Added the option to specify the maximum number of agent loops.

[knziiy]

Description of Changes

This PR implements a configurable maximum iteration limit for the Agent Core Runtime to resolve issue #1308 and prevent potential infinite loops.

Changes Made:

• Added iteration limit configuration: Introduced get_max_iterations() function in config.py that reads from MAX_ITERATIONS environment variable (defaults to 20)
• Implemented iteration tracking: Added iteration counter and limit validation to AgentManager class
• Created custom exception: Added IterationLimitExceededError for proper error handling when limit is exceeded
• Integrated callback handler: Connected iteration limit enforcement to agent's callback system

Impact on Existing Users:

• No breaking changes: Existing functionality remains unchanged
• Backward compatible: Default limit of 20 iterations ensures existing agents continue to work
• Optional configuration: Users can adjust limits via environment variable if needed
• Improved stability: Prevents runaway processes that could affect system performance

The changes are non-breaking and provide additional safety without affecting existing user workflows.

Checklist

• Modified relevant documentation
• Verified operation in local environment
• Executed npm run cdk:test and if there are snapshot differences, execute npm run cdk:test:update-snapshot to update snapshots

Related Issues

• AgentCore Runtime - Specify a maximum loop limit for agents to prevent potential infinite loops #1308: AgentCore Runtime - Specify a maximum loop limit for agents to prevent potential infinite loops

[tbrand]

I apologize for the lack of guidance in the documentation. Could you please address the following error that appears in CI?

Linting changes detected. Please run 'uv run ruff check --fix .' and 'uv run ruff format .' locally and commit the changes.

[knziiy]

Thanks for highlighting the CI issue! I've resolved the errors by:

• Ruff linting errors: Fixed import statement ordering and added proper blank lines
• CDK snapshot test errors: Updated test snapshots after the code changes

[tbrand]

Currently, there are 2 places where self.iteration_count = 0 is set, but I think the most accurate code would be to set self.iteration_count = 0 when receiving the init_event_loop event. What do you think?

Everything else LGTM.

[knziiy]

Thank you for your feedback. I agree with your suggestion, so I've updated the code to set self.iteration_count = 0 when receiving the init_event_loop event.

Note that I've kept the initialization in the constructor to make the instance variable definition clear.
Please let me know if this should also be removed.