X_MCP_PATH_DUPLICATE
Means
two MCP endpoints claim one path
Typical cause
apps/<app>/mcp.ts exports mcp as an array and two endpoints resolve to one POST path — a second defineAppMcp with no path defaults to /mcp — or to one RFC 9728 metadata path. Thrown at boot by the web role (x dev and runRole alike): one URL cannot answer two populations with two catalogs
Fix
give each defineAppMcp after the first its own path: '/mcp/admin'; every endpoint mounts at its own defineAppMcp path (default /mcp)