ChatGPT plugin: one public MCP URL on the cloud root domain (workspace-independent OAuth clients + root-domain discovery)

Summary A published ChatGPT/Codex plugin has exactly one MCP server URL in its .mcp.json. Cloud Outline has one MCP endpoint per team subdomain ( and the OAuth discovery documents use the request origin. To publish Outline in the plugin directory we need one canonical MCP URL on the root domain ( that works for every workspace, and an OAuth flow that lets the user pick the workspace. Self-hosted installs are not affected: they have one origin already and keep working as "custom MCP server" connections. Related: #13958 (plugin manifest needs this URL), #13959. Reference docs • ChatGPT MCP authorization requirements (resource metadata, resource parameter, issuer rules): • RFC 9728 protected resource metadata: • Example .mcp.json with a single URL and oauth_resource: Current state • Discovery server/routes/discovery/mcp.ts: origin = env.isCloudHosted ? ctx.request.URL.origin : new URL(env.URL).origin. Both /.well-known/oauth-authorization-serve…