Event
Event is the record of one thing that happened in a session — a message, a
tool call, a state change, a node's output. It is the unit of persistence and
the substrate every resume path reads. It extends LlmResponse, so response
fields (content, partial, error_code, error_message, ...) are Event
fields too.
Key fields
| Field | Meaning |
|---|---|
invocation_id |
Invocation this event belongs to. Non-empty before appending to a session. |
author |
'user' or the name of the agent/node that appended it. |
content |
The message payload, inherited from LlmResponse. |
actions |
EventActions — state_delta, artifact_delta, route, transfer_to_agent, escalate, agent_state, end_of_agent, requested auth configs and tool confirmations. Function calls live in content, not here. |
output |
Generic data output from a workflow node. |
node_info |
NodeInfo: path (e.g. wf@1/child@2), output_for, message_as_output. |
long_running_tool_ids |
IDs of long-running calls. Setting these is what makes the framework treat the event as an interrupt. |
branch |
Dot-separated branch path for isolating peer sub-agents' history. |
isolation_scope |
Scope tag for which logical context this event belongs to. |
id, timestamp |
Identity and time. |
NodeInfo.run_id is a derived property, not a stored field: it is parsed
off the last name@run_id segment of node_info.path. Nothing stamps it
separately, so a path without an @ yields an empty run id.
Convenience kwargs
The constructor routes four shorthand kwargs onto nested fields, so these are equivalent to writing the nested form:
| Kwarg | Lands on |
|---|---|
message= |
content (converted via the genai content transformer) |
state= |
actions.state_delta |
route= |
actions.route |
node_path= |
node_info.path |
Passing both message and content raises ValueError.
Methods
get_function_calls()/get_function_responses()— inherited fromLlmResponse; pull the function calls or responses out ofcontent.is_final_response()— whether this is an agent's final response.has_trailing_code_execution_result()— whether the content ends in a code execution result.message— property aliasingcontent, with a matching setter.node_name— the node name parsed offnode_info.path.
State lifecycle and immutability
- Events are immutable once saved. Never assume an event is mutated or cleared after it lands in a session; resume works by reading the log forward, not by rewriting it.
- Signals resolve by later events, not by edits. To decide whether a request is pending or resolved, look for the matching later event (the function response), not a flag flipped on the original.
- Aborted invocations seal dangling calls. When an invocation is cancelled
via
abort_signal, the runner appends a terminal event witherror_code='INVOCATION_ABORTED'carrying syntheticFunctionResponseparts for any unclosedFunctionCalls so later turns see a balanced log. - Beware stateful flags on events. Background compaction may rewrite or drop aged events, so a transient status stored on one can survive or vanish in ways you did not intend.