feat(planner): persist reusable action semantics

tests/test_ai_planner_task_runner.py

@@ -193,7 +193,12 @@ def test_multi_step_timeline_records_actual_per_step_prompts(tmp_path) -> None:
     """When AIPlanner is used, each timeline step's prompt is the real
     per-step user prompt (containing scene JSON), not the bare task goal."""
     decisions = [
-        ToolCallDecision(tool_name="tap", arguments={"x": 1, "y": 2}),
+        ToolCallDecision(
+            tool_name="tap",
+            arguments={"x": 1, "y": 2},
+            purpose="Open the send control.",
+            expected_outcome="The message composer is focused.",
+        ),
         ToolCallDecision(tool_name="finish_task", arguments={"success": True}),
     ]
     client = ScriptedToolCallingClient(decisions)
@@ -228,6 +233,12 @@ def test_multi_step_timeline_records_actual_per_step_prompts(tmp_path) -> None:
     assert "Current Scene (JSON)" in prompt
     assert "Call exactly one tool" in prompt
     assert "tap the button" in prompt
+    assert records[0]["tool_call"]["args"] == {"x": 1, "y": 2}
+    assert records[0]["tool_call"]["purpose"] == "Open the send control."
+    assert (
+        records[0]["tool_call"]["expected_outcome"]
+        == "The message composer is focused."
+    )
 
 
 def test_non_ai_planner_falls_back_to_task_goal_for_prompt(tmp_path) -> None: