Sage | Devpost

Inspiration

Every time you see a new doctor, you're handed a clipboard and asked to recall your entire medical history from memory. You forget medications, can't remember dates, and miss important details. Doctors end up making decisions with incomplete information.

We wanted to fix that not with another form, but with a conversation.

What it does

Sage is an AI-powered health passport that lives on your phone.

You chat with it naturally "I take Metformin for diabetes and I'm allergic to penicillin" and it automatically builds a structured health profile. It can also scan prescription bottles with your camera and extract the information.

When you see a doctor, you can instantly share your full history as:

a PDF, or
a QR code they scan on the spot

Every time you add a medication, Sage checks the FDA database for:

drug interactions
safety warnings
allergy conflicts

All in real time.

How we built it

Sage is a two-part system:

Mobile app

Built with React Native + Expo
All health data stored locally in on-device SQLite
Nothing leaves your phone unless you explicitly share it

Backend (Vercel serverless)

AI proxy → sends messages to Claude (claude-opus-4-6), returns structured JSON written directly to the database
Share service → generates temporary passport links using Upstash Redis (24-hour expiry)

Safety layer

Uses the OpenFDA API
Runs checks in parallel for:
- drug interactions
- warnings
- allergy contraindications

Challenges we ran into

Reliable structured output from Claude We needed strict JSON, not prose. Built a parser that handles:
- clean JSON
- JSON inside markdown fences
- plain text fallback
Stale state bug in React Callbacks captured outdated conversation history. Fixed using a ref that stays synced with state, ref feeds Claude, state renders UI.
Secure architecture vs speed Keeping API keys off-device while maintaining a fast, seamless experience required careful proxy design.

Accomplishments that we're proud of

Real-time medication safety checks Adding a drug and instantly seeing FDA warnings makes it feel like a real medical tool.
Privacy-first design
- Data stays on-device by default
- Shared data expires in 24 hours
Full product in 48 hours (2 people) AI chat, camera OCR, PDF export, QR sharing, dark mode — all working end-to-end.

What we learned

Prompt engineering is real engineering Designing a system prompt that enforces a strict JSON schema took more iteration than any feature.
Structured AI changes everything The model isn’t just responding — it’s writing to your database. It becomes part of the data pipeline, not just the UI.