[BUG] Shift+Up/Down pane switching in Agent Teams auto-sends pre-filled suggestion to target agent

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?

When using Agent Teams (multi-agent sessions), Claude Code sometimes pre-fills a suggested response in the user's input prompt. If the user presses Shift+Up or Shift+Down to switch to a different agent pane before pressing Enter, the pre-filled suggestion text is automatically sent to the agent in the newly-focused pane — without the user confirming or pressing Enter.

This means text intended as a suggestion for one agent gets submitted to a completely different agent, which can cause confusion, wasted tokens, and unintended actions by the wrong agent.

What Should Happen?

Switching panes with Shift+Up/Down should only change focus to the target agent pane. Any pre-filled suggestion text from the previous pane should be discarded (or at minimum, not auto-submitted). The user should have to explicitly press Enter to send any message to an agent.

Error Messages/Logs

No error messages — the suggestion text silently sends to the wrong agent.

Steps to Reproduce

1. Start a Claude Code session with Agent Teams enabled (e.g., claude --team)
2. Have multiple agents running (e.g., a team-lead pane and a dev-01 pane)
3. Wait for Claude to pre-fill a suggested response in the input prompt of the current pane (the grey/dimmed text that appears)
4. Without pressing Enter, press Shift+Up or Shift+Down to switch to a different agent's pane
5. Observe: the pre-filled suggestion text from step 3 is automatically sent as a message to the agent in the new pane

Claude Model

Opus

Is this a regression?

I don't know

Claude Code Version

2.1.45 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Ghostty

Additional Information

• macOS 26.3
• This occurs specifically in the multi-agent "Agent Teams" mode where Shift+Up/Down cycles between agent panes
• The pre-filled suggestion text is the dimmed/grey auto-complete text that Claude sometimes shows in the input field
• The issue is that the pane-switch action appears to also trigger a "submit" of whatever is in the input buffer