Input field unresponsive after completing session with heavy sub-agent/task usage

Description

After completing a session with 18 tasks and ~71 sub-agents (Task tool with general-purpose type), the input field became unresponsive. The session appeared to complete normally ("Session Completed" message displayed), but the user could not type anything in the input field. The window had to be force-closed.

Environment

• Claude Code version: 2.1.25
• Platform: macOS (Darwin 24.6.0)
• Session ID: 5607673a-1fbc-480c-987d-cfa15bc3e9e0

Steps to Reproduce

1. Start a session with multiple tasks (18 in this case)
2. Use the Task tool extensively to spawn sub-agents (~71 general-purpose agents)
3. Complete all tasks
4. After final task completion, attempt to type in the input field

Expected Behavior

Input field should remain responsive after task completion, allowing continued conversation.

Actual Behavior

Input field appears visually present but does not accept keyboard input. Session must be force-closed.

Debug Log Analysis

Key findings from ~/.claude/debug/5607673a-1fbc-480c-987d-cfa15bc3e9e0.txt:

1. 100% write ratio throughout session:

``
High write ratio: blit=0, write=123536 (100.0% writes), screen=3019x110
``
Normal rendering should mix "blit" with "write". 100% writes indicates constant full-screen redraws.

1. AbortError near session end (18:59:52):

``
AbortError: The operation was aborted
``

1. Timeline at session end:

• 19:00:07 - Main agent stopped
• 19:00:14 - prompt_suggestion agent finished
• 19:00:14 to 19:05:30 - Session idle, input unresponsive
• 19:05:30 - SessionEnd with reason "other" (force-closed)

Hypothesis

Heavy sub-agent usage + constant 100% screen redraws + state transition after task completion may have caused the input handler to become blocked.