ChatGPT setup: Plugins, Add custom MCP server

[helpcodeai]

OpenAI removed the separate developer mode toggle on 1 Oct 2026. A custom remote MCP server is now added at chatgpt.com/plugins: + → Add custom MCP server → Server URL with OAuth → I understand and want to continue → Create as a plugin, then install it from the personal plugins and @-mention it in a chat. On Business, Enterprise and Edu workspaces this needs the "Create plugins with MCPs" permission (Business: admins and owners only).

• Server page, ChatGPT tab: new four-step instructions, button to chatgpt.com/plugins instead of the old chatgpt.com/admin/mcp, and a note on workspace permissions.
• anythingmcp_connect_client (chatgpt): the real steps instead of "add it in ChatGPT's settings", with a spec.
• docs/integrations/chatgpt.md: Step 3 rewritten; OAuth (MCP_AUTH_MODE oauth2 or both) instead of a bearer token, since ChatGPT's dialog has no token field. Responses API section unchanged.
• README (all four languages), docs/guides.md and the Sorare ChatGPT guide: same flow.

Sources: https://developers.openai.com/api/docs/guides/custom-mcp-server and https://help.openai.com/en/articles/12584461

Checks run locally: backend lint (0 errors), tsc --noEmit, jest (593 suites passed, 4 skipped); frontend lint (0 errors), tsc --noEmit.