Tidepool

Build a web app called Tidepool: a calm money dashboard that reads your bank exports.

What it does

Tidepool turns the CSV files every bank lets you download into a dashboard you can actually read. It sorts transactions into categories, spots subscriptions you forgot about and shows where the month went, without connecting to your bank or sending your data anywhere.

Stack

Use Next.js, Supabase, Tailwind, shadcn/ui, Vercel. The original was built with Claude Code and v0 and ChatGPT in 3 weekends, for about $46 in AI usage.

How it fits together

• A server-rendered web app with a small API layer
• A database for user data, with row level security on every table
• Sign-in so each person only sees their own data

Build it in this order

1. Set up the project, the database and sign-in, and deploy an empty page
2. Build the main screen with realistic sample data
3. Connect it to real data and add the one action the app exists for
4. Add the empty states and error messages a new user will hit
5. Write tests for anything that touches money, dates or other people's data

Tools to connect

• Supabase MCP: schema, migrations and seed data straight from the agent
• Playwright MCP: end-to-end tests and the demo recording
• GitHub MCP: issues and pull requests from contributors

A prompt that worked: Teach the agent a new bank format

Here is an anonymised CSV export from a bank we don't support yet (attached as fixtures/new-bank.csv).

1. Work out the column mapping, date format, decimal separator and how refunds are shown.
2. Write a parser in lib/parsers/ that follows the same interface as lib/parsers/nordea.ts.
3. Write tests first using the fixture. Cover refunds, foreign currency rows and the summary line at the bottom.
4. Run the tests until they pass. Do not change other parsers.

When you're done, list anything in the file you weren't sure about.

Watch out for

• Don't build settings, teams or billing before the main screen works
• Keep the first screen useful with sample data, so the app makes sense before anyone has set it up

Done when

• A new user can sign in and get value in under two minutes
• Everything works on a phone
• Tests pass for the core logic

Before writing code, ask me up to five questions about who this finance web app is for and what the first version must do. Then work in small steps: after each one, tell me how to try it and wait for my feedback.