diff --git a/lib/crewai/src/crewai/events/types/a2a_events.py b/lib/crewai/src/crewai/events/types/a2a_events.py
index 55de064f8..4131a1fea 100644
--- a/lib/crewai/src/crewai/events/types/a2a_events.py
+++ b/lib/crewai/src/crewai/events/types/a2a_events.py
@@ -73,7 +73,7 @@ class A2ADelegationStartedEvent(A2AEventBase):
         extensions: List of A2A extension URIs in use.
     """
 
-    type: str = "a2a_delegation_started"
+    type: Literal["a2a_delegation_started"] = "a2a_delegation_started"
     endpoint: str
     task_description: str
     agent_id: str
@@ -106,7 +106,7 @@ class A2ADelegationCompletedEvent(A2AEventBase):
         extensions: List of A2A extension URIs in use.
     """
 
-    type: str = "a2a_delegation_completed"
+    type: Literal["a2a_delegation_completed"] = "a2a_delegation_completed"
     status: str
     result: str | None = None
     error: str | None = None
@@ -140,7 +140,7 @@ class A2AConversationStartedEvent(A2AEventBase):
         extensions: List of A2A extension URIs in use.
     """
 
-    type: str = "a2a_conversation_started"
+    type: Literal["a2a_conversation_started"] = "a2a_conversation_started"
     agent_id: str
     endpoint: str
     context_id: str | None = None
@@ -171,7 +171,7 @@ class A2AMessageSentEvent(A2AEventBase):
         extensions: List of A2A extension URIs in use.
     """
 
-    type: str = "a2a_message_sent"
+    type: Literal["a2a_message_sent"] = "a2a_message_sent"
     message: str
     turn_number: int
     context_id: str | None = None
@@ -203,7 +203,7 @@ class A2AResponseReceivedEvent(A2AEventBase):
         extensions: List of A2A extension URIs in use.
     """
 
-    type: str = "a2a_response_received"
+    type: Literal["a2a_response_received"] = "a2a_response_received"
     response: str
     turn_number: int
     context_id: str | None = None
@@ -237,7 +237,7 @@ class A2AConversationCompletedEvent(A2AEventBase):
         extensions: List of A2A extension URIs in use.
     """
 
-    type: str = "a2a_conversation_completed"
+    type: Literal["a2a_conversation_completed"] = "a2a_conversation_completed"
     status: Literal["completed", "failed"]
     final_result: str | None = None
     error: str | None = None
@@ -263,7 +263,7 @@ class A2APollingStartedEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_polling_started"
+    type: Literal["a2a_polling_started"] = "a2a_polling_started"
     task_id: str
     context_id: str | None = None
     polling_interval: float
@@ -286,7 +286,7 @@ class A2APollingStatusEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_polling_status"
+    type: Literal["a2a_polling_status"] = "a2a_polling_status"
     task_id: str
     context_id: str | None = None
     state: str
@@ -309,7 +309,9 @@ class A2APushNotificationRegisteredEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_push_notification_registered"
+    type: Literal["a2a_push_notification_registered"] = (
+        "a2a_push_notification_registered"
+    )
     task_id: str
     context_id: str | None = None
     callback_url: str
@@ -334,7 +336,7 @@ class A2APushNotificationReceivedEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_push_notification_received"
+    type: Literal["a2a_push_notification_received"] = "a2a_push_notification_received"
     task_id: str
     context_id: str | None = None
     state: str
@@ -359,7 +361,7 @@ class A2APushNotificationSentEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_push_notification_sent"
+    type: Literal["a2a_push_notification_sent"] = "a2a_push_notification_sent"
     task_id: str
     context_id: str | None = None
     callback_url: str
@@ -381,7 +383,7 @@ class A2APushNotificationTimeoutEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_push_notification_timeout"
+    type: Literal["a2a_push_notification_timeout"] = "a2a_push_notification_timeout"
     task_id: str
     context_id: str | None = None
     timeout_seconds: float
@@ -405,7 +407,7 @@ class A2AStreamingStartedEvent(A2AEventBase):
         extensions: List of A2A extension URIs in use.
     """
 
-    type: str = "a2a_streaming_started"
+    type: Literal["a2a_streaming_started"] = "a2a_streaming_started"
     task_id: str | None = None
     context_id: str | None = None
     endpoint: str
@@ -434,7 +436,7 @@ class A2AStreamingChunkEvent(A2AEventBase):
         extensions: List of A2A extension URIs in use.
     """
 
-    type: str = "a2a_streaming_chunk"
+    type: Literal["a2a_streaming_chunk"] = "a2a_streaming_chunk"
     task_id: str | None = None
     context_id: str | None = None
     chunk: str
@@ -462,7 +464,7 @@ class A2AAgentCardFetchedEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_agent_card_fetched"
+    type: Literal["a2a_agent_card_fetched"] = "a2a_agent_card_fetched"
     endpoint: str
     a2a_agent_name: str | None = None
     agent_card: dict[str, Any] | None = None
@@ -486,7 +488,7 @@ class A2AAuthenticationFailedEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_authentication_failed"
+    type: Literal["a2a_authentication_failed"] = "a2a_authentication_failed"
     endpoint: str
     auth_type: str | None = None
     error: str
@@ -517,7 +519,7 @@ class A2AArtifactReceivedEvent(A2AEventBase):
         extensions: List of A2A extension URIs in use.
     """
 
-    type: str = "a2a_artifact_received"
+    type: Literal["a2a_artifact_received"] = "a2a_artifact_received"
     task_id: str
     artifact_id: str
     artifact_name: str | None = None
@@ -550,7 +552,7 @@ class A2AConnectionErrorEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_connection_error"
+    type: Literal["a2a_connection_error"] = "a2a_connection_error"
     endpoint: str
     error: str
     error_type: str | None = None
@@ -571,7 +573,7 @@ class A2AServerTaskStartedEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_server_task_started"
+    type: Literal["a2a_server_task_started"] = "a2a_server_task_started"
     task_id: str
     context_id: str
     metadata: dict[str, Any] | None = None
@@ -587,7 +589,7 @@ class A2AServerTaskCompletedEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_server_task_completed"
+    type: Literal["a2a_server_task_completed"] = "a2a_server_task_completed"
     task_id: str
     context_id: str
     result: str
@@ -603,7 +605,7 @@ class A2AServerTaskCanceledEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_server_task_canceled"
+    type: Literal["a2a_server_task_canceled"] = "a2a_server_task_canceled"
     task_id: str
     context_id: str
     metadata: dict[str, Any] | None = None
@@ -619,7 +621,7 @@ class A2AServerTaskFailedEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_server_task_failed"
+    type: Literal["a2a_server_task_failed"] = "a2a_server_task_failed"
     task_id: str
     context_id: str
     error: str
@@ -634,7 +636,7 @@ class A2AParallelDelegationStartedEvent(A2AEventBase):
         task_description: Description of the task being delegated.
     """
 
