Bit Lazarus is a hackathon demo for recovering a dead torrent with a bonded requester/hunter flow.

The demo flow is:

1. A requester creates a bounty from a real .torrent file.
2. The backend funds the requester escrow from a Polar-backed Lightning node.
3. A hunter joins the bounty.
4. The requester creates the delivery contract.
5. Both sides lock bonds.
6. The hunter seeds the recovered file over WebTorrent.
7. The requester downloads it, hashes it, and the backend settles if the SHA-256 matches.

• Node >=20
• Polar

This repo includes the Polar network export you should use for the demo:

• bit-lazarus.polar.zip

In Polar:

1. Import bit-lazarus.polar.zip
2. Start the network
3. Load the nodes with funds before running the app

The imported network is expected to provide:

• lazarus for the app backend
• requester for requester-side demo payments
• hunter for hunter-side demo payments

npm install

Start the backend from the repo root:

WALLET_AUTH_BACKEND=bitcoin-cli \
BITCOIN_CLI_CHAIN=regtest \
BITCOIN_CLI_RPCCONNECT=127.0.0.1 \
BITCOIN_CLI_RPCPORT=18443 \
BITCOIN_CLI_RPCUSER=polaruser \
BITCOIN_CLI_RPCPASSWORD=polarpass \
LIGHTNING_BACKEND=lnd-rest \
LIGHTNING_LND_REST_URL='https://127.0.0.1:8084' \
LIGHTNING_LND_MACAROON_HEX="$(xxd -p -c 999999 ~/.polar/networks/1/volumes/lnd/lazarus/data/chain/bitcoin/regtest/admin.macaroon | tr -d '\n')" \
LIGHTNING_LND_TLS_SKIP_VERIFY=1 \
POLAR_DEMO_REQUESTER_LND_REST_URL='https://127.0.0.1:8085' \
POLAR_DEMO_REQUESTER_LND_MACAROON_HEX="$(xxd -p -c 999999 ~/.polar/networks/1/volumes/lnd/requester/data/chain/bitcoin/regtest/admin.macaroon | tr -d '\n')" \
POLAR_DEMO_REQUESTER_LND_TLS_SKIP_VERIFY=1 \
POLAR_DEMO_HUNTER_LND_REST_URL='https://127.0.0.1:8081' \
POLAR_DEMO_HUNTER_LND_MACAROON_HEX="$(xxd -p -c 999999 ~/.polar/networks/1/volumes/lnd/hunter/data/chain/bitcoin/regtest/admin.macaroon | tr -d '\n')" \
POLAR_DEMO_HUNTER_LND_TLS_SKIP_VERIFY=1 \
POLAR_DEMO_BITCOIN_RPC_URL='http://127.0.0.1:18443' \
POLAR_DEMO_BITCOIN_RPC_USER='polaruser' \
POLAR_DEMO_BITCOIN_RPC_PASSWORD='polarpass' \
POLAR_DEMO_REQUESTER_BITCOIN_WALLET='requester-auth' \
POLAR_DEMO_HUNTER_BITCOIN_WALLET='hunter-auth' \
WEBTORRENT_TRACKER_HOST='127.0.0.1' \
WEBTORRENT_TRACKER_PORT='8001' \
WEBTORRENT_TRACKER_PUBLIC_HOST='127.0.0.1' \
WEBTORRENT_TRACKER_PUBLIC_PORT='8001' \
PORT=3000 \
DATA_DIR=./data/polar-demo \
npm start

The backend runs on:

• http://127.0.0.1:3000

In a second terminal:

npm run frontend:dev

Open the Vite URL it prints, usually:

• http://127.0.0.1:5173

Use two separate browser profiles or one normal window plus one private window.

On the Home page:

• click Login as Requester in one browser profile
• click Login as Hunter in the other

Those buttons use the backend's Polar/Bitcoin Core integration, so no shell auth step or token copy/paste is needed.

Use the bundled fixture files:

• fixture-a.torrent
• fixture-a.bin

1. Log in as requester and hunter in separate browser profiles.
2. As requester, create a bounty with fixture-a.torrent.
3. As hunter, open the bounty and click Hunt bounty.
4. As requester, create the delivery contract.
5. As hunter, create and register the payout invoice.
6. Both sides pay their bond from Polar.
7. As hunter, load fixture-a.bin, commit the SHA-256, and start seeding.
8. As requester, start the download.
9. After the download completes, save the file with Download recovered file.

npm test
npm run frontend:build

Won 1st place at MIT Bitcoin Hackathon