fix: allow subgoals in triggers and empty plan

Copies the goal and changes can_fail to false. Also add a warning for empty plans in goals.

ref: N25B-460

src/control_backend/agents/bdi/agentspeak_generator.py

@@ -1,3 +1,4 @@
+import logging
 from functools import singledispatchmethod
 
 from slugify import slugify
@@ -59,6 +60,7 @@ class AgentSpeakGenerator:
     """
 
     _asp: AstProgram
+    logger = logging.getLogger(__name__)
 
     def generate(self, program: Program) -> str:
         """
@@ -472,6 +474,7 @@ class AgentSpeakGenerator:
         :param main_goal: Whether this is a main goal (for UI notification purposes).
         """
         context: list[AstExpression] = [self._astify(phase)]
+        if goal.can_fail:
             context.append(~self._astify(goal, achieved=True))
         if previous_goal and previous_goal.can_fail:
             context.append(self._astify(previous_goal, achieved=True))
@@ -496,6 +499,10 @@ class AgentSpeakGenerator:
         if not goal.can_fail and not continues_response:
             body.append(AstStatement(StatementType.ADD_BELIEF, self._astify(goal, achieved=True)))
 
+        if len(body) == 0:
+            self.logger.warning("Goal with no plan detected: %s", goal.name)
+            body.append(AstStatement(StatementType.EMPTY, AstLiteral("true")))
+
         self._asp.plans.append(AstPlan(TriggerType.ADDED_GOAL, self._astify(goal), context, body))
 
         self._asp.plans.append(
@@ -556,10 +563,10 @@ class AgentSpeakGenerator:
             )
         )
         for step in trigger.plan.steps:
-            body.append(self._step_to_statement(step))
             if isinstance(step, Goal):
-                step.can_fail = False  # triggers are continuous sequence
-                subgoals.append(step)
+                new_step = step.model_copy(update={"can_fail": False})  # triggers are sequence
+                subgoals.append(new_step)
+            body.append(self._step_to_statement(step))
 
         # Arbitrary wait for UI to display nicely
         body.append(