-    type: str = "a2a_parallel_delegation_started"
+    type: Literal["a2a_parallel_delegation_started"] = "a2a_parallel_delegation_started"
     endpoints: list[str]
     task_description: str
 
@@ -649,7 +651,9 @@ class A2AParallelDelegationCompletedEvent(A2AEventBase):
         results: Summary of results from each agent.
     """
 
-    type: str = "a2a_parallel_delegation_completed"
+    type: Literal["a2a_parallel_delegation_completed"] = (
+        "a2a_parallel_delegation_completed"
+    )
     endpoints: list[str]
     success_count: int
     failure_count: int
@@ -675,7 +679,7 @@ class A2ATransportNegotiatedEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_transport_negotiated"
+    type: Literal["a2a_transport_negotiated"] = "a2a_transport_negotiated"
     endpoint: str
     a2a_agent_name: str | None = None
     negotiated_transport: str
@@ -708,7 +712,7 @@ class A2AContentTypeNegotiatedEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_content_type_negotiated"
+    type: Literal["a2a_content_type_negotiated"] = "a2a_content_type_negotiated"
     endpoint: str
     a2a_agent_name: str | None = None
     skill_name: str | None = None
@@ -738,7 +742,7 @@ class A2AContextCreatedEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_context_created"
+    type: Literal["a2a_context_created"] = "a2a_context_created"
     context_id: str
     created_at: float
     metadata: dict[str, Any] | None = None
@@ -755,7 +759,7 @@ class A2AContextExpiredEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_context_expired"
+    type: Literal["a2a_context_expired"] = "a2a_context_expired"
     context_id: str
     created_at: float
     age_seconds: float
@@ -775,7 +779,7 @@ class A2AContextIdleEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_context_idle"
+    type: Literal["a2a_context_idle"] = "a2a_context_idle"
     context_id: str
     idle_seconds: float
     task_count: int
@@ -792,7 +796,7 @@ class A2AContextCompletedEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_context_completed"
+    type: Literal["a2a_context_completed"] = "a2a_context_completed"
     context_id: str
     total_tasks: int
     duration_seconds: float
@@ -811,7 +815,7 @@ class A2AContextPrunedEvent(A2AEventBase):
         metadata: Custom A2A metadata key-value pairs.
     """
 
-    type: str = "a2a_context_pruned"
+    type: Literal["a2a_context_pruned"] = "a2a_context_pruned"
     context_id: str
     task_count: int
     age_seconds: float
diff --git a/lib/crewai/src/crewai/events/types/agent_events.py b/lib/crewai/src/crewai/events/types/agent_events.py
index 49e24e059..8c811d176 100644
--- a/lib/crewai/src/crewai/events/types/agent_events.py
+++ b/lib/crewai/src/crewai/events/types/agent_events.py
@@ -3,7 +3,7 @@
 from __future__ import annotations
 
 from collections.abc import Sequence
-from typing import Any
+from typing import Any, Literal
 
 from pydantic import ConfigDict, model_validator
 from typing_extensions import Self
@@ -21,7 +21,7 @@ class AgentExecutionStartedEvent(BaseEvent):
     task: Any
     tools: Sequence[BaseTool | CrewStructuredTool] | None
     task_prompt: str
-    type: str = "agent_execution_started"
+    type: Literal["agent_execution_started"] = "agent_execution_started"
 
     model_config = ConfigDict(arbitrary_types_allowed=True)
 
@@ -38,7 +38,7 @@ class AgentExecutionCompletedEvent(BaseEvent):
     agent: BaseAgent
     task: Any
     output: str
-    type: str = "agent_execution_completed"
+    type: Literal["agent_execution_completed"] = "agent_execution_completed"
 
     model_config = ConfigDict(arbitrary_types_allowed=True)
 
@@ -55,7 +55,7 @@ class AgentExecutionErrorEvent(BaseEvent):
     agent: BaseAgent
     task: Any
     error: str
-    type: str = "agent_execution_error"
+    type: Literal["agent_execution_error"] = "agent_execution_error"
 
     model_config = ConfigDict(arbitrary_types_allowed=True)
 
@@ -73,7 +73,7 @@ class LiteAgentExecutionStartedEvent(BaseEvent):
     agent_info: dict[str, Any]
     tools: Sequence[BaseTool | CrewStructuredTool] | None
     messages: str | list[dict[str, str]]
-    type: str = "lite_agent_execution_started"
+    type: Literal["lite_agent_execution_started"] = "lite_agent_execution_started"
 
     model_config = ConfigDict(arbitrary_types_allowed=True)
 
@@ -83,7 +83,7 @@ class LiteAgentExecutionCompletedEvent(BaseEvent):
 
     agent_info: dict[str, Any]
     output: str
-    type: str = "lite_agent_execution_completed"
+    type: Literal["lite_agent_execution_completed"] = "lite_agent_execution_completed"
 
 
 class LiteAgentExecutionErrorEvent(BaseEvent):
@@ -91,7 +91,7 @@ class LiteAgentExecutionErrorEvent(BaseEvent):
 
     agent_info: dict[str, Any]
     error: str
-    type: str = "lite_agent_execution_error"
+    type: Literal["lite_agent_execution_error"] = "lite_agent_execution_error"
 
