kvitt/initial_prompt.md

I'm starting a brand-new project and want your help producing a SPEC.md that coding agents will build from.

The idea

A Splitwise-style app for splitting shared expenses between me and my spouse. households, day-to-day and trip expenses. Working name: Kvitt.

What I know so far

• Who it's for: Me and my partner

• Platforms: native Android app (Kotlin). Both have Samsung Galaxy S26 phones. One have normal and one have plus size.

• Hosting: On raspberry pi via docker at my home. I have a domain that points to my IP.

• Preferred stack: Kotlin for Android, server backend in rust, database which is lightweight enough for RPI but I also want nice analytics and graphs in the app for how we spend over time.

• Must-haves: Expenses, pre-defined uneven splits (i.e. me pay 60% and my partner pay 40%, configurable), balances, settle up, total spend each month (down to weeks) + ability to group by category of expense. Be able to invite my Spouse, set name on both of us + a profile picture.  Also to have multiple "expense acocunts", like we want to have daily expenses, house expenses, travels etc. this was just examples so it needs to be dynamic, basically how Spendwise's groups work, but it will always be a group with me and my spouse. It needs to work offline, and then later sync once back online.

• Nice-to-haves: Receipt scanning, connect to our creditcard to figure out exact foreign exchange rate (We use Spendwise in Sweden, maybe they have an API?)

• Explicitly NOT doing: No bank integrations in v1,

How I want you to work

1. Don't write the spec yet. First interview me, in rounds of 3–5

   questions. Ask about anything that would change the architecture,

   data model or scope. Challenge assumptions and point out things

   I haven't thought of (e.g. debt simplification, rounding, currency,

   deleted users, offline use, auth).

2. When you have enough, propose a v1 scope and a short list of

   key decisions with your recommendation for each. Wait for my OK.

3. Then write SPEC.md with these sections:

   • Overview & goals

   • Non-goals

   • Users & core user stories

   • Functional requirements (v1), with acceptance criteria

   • Data model

   • Architecture & stack (with reasoning)

   • API outline

   • Auth & security

   • Edge cases & business rules (splits, rounding, settlement)

   • Deployment & ops

   • Milestones (small, independently shippable steps)

   • Open questions

4. Make an explicit UX-sprint spec which a UX agent can do with some proposals for how the app could look like.

5. Write it so multiple coding agents with no other context could implement it without guessing. 

Start with your first round of questions.