Kudos

A loyalty/rewards points program on Solana, where the points are a real SPL token — not an integer in a database column. Users sign up with an email, the app provisions a custodial Solana wallet for each of them, a business issues a branded points token, and users earn points (minted to their wallet) and redeem rewards (points burned).

Kudos is the second SolRengine reference app and the issuance showcase for the custodial Wallet-per-User path on the Solana Developer Platform (SDP). It's the counterpart to Lamport, which covers wallets and payments — Kudos covers token issuance: create, deploy, mint, burn.

A complete Rails 8 app, verified end-to-end on devnet. See the showcase writeup.

How it works

1. A business issues the points token. Token.register! records it off-chain (mint authority = the business's custodial treasury wallet), then deploy! puts the mint on-chain. The token is KUDO, 0 decimals — points are whole numbers.
2. A user signs up with an email. No wallet, no seed phrase. after_create_commit enqueues an async job that provisions a custody wallet for them through SDP; the dashboard polls pending → provisioning → ready.
3. Earn. A custodial mint sends points to the user's wallet (token.mint!). The demo awards a fixed amount; a real app mints on a genuine event (a purchase, a referral) — the engine call is identical, only the trigger differs.
4. Redeem. A custodial burn removes points from the user's wallet (token.burn!), affordability-checked against the on-chain balance and a rewards catalog. The burn is signed on the user's behalf, because burn authority is the token-account owner, not the mint authority.
5. Live balance. Because the app initiates every mint and burn, the job that settles them is the doorbell: it re-reads the balance from chain and pushes it to the browser over a Turbo Stream — no polling, no page reload.

Lives in Rails (SQLite)	Lives on Solana (via SDP)
Users, rewards catalog, mint/burn audit rows	The points token (a real SPL mint)
Affordability checks, demo earn trigger	A custodial wallet per user
Session auth (has_secure_password)	Every mint and burn, signed custodially

Each mint!/burn! writes an audit row, then sends a single, never-retried POST — SDP has no idempotency key, so a blind re-send could double-mint. An atomic claim guarantees one send.

Stack

• Ruby on Rails 8, Ruby 3.3.6
• Hotwire (Turbo + Stimulus), Tailwind CSS 4, esbuild, propshaft
• SQLite multi-database: primary + Solid Cache + Solid Queue + Solid Cable
• Minitest + WebMock (the suite stubs SDP HTTP — no live stack needed to test)

SolRengine gems

• solana-sdp (~> 0.2) — Ruby client for the SDP API
• solrengine-sdp (~> 0.3) — Rails engine: Wallet-per-User provisioning + token issuance (Token / TokenMint / TokenBurn)
• solrengine-realtime (~> 0.2) — the realtime doorbell that pushes live balances
• solrengine-rpc (~> 0.1) — chain WebSocket subscription for the balance monitor

Prerequisites

SDP is pre-mainnet and devnet-oriented, so there's no hosted demo — running Kudos needs an SDP stack of your own:

• A running SDP instance — self-hosted or managed. See the self-hosting guide.
• A managed custody provider (e.g. Privy) — local custody is single-wallet and can't provision a wallet per user.
• Kora as the fee-payment provider — the native adapter can't submit transfers.
• A Helius-class RPC endpoint for SPL token balances (public devnet RPC lacks the indexing).

Getting started

bin/setup            # installs deps, prepares the databases, starts the dev server

Set your SDP credentials first — a missing SDP_API_KEY fails loudly at boot:

# .env
SDP_API_KEY