mobile: implement BLE proximity discovery for nearby DevCard users

[ShantKhatri]

Summary

Product doc section 4.3 specifies AirDrop-style proximity sharing via Bluetooth Low Energy (BLE). Implement the native BLE scanning and advertising layer in the React Native mobile app using react-native-ble-plx.

Context

This is one of DevCard's core differentiators. When two users are nearby and both have the app open, they should see each other's cards without needing a QR scan. The ScanScreen.tsx screen at apps/mobile/src/screens/ScanScreen.tsx is the natural mount point for the discovery flow.

Tasks

• install and configure react-native-ble-plx in apps/mobile.
• add required permissions in AndroidManifest.xml (BLUETOOTH_SCAN, BLUETOOTH_ADVERTISE, ACCESS_FINE_LOCATION) and Info.plist for iOS.
• create apps/mobile/src/context/BLEContext.tsx providing startAdvertising(userId), startScanning(), and discoveredUsers state.
• BLE service UUID should be a static DevCard UUID defined in packages/shared/src/constants.ts.
• discovered devices broadcast only their DevCard userId — no raw profile data over BLE.
• on discovery, fetch the discovered user's public profile from the backend and surface a local notification/banner.
• expose a ProximityBanner component rendered on ScanScreen showing discovered users with a 'View Card' CTA.
• handle graceful degradation: if BLE is unavailable or permission denied, fall back to QR mode silently.

Acceptance Criteria

• two devices with the app open and BLE enabled see each other in the discovery banner.
• tapping 'View Card' opens DevCardViewScreen with the discovered user's data.
• no raw profile data is transmitted over BLE.
• permission denial path does not crash the app.

Difficulty

advanced — requires native BLE APIs, background permission handling, and cross-platform (iOS + Android) compatibility.

[Vishakhayadavv]

Hey! I'm a GSSoC contributor and I'd love to work on this issue. I've gone through the codebase and have a good idea of how to approach it. Could you please assign it to me?

[ShantKhatri]

Hey! I'm a GSSoC contributor and I'd love to work on this issue. I've gone through the codebase and have a good idea of how to approach it. Could you please assign it to me?

Hi @Vishakhayadavv , you can jump to this, once we have PR for good-first one. Assigning this to you for now.

[ShantKhatri]

Add on to previous comment, you can also create sub-issues for this, to make your deliverables tracked and better delivery alignment. Happy to discuss further on this.

[Vishakhayadavv]

Got it, thank you! I’ll start with a good first issue to understand the project better and then continue with this one

[Shikhar-404exe]

I would like to work on this issue, please assign this issue to me for gssoc26 so I can start working on it.

[Shikhar-404exe]

Hi ,

I reviewed this issue and the related files. I have experience in this field of work.

I’d like to work on this issue and can start immediately. My plan is to:

• reproduce the issue locally
• trace the affected components
• implement and test the fix carefully

Please assign this issue to me if it's available.
Thank you!

[Aaryan1005194]

Hi @ShantKhatri, I’d like to work on this issue.

This feature is genuinely one of the most interesting parts of DevCard, and I’d love to contribute to it. I’ve worked with React Native integrations and real-time interaction features before, and I’m comfortable handling both the native configuration and app-side BLE flow.

My implementation approach would include:

• Setting up and configuring react-native-ble-plx
• Adding proper Android and iOS BLE permissions/configuration
• Creating a reusable BLEContext to manage advertising, scanning, and discovered users state
• Ensuring only the DevCard userId is transmitted over BLE for privacy and security
• Fetching public profile data securely from the backend after discovery
• Building a smooth proximity discovery experience inside ScanScreen
• Adding graceful fallback behavior when BLE is unavailable or permissions are denied
• Testing cross-platform behavior carefully to avoid crashes or unstable scanning states

I’ll focus on keeping the implementation modular, secure, and optimized for real-world usage, especially around permission handling and device discovery stability.

This looks like a challenging and impactful feature, and I’d be excited to work on it if it’s available.
Please consider assigning it to me and marking it under GSSoC’26.