Feature: Auto-expand sub-agent thinking in conversation, then auto-collapse when done

Feature Request

Desired Behavior

1. While thinking: Sub-agent thinking content should automatically expand and be visible inline in the conversation, so users can see the reasoning process without any clicks.
2. After thinking completes: The thinking block should automatically collapse, keeping the conversation clean and readable.

Current Behavior

• Sub-agent thinking is collapsed by default
• Users must manually click to expand and view thinking content

Use Case

When running complex multi-step tasks with sub-agents, it's useful to observe the thinking process in real-time without having to click into each thinking block individually.

Proposed UX

• Thinking block auto-expands as soon as a sub-agent starts thinking
• Content streams in live
• Once thinking is complete, the block auto-collapses back to the summary view