Complete UI freeze during Bash tool execution - timer stops, escape unresponsive

Description

Claude Code UI completely freezes during Bash tool execution. The entire interface becomes unresponsive - not just slow, but completely frozen.

Symptoms

• Status line shows something like Coalescing… (esc to interrupt · 1m 15s · ↑ 2.1k tokens) but:
• Timer stops updating (stuck at same value)
• Token count frozen
• Escape key has no effect
• No keyboard input works
• The configured tool timeout does not fire
• Requires force-killing the process (pkill -9 -f claude or closing terminal)

Context When It Occurs

• Happened 3 times in ~20 minutes during a session
• Several Bash tool calls (including SSH commands) succeeded before the freeze
• Freeze occurred during a Bash tool call (SSH command to remote host)
• The same type of commands worked fine moments before
• Plenty of RAM available on system
• Not reproducible on demand - seems intermittent

Expected Behavior

• UI should remain responsive regardless of child process state
• Timer should continue updating
• Escape key should always work to interrupt
• Tool timeout should fire and kill hung commands

Environment

• Claude Code version: 2.0.76
• OS: Linux 6.14.0-37-generic
• Running inside PyCharm terminal
• PyCharm was restarted between freeze 2 and 3 - issue persisted, so it's not something accumulating in PyCharm's state

Additional Notes

This appears to be an event loop freeze in the Node.js process, not just a slow response. The complete unresponsiveness of the UI (including escape handling) suggests something is blocking the main thread.

🤖 Generated with Claude Code