[BUG] Plugin connector Install button greyed out for OAuth-based MCP server (Todoist)

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?

Installed a custom plugin with an MCP connector pointing to https://ai.todoist.net/mcp (Todoist's official hosted MCP server, Streamable HTTP transport). The plugin installs correctly and all skills/commands appear, but the Install button in the Connectors section is permanently greyed out — clicking does nothing, no OAuth flow is triggered.

Steps to reproduce:

What Should Happen?

Clicking Install triggers OAuth login flow for Todoist
Actual: Button is greyed out and unresponsive
Account: Todoist Pro. Environment variable TODOIST_API_TOKEN is set. Also attempted "type": "sse" — same result.

Error Messages/Logs

Steps to Reproduce

Create a plugin with .mcp.json using {"type": "http", "url": "https://ai.todoist.net/mcp"}
Install the plugin in Cowork
Navigate to the plugin's Connectors section
Install button is greyed out

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.92

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_