 
 # Agent Eval events
@@ -100,7 +100,7 @@ class AgentEvaluationStartedEvent(BaseEvent):
     agent_role: str
     task_id: str | None = None
     iteration: int
-    type: str = "agent_evaluation_started"
+    type: Literal["agent_evaluation_started"] = "agent_evaluation_started"
 
 
 class AgentEvaluationCompletedEvent(BaseEvent):
@@ -110,7 +110,7 @@ class AgentEvaluationCompletedEvent(BaseEvent):
     iteration: int
     metric_category: Any
     score: Any
-    type: str = "agent_evaluation_completed"
+    type: Literal["agent_evaluation_completed"] = "agent_evaluation_completed"
 
 
 class AgentEvaluationFailedEvent(BaseEvent):
@@ -119,7 +119,7 @@ class AgentEvaluationFailedEvent(BaseEvent):
     task_id: str | None = None
     iteration: int
     error: str
-    type: str = "agent_evaluation_failed"
+    type: Literal["agent_evaluation_failed"] = "agent_evaluation_failed"
 
 
 def _set_agent_fingerprint(event: BaseEvent, agent: BaseAgent) -> None:
diff --git a/lib/crewai/src/crewai/events/types/crew_events.py b/lib/crewai/src/crewai/events/types/crew_events.py
index fa198f5ae..cf71cbfe3 100644
--- a/lib/crewai/src/crewai/events/types/crew_events.py
+++ b/lib/crewai/src/crewai/events/types/crew_events.py
@@ -1,4 +1,4 @@
-from typing import TYPE_CHECKING, Any
+from typing import TYPE_CHECKING, Any, Literal
 
 from crewai.events.base_events import BaseEvent
 
@@ -37,14 +37,14 @@ class CrewKickoffStartedEvent(CrewBaseEvent):
     """Event emitted when a crew starts execution"""
 
     inputs: dict[str, Any] | None
-    type: str = "crew_kickoff_started"
+    type: Literal["crew_kickoff_started"] = "crew_kickoff_started"
 
 
 class CrewKickoffCompletedEvent(CrewBaseEvent):
     """Event emitted when a crew completes execution"""
 
     output: Any
-    type: str = "crew_kickoff_completed"
+    type: Literal["crew_kickoff_completed"] = "crew_kickoff_completed"
     total_tokens: int = 0
 
 
@@ -52,7 +52,7 @@ class CrewKickoffFailedEvent(CrewBaseEvent):
     """Event emitted when a crew fails to complete execution"""
 
     error: str
-    type: str = "crew_kickoff_failed"
+    type: Literal["crew_kickoff_failed"] = "crew_kickoff_failed"
 
 
 class CrewTrainStartedEvent(CrewBaseEvent):
@@ -61,7 +61,7 @@ class CrewTrainStartedEvent(CrewBaseEvent):
     n_iterations: int
     filename: str
     inputs: dict[str, Any] | None
-    type: str = "crew_train_started"
+    type: Literal["crew_train_started"] = "crew_train_started"
 
 
 class CrewTrainCompletedEvent(CrewBaseEvent):
@@ -69,14 +69,14 @@ class CrewTrainCompletedEvent(CrewBaseEvent):
 
     n_iterations: int
     filename: str
-    type: str = "crew_train_completed"
+    type: Literal["crew_train_completed"] = "crew_train_completed"
 
 
 class CrewTrainFailedEvent(CrewBaseEvent):
     """Event emitted when a crew fails to complete training"""
 
     error: str
-    type: str = "crew_train_failed"
+    type: Literal["crew_train_failed"] = "crew_train_failed"
 
 
 class CrewTestStartedEvent(CrewBaseEvent):
@@ -85,20 +85,20 @@ class CrewTestStartedEvent(CrewBaseEvent):
     n_iterations: int
     eval_llm: str | Any | None
     inputs: dict[str, Any] | None
-    type: str = "crew_test_started"
+    type: Literal["crew_test_started"] = "crew_test_started"
 
 
 class CrewTestCompletedEvent(CrewBaseEvent):
     """Event emitted when a crew completes testing"""
 
-    type: str = "crew_test_completed"
+    type: Literal["crew_test_completed"] = "crew_test_completed"
 
 
 class CrewTestFailedEvent(CrewBaseEvent):
     """Event emitted when a crew fails to complete testing"""
 
     error: str
-    type: str = "crew_test_failed"
+    type: Literal["crew_test_failed"] = "crew_test_failed"
 
 
 class CrewTestResultEvent(CrewBaseEvent):
@@ -107,4 +107,4 @@ class CrewTestResultEvent(CrewBaseEvent):
     quality: float
     execution_duration: float
     model: str
-    type: str = "crew_test_result"
+    type: Literal["crew_test_result"] = "crew_test_result"
diff --git a/lib/crewai/src/crewai/events/types/flow_events.py b/lib/crewai/src/crewai/events/types/flow_events.py
index d820b8a05..c2c1e2912 100644
--- a/lib/crewai/src/crewai/events/types/flow_events.py
+++ b/lib/crewai/src/crewai/events/types/flow_events.py
@@ -1,4 +1,4 @@
-from typing import Any
+from typing import Any, Literal
 
 from pydantic import BaseModel, ConfigDict
 
@@ -17,14 +17,14 @@ class FlowStartedEvent(FlowEvent):
 
     flow_name: str
     inputs: dict[str, Any] | None = None
-    type: str = "flow_started"
+    type: Literal["flow_started"] = "flow_started"
 
 
 class FlowCreatedEvent(FlowEvent):
     """Event emitted when a flow is created"""
 
     flow_name: str
-    type: str = "flow_created"
+    type: Literal["flow_created"] = "flow_created"
 
 
 class MethodExecutionStartedEvent(FlowEvent):
@@ -34,7 +34,7 @@ class MethodExecutionStartedEvent(FlowEvent):
     method_name: str
     state: dict[str, Any] | BaseModel
     params: dict[str, Any] | None = None
-    type: str = "method_execution_started"
+    type: Literal["method_execution_started"] = "method_execution_started"
 
 
 class MethodExecutionFinishedEvent(FlowEvent):
@@ -44,7 +44,7 @@ class MethodExecutionFinishedEvent(FlowEvent):
     method_name: str
     result: Any = None
     state: dict[str, Any] | BaseModel
-    type: str = "method_execution_finished"
+    type: Literal["method_execution_finished"] = "method_execution_finished"
 
 
 class MethodExecutionFailedEvent(FlowEvent):
@@ -53,7 +53,7 @@ class MethodExecutionFailedEvent(FlowEvent):
     flow_name: str
     method_name: str
     error: Exception
-    type: str = "method_execution_failed"
+    type: Literal["method_execution_failed"] = "method_execution_failed"
 
     model_config = ConfigDict(arbitrary_types_allowed=True)
 
