feat(cache): add TTL support to CachePoint for prompt caching

[kpx-dev]

Description

Add optional ttl field to CachePoint TypedDict to support AWS Bedrock's cache TTL configuration. The field accepts "5m" or "1h" values as specified in the Bedrock API. Updated BedrockModel to preserve ttl field when formatting cache point content blocks. Includes tests for TTL preservation and backward compatibility.

Doc shows API supports ttl option now:
https://docs.aws.amazon.com/bedrock/latest/APIReference/API_runtime_CachePointBlock.html

launch announcement:
https://aws.amazon.com/about-aws/whats-new/2026/01/amazon-bedrock-one-hour-duration-prompt-caching/

more details:
https://docs.aws.amazon.com/bedrock/latest/userguide/prompt-caching.html

Related Issues

#1243

Documentation PR

Type of Change

New feature

Testing

How have you tested the change? Verify that the changes do not break functionality or introduce warnings in consuming repositories: agents-docs, agents-tools, agents-cli

• [x ] I ran hatch run prepare

Checklist

• [x ] I have read the CONTRIBUTING document
• [ x] I have added any necessary tests that prove my fix is effective or my feature works
• [x ] I have updated the documentation accordingly
• [ x] I have added an appropriate example to the documentation to outline the feature, or no new docs are needed
• [x ] My changes generate no new warnings
• [ x] Any dependent changes have been merged and published

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[kpx-dev]

FYI this PR fails label size: https://github.com/strands-agents/sdk-python/actions/runs/22110060966 . Not sure if CI needs update or label input needs update

[zastrowm]

One last nit (imports) - looks good

[mkmeral]

I'll approve. I want to try following up with strands command for nits, let's see how that works. the only nit is the import in the test

[kpx-dev]

@mkmeral ing test failed due to the streaming model doesn't support 1hr, only 5m (not all model support both): https://docs.aws.amazon.com/bedrock/latest/userguide/prompt-caching.html#prompt-caching-models

So I updated the PR to target a specific model only.

[mkmeral]

@kpx-dev I think it's more of a model limitation rather than streaming/nonstreaming difference, like the model list you sent.

The problem was the default bedrock model id we use is sonnet 4, which doesnt support 1hr TTL. But either way, as long as the integ tests pass, I'm happy 😅

[kpx-dev]

@kpx-dev I think it's more of a model limitation rather than streaming/nonstreaming difference, like the model list you sent.

The problem was the default bedrock model id we use is sonnet 4, which doesnt support 1hr TTL. But either way, as long as the integ tests pass, I'm happy 😅

@mkmeral yea make sense. Looks like I need 2 approval before it can trigger CI for ing test?
@zastrowm can you help approve so I can verify CI for ing test working fine now? Thanks!