[nborges-aws]

Description of changes:
Fix a case where Strands guardrail redaction could leave the original message in AgentCore Memory. This issue was seen on large messages stored as blobs or for messages flushed during batching.

The changes in this PR aim to address that with the following:

• Read the event id from blob events, so a persisted message can be replaced with its redacted version
• Correct buffered-message matching so redaction updates the intended message
• keep the latest message in buffer during flushes, if it is still awaiting a guardrails decision (older messages are still sent, latest is sent when invocation completes)
• Preserves message order if flush fails
• deferred agent snapshots sent in groups of up to 100 (matching API constraint for max items)

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

[github-actions]

✅ No Breaking Changes Detected

No public API breaking changes found in this PR.

[agentcore-devx-automation]

Claude Security Review: no high-confidence findings. (run)