Dishd

Inspiration

The "where do you wanna eat?" group text — we've all spent 45 minutes negotiating dinner, lost to indecision and dueling Yelp tabs. We wanted Tinder's swipe-to-decide UX but for a group's collective taste, so picking a restaurant feels like a game instead of a chore.

What it does

One person spins up a session, drops a pin on the map, and gets a 4-digit code. Friends join from anywhere and everyone swipes yes/no on real nearby restaurants pulled from Google Places.

The instant every active member yes-swipes the same spot, an instant-match overlay fires with confetti.

If there's no unanimous match, you get a Top 3 leaderboard ranked by agreement %, each with a Gemini-powered personalized "why this fits you" note.

Solo mode is built in for when you're picking lunch alone.

How we built it

iOS App

SwiftUI (iOS 16+)
URLSessionWebSocketTask for realtime
Keychain for tokens
MapKit for pin + result map
iMessage app extension so invites work as a blue bubble

Backend

FastAPI (async)
MongoDB Atlas via Beanie ODM
JWT access + refresh tokens
slowapi rate limiting
Full security middleware:
- CSP
- HSTS
- size limits
- startup sanity checks

Realtime

Per-session WebSocket rooms broadcast:

member_joined
swipe_progress
instant_match
phase_change
top3_ready

AI Layer

Gemini 2.5 Flash generates:

vibe blurbs for restaurant cards
personalized fit narratives for each Top-3 pick

Cost Control

A 6-hour TTL cache over Google Places nearby-search queries keyed by rounded lat/lng, so a crowd in the same neighborhood hits Places once.

Challenges we ran into

Beanie + UUIDs

UUID fields are stored as BSON Binary subtype 4, so raw-dict queries with str(uuid) silently matched nothing. Cost us hours.

SwiftUI Navigation

Using @Environment(\.dismiss) inside a fullScreenCover + NavigationStack caused the nav stack to pop back to a stale swipe view that re-ran its .task, hit a 500, and landed on a mock list.

Fixed by routing every "close" action through a single onClose callback owned by the cover root.

Match-popup Race Conditions

The swipe ack and WS instant_match event both fired for the same yes-swipe, while three separate flows could request navigation to results.

Every navigation path now goes through one-shot guards.

Google Places Deprecation

The legacy Places API got deprecated mid-build and started returning REQUEST_DENIED.

We shipped:

a 20s timeout
mock fallback data

So the swipe stack is never empty during demos.

Async Generator Bug

Using await inside generator comprehensions returns an async generator that a sync for loop cannot iterate.

We hit this 500 twice before switching to explicit asyncio.gather for member fan-outs.

Accomplishments that we're proud of

A genuinely multiplayer, real-time app that works across multiple devices — not a demo with hardcoded state.
A production-shaped stack:
- containerized backend
- env-driven config
- per-route rate limits
- JWT refresh
- push notifications
- security headers
- graceful degradation when the LLM key is missing
The iMessage extension — joining a session straight from a blue bubble feels like magic.
A query cache that keeps Google Places spend bounded even when judges hammer it.