@@ -78,7 +78,7 @@ class MethodExecutionPausedEvent(FlowEvent):
     flow_id: str
     message: str
     emit: list[str] | None = None
-    type: str = "method_execution_paused"
+    type: Literal["method_execution_paused"] = "method_execution_paused"
 
 
 class FlowFinishedEvent(FlowEvent):
@@ -86,7 +86,7 @@ class FlowFinishedEvent(FlowEvent):
 
     flow_name: str
     result: Any | None = None
-    type: str = "flow_finished"
+    type: Literal["flow_finished"] = "flow_finished"
     state: dict[str, Any] | BaseModel
 
 
@@ -110,14 +110,14 @@ class FlowPausedEvent(FlowEvent):
     state: dict[str, Any] | BaseModel
     message: str
     emit: list[str] | None = None
-    type: str = "flow_paused"
+    type: Literal["flow_paused"] = "flow_paused"
 
 
 class FlowPlotEvent(FlowEvent):
     """Event emitted when a flow plot is created"""
 
     flow_name: str
-    type: str = "flow_plot"
+    type: Literal["flow_plot"] = "flow_plot"
 
 
 class FlowInputRequestedEvent(FlowEvent):
@@ -138,7 +138,7 @@ class FlowInputRequestedEvent(FlowEvent):
     method_name: str
     message: str
     metadata: dict[str, Any] | None = None
-    type: str = "flow_input_requested"
+    type: Literal["flow_input_requested"] = "flow_input_requested"
 
 
 class FlowInputReceivedEvent(FlowEvent):
@@ -163,7 +163,7 @@ class FlowInputReceivedEvent(FlowEvent):
     response: str | None = None
     metadata: dict[str, Any] | None = None
     response_metadata: dict[str, Any] | None = None
-    type: str = "flow_input_received"
+    type: Literal["flow_input_received"] = "flow_input_received"
 
 
 class HumanFeedbackRequestedEvent(FlowEvent):
@@ -187,7 +187,7 @@ class HumanFeedbackRequestedEvent(FlowEvent):
     message: str
     emit: list[str] | None = None
     request_id: str | None = None
-    type: str = "human_feedback_requested"
+    type: Literal["human_feedback_requested"] = "human_feedback_requested"
 
 
 class HumanFeedbackReceivedEvent(FlowEvent):
@@ -209,4 +209,4 @@ class HumanFeedbackReceivedEvent(FlowEvent):
     feedback: str
     outcome: str | None = None
     request_id: str | None = None
-    type: str = "human_feedback_received"
+    type: Literal["human_feedback_received"] = "human_feedback_received"
diff --git a/lib/crewai/src/crewai/events/types/knowledge_events.py b/lib/crewai/src/crewai/events/types/knowledge_events.py
index a2d9af728..086e89377 100644
--- a/lib/crewai/src/crewai/events/types/knowledge_events.py
+++ b/lib/crewai/src/crewai/events/types/knowledge_events.py
@@ -1,4 +1,4 @@
-from typing import Any
+from typing import Any, Literal
 
 from crewai.events.base_events import BaseEvent
 
@@ -20,14 +20,16 @@ class KnowledgeEventBase(BaseEvent):
 class KnowledgeRetrievalStartedEvent(KnowledgeEventBase):
     """Event emitted when a knowledge retrieval is started."""
 
-    type: str = "knowledge_search_query_started"
+    type: Literal["knowledge_search_query_started"] = "knowledge_search_query_started"
 
 
 class KnowledgeRetrievalCompletedEvent(KnowledgeEventBase):
     """Event emitted when a knowledge retrieval is completed."""
 
     query: str
-    type: str = "knowledge_search_query_completed"
+    type: Literal["knowledge_search_query_completed"] = (
+        "knowledge_search_query_completed"
+    )
     retrieved_knowledge: str
 
 
@@ -35,13 +37,13 @@ class KnowledgeQueryStartedEvent(KnowledgeEventBase):
     """Event emitted when a knowledge query is started."""
 
     task_prompt: str
-    type: str = "knowledge_query_started"
+    type: Literal["knowledge_query_started"] = "knowledge_query_started"
 
 
 class KnowledgeQueryFailedEvent(KnowledgeEventBase):
     """Event emitted when a knowledge query fails."""
 
-    type: str = "knowledge_query_failed"
+    type: Literal["knowledge_query_failed"] = "knowledge_query_failed"
     error: str
 
 
@@ -49,12 +51,12 @@ class KnowledgeQueryCompletedEvent(KnowledgeEventBase):
     """Event emitted when a knowledge query is completed."""
 
     query: str
-    type: str = "knowledge_query_completed"
+    type: Literal["knowledge_query_completed"] = "knowledge_query_completed"
 
 
 class KnowledgeSearchQueryFailedEvent(KnowledgeEventBase):
     """Event emitted when a knowledge search query fails."""
 
     query: str
-    type: str = "knowledge_search_query_failed"
+    type: Literal["knowledge_search_query_failed"] = "knowledge_search_query_failed"
     error: str
diff --git a/lib/crewai/src/crewai/events/types/llm_events.py b/lib/crewai/src/crewai/events/types/llm_events.py
index 4b8c96d9e..b138f908c 100644
--- a/lib/crewai/src/crewai/events/types/llm_events.py
+++ b/lib/crewai/src/crewai/events/types/llm_events.py
@@ -1,5 +1,5 @@
 from enum import Enum
-from typing import Any
+from typing import Any, Literal
 
 from pydantic import BaseModel
 
@@ -43,7 +43,7 @@ class LLMCallStartedEvent(LLMEventBase):
             multimodal content (text, images, etc.)
     """
 
-    type: str = "llm_call_started"
+    type: Literal["llm_call_started"] = "llm_call_started"
     messages: str | list[dict[str, Any]] | None = None
     tools: list[dict[str, Any]] | None = None
     callbacks: list[Any] | None = None
@@ -53,7 +53,7 @@ class LLMCallStartedEvent(LLMEventBase):
 class LLMCallCompletedEvent(LLMEventBase):
     """Event emitted when a LLM call completes"""
 
