Statusline renders characters vertically at standard terminal widths

When using a custom statusline command, the statusline temporarily renders each character on its own line (vertical stacking) instead of on a single horizontal line.

This happens:

• When opening Claude Code in a standard 80-column terminal
• When resizing the terminal window

The display eventually corrects itself after a few seconds, but the initial render is broken.

Statusline config:

"statusLine": {
  "type": "command",
  "command": "bash ~/.claude/statusline-command.sh"
}

The script outputs a single line of text with ANSI color codes. The issue also reproduces with plain text (no escape sequences), so it's not related to ANSI width calculation.

Environment:

• Linux 6.14.0-37-generic
• Terminal: 80 columns