Build Your Own Finance Tracker

Preface

1. What you will build
2. What you will use
3. A short and honest disclaimer
4. How this book works
5. The book’s motto
6. What you need to start
7. A note on pace
8. Who wrote this
9. How to get the most out of this book
10. How to begin

Chapter 1: Why Build Your Own Finance Tracker

1. What you will learn
2. Why it matters
3. Where the spreadsheet quietly wins and loses
4. What the AI coding agent changes
5. What this looks like in practice
6. A month in the life of five apps
7. What “owning your own tool” actually means
8. The three honest limits
9. When to use an existing app instead
10. The honest case for building
11. A very short first prompt
12. How a first week actually looks
13. The honest cost of building
14. A five-minute decision loop
15. Common mistakes and fixes
16. Chapter checklist
17. Summary
18. Try it yourself

Chapter 2: Setting Up Flutter and Your AI Coding Workflow

1. What you will learn
2. Why it matters
3. Step 1: Install Flutter
4. Step 2: Install the Android tools
5. Step 3: Prepare a device
6. Step 4: Create the project folder
7. Step 5: Install OpenCode
8. Step 6: Write your rules file
9. Step 7: Make your first checkpoint
10. Step 8: Learn to talk to the agent
11. Step 9: Learn the two modes
12. Step 10: Your first conversation
13. What a good result looks like
14. What the AI typically produces and how to check it
15. A setup day that went wrong
16. Common mistakes and fixes
17. Chapter checklist
18. Summary
19. Try it yourself

Chapter 3: Writing the Product Spec

1. What you will learn
2. Why it matters
3. The six parts of a spec
4. Step 1: Write the problem
5. Step 2: Name the persona
6. Step 3: List the screens
7. Step 4: Write user stories
8. Step 5: Sketch the data
9. Step 6: Write acceptance criteria
10. Step 7: Add non-goals
11. Step 8: Ask the agent to review the spec
12. Step 9: Write the build order
13. What a good result looks like
14. Turning one story into one build prompt
15. A worked review, so you know what to expect
16. A spec prompt to reuse
17. What the AI typically produces and how to check it
18. Common mistakes and fixes
19. Chapter checklist
20. Summary
21. Try it yourself

Chapter 4: Local Database with SQLite

1. What you will learn
2. Why it matters
3. What a database layer looks like
4. Step 1: Add the packages
5. Step 2: Ask for the schema first
6. Step 3: Build the database file
7. Step 4: Show the database path on screen
8. Step 5: Understand versions and migrations
9. Step 6: Add row classes and one repository
10. Step 7: Check it with a quick test
11. What the AI typically produces and how to check it
12. Common mistakes and fixes
13. Chapter checklist
14. Summary
15. Try it yourself

Chapter 5: Budget Categories and Accounts

1. What you will learn
2. Why it matters
3. Category or account: a quick way to remember
4. Step 1: Seed the defaults
5. Step 2: Build the category list screen
6. Step 3: Add edit and archive
7. Step 4: Build the account list with balances
8. Step 5: Test the balance by hand
9. Step 6: Wire the screens together
10. What the AI typically produces and how to check it
11. The double-counting trap
12. A worked balance, so the numbers feel real
13. Common mistakes and fixes
14. Chapter checklist
15. Summary
16. Try it yourself

Chapter 6: Recording and Browsing Transactions

1. What you will learn
2. Why it matters
3. The ten-second rule
4. Step 1: The add transaction form
5. Step 2: List this month’s transactions
6. Step 3: Add the Home summary
7. Step 4: Filter and search
8. Step 5: Edit and delete
9. Step 6: The transfer trap (and why we skip it)
10. What the AI typically produces and how to check it
11. The month boundary, carefully
12. Common mistakes and fixes
13. Chapter checklist
14. Summary
15. Try it yourself