-    type: str = "llm_call_completed"
+    type: Literal["llm_call_completed"] = "llm_call_completed"
     messages: str | list[dict[str, Any]] | None = None
     response: Any
     call_type: LLMCallType
@@ -64,7 +64,7 @@ class LLMCallFailedEvent(LLMEventBase):
     """Event emitted when a LLM call fails"""
 
     error: str
-    type: str = "llm_call_failed"
+    type: Literal["llm_call_failed"] = "llm_call_failed"
 
 
 class FunctionCall(BaseModel):
@@ -82,7 +82,7 @@ class ToolCall(BaseModel):
 class LLMStreamChunkEvent(LLMEventBase):
     """Event emitted when a streaming chunk is received"""
 
-    type: str = "llm_stream_chunk"
+    type: Literal["llm_stream_chunk"] = "llm_stream_chunk"
     chunk: str
     tool_call: ToolCall | None = None
     call_type: LLMCallType | None = None
@@ -92,6 +92,6 @@ class LLMStreamChunkEvent(LLMEventBase):
 class LLMThinkingChunkEvent(LLMEventBase):
     """Event emitted when a thinking/reasoning chunk is received from a thinking model"""
 
-    type: str = "llm_thinking_chunk"
+    type: Literal["llm_thinking_chunk"] = "llm_thinking_chunk"
     chunk: str
     response_id: str | None = None
diff --git a/lib/crewai/src/crewai/events/types/llm_guardrail_events.py b/lib/crewai/src/crewai/events/types/llm_guardrail_events.py
index fdf82cd2a..8bbcf6e0b 100644
--- a/lib/crewai/src/crewai/events/types/llm_guardrail_events.py
+++ b/lib/crewai/src/crewai/events/types/llm_guardrail_events.py
@@ -1,6 +1,6 @@
 from collections.abc import Callable
 from inspect import getsource
-from typing import Any
+from typing import Any, Literal
 
 from crewai.events.base_events import BaseEvent
 
@@ -27,7 +27,7 @@ class LLMGuardrailStartedEvent(LLMGuardrailBaseEvent):
         retry_count: The number of times the guardrail has been retried
     """
 
-    type: str = "llm_guardrail_started"
+    type: Literal["llm_guardrail_started"] = "llm_guardrail_started"
     guardrail: str | Callable[..., Any]
     retry_count: int
 
@@ -53,7 +53,7 @@ class LLMGuardrailCompletedEvent(LLMGuardrailBaseEvent):
         retry_count: The number of times the guardrail has been retried
     """
 
-    type: str = "llm_guardrail_completed"
+    type: Literal["llm_guardrail_completed"] = "llm_guardrail_completed"
     success: bool
     result: Any
     error: str | None = None
@@ -68,6 +68,6 @@ class LLMGuardrailFailedEvent(LLMGuardrailBaseEvent):
         retry_count: The number of times the guardrail has been retried
     """
 
-    type: str = "llm_guardrail_failed"
+    type: Literal["llm_guardrail_failed"] = "llm_guardrail_failed"
     error: str
     retry_count: int
diff --git a/lib/crewai/src/crewai/events/types/logging_events.py b/lib/crewai/src/crewai/events/types/logging_events.py
index 31b8bdd1e..6bd0ff3e3 100644
--- a/lib/crewai/src/crewai/events/types/logging_events.py
+++ b/lib/crewai/src/crewai/events/types/logging_events.py
@@ -1,6 +1,6 @@
 """Agent logging events that don't reference BaseAgent to avoid circular imports."""
 
-from typing import Any
+from typing import Any, Literal
 
 from pydantic import ConfigDict
 
@@ -13,7 +13,7 @@ class AgentLogsStartedEvent(BaseEvent):
     agent_role: str
     task_description: str | None = None
     verbose: bool = False
-    type: str = "agent_logs_started"
+    type: Literal["agent_logs_started"] = "agent_logs_started"
 
 
 class AgentLogsExecutionEvent(BaseEvent):
@@ -22,6 +22,6 @@ class AgentLogsExecutionEvent(BaseEvent):
     agent_role: str
     formatted_answer: Any
     verbose: bool = False
-    type: str = "agent_logs_execution"
+    type: Literal["agent_logs_execution"] = "agent_logs_execution"
 
     model_config = ConfigDict(arbitrary_types_allowed=True)
diff --git a/lib/crewai/src/crewai/events/types/mcp_events.py b/lib/crewai/src/crewai/events/types/mcp_events.py
index a89d4df70..c9278dec0 100644
--- a/lib/crewai/src/crewai/events/types/mcp_events.py
+++ b/lib/crewai/src/crewai/events/types/mcp_events.py
@@ -1,5 +1,5 @@
 from datetime import datetime
-from typing import Any
+from typing import Any, Literal
 
 from crewai.events.base_events import BaseEvent
 
@@ -24,7 +24,7 @@ class MCPEvent(BaseEvent):
 class MCPConnectionStartedEvent(MCPEvent):
     """Event emitted when starting to connect to an MCP server."""
 
-    type: str = "mcp_connection_started"
+    type: Literal["mcp_connection_started"] = "mcp_connection_started"
     connect_timeout: int | None = None
     is_reconnect: bool = (
         False  # True if this is a reconnection, False for first connection
@@ -34,7 +34,7 @@ class MCPConnectionStartedEvent(MCPEvent):
 class MCPConnectionCompletedEvent(MCPEvent):
     """Event emitted when successfully connected to an MCP server."""
 
-    type: str = "mcp_connection_completed"
+    type: Literal["mcp_connection_completed"] = "mcp_connection_completed"
     started_at: datetime | None = None
     completed_at: datetime | None = None
     connection_duration_ms: float | None = None
@@ -46,7 +46,7 @@ class MCPConnectionCompletedEvent(MCPEvent):
 class MCPConnectionFailedEvent(MCPEvent):
     """Event emitted when connection to an MCP server fails."""
 
-    type: str = "mcp_connection_failed"
+    type: Literal["mcp_connection_failed"] = "mcp_connection_failed"
     error: str
     error_type: str | None = None  # "timeout", "authentication", "network", etc.
     started_at: datetime | None = None
@@ -56,7 +56,7 @@ class MCPConnectionFailedEvent(MCPEvent):
 class MCPToolExecutionStartedEvent(MCPEvent):
     """Event emitted when starting to execute an MCP tool."""
 
