Refactor Session class methods for better maintainability

[tofarr]

I used OpenHands to write this PR - It is actually depenendent on 2 other PRs which I would like to merge first:

• Fix agent session error in logs #4669
• Fix : app unresponsive on startup #4668

Also, I have not tested this properly yet nor reviewed the code myself, so probably a good idea to get that out of the way before review...

This PR refactors two complex methods in the Session class to improve code maintainability and readability:

Changes

1. Split _initialize_agent into smaller focused methods:

   • _set_loading_state: Handles setting the initial loading state
   • _extract_config_args: Extracts and processes configuration arguments
   • _configure_llm: Configures LLM settings
   • _start_agent_session: Handles starting the agent session

2. Split on_event into smaller focused methods:

   • _should_skip_event: Checks if an event should be skipped
   • _is_environment_feedback_event: Checks if an event is environment feedback
   • _send_as_agent_event: Handles sending events to the UI

Benefits

• Better Single Responsibility: Each method has a clear, single purpose
• Improved Readability: More self-documenting with descriptive method names
• Better Maintainability: Smaller methods are easier to test and modify
• Reusability: Helper methods could be reused if needed
• Better Error Handling: Clearer separation of error handling logic
• Improved Documentation: Each method has a clear docstring

The functionality remains exactly the same, but the code is now more organized and easier to understand.

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To run this PR locally, use the following command:

docker run -it --rm   -p 3000:3000   -v /var/run/docker.sock:/var/run/docker.sock   --add-host host.docker.internal:host-gateway   -e SANDBOX_RUNTIME_CONTAINER_IMAGE=ghcr.io/all-hands-ai/runtime:9a9aebc-nikolaik   --name openhands-app-9a9aebc   ghcr.io/all-hands-ai/runtime:9a9aebc