Chapter 7: Reports and Charts

1. What you will learn
2. Why it matters
3. The three honest rules of a report
4. Step 1: Add the chart package
5. Step 2: Spending by category for one month
6. Step 3: One chart
7. Step 4: The six-month trend
8. Step 5: Keep the reports read-only
9. What the AI typically produces and how to check it
10. A worked report, so you can check percentages
11. One query, two views
12. What a report cannot tell you
13. Common mistakes and fixes
14. Chapter checklist
15. Summary
16. Try it yourself

Chapter 8: Tracking US Stocks with Live Prices

1. What you will learn
2. A word before we start
3. Why it matters
4. The plan: borrow, cache, and be honest
5. Step 1: Add the network and key packages
6. Step 2: Build the holdings screen
7. Step 3: Design the price source abstraction
8. Step 4: Cache the last good price
9. Step 5: Show the value and the “last updated” time
10. Step 6: Keep the key out of the code
11. What the AI typically produces and how to check it
12. What “graceful failure” actually looks like
13. Common mistakes and fixes
14. Chapter checklist
15. Summary
16. Try it yourself

Chapter 9: Backup, Export, and Import

1. What you will learn
2. Why it matters
3. Two kinds of export, two jobs
4. Step 1: Add the file and sharing packages
5. Step 2: Export to CSV
6. Step 3: Share the exported file
7. Step 4: Full JSON backup
8. Step 5: Import with checks
9. Step 6: Rehearse the disaster
10. What the AI typically produces and how to check it
11. A safe backup habit
12. Common mistakes and fixes
13. Chapter checklist
14. Summary
15. Try it yourself

Chapter 10: Testing and Fixing What the AI Gets Wrong

1. What you will learn
2. Why it matters
3. Layer one: the manual test plan
4. Layer two: a few small automated tests
5. The mistakes the AI makes most often
6. How to describe a bug so it gets fixed
7. The escalation ladder
8. Reading the diff, and using /undo
9. A workflow that catches bugs early
10. What a good result looks like
11. A real bug, start to finish
12. What not to automate yet
13. Common mistakes and fixes
14. Chapter checklist
15. Summary
16. Try it yourself

Chapter 11: Privacy and Security for Personal Financial Data

1. What you will learn
2. Why it matters
3. Start with a threat model
4. Step 1: Add a device lock
5. Step 2: Block screenshots (optional, Android)
6. Step 3: Keep secrets out of Git
7. Step 4: Make backups safe
8. Step 5: Practice data minimization
9. Why we did not build a login
10. What this app cannot protect against
11. A security review prompt
12. What the AI typically produces and how to check it
13. Common mistakes and fixes
14. Chapter checklist
15. Summary
16. Try it yourself

Chapter 12: Building and Releasing Your App

1. What you will learn
2. Why it matters
3. Step 1: Set the app name, icon, and version
4. Step 2: Understand debug and release
5. Step 3: Create a signing key
6. Step 4: Build the release APK
7. Step 5: Test the release build like a new user
8. Step 6: Decide about Google Play
9. Step 7: Write a short release note
10. After the release: keeping the app alive
11. If you want to extend the app
12. What a good result looks like
13. What the AI typically produces and how to check it
14. Common mistakes and fixes
15. Chapter checklist
16. Summary
17. Try it yourself

Appendix A: Prompt Templates

1. 1. Spec prompt (plan first, before any code)
2. 2. Feature prompt (one small, runnable step)
3. 3. Bug-fix prompt (full evidence, small territory)
4. 4. Refactor prompt (same behavior, cleaner code)
5. 5. Security and data review prompt (every season)
6. 6. Price source prompt (choose and verify before building)
7. How to adapt these

Appendix B: Checklists

1. Pre-release checklist (before you build a release)
2. Privacy checklist (monthly or before sharing anything)
3. Backup checklist (weekly)
4. Money-data sanity checklist (monthly)
5. New-feature checklist (each time you add something)
6. Recovery checklist (when something is lost)

Appendix C: Troubleshooting

1. Setup problems
2. Package and dependency problems
3. Running and UI problems
4. Database problems
5. Network and price problems
6. Release-build problems
7. Agent problems
8. When to stop and rest

Glossary

About the Author