T1"])
+    
+    dag = TrackDAG([t1, t2])
+    engine = ExecutionEngine(dag, auto_queue=True)
+    
+    # Tick 1: T1 is ready and should be automatically marked as 'in_progress'
+    ready = engine.tick()
+    assert len(ready) == 1
+    assert ready[0].id == "T1"
+    assert t1.status == "in_progress"
+    
+    # Tick 2: T1 is in_progress, so T2 is NOT ready yet (T1 must be 'completed')
+    ready = engine.tick()
+    assert len(ready) == 0
+    assert t2.status == "todo"
+    
+    # Complete T1
+    engine.update_task_status("T1", "completed")
+    
+    # Tick 3: T2 is now ready and should be automatically marked as 'in_progress'
+    ready = engine.tick()
+    assert len(ready) == 1
+    assert ready[0].id == "T2"
+    assert t2.status == "in_progress"
+
+def test_execution_engine_step_mode():
+    t1 = Ticket(id="T1", description="Task 1", status="todo", assigned_to="worker", step_mode=True)
+    
+    dag = TrackDAG([t1])
+    engine = ExecutionEngine(dag, auto_queue=True)
+    
+    # Tick 1: T1 is ready, but step_mode=True, so it should NOT be automatically marked as 'in_progress'
+    ready = engine.tick()
+    assert len(ready) == 1
+    assert ready[0].id == "T1"
+    assert t1.status == "todo"
+    
+    # Manual approval
+    engine.approve_task("T1")
+    assert t1.status == "in_progress"
+    
+    # Tick 2: T1 is already in_progress, should not be returned by tick() (it's not 'ready'/todo)
+    ready = engine.tick()
+    assert len(ready) == 0
+
+def test_execution_engine_approve_task():
+    t1 = Ticket(id="T1", description="Task 1", status="todo", assigned_to="worker")
+    dag = TrackDAG([t1])
+    engine = ExecutionEngine(dag, auto_queue=False)
+    
+    # Should be able to approve even if auto_queue is False
+    engine.approve_task("T1")
+    assert t1.status == "in_progress"