[BUG] claude.ai-managed MCP integrations (Google Calendar) unavailable in CLI until claude.ai Windows app is used first

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

## Description

When using claude.ai-managed MCP integrations (e.g. Google Calendar) in Claude Code CLI, the tools are not available until the same integration is first triggered via the claude.ai Windows desktop app. After the app "warms up" the session, the CLI picks up the connection and works correctly.

## Actual Behavior

CLI only picks up the MCP connection after the claude.ai Windows app has touched it. This suggests the CLI is inheriting OAuth/session state established by the app rather than initializing it independently.

## Environment

• OS: Windows 11 Pro
• Claude Code version: 2.1.122
• Integration type: claude.ai-managed (not a local MCP server)
• Integration: Google Calendar

## Related

Similar pattern (inverse direction) reported in #38934.

What Should Happen?

Claude Code CLI should be able to independently initialize and use claude.ai-managed MCP
integrations without requiring the desktop app to establish the session first.

Error Messages/Logs

Steps to Reproduce

## Steps to Reproduce

1. Open Claude Code CLI (fresh session, claude.ai Windows app not used)
2. Attempt to use a claude.ai-managed MCP integration (Google Calendar in my case)
3. Integration is unavailable / tools not loaded
4. Open claude.ai Windows app and trigger the same integration (e.g. ask it to list calendar events)
5. Return to Claude Code CLI (new or same session)
6. Integration now works correctly

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.122

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

_No response_