TabsAI

Tabs is an agentic, middleman platform that removes the social awkwardness and financial vulnerability of splitting group expenses. Upload a receipt to Discord, and Tabs handles the rest — extracting line items, splitting the bill, generating personal checkout links, and nudging people who haven't paid.

How It Works

1. A user uploads a receipt image to a Discord channel.
2. The bot runs vision-based OCR (Groq) to extract line items, tax, tip, and totals.
3. A LangGraph state machine validates the extraction and prompts the user to resolve any math discrepancies.
4. The user chooses a split method via Discord buttons:
   • Even split — pick participants with a native user selector; each person gets a checkout link for their equal share.
   • Itemized split — the organizer opens a drag-and-drop tagger UI to assign specific items to each person, then per-invitee checkout links are generated.
5. Each participant receives a single-use, time-limited checkout link where they pay their share via Stripe.
6. If someone hasn't paid, the nudge engine sends AI-generated reminders to the Discord channel on an escalating tone schedule.

Architecture

app/
├── discord-bot/     # Python — Discord gateway bot, receipt ingestion, LangGraph intent engine
├── worker/          # TypeScript — Cloudflare Worker handling Discord interactions via HTTP
├── checkout-ui/     # Next.js — checkout and itemized split tagger UI, Stripe integration
└── nudge/           # TypeScript — Cloudflare Worker cron job for AI-driven payment reminders

Discord Bot (app/discord-bot)

Python bot using discord.py that listens for image uploads, provisions users in Supabase, streams receipt images to Supabase Storage, and kicks off the OCR + split workflow. Includes a LangGraph state machine (intent_engine.py) with validation, human-in-the-loop fix prompts, split-type resolution, and interactive Discord UI views (buttons, user selects).

Interactions Worker (app/worker)

TypeScript Cloudflare Worker that handles Discord interactions over HTTP (slash commands, button clicks, user selects) with Ed25519 signature verification. Mirrors the bot's split logic for the serverless path.

Checkout UI (app/checkout-ui)

Next.js app deployed on Cloudflare Pages. Provides:

• /split/[tab_id] — drag-and-drop item tagger for itemized splits
• /checkout/[tab_id] — per-invitee payment page with Stripe Elements
• /api/create-payment-intent — Stripe payment intent creation
• /api/stripe-webhook — webhook handler for payment confirmation
• /api/confirm-split — finalizes itemized split assignments

All routes are gated by single-use, 15-minute auth tokens.

Nudge Engine (app/nudge)

Cloudflare Worker cron trigger (every 6 hours) that queries unpaid assignments, generates tone-escalating reminders via Groq, and dispatches them to Discord channels. Tracks nudge count and cooldown per assignment.

Tech Stack

• AI/LLM: Groq (vision OCR + nudge generation), LangGraph (state machine orchestration)
• Backend: Supabase (Postgres DB + Storage + Auth tokens), Cloudflare Workers
• Frontend: Next.js, Tailwind CSS, Stripe Elements
• Payments: Stripe
• Messaging: Discord (gateway bot + HTTP interactions API)

Key Data Model

Table	Purpose
users	Discord users provisioned on first interaction
tabs	One row per receipt upload — tracks status, split type, totals
receipt_items	Line items extracted from the receipt (prices in cents)
tab_assignments	Per-invitee share amounts, payment status, nudge tracking
auth_tokens	Single-use, time-limited tokens for checkout links