feat: add emission sequence for event ordering

lib/crewai/src/crewai/events/base_events.py

@@ -1,9 +1,35 @@
+from collections.abc import Iterator
 from datetime import datetime, timezone
+import itertools
 from typing import Any
+import uuid
 
 from pydantic import BaseModel, Field
 
-from crewai.utilities.serialization import to_serializable
+from crewai.utilities.serialization import Serializable, to_serializable
+
+
+_emission_counter: Iterator[int] = itertools.count(start=1)
+
+
+def get_next_emission_sequence() -> int:
+    """Get the next emission sequence number.
+
+    Thread-safe due to atomic next() on itertools.count under the GIL.
+
+    Returns:
+        The next sequence number.
+    """
+    return next(_emission_counter)
+
+
+def reset_emission_counter() -> None:
+    """Reset the emission sequence counter to 1.
+
+    Useful for test isolation.
+    """
+    global _emission_counter
+    _emission_counter = itertools.count(start=1)
 
 
 class BaseEvent(BaseModel):
@@ -22,7 +48,11 @@ class BaseEvent(BaseModel):
     agent_id: str | None = None
     agent_role: str | None = None
 
-    def to_json(self, exclude: set[str] | None = None):
+    event_id: str = Field(default_factory=lambda: str(uuid.uuid4()))
+    parent_event_id: str | None = None
+    emission_sequence: int | None = None
+
+    def to_json(self, exclude: set[str] | None = None) -> Serializable:
         """
         Converts the event to a JSON-serializable dictionary.
 
@@ -34,13 +64,13 @@ class BaseEvent(BaseModel):
         """
         return to_serializable(self, exclude=exclude)
 
-    def _set_task_params(self, data: dict[str, Any]):
+    def _set_task_params(self, data: dict[str, Any]) -> None:
         if "from_task" in data and (task := data["from_task"]):
             self.task_id = str(task.id)
             self.task_name = task.name or task.description
             self.from_task = None
 
-    def _set_agent_params(self, data: dict[str, Any]):
+    def _set_agent_params(self, data: dict[str, Any]) -> None:
         task = data.get("from_task", None)
         agent = task.agent if task else data.get("from_agent", None)
 

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

@@ -15,5 +15,8 @@ class TraceEvent:
     type: str = ""
     event_data: dict[str, Any] = field(default_factory=dict)
 
+    emission_sequence: int | None = None
+    parent_event_id: str | None = None
+
     def to_dict(self) -> dict[str, Any]:
         return asdict(self)