Account-level connectors no longer appear in `claude mcp list` (Vertex AI auth)

Summary

Since May 12-13, claude.ai account-level connectors (Desktop app integrations) no longer appear as a separate section in claude mcp list when using Vertex AI auth. They worked correctly until May 11.

Auth Status

{
  "loggedIn": true,
  "authMethod": "third_party",
  "apiProvider": "vertex"
}

Behavior Before (working, until May 11)

claude mcp list showed two sections:

1. Manually configured MCP servers (Atlassian, Grafana, Jenkins, etc.)
2. A separate section listing 26 account-level connectors from the claude.ai Desktop app (Google Drive, Gmail, Databricks, Linear, Notion, etc.)

Behavior After (broken, May 12+)

claude mcp list only shows the 8 manually configured servers. The account-level connectors section is completely absent.

Reproduction Steps

1. Authenticate Claude Code CLI with Vertex AI (authMethod: third_party, apiProvider: vertex)
2. Connect integrations in the Claude Desktop app (Google Drive, Gmail, Databricks, Linear, etc.)
3. Run claude mcp list — connectors section missing
4. Clear ~/.claude/mcp-needs-auth-cache.json and run again in a new session — no re-discovery occurs

Additional Context

• ~/.claude/mcp-needs-auth-cache.json was populated on May 11 with 33 entries (26 claude.ai connectors + 7 plugins), but clearing it does not trigger re-discovery — the endpoint returns nothing
• Claude Desktop app shows all connectors correctly (Desktop uses claude.ai auth directly)
• Rollback to Claude Code 2.1.139 did not restore the behavior, suggesting a server-side change
• Version at time of breakage: 2.1.139 → 2.1.140 auto-update at 00:30 May 13, but rollback to 2.1.139 did not fix it

Expected Behavior

Account-level connectors should appear in claude mcp list as a separate section, as they did until May 11, regardless of whether auth is via claude.ai or a third-party provider (Vertex AI).