Agent Teams tmux backend: Edit tool error dumps minified JS bundle to terminal

Description

When using Agent Teams with the tmux backend (teammateMode: "tmux"), teammates spawned in new tmux panes encounter an Error editing file that dumps Claude Code's minified JavaScript bundle source code to the terminal instead of a clean error message.

This results in massive red error blocks filling the entire tmux pane, making the teammate unusable.

Steps to reproduce

1. Enable Agent Teams in ~/.claude/settings.json:

``json
{
"env": {
"CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS": "1"
},
"teammateMode": "tmux"
}
``

1. Start Claude Code inside a tmux session
2. Use the agent-team-orchestrator skill (or manually spawn teammates via the Task tool with team_name and name parameters)
3. Observe the teammate panes — when a teammate attempts to use the Edit tool, the error occurs

Actual behavior

The teammate's tmux pane shows Error editing file followed by thousands of lines of minified JavaScript source code from Claude Code's own bundle (terminal rendering engine, semver library, React internals, etc.).

Example of the error output (truncated):

Error editing file
    H.charPool.get(H.cells[K])}function Rq_(H,_,q,K){if(_<0||q<0||_>=H.width||q>=H.height)return;let
    O=q*H.width+_<<1,T=H.cells,$=T[O+1]&fU;if($===1&&K.width!==1){if(_+1<H.width){let
    D=O+2;if((T[D+1]&fU)===2)T[D]=Bg_,T[D+1]=T5H(H.emptyStyleId,0,0)}}...

The output contains xterm.js-like cell buffer management code, selection handling, semver parsing, and other Claude Code internals — clearly the bundled source being included in a stack trace.

Expected behavior

A clean, readable error message explaining why the Edit tool failed (e.g., file conflict, path issue, permission error).

Screenshot

The error manifests as massive red/pink blocks filling the teammate's tmux pane, while the leader pane continues to work normally.

Environment

• OS: macOS (Darwin 25.3.0)
• Terminal: tmux inside VSCode integrated terminal
• Claude Code: latest (CLI via VSCode extension)
• Backend: tmux (teammateMode: "tmux")
• Feature flag: CLAUDE_CODE_EXPERIMENTAL_AGENT_TEAMS=1

Additional context

• The leader/orchestrator pane works correctly — only teammates in spawned tmux panes are affected
• The error appears to trigger when teammates use the Edit tool, possibly due to file path resolution differences in the spawned tmux process
• The minified JS dump suggests the error serialization path is accidentally including the source map or bundle contents instead of formatting a proper error message

🤖 Generated with Claude Code