How to Clone Venmo

Create a Venmo-style SOCIAL payments app called SplitPay using Next.js (App Router), Tailwind, Prisma + SQLite. SIMULATED balances only - no real money, no banking license.

## What to build
Pay/charge friends with expressive notes that post to a friends feed (amount hidden) with likes and comments, plus bill-splitting and a free-vs-instant cash-out with fee math.

## Screens
- Onboarding: pick a unique @username and avatar, add a few friends, simulation notice
- Landing: hero with social-feed mockup, feature cards, simulation disclaimer
- Feed: friends' payments ('Alex paid Sam 🍕', no amount), like + comment, floating Pay/Request button
- Pay/Request flow: pick friend(s), amount, note + emoji, audience (public/friends/private), confirm → success
- Bill split: total + friends, split evenly or custom, send charges in one action
- My activity: personal history WITH amounts, status, 'remind' on unpaid requests
- Profile: avatar, @username, friends, public feed, shareable link
- Wallet: balance, simulated add money, cash out FREE standard vs INSTANT (1.75% fee), debit-card waitlist

## Prisma schema
User (id, name, username unique, avatar, balance), Transaction (id, senderId, recipientId, amount, note, emoji, audience, type, status, createdAt), Friendship (id, userId, friendId, status), Like (id, transactionId, userId), Comment (id, transactionId, userId, text, createdAt)

## Money + feed logic (server-side, transactional)
- Payment: in one Prisma $transaction, verify sender.balance >= amount, debit sender, credit recipient, write the Transaction; reject insufficient funds
- Charge: creates a pending request; paying runs the same atomic payment; bill-split creates one charge per friend
- Top-up: a simulated add-money credits the balance and logs a topup transaction
- Feed query returns friends' public/friends-audience transactions with note + emoji but the amount field stripped from the response - enforce this server-side, not in the UI
- Likes/comments attach to a transaction; counts shown in the feed
- Cash out: standard free (pending→completed); instant = balance -= amount, fee = round(amount × 0.0175)
- Use integer cents for all amounts; balance must equal the sum of a user's signed transactions; add /api/reconcile

## Routes
- POST /api/pay, POST /api/charge, POST /api/charge/[id]/pay, POST /api/split, POST /api/cashout, POST /api/topup
- GET /api/feed (privacy-filtered, no amounts), POST /api/transactions/[id]/like, POST /api/transactions/[id]/comment

## Style
Friendly and bold: a confident blue/indigo accent, emoji-forward notes, rounded cards, smooth like/comment and payment-success animations, mobile-first. Persistent 'simulation - not a real payment service' disclaimer.

Seed: 6 demo friends with usernames and avatars, the signed-in user with a starting balance, ~12 feed transactions with notes/emoji and a few likes and comments, and a couple of pending charges so the activity tab is populated.

Build a production-quality Venmo-style SOCIAL payments platform. Balances are SIMULATED for the MVP (no license, no real funds), but the money engine must be a correct append-only DOUBLE-ENTRY ledger, and the social feed must respect privacy. Assume hostile clients trying to overspend, double-send, or scrape amounts.

## Stack
- Next.js 14 App Router + TypeScript + Tailwind + shadcn/ui; Framer Motion for payment-success + like animations
- PostgreSQL via Prisma; NextAuth (email + phone OTP); Redis for feed fan-out and counters; integer-cents money math
- A BaaS adapter interface (Stripe Treasury / Dwolla) with a SimulatedProvider now so a licensed provider drops in later

## Core design: ledger + privacy-aware feed
- Money: accounts (per-user wallet + system accounts: house, fees, external) and append-only ledger_entries that net to zero per movement. Balance = sum of entries, never a stored field - makes overspend and double-send impossible under SERIALIZABLE isolation
- Feed: a separate social_events stream derived from transactions. CRITICAL: the amount is NEVER serialized into any feed/social response. Enforce audience (public/friends/private) at the query layer, not the client

## Transfer execution (server-authoritative, atomic, idempotent)
- POST /api/payments: { toUsername, amountCents, note, emoji, audience, idempotencyKey }. One SERIALIZABLE transaction: verify funds, write balanced entries, emit a social_event honoring audience, return the receipt
- Charges are a request object; paying triggers the same path; bill-split creates N charges atomically
- Idempotency keys reject replays

## Schema
users, accounts, ledger_entries (immutable), payments (user-facing, links entries), charges, friendships, social_events, likes, comments, idempotency_keys. Indexes on ledger_entries(account_id, created_at), social_events(audience, created_at), friendships(user_id).

## Implementation order
1. Schema + auth + ledger primitives with property tests (entries sum to 0; balance never negative; concurrent double-send cannot overspend)
2. Payment endpoint + idempotency + receipt
3. Pay/Request UI + bill-split flow
4. Social feed (privacy/audience enforced server-side; amount provably absent) + likes/comments
5. Personal activity (WITH amounts) + reminders on unpaid charges
6. Wallet: add money + free-vs-instant cash-out (fee posts to the fees account)
7. BaaS adapter seam documented so a licensed provider replaces SimulatedProvider without UI changes

## Quality bar
- Unmissable 'Simulation - not a regulated payment service' disclaimer; never imply real money transmission
- Add a test asserting no feed/social response ever contains an amount field for someone else's transaction
- Default new users to a sane audience (friends, not public); make the privacy control obvious
- Integer-cents money math; ledger invariants property-tested in CI; rate limiting + velocity checks on payments

Start with step 1; show me the ledger schema, the social_event privacy model, and the concurrent-double-send test before continuing.

