Real AI agent use cases, with sources and setup prompts

Write personal apps for QuickBooks, Garmin and your kid's studying

He used Claude Code and Codex to write his own apps for QuickBooks and Garmin data, a study tool for his daughter and a stock investing learning and tracking tool, each with a web interface and a native desktop app.

$17/moWeeksIntermediateSource linked

Source

@sanjeevpai on X · 2026-10-12

Written in our own words. Credit to the original author. Link checked 2026-10-21.

What they did

He used Claude Code and Codex to write his own apps for QuickBooks and Garmin data, a study tool for his daughter and a stock investing learning and tracking tool, each with a web interface and a native desktop app.

Result (as claimed)

All are in daily use under his control, with phone apps ready.

Tools they used

Claude CodeOpenAI CodexQuickBooksGarmin

Cost: Claude Code: from $17/mo; OpenAI Codex: free plan, paid from $8/mo.

Set it up

  1. Define the job

    Say exactly what you want done and what the agent may and may not do on your behalf.

  2. Share only what is needed

    Give Claude Code the minimum files or access required. Avoid sharing passwords in chat when a safer login flow exists.

  3. Review the plan

    Ask the agent to show its plan or draft before it acts, and approve each step that has real consequences.

  4. Check the result

    Confirm the outcome yourself (order placed, request sent, document understood) and keep a record.

Copy the full setup prompt

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Goal: Write personal apps for QuickBooks, Garmin and your kid's studying
What the original author did: He used Claude Code and Codex to write his own apps for QuickBooks and Garmin data, a study tool for his daughter and a stock investing learning and tracking tool, each with a web interface and a native desktop app.
Reported result (as claimed by the author): All are in daily use under his control, with phone apps ready.
Source: https://x.com/sanjeevpai/status/2109445799620833736
Tools they used: Claude Code, OpenAI Codex, QuickBooks, Garmin
Category: Personal & life

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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Guides for this use case

How to vibe code an app with Claude Code · How to build your own invoicing and bookkeeping app with AI · How to use Claude Code and Codex together · How to build AI trading and investing agents

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