The napkin ledger
Sandwich Bets started with a tiny social failure: two friends make a dumb prediction, forget the terms, and later remember the outcome differently. The joke only works if the system remembers exactly what was proposed, what changed, who accepted it, and whether the resulting sandwich was ever delivered.
That turned a novelty into a real product exercise. The app separates theatrical odds from settlement, caps every consequence at one sandwich, versions negotiated terms, keeps the ledger private to participants, and leaves an obligation open until lunch is delivered or forgiven.
This is the actual stateful interface prototype, not a video or flattened mockup. Tap through the wager, negotiation, odds, resolution, and ledger screens.
One person records the prediction, the counterparty, an expiration, and the exact lunch stakes before memory can begin editing the deal.
The other person may accept, decline, or raise formal qualms. Every revision produces explicit terms instead of an argument about what everyone meant.
Decorative odds add ceremony without changing the consequence. Resolution records the outcome, then the ledger follows the physical sandwich to delivery or mercy.
Bet state
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The joke needed rules
A casual bet becomes contentious in the gaps: who accepted which terms, whether the odds mattered, who won, and whether the loser actually followed through. The product makes those gaps explicit without converting lunch into a financial instrument.
Decorative odds. Real lunch consequences.
Every guardrail protects the same distinction: this is a private social ritual with a ledger, not a gambling platform wearing a novelty hat.
Expo Router, React Native, and TypeScript keep the core interaction model consistent across iOS, Android, and web.
Supabase Auth and Postgres store participant-scoped wagers, negotiated terms, outcomes, obligations, and fulfillment events.
Edge Functions validate invitations, qualms, odds, resolution, reminders, and fulfillment instead of trusting a client-side state change.
The actual product
Sandwich Bets works because it treats a trivial wager with exactly enough seriousness: explicit terms, mutual consent, a recorded outcome, and an obligation that remains open until lunch changes hands.
The result is less a betting app than a tiny social contract. The software does not make the prediction matter. It makes the promise harder to rewrite.