-    type: str = "mcp_tool_execution_started"
+    type: Literal["mcp_tool_execution_started"] = "mcp_tool_execution_started"
     tool_name: str
     tool_args: dict[str, Any] | None = None
 
@@ -64,7 +64,7 @@ class MCPToolExecutionStartedEvent(MCPEvent):
 class MCPToolExecutionCompletedEvent(MCPEvent):
     """Event emitted when MCP tool execution completes."""
 
-    type: str = "mcp_tool_execution_completed"
+    type: Literal["mcp_tool_execution_completed"] = "mcp_tool_execution_completed"
     tool_name: str
     tool_args: dict[str, Any] | None = None
     result: Any | None = None
@@ -76,7 +76,7 @@ class MCPToolExecutionCompletedEvent(MCPEvent):
 class MCPToolExecutionFailedEvent(MCPEvent):
     """Event emitted when MCP tool execution fails."""
 
-    type: str = "mcp_tool_execution_failed"
+    type: Literal["mcp_tool_execution_failed"] = "mcp_tool_execution_failed"
     tool_name: str
     tool_args: dict[str, Any] | None = None
     error: str
@@ -92,7 +92,7 @@ class MCPConfigFetchFailedEvent(BaseEvent):
     failed, or native MCP resolution failed after config was fetched.
     """
 
-    type: str = "mcp_config_fetch_failed"
+    type: Literal["mcp_config_fetch_failed"] = "mcp_config_fetch_failed"
     slug: str
     error: str
     error_type: str | None = None  # "not_connected", "api_error", "connection_failed"
diff --git a/lib/crewai/src/crewai/events/types/memory_events.py b/lib/crewai/src/crewai/events/types/memory_events.py
index 0fd57a352..1d6b05017 100644
--- a/lib/crewai/src/crewai/events/types/memory_events.py
+++ b/lib/crewai/src/crewai/events/types/memory_events.py
@@ -1,4 +1,4 @@
-from typing import Any
+from typing import Any, Literal
 
 from crewai.events.base_events import BaseEvent
 
@@ -23,7 +23,7 @@ class MemoryBaseEvent(BaseEvent):
 class MemoryQueryStartedEvent(MemoryBaseEvent):
     """Event emitted when a memory query is started"""
 
-    type: str = "memory_query_started"
+    type: Literal["memory_query_started"] = "memory_query_started"
     query: str
     limit: int
     score_threshold: float | None = None
@@ -32,7 +32,7 @@ class MemoryQueryStartedEvent(MemoryBaseEvent):
 class MemoryQueryCompletedEvent(MemoryBaseEvent):
     """Event emitted when a memory query is completed successfully"""
 
-    type: str = "memory_query_completed"
+    type: Literal["memory_query_completed"] = "memory_query_completed"
     query: str
     results: Any
     limit: int
@@ -43,7 +43,7 @@ class MemoryQueryCompletedEvent(MemoryBaseEvent):
 class MemoryQueryFailedEvent(MemoryBaseEvent):
     """Event emitted when a memory query fails"""
 
-    type: str = "memory_query_failed"
+    type: Literal["memory_query_failed"] = "memory_query_failed"
     query: str
     limit: int
     score_threshold: float | None = None
@@ -53,7 +53,7 @@ class MemoryQueryFailedEvent(MemoryBaseEvent):
 class MemorySaveStartedEvent(MemoryBaseEvent):
     """Event emitted when a memory save operation is started"""
 
-    type: str = "memory_save_started"
+    type: Literal["memory_save_started"] = "memory_save_started"
     value: str | None = None
     metadata: dict[str, Any] | None = None
     agent_role: str | None = None
@@ -62,7 +62,7 @@ class MemorySaveStartedEvent(MemoryBaseEvent):
 class MemorySaveCompletedEvent(MemoryBaseEvent):
     """Event emitted when a memory save operation is completed successfully"""
 
-    type: str = "memory_save_completed"
+    type: Literal["memory_save_completed"] = "memory_save_completed"
     value: str
     metadata: dict[str, Any] | None = None
     agent_role: str | None = None
@@ -72,7 +72,7 @@ class MemorySaveCompletedEvent(MemoryBaseEvent):
 class MemorySaveFailedEvent(MemoryBaseEvent):
     """Event emitted when a memory save operation fails"""
 
-    type: str = "memory_save_failed"
+    type: Literal["memory_save_failed"] = "memory_save_failed"
     value: str | None = None
     metadata: dict[str, Any] | None = None
     agent_role: str | None = None
@@ -82,14 +82,14 @@ class MemorySaveFailedEvent(MemoryBaseEvent):
 class MemoryRetrievalStartedEvent(MemoryBaseEvent):
     """Event emitted when memory retrieval for a task prompt starts"""
 
-    type: str = "memory_retrieval_started"
+    type: Literal["memory_retrieval_started"] = "memory_retrieval_started"
     task_id: str | None = None
 
 
 class MemoryRetrievalCompletedEvent(MemoryBaseEvent):
     """Event emitted when memory retrieval for a task prompt completes successfully"""
 
-    type: str = "memory_retrieval_completed"
+    type: Literal["memory_retrieval_completed"] = "memory_retrieval_completed"
     task_id: str | None = None
     memory_content: str
     retrieval_time_ms: float
@@ -98,6 +98,6 @@ class MemoryRetrievalCompletedEvent(MemoryBaseEvent):
 class MemoryRetrievalFailedEvent(MemoryBaseEvent):
     """Event emitted when memory retrieval for a task prompt fails."""
 
