[BUG] Agent View: right-arrow into running agent freezes Terminal.app with partial black render (process idle, Terminal stops drawing)

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Summary

From Agent View, pressing right-arrow to enter a running agent occasionally
freezes the Terminal.app window with a partial-text render and large black
regions. The window stops accepting input. Workaround: open Agent View in a
new Terminal tab, which usually succeeds on the second try.

Likely related to #58990 (left-arrow nav issues), and shares symptoms with
#53353 (transcript view freeze), but the trigger here is specifically
right-arrow into a running agent.

Environment

• Claude Code: 2.1.150
• macOS: 15.7.3 (24G419), Apple Silicon
• Terminal: Terminal.app (default macOS)
• Shell: zsh

Diagnostics

Captured one occurrence with a sample-based diagnostic script. Key findings:

• Foreground claude PID (25668): main thread spent ~99% of samples in

kevent64 in libsystem_kernel.dylib. The Node event loop was idle and
waiting for I/O. Not a CPU hang.

• Agent claude PID being entered (79211): also overwhelmingly idle in

kevent64. The agent was healthy.

• WindowServer: 8.4% CPU at moment of freeze (elevated but not pegged).
• mds_stores / mdworker (Spotlight): 0% CPU. Rules out Spotlight indexing.
• Frontmost app: Terminal.

Interpretation: both Claude Code processes were alive and event-loop-idle.
Terminal stopped drawing them and stopped accepting input. This looks like a
render-layer wedge in Terminal.app or WindowServer, possibly triggered by
something Claude Code emits on agent-entry (cursor/alt-screen/SGR sequences,
PTY resize).

Full capture (sample stacks, ps, env, render-suspects list) available on
request. Generated by a small script at ~/.claude/scripts/capture-agent-freeze.sh.

Asks

1. Are there known sequences Claude Code emits on agent entry that could put

Terminal.app's renderer in a bad state? (Alt screen toggles, mouse mode,
bracketed paste, SGR resets.)

1. Is there a debug flag that logs each TTY write so the offending sequence

can be isolated next time?

1. Has this been reproduced on iTerm2 or Ghostty? If it is Terminal.app

specific, that materially narrows the surface.

Happy to provide the full capture, run additional diagnostics, or test a
candidate fix.

What Should Happen?

Claude agent view should enter agent sessions without freezing terminal

Error Messages/Logs

Steps to Reproduce

1. From an active session, open Agent View (Ctrl+O or equivalent).
2. With one or more agents running, press right-arrow to enter one.
3. Intermittently: window renders a partial frame, large blacked-out regions

appear, and the tab stops accepting any input.

1. Recovery: kill the tab and open Agent View in a new tab. Usually works on

second attempt.

Frequency: several times per week. No reliable reproducer.

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.150

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_