feat(tracing): carry task_prompt and output in agent_execution payloads (#7498)

`agent_execution_started` and `agent_execution_completed` are in
`complex_events`, so `_build_event_data` hand-builds their payloads. Those
payloads shipped only agent_role/goal/backstory and dropped two required bus
fields: `AgentExecutionStartedEvent.task_prompt` and
`AgentExecutionCompletedEvent.output`. A trace therefore said which agent ran
but not what it was asked or what it answered.

Add `task_prompt` to the started payload and `output` to the completed one,
whole and untruncated. No new event types, no TraceEvent change.

Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>
Co-authored-by: Vidit Ostwal <110953813+Vidit-Ostwal@users.noreply.github.com>

lib/crewai/src/crewai/events/listeners/tracing/trace_listener.py

@@ -1013,12 +1013,14 @@ class TraceCollectionListener(BaseEventListener):
                 "agent_role": event.agent.role,
                 "agent_goal": event.agent.goal,
                 "agent_backstory": event.agent.backstory,
+                "task_prompt": event.task_prompt,
             }
         if event_type == "agent_execution_completed":
             return {
                 "agent_role": event.agent.role,
                 "agent_goal": event.agent.goal,
                 "agent_backstory": event.agent.backstory,
+                "output": event.output,
             }
         if event_type == "llm_call_started":
             event_data = safe_serialize_to_dict(event)

lib/crewai/tests/tracing/test_trace_agent_prompt_output.py

@@ -0,0 +1,58 @@
+"""The agent_execution_* trace payloads must carry the prompt and the output.
+
+Both types are in ``TraceCollectionListener.complex_events``, so their payload
+is hand-built by ``_build_event_data`` rather than serialized from the event:
+a bus field reaches the trace only if it is named there. ``task_prompt`` and
+``output`` are required on the bus events but were dropped, leaving a trace
+that said which agent ran without saying what it was asked or what it said.
+"""
+
+from __future__ import annotations
+
+from crewai import Agent
+from crewai.events.listeners.tracing.trace_listener import TraceCollectionListener
+from crewai.events.types.agent_events import (
+    AgentExecutionCompletedEvent,
+    AgentExecutionStartedEvent,
+)
+
+
+# Long and non-repeating, so a truncated or elided copy cannot compare equal.
+LONG_TEXT = "".join(f"paragraph {i}: the quick brown fox jumps over the lazy dog\n" for i in range(400))
+assert len(LONG_TEXT) > 20_000
+
+
+def _listener() -> TraceCollectionListener:
+    """A bare listener: `_build_event_data` needs no batch manager or bus."""
+    return TraceCollectionListener.__new__(TraceCollectionListener)
+
+
+def _agent() -> Agent:
+    return Agent(
+        role="Researcher",
+        goal="Find things out",
+        backstory="Curious by nature",
+        llm="openai/gpt-4o-mini",
+    )
+
+
+def test_started_payload_carries_the_whole_task_prompt() -> None:
+    agent = _agent()
+    event = AgentExecutionStartedEvent(
+        agent=agent, task=None, tools=None, task_prompt=LONG_TEXT
+    )
+
+    data = _listener()._build_event_data("agent_execution_started", event, agent)
+
+    assert data["task_prompt"] == LONG_TEXT
+    assert data["agent_role"] == "Researcher"
+
+
+def test_completed_payload_carries_the_whole_output() -> None:
+    agent = _agent()
+    event = AgentExecutionCompletedEvent(agent=agent, task=None, output=LONG_TEXT)
+
+    data = _listener()._build_event_data("agent_execution_completed", event, agent)
+
+    assert data["output"] == LONG_TEXT
+    assert data["agent_role"] == "Researcher"