Analytics service that answers plain-English questions with funnels, retention and user-path reports, and shows the exact SQL behind every number, on a NestJS backend with a React dashboard. Safe by construction: the model can only fill a fixed, read-only query template, enforced by a typed query grammar and a read-only database role, not by prompt wording. Also runs as an MCP server so AI assistants like Claude can query the metrics directly. Stack: NestJS, Node.js, TypeScript, PostgreSQL, React, Zod, Docker.