-    type: str = "memory_retrieval_failed"
+    type: Literal["memory_retrieval_failed"] = "memory_retrieval_failed"
     task_id: str | None = None
     error: str
diff --git a/lib/crewai/src/crewai/events/types/observation_events.py b/lib/crewai/src/crewai/events/types/observation_events.py
index 2c95f3ae0..beac6d235 100644
--- a/lib/crewai/src/crewai/events/types/observation_events.py
+++ b/lib/crewai/src/crewai/events/types/observation_events.py
@@ -5,7 +5,7 @@ PlannerObserver analyzes step execution results and decides on plan
 continuation, refinement, or replanning.
 """
 
-from typing import Any
+from typing import Any, Literal
 
 from crewai.events.base_events import BaseEvent
 
@@ -32,7 +32,7 @@ class StepObservationStartedEvent(ObservationEvent):
     Fires after every step execution, before the observation LLM call.
     """
 
-    type: str = "step_observation_started"
+    type: Literal["step_observation_started"] = "step_observation_started"
 
 
 class StepObservationCompletedEvent(ObservationEvent):
@@ -42,7 +42,7 @@ class StepObservationCompletedEvent(ObservationEvent):
     the plan is still valid, and what action to take next.
     """
 
-    type: str = "step_observation_completed"
+    type: Literal["step_observation_completed"] = "step_observation_completed"
     step_completed_successfully: bool = True
     key_information_learned: str = ""
     remaining_plan_still_valid: bool = True
@@ -59,7 +59,7 @@ class StepObservationFailedEvent(ObservationEvent):
     but the event allows monitoring/alerting on observation failures.
     """
 
-    type: str = "step_observation_failed"
+    type: Literal["step_observation_failed"] = "step_observation_failed"
     error: str = ""
 
 
@@ -70,7 +70,7 @@ class PlanRefinementEvent(ObservationEvent):
     sharpening pending todo descriptions based on new information.
     """
 
-    type: str = "plan_refinement"
+    type: Literal["plan_refinement"] = "plan_refinement"
     refined_step_count: int = 0
     refinements: list[str] | None = None
 
@@ -82,7 +82,7 @@ class PlanReplanTriggeredEvent(ObservationEvent):
     regenerated from scratch, preserving completed step results.
     """
 
-    type: str = "plan_replan_triggered"
+    type: Literal["plan_replan_triggered"] = "plan_replan_triggered"
     replan_reason: str = ""
     replan_count: int = 0
     completed_steps_preserved: int = 0
@@ -94,6 +94,6 @@ class GoalAchievedEarlyEvent(ObservationEvent):
     Remaining steps will be skipped and execution will finalize.
     """
 
-    type: str = "goal_achieved_early"
+    type: Literal["goal_achieved_early"] = "goal_achieved_early"
     steps_remaining: int = 0
     steps_completed: int = 0
diff --git a/lib/crewai/src/crewai/events/types/reasoning_events.py b/lib/crewai/src/crewai/events/types/reasoning_events.py
index f9c9c1dc3..cb565a66e 100644
--- a/lib/crewai/src/crewai/events/types/reasoning_events.py
+++ b/lib/crewai/src/crewai/events/types/reasoning_events.py
@@ -1,4 +1,4 @@
-from typing import Any
+from typing import Any, Literal
 
 from crewai.events.base_events import BaseEvent
 
@@ -24,7 +24,7 @@ class ReasoningEvent(BaseEvent):
 class AgentReasoningStartedEvent(ReasoningEvent):
     """Event emitted when an agent starts reasoning about a task."""
 
-    type: str = "agent_reasoning_started"
+    type: Literal["agent_reasoning_started"] = "agent_reasoning_started"
     agent_role: str
     task_id: str
 
@@ -32,7 +32,7 @@ class AgentReasoningStartedEvent(ReasoningEvent):
 class AgentReasoningCompletedEvent(ReasoningEvent):
     """Event emitted when an agent finishes its reasoning process."""
 
-    type: str = "agent_reasoning_completed"
+    type: Literal["agent_reasoning_completed"] = "agent_reasoning_completed"
     agent_role: str
     task_id: str
     plan: str
@@ -42,7 +42,7 @@ class AgentReasoningCompletedEvent(ReasoningEvent):
 class AgentReasoningFailedEvent(ReasoningEvent):
     """Event emitted when the reasoning process fails."""
 
-    type: str = "agent_reasoning_failed"
+    type: Literal["agent_reasoning_failed"] = "agent_reasoning_failed"
     agent_role: str
     task_id: str
     error: str
diff --git a/lib/crewai/src/crewai/events/types/skill_events.py b/lib/crewai/src/crewai/events/types/skill_events.py
index f99d6bd70..aab625dda 100644
--- a/lib/crewai/src/crewai/events/types/skill_events.py
+++ b/lib/crewai/src/crewai/events/types/skill_events.py
@@ -6,7 +6,7 @@ Events emitted during skill discovery, loading, and activation.
 from __future__ import annotations
 
 from pathlib import Path
-from typing import Any
+from typing import Any, Literal
 
 from crewai.events.base_events import BaseEvent
 
@@ -28,14 +28,14 @@ class SkillEvent(BaseEvent):
 class SkillDiscoveryStartedEvent(SkillEvent):
     """Event emitted when skill discovery begins."""
 
-    type: str = "skill_discovery_started"
+    type: Literal["skill_discovery_started"] = "skill_discovery_started"
     search_path: Path
 
 
 class SkillDiscoveryCompletedEvent(SkillEvent):
     """Event emitted when skill discovery completes."""
 
-    type: str = "skill_discovery_completed"
+    type: Literal["skill_discovery_completed"] = "skill_discovery_completed"
     search_path: Path
     skills_found: int
     skill_names: list[str]
@@ -44,19 +44,19 @@ class SkillDiscoveryCompletedEvent(SkillEvent):
 class SkillLoadedEvent(SkillEvent):
     """Event emitted when a skill is loaded at metadata level."""
 
-    type: str = "skill_loaded"
+    type: Literal["skill_loaded"] = "skill_loaded"
     disclosure_level: int = 1
 
 
 class SkillActivatedEvent(SkillEvent):
     """Event emitted when a skill is activated (promoted to instructions level)."""
 
-    type: str = "skill_activated"
+    type: Literal["skill_activated"] = "skill_activated"
     disclosure_level: int = 2
 
 
 class SkillLoadFailedEvent(SkillEvent):
     """Event emitted when skill loading fails."""
 
