I run the app locally and open Claude Code in my project folder. When I load a CSV and type a hypothesis like "template users churn faster," Claude has access to the app's codebase.
Every pattern gets verified through actual SQL queries but instead, Claude writes queries, SQLite runs them, real numbers come back. When we test if template users churn faster, we're not discussing it theoretically. We run the actual queries, get actual counts and calculate percentages.
Claude isn't just generating code in a vacuum. It's working with my local database, using Prisma to write queries, accessing the exact libraries I have installed. The conversation guides the investigation, but the database does the math.
There's almost no UI. Want to load data? Type "load analytics.csv". Need to join tables? Just ask. Since Claude Code can see and run everything in the project folder, I didn't need to build any custodial features.