BouncePay

Payments that bounce until they connect.

A payment created on a phone with no internet hops over Bluetooth Low Energy through nearby devices until it reaches one that is online, which carries it to settlement. Neither the buyer nor the merchant needs connectivity — only someone in the chain does.

Built for iQOO City Battles 2026 · Track 01: Fintech & Commerce.

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What's in here

Path	What it is
android/	The Android app — real BLE mesh, Keystore signing, store-and-forward
mock-bank/	The settlement service the bridge phone posts to, with a live dashboard
mock-phone/	A second phone in Python (Bumble), for testing the app's Bluetooth against one emulator
index.html	The marketing site — hand-written HTML/CSS/JS, no framework
public/demo/	Build output of the prototype, served at /demo/
scripts/build-demo.mjs	Builds the prototype and applies the site's theme
scripts/demo-theme.css	Dark Material You overlay for the prototype
scripts/generate_deck.py	Generates the pitch deck
public/images/	Artwork used by the site
assets/deck/	Artwork used only by the deck (not deployed)

The site is a single self-contained HTML file. Vite is used only to serve and copy public/ — there is no bundling step for the page itself.

The app and the bank

cd mock-bank && npm start                 # settlement service + dashboard on :4000
cd android && ./gradlew assembleDebug     # APK for the phones

android/README.md walks through a three-phone demo: payer and relay forced offline, a bridge on the laptop's Wi-Fi, and the payment appearing on the bank's dashboard with the route it took.

The two halves are written in different languages but must agree on every byte that is signed. ./gradlew testDebugUnitTest signs a packet exactly as the phone does and writes it out; npm test in mock-bank/ then verifies that same file with Node's independent crypto.

Running the site

npm install
npm run dev          # http://localhost:3000
npm run build        # → dist/

The prototype

The interactive demo in the Demo section is a real app, not a reimplementation. It lives in a sibling repo and is built into this one:

Desktop/
├── bouncepay/     ← the prototype (separate project)
└── bpay/          ← this repo

npm run build:demo   # rebuilds public/demo/ from ../bouncepay

That script does three things beyond a plain build:

1. Builds with a relative base so it can be served from /demo/.
2. Links scripts/demo-theme.css, which re-points the prototype's --md-sys-color-* tokens at the site's dark palette. Both are Material You seeded from #6750A4, so this is a token swap rather than a restyle.
3. Applies the post-build polish: numbers the route nodes instead of emoji, removes the internal POS device id, de-brands the handset, hides the duplicate step ticker, and injects the packet-absorption script.

Do not hand-edit public/demo/. It is build output — --emptyOutDir wipes it on every build. Anything that needs to survive belongs in build-demo.mjs or demo-theme.css.

The deck

npm run build:deck   # → BouncePay_iQOO_Final_Deck.pptx

Requires python-pptx. Generated decks are gitignored — rebuild rather than commit them.

What actually works

	Status
Signing: ECDSA P-256 in Android Keystore, payer bound to key	Built; Keystore-signed payments from an Android 16 emulator settle at the Node bank, and the wire format is also checked byte-for-byte in CI
Settlement: signature, key binding, freshness, limits, replay, idempotent duplicates	Built and tested (24 bank tests)
CI	Every push builds the APK and runs both suites on GitHub Actions; the APK is kept as a build artifact
Store-and-forward queue that survives restarts	Built
Bank-signed receipts passed back through the mesh to an offline payer	Built; verified across Node and Kotlin with a shared fixture
Paying any phone in range, not just a merchant; payee credited on the bank's receipt	Built; simulated in unit tests
Mesh routing: forwarding, loop avoidance, dedup, receipt gossip	Built; simulated across chains, diamonds and a 4×4 grid of phones in unit tests
BLE transport: advertise, scan, GATT transfer with chunking	Built; packets and receipts exchanged over the emulator's virtual Bluetooth between two emulators running the app, and with mock-phone/ at MTU 517 and 23. Not yet tried between physical phones
Routing model, end to end, in the browser	The interactive prototype on the site

The site's Built with section still labels these layers as planned; update it once the BLE path has been run on real handsets. Everything still to do is in TODO.md.

Team

Alan James · Anuroop Phukan · Ishaan Sridharan