Design the complete UI for a Venmo-style SOCIAL payments app called SplitPay. React + Tailwind + shadcn/ui + lucide-react. Aesthetic: friendly, bold, expressive - a confident blue/indigo accent (plus clean light mode), emoji-forward payment notes, rounded cards, playful but trustworthy, smooth like and success animations. Mobile-first.

## Screens

### 1. Social feed (home)
- Top bar: logo, search, avatar; tabs 'Friends / All'
- Scrollable feed cards: '[avatar] Alex paid Sam', note with emoji ('🍕 pizza night'), timestamp, like (heart) + comment icons with counts - NO amount shown; a few cards with a comment thread expanded
- Floating 'Pay or Request' button bottom-right; small 'Simulation' badge
- Bottom tab bar: Feed, Activity, Pay, Cards, Profile

### 2. Pay / request flow
- Recipient picker (search by @username, recent + suggested friends)
- Amount on a clean numeric input; note field with a prominent emoji picker; audience selector (Public / Friends / Private)
- Two big buttons: Pay (accent) and Request (outline); confirm card; animated success state

### 3. Bill split
- Total amount, add friends as chips; split-evenly toggle or per-person custom amounts (live remaining tally); 'Send charges' button with a summary

### 4. My activity
- Personal history WITH amounts (in green / gray), status pills (completed / pending), 'Remind' button on unpaid requests; transaction detail sheet

### 5. Profile
- Avatar, @username, friends count, join date; your public payment feed; 'Share profile' link + QR

### 6. Wallet & cash-out
- Balance card; 'Add money' (mock card); cash out chooser: FREE Standard (1–3 days) vs INSTANT (1.75% fee) showing fee + net; debit-card waitlist upsell card with benefits

### 7. Friends
- Friends list with search; 'Add friends' (by @username or from contacts) with suggested-friends cards; friend request states

## Components to design once and reuse
- Feed payment card (avatar, 'X paid Y', emoji note, like + comment, NO amount)
- Recipient/friend chip used in the picker, bill-split and friends list
- Audience selector segmented control (Public / Friends / Private)

Fully responsive, mobile-first. Fill every screen with realistic friends, @usernames, avatars, emoji-rich notes, likes and comments (a populated feed of ~12 items), and include a clear 'Simulated social payments - not a regulated money service' disclaimer in onboarding and the footer.

Build a Venmo-style SOCIAL payments app called SplitPay for paying friends and splitting bills. Balances are SIMULATED - no real money moves and no banking license is involved. Show that disclaimer clearly.

## Entities
- User: name, username (unique), avatar, balance
- Transaction: sender, recipient, amount, note, emoji, audience (public/friends/private), type (payment/charge/cashout/topup), status, createdAt
- Friendship: user, friend, status
- Like: transaction, user; Comment: transaction, user, text, createdAt

## Roles
- Member: pays and charges friends, splits bills, posts to and interacts with the feed, manages friends and wallet
- Admin: views all users and transactions, dashboard with total volume and active users per day, can freeze a user

## Pages
1. Feed: friends' payments shown with note and emoji but NOT the amount; like and comment; floating Pay/Request button
2. Pay/Request: pick friend(s), enter amount, write an emoji note, set audience, confirm with a success screen
3. Bill split: enter a total, pick friends, split evenly or custom, send a charge to each
4. My activity: personal history WITH amounts and statuses, with a 'remind' action on unpaid requests
5. Profile: avatar, @username, friends, public feed, shareable link
6. Friends: search, add by @username or from contacts, suggested friends, request states
7. Wallet: balance, simulated add money, cash out FREE standard vs INSTANT with a 1.75% fee, debit-card waitlist upsell
8. Admin: all users and transactions, dashboard of total volume and active users per day

## Rules
- A payment requires balance >= amount; debits the sender and credits the recipient atomically; insufficient funds is blocked
- A charge creates a pending request; paying it runs the payment; bill-split creates one charge per friend
- Top-up: a simulated add-money credits the balance and logs a topup transaction
- The feed shows note and emoji but never the amount; respect each transaction's audience setting
- Cash out: standard is free and settles later; instant charges a 1.75% fee immediately
- Balances must always reconcile to a user's transaction history; store amounts in integer cents
- New users default to a 'friends' audience; privacy is a clear per-payment control

## Look & feel
Friendly bold social fintech: a confident blue/indigo accent, emoji-forward notes, rounded cards, smooth like and payment-success animations, mobile-first. Persistent 'simulated payments' disclaimer.

Seed: 6 demo friends with usernames and avatars, the signed-in user with a starting balance, ~12 feed transactions with notes, emoji, likes and comments, and a couple of pending charges so the app looks social.