fix(memory): use current Strands bidi session hooks

[pgrayy]

Issue #, if available:

N/A

Description of changes:

Importing AgentCoreMemorySessionManager fails with Strands 1.56.0 because it references bidi hook events removed in strands-agents/harness-sdk#4280. Use the shared initialization and message hooks for both Agent and BidiAgent, and use BidiAgentStopEvent to save state when a bidi session stops. Keep initialization synchronous and offload persistence callbacks when async_mode=True.

Flush pending message and state batches after the final state sync for both AfterInvocationEvent and BidiAgentStopEvent. Skip automatic context retrieval for BidiAgent, because modifying local message history does not deliver that context to the live model.

Update the agent annotations to LocalAgent, raise the minimum strands-agents version to 1.56.0, and add regression coverage for callback ordering and bidi persistence without retrieval in both callback modes.

Validation:

• All pre-commit checks and the Bandit security scan passed.
• The full test suite with coverage passed in the locked Python 3.10 development environment (91% coverage). The focused session-manager and configuration suites passed (200 tests).
• Before the review fixes, five existing live AWS integration tests passed, covering initialization, conversation persistence, batching, and session restoration.
• Before the review fixes, two one-off bidi checks passed against live AgentCore storage with a scripted model and the default batch size of 1. These exercised public start, send, receive, and stop calls in both callback modes, including message restoration and state saved on stop.

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.
⚠️ Please upload report for BASE (main@9f31042). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
...ore/memory/integrations/strands/session_manager.py	92.85%	1 Missing ⚠️

Additional details and impacted files

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[notgitika]

Thanks for the fix, added 2 comments

[notgitika]

I might be missing something here, but with batching enabled, doesn’t sync_agent() just add the state to the buffer?

since Bidi doesn’t fire AfterInvocationEvent, what flushes the pending messages and state after agent.stop()?

[pgrayy]

Added a flush and also adjusted the ordering for AfterInvocationEvent. The inline comment explains under the batch_size > 1 blocks.

[notgitika]

Now that bidi uses MessageAddedEvent, will retrieve_customer_context run for bidi too? It looks like it updates agent.messages, while the model still receives the original input event. could we skip retrieval for bidi or inject it into the outgoing event?

[pgrayy]

Added a skip. This also highlights an important behavioral difference. It may actually make sense to go back to BidiMessageAddedEvent. I'll give this some thought. If I do update, I'll be sure to update here as well.

Another approach could be that Bidi just doesn't emit the event at all. And this is also something to consider for model providers that allow server side conversation management (e.g., OpenAI responses).

[notgitika]

Makes sense!

[notgitika]

LGTM

[notgitika]

Breaking Change Check / Detect Breaking Changes
Failing due to a 403 and not a breaking change.