[BUG] Status bar duplicates teammate indicators on arrow key navigation

Bug

When teammates are running, using arrow-down to inspect a teammate process and then arrow-up to return to the main conversation causes the teammate indicators in the status bar to duplicate. Each navigation cycle adds another copy of every teammate badge.

Screenshot

The status bar shows dozens of duplicated @d and ev entries instead of one per teammate:

@m @d @d @d @d @d @d @d @d @d @d @d @d @d @d @d @d @d @d @d ...
ai ev ev ev ev ev ev ev ev ev ev ev ev ev ev ev ev ev ev ev ...
n  -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 -2 ...

Reproduction steps

1. Start a Claude Code session
2. Spawn 2+ teammates (Agent tool with run_in_background: true)
3. Arrow-down to view a teammate's output
4. Arrow-up to return to the main conversation
5. Observe the status bar — teammate badges are now duplicated
6. Repeat steps 3-4 — more duplicates appear each time

Expected behavior

Each teammate should appear once in the status bar regardless of how many times you navigate to/from their output.

Environment

• macOS (Darwin 25.2.0)
• Claude Code CLI
• Model: claude-opus-4-6