-    type: str = "skill_load_failed"
+    type: Literal["skill_load_failed"] = "skill_load_failed"
     error: str
diff --git a/lib/crewai/src/crewai/events/types/task_events.py b/lib/crewai/src/crewai/events/types/task_events.py
index d042db22e..69609e3fd 100644
--- a/lib/crewai/src/crewai/events/types/task_events.py
+++ b/lib/crewai/src/crewai/events/types/task_events.py
@@ -1,4 +1,4 @@
-from typing import Any
+from typing import Any, Literal
 
 from crewai.events.base_events import BaseEvent
 from crewai.tasks.task_output import TaskOutput
@@ -24,7 +24,7 @@ def _set_task_fingerprint(event: BaseEvent, task: Any) -> None:
 class TaskStartedEvent(BaseEvent):
     """Event emitted when a task starts"""
 
-    type: str = "task_started"
+    type: Literal["task_started"] = "task_started"
     context: str | None
     task: Any | None = None
 
@@ -37,7 +37,7 @@ class TaskCompletedEvent(BaseEvent):
     """Event emitted when a task completes"""
 
     output: TaskOutput
-    type: str = "task_completed"
+    type: Literal["task_completed"] = "task_completed"
     task: Any | None = None
 
     def __init__(self, **data: Any) -> None:
@@ -49,7 +49,7 @@ class TaskFailedEvent(BaseEvent):
     """Event emitted when a task fails"""
 
     error: str
-    type: str = "task_failed"
+    type: Literal["task_failed"] = "task_failed"
     task: Any | None = None
 
     def __init__(self, **data: Any) -> None:
@@ -60,7 +60,7 @@ class TaskFailedEvent(BaseEvent):
 class TaskEvaluationEvent(BaseEvent):
     """Event emitted when a task evaluation is completed"""
 
-    type: str = "task_evaluation"
+    type: Literal["task_evaluation"] = "task_evaluation"
     evaluation_type: str
     task: Any | None = None
 
diff --git a/lib/crewai/src/crewai/events/types/tool_usage_events.py b/lib/crewai/src/crewai/events/types/tool_usage_events.py
index c4e681546..44edbe0ac 100644
--- a/lib/crewai/src/crewai/events/types/tool_usage_events.py
+++ b/lib/crewai/src/crewai/events/types/tool_usage_events.py
@@ -1,6 +1,6 @@
 from collections.abc import Callable
 from datetime import datetime
-from typing import Any
+from typing import Any, Literal
 
 from pydantic import ConfigDict
 
@@ -55,7 +55,7 @@ class ToolUsageEvent(BaseEvent):
 class ToolUsageStartedEvent(ToolUsageEvent):
     """Event emitted when a tool execution is started"""
 
-    type: str = "tool_usage_started"
+    type: Literal["tool_usage_started"] = "tool_usage_started"
 
 
 class ToolUsageFinishedEvent(ToolUsageEvent):
@@ -65,35 +65,35 @@ class ToolUsageFinishedEvent(ToolUsageEvent):
     finished_at: datetime
     from_cache: bool = False
     output: Any
-    type: str = "tool_usage_finished"
+    type: Literal["tool_usage_finished"] = "tool_usage_finished"
 
 
 class ToolUsageErrorEvent(ToolUsageEvent):
     """Event emitted when a tool execution encounters an error"""
 
     error: Any
-    type: str = "tool_usage_error"
+    type: Literal["tool_usage_error"] = "tool_usage_error"
 
 
 class ToolValidateInputErrorEvent(ToolUsageEvent):
     """Event emitted when a tool input validation encounters an error"""
 
     error: Any
-    type: str = "tool_validate_input_error"
+    type: Literal["tool_validate_input_error"] = "tool_validate_input_error"
 
 
 class ToolSelectionErrorEvent(ToolUsageEvent):
     """Event emitted when a tool selection encounters an error"""
 
     error: Any
-    type: str = "tool_selection_error"
+    type: Literal["tool_selection_error"] = "tool_selection_error"
 
 
 class ToolExecutionErrorEvent(BaseEvent):
     """Event emitted when a tool execution encounters an error"""
 
     error: Any
-    type: str = "tool_execution_error"
+    type: Literal["tool_execution_error"] = "tool_execution_error"
     tool_name: str
     tool_args: dict[str, Any]
     tool_class: Callable[..., Any]
diff --git a/lib/crewai/src/crewai/state/event_record.py b/lib/crewai/src/crewai/state/event_record.py
index a06dec398..7b8c20c5b 100644
--- a/lib/crewai/src/crewai/state/event_record.py
+++ b/lib/crewai/src/crewai/state/event_record.py
@@ -6,14 +6,48 @@ sequential relationships.  Provides O(1) lookups and traversal.
 
 from __future__ import annotations
 
-from typing import Literal
+from typing import Annotated, Any, Literal
 
-from pydantic import BaseModel, Field, PrivateAttr
+from pydantic import BaseModel, BeforeValidator, Field, PlainSerializer, PrivateAttr
 
 from crewai.events.base_events import BaseEvent
 from crewai.utilities.rw_lock import RWLock
 
 
+_event_type_map: dict[str, type[BaseEvent]] = {}
+
+
+def _resolve_event(v: Any) -> BaseEvent:
+    """Validate an event value into the correct BaseEvent subclass."""
+    if isinstance(v, BaseEvent):
+        return v
+    if not isinstance(v, dict):
+        return BaseEvent.model_validate(v)
+    if not _event_type_map:
+        _build_event_type_map()
+    event_type = v.get("type", "")
+    cls = _event_type_map.get(event_type, BaseEvent)
+    if cls is BaseEvent:
+        return BaseEvent.model_validate(v)
+    try:
+        return cls.model_validate(v)
+    except Exception:
+        return BaseEvent.model_validate(v)
+
+
+def _build_event_type_map() -> None:
+    """Populate _event_type_map from all BaseEvent subclasses."""
+
+    def _collect(cls: type[BaseEvent]) -> None:
+        for sub in cls.__subclasses__():
+            type_field = sub.model_fields.get("type")
+            if type_field and type_field.default:
+                _event_type_map[type_field.default] = sub
+            _collect(sub)
+
+    _collect(BaseEvent)
+
+
 EdgeType = Literal[
     "parent",
     "child",
@@ -29,7 +63,11 @@ EdgeType = Literal[
 class EventNode(BaseModel):
     """A node wrapping a single event with its adjacency lists."""
 
-    event: BaseEvent
+    event: Annotated[
+        BaseEvent,
+        BeforeValidator(_resolve_event),
+        PlainSerializer(lambda v: v.model_dump()),
+    ]
     edges: dict[EdgeType, list[str]] = Field(default_factory=dict)
 
     def add_edge(self, edge_type: EdgeType, target_id: str) -> None: