Desktop app launches claude with --permission-mode default hardcoded; auto mode toggle fails

Bug description

When Claude Code is launched via the Claude desktop app, it is started with --permission-mode default hardcoded in the process arguments. The UI toggle to switch to auto mode fails with "Permission mode couldn't be changed. You can try again." and never successfully enables auto mode.

Steps to reproduce

1. Open Claude Code in the Claude desktop app (v1.8555.0)
2. Ensure you are on a Max plan with Claude Sonnet 4.6 (all auto mode requirements met)
3. Click the permission mode dropdown and select Auto
4. Observe: "Permission mode couldn't be changed. You can try again."

Root cause

Inspecting the running process confirms the desktop app passes --permission-mode default explicitly on launch:

/Users/.../claude.app/Contents/MacOS/claude \
  --permission-mode default \
  --model claude-sonnet-4-6 \
  ...

The UI toggle is supposed to relaunch the process with --permission-mode auto, but fails to do so. Settings files (~/.claude/settings.json with "defaultMode": "auto") have no effect because the command-line flag overrides them.

Sessions that were already in auto mode before this regression continue to work — they have --permission-mode auto in their process args. Only newly initiated sessions are affected.

Environment

• Claude desktop app version: 1.8555.0
• Claude Code version: 2.1.146
• OS: macOS
• Plan: Max
• Model: Claude Sonnet 4.6

Expected behavior

The UI toggle successfully relaunches the Claude Code process with --permission-mode auto.