Statusline model.display_name not updating after /model command

Description

After using the /model command to switch models mid-session (e.g., from Sonnet to Opus), the statusline model.display_name field in the JSON payload does not update. Other fields like context_window.current_usage DO update correctly.

Steps to Reproduce

1. Start Claude Code (defaults to Sonnet 4.5)
2. Configure a statusline command that displays the model name:

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

1. Statusline correctly shows "Sonnet 4.5"
2. Run /model and select Opus
3. Send a message to trigger statusline refresh
4. Statusline still shows "Sonnet 4.5" (should show "Opus")

Expected Behavior

The model.display_name field in the JSON payload sent to the statusline command should reflect the current model after using /model to switch.

Actual Behavior

• Context percentage updates correctly (confirms JSON payload IS being refreshed)
• Model display_name remains at session-start value
• Model IS actually switched (responses come from new model)
• Only the statusline display is stale

Environment

• Claude Code version: 2.1.19
• macOS (Darwin 25.3.0)
• Statusline script extracts model via: jq -r '.model.display_name'

Screenshot

Statusline shows "Sonnet 4.5" after switching to Opus:

• Context bar updates (31%)
• Model name does not update

Workaround

Starting a new session shows the correct model, but /model mid-session doesn't update the statusline.