Claude Code periodically writes to all open terminal tabs, triggering iTerm2 activity indicators

Bug Description

Claude Code periodically emits output (likely escape sequences, cursor movements, or status updates) to all open terminal tabs, not just the currently active session. This causes iTerm2's tab activity indicator (blue dot) to light up on inactive tabs, misleading users into thinking there is new content to review.

Steps to Reproduce

1. Open multiple iTerm2 tabs, each running a separate Claude Code session
2. Work in one tab while leaving others idle
3. Observe blue activity dots appearing on idle tabs at regular intervals
4. Switch to those tabs — no new visible output or messages are present

Expected Behavior

Idle Claude Code sessions should not emit output to their terminal unless there is actual new content for the user.

Actual Behavior

Claude Code appears to poll or broadcast to all open terminal sessions periodically, triggering iTerm2's tab activity indicator even when no meaningful new content exists.

Environment

• Terminal: iTerm2 (macOS)
• OS: macOS Darwin 25.3.0
• Shell: zsh

Impact

Causes notification fatigue — users repeatedly check idle tabs expecting new output or a completed task, but find nothing. Disabling iTerm2's activity indicator globally is the only workaround, which removes a useful signal for other programs.