Moving Cell Execution State to Document Awareness

[Zsailer]

Summary

This PR optimizes cell execution state tracking by moving execution states from YDoc transactions to the document awareness layer, significantly reducing memory usage and improving performance in collaborative Jupyter notebooks.

Key Changes

Architectural Improvements

• Move execution states to awareness layer: Cell execution states ("busy", "idle") now live in ephemeral awareness instead of persistent YDoc
• Reduce YDoc transaction volume: Separate persistent document state from ephemeral collaboration state
• Improve memory efficiency: Eliminate execution state accumulation in YDoc transaction history
• Enhance scalability: Better performance for notebooks with heavy cell execution patterns

Performance Optimizations

• Dramatically reduced YDoc transactions during cell execution cycles
• Lower memory footprint for long-running notebook sessions
• Faster document synchronization without execution state noise
• Better collaborative experience with real-time state updates

Technical Implementation

• Store execution states in YRoom._cell_execution_states (in-memory)
• Broadcast states via awareness for real-time collaboration
• Maintain state persistence across client reconnections
• Preserve execution counts and outputs in YDoc for true persistence

[3coins]

@Zsailer
This is a great improvement, thanks for working on these changes. Left some minor feedback.

[Zsailer]

Thanks for the feedback @3coins! I've addressed all your suggestions:

1. Simplified conditional logic: Combined the three else blocks in _updatePrompt method into a single else block since they all had the same behavior
2. Improved null checking: Used optional chaining (notebook?.model?.sharedModel?.awareness) to simplify the null checking in _getCellExecutionStateFromAwareness
3. Added YRoom helper method: Created set_cell_awareness_state() method in YRoom class for better encapsulation and updated the kernel client to use this new method

The changes improve code readability and maintainability while keeping the same functionality. All updates have been pushed to the branch.

[3coins]

LGTM!