feat(hooks): Add invocation state #1550
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added 2 commits
January 7, 2026 16:48
…Event, BeforeModelCallEvent, and AfterModelCallEvent This change extends the invocation_state attribute (already present in tool-related hook events) to the four core hook events as scoped in issue strands-agents#914: - BeforeInvocationEvent - AfterInvocationEvent - BeforeModelCallEvent - AfterModelCallEvent Changes: - Added invocation_state: dict[str, Any] attribute to the 4 target event classes in hooks/events.py - Updated event creation in agent.py to pass invocation_state to Before/AfterInvocationEvent - Updated event creation in event_loop.py to pass invocation_state to Before/AfterModelCallEvent - Updated all affected tests to use invocation_state parameter - Added new tests to verify invocation_state is properly accessible in the events This enables better multi-agent coordination by allowing hooks to access shared context throughout the agent invocation lifecycle, including request tracking, dynamic configuration, and context-aware processing. Addresses: strands-agents#914
Combined invocation_state feature with messages attribute from main: - BeforeInvocationEvent now has both invocation_state and messages attributes - AfterInvocationEvent, BeforeModelCallEvent, AfterModelCallEvent have invocation_state - Updated tests to verify both features work together
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mkmeral
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Jan 23, 2026
| stacklevel=2, | ||
| ) | ||
| await self.hooks.invoke_callbacks_async(BeforeInvocationEvent(agent=self)) | ||
| await self.hooks.invoke_callbacks_async(BeforeInvocationEvent(agent=self, invocation_state={})) |
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This is old structured input. It's deprecated and it doesn't allow to pass invocation state, but we pass empty dict for completeness
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Codecov Report✅ All modified and coverable lines are covered by tests. 📢 Thoughts on this report? Let us know! |
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Jan 23, 2026
…Event, BeforeModelCallEvent, and AfterModelCallEvent
- Add invocation_state attribute with default_factory=dict for backwards compatibility
- Pass invocation_state through in agent.py and event_loop.py
- Add tests for invocation_state accessibility in all four events
- Update existing tests to use ANY matcher for invocation_state comparisons
Note: The deprecated structured_output_async method passes invocation_state={} since
it predates this feature and doesn't accept invocation_state as a parameter.
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Pull Request and Push Action / check-api (pull_request)F is calling out a breaking change. Under most circumstances I'd agree, but in this case Hook objects are constructed by the framework and "distributed" to implementations defined by customers. So afaict this should not be truly breaking |
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Description
This PR extends
invocation_stateto four core hook events that previously lacked it:BeforeInvocationEventAfterInvocationEventBeforeModelCallEventAfterModelCallEventThe
invocation_statedictionary was already available in tool-related events (BeforeToolCallEvent,AfterToolCallEvent), but not accessible during the broader invocation and model call phases. This made it difficult to implement cross-cutting concerns like request tracking, multi-agent coordination, and context-aware logging throughout the entire request lifecycle.Events intentionally without
invocation_stateAgentInitializedEvent- Fires during agent construction, before any invocation existsMessageAddedEvent- Low-level notification where the message itself is self-containedNote on deprecated
structured_output_asyncThe deprecated
structured_output_asyncmethod passesinvocation_state={}since it predates this feature and doesn't acceptinvocation_stateas a parameter. Users should migrate toagent("prompt", structured_output_model=Model)which properly supportsinvocation_state.Related Issues
N/A
Documentation PR
N/A
Type of Change
New feature
Testing
Added unit tests verifying
invocation_stateis accessible in all four eventsUpdated existing hook tests to include
invocation_stateassertionsAll 50+ related tests pass
I ran
hatch run prepareChecklist
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