Bug: Claude unexpectedly terminated during tmux statusline debugging session

Title: Bug: Claude unexpectedly terminated during tmux statusline debugging session

Description

Claude suddenly stopped responding and quit while in the middle of a debugging session. I was working with it to troubleshoot an issue where the AI model name was not appearing in my tmux status bar. The agent was actively running commands and then hung indefinitely on a grep command, forcing me to interrupt.

Context

The initial problem was that my custom statusline.sh script wasn't displaying the current Claude model in the tmux status bar. I asked Claude to help troubleshoot this, specifically using tmux to replicate the environment.

Debugging Transcript

The following is the sequence of actions Claude took right before it terminated. It successfully tested the script in isolation, then moved on to testing within a live tmux session before it hung.

<details>
<summary>Click to expand full agent transcript</summary>

i still dont see model showin in my statusbar. use tmux for troubleshooting

[ASSISTANT] I'll help you troubleshoot why the model isn't showing in your statusbar. Let me start by checking the current state and testing with tmux.

[TOOL] TodoWrite
  - Test statusline output directly (pending)
  - Check model_renderer.sh implementation (pending)
  - Test with tmux to see actual statusbar (pending)
  - Debug model data parsing (pending)
  - Fix model display issue (pending)

[ASSISTANT] Let me first test the statusline directly to see what output it's producing:

[TOOL] Bash: echo '{"session_id":"test123","model":{"display_name":"Claude 3.5 Sonnet"}}' | .claude/scripts/statusline.sh
  - STDOUT: 🤖 Claude 3.5 Sonnet │ 🌿 main [M3 U2] │ 🏛️ Anthropic

[ASSISTANT] Good! The model is showing in the output. Let me mark this task complete and check the actual tmux setup:

[TOOL] TodoWrite
  - Test statusline output directly (completed)
  - Check model_renderer.sh implementation (in_progress)
  ...

[ASSISTANT] Let me check the model_renderer.sh to see how it's configured:

[TOOL] Read: .claude/lib/renderers/model_renderer.sh
  - (File content was read successfully)

[ASSISTANT] Now let me check how the orchestrator is calling this renderer:
[ASSISTANT] Let me set up tmux to see the actual statusbar output:

[TOOL] Bash: tmux new-session -d -s test_statusline
  - (Success)

[TOOL] Bash: tmux set-option -t test_statusline status-right '#(echo "{\"session_id\":\"test123\",\"model\":{\"display_name\":\"Claude 3.5 Sonnet\"}}" | /Users/user/Desktop/2025-08-09-statusline/.claude/scripts/statusline.sh)'
  - (Success)

[TOOL] Bash: tmux set-option -t test_statusline status-right-length 200
  - (Success)

[TOOL] Bash: tmux capture-pane -t test_statusline -p | tail -1
  - STDOUT: (No content)

[ASSISTANT] Let me check the actual tmux configuration being used:

[TOOL] Bash: tmux show-options -g status-right 2>/dev/null || echo "No global status-right set"
  - STDOUT: status-right "#{?window_bigger,[#{window_offset_x}#,#{window_offset_y}] ,}\"#{=21:pane_title}\" %H:%M %d-%b-%y"

[ASSISTANT] Let me check your tmux config file to see if there's a custom statusline setup:

[TOOL] Bash: ls -la ~/.tmux.conf 2>/dev/null || echo "No .tmux.conf found"
  - STDOUT: No .tmux.conf found

[ASSISTANT] Let me check how Claude Code actually integrates with the statusline:

[TOOL] Grep: pattern: "statusline\.sh"
  - Found 25 files

[SPINNING...] Claude hung at this point.

</details>

Expected Behavior

The agent should have continued the debugging process after the grep command. It should have analyzed the results and proposed the next step to resolve the status bar issue, or asked for more information. It should not have quit or hung without an error.

Actual Behavior

After successfully executing the grep command and reporting "Found 25 files", the agent's status changed to "Spinning..." and it never responded again. No further actions were taken, and no error message was displayed.

Environment

• OS: macOS (inferred from file paths)
• Shell: zsh (inferred from prompt ➜)
• Tool Version: 1.0.81 (from log metadata)
• Terminal: tmux