Real AI agent use cases, with sources and setup prompts

Return to coding after years away by building calculators

Someone who quit coding years ago used AI to build Calquio, a site of finance calculators.

See pricing pageweeksBeginnerSource linked

Source

ivcatcher on Hacker News · 2026-01-19 · Project link

Written in our own words. Credit to the original author. Link checked 2026-10-14.

What they did

Someone who quit coding years ago used AI to build Calquio, a site of finance calculators.

Result (as claimed)

Live and shared on HN.

Tools they used

ClaudeWindsurf

Cost: Pricing depends on the tools you pick; check each official pricing page.

Set it up

  1. Write a one-page brief

    Describe the app in plain words: who it is for, the 3 core screens or actions, and what "done" looks like.

  2. Start the project with your agent

    Open Claude and paste the brief. Ask it to propose a stack and a file plan before writing code.

  3. Build one slice at a time

    Ship the smallest working flow first, run it, then add features one by one. Commit after each working step.

  4. Test it like a user

    Click through on desktop and phone. Ask the agent to add basic tests and fix anything that breaks.

  5. Check security and ship

    Keep keys in environment variables, check auth and database rules, then deploy and share the link.

Copy the full setup prompt

Paste into your agent and it will walk you through the setup, asking before anything that sends, posts or spends.

You are helping me set up this AI use case end to end in Claude Code.

Goal: Return to coding after years away by building calculators
What the original author did: Someone who quit coding years ago used AI to build Calquio, a site of finance calculators.
Reported result (as claimed by the author): Live and shared on HN.
Source: https://news.ycombinator.com/item?id=46673809
Tools they used: Claude, Windsurf
Category: Vibe coding & apps

Please:
1. Ask me 3 short questions about my situation (accounts I have, budget, what I want the output to look like).
2. Propose a step-by-step plan using these tools or cheaper alternatives, with the time and cost of each step. Use official pricing pages; say "check pricing" if unsure.
3. Then do the setup with me one step at a time, waiting for my OK before anything that sends messages, posts publicly, spends money or deletes data.
4. Finish with a checklist to run it again next time.

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