statusLine.refreshIntervalMs is removed from settings.json when switching models

Describe the bug

When switching models via /model or config, Claude Code rewrites the statusLine section in settings.json and drops any custom properties (e.g. refreshIntervalMs) that are not part of its default schema.

Steps to reproduce

1. Add refreshIntervalMs: 1000 to the statusLine object in settings.json
2. Switch model (e.g. via /model command)
3. Observe that refreshIntervalMs is gone from settings.json

Expected behavior

Custom properties inside statusLine should be preserved when Claude Code updates unrelated settings (e.g. model).

Actual behavior

refreshIntervalMs is silently removed from settings.json.

Workaround

Put the setting in settings.local.json instead — it is not overwritten by model switching.

Environment

• OS: Windows 11
• Claude Code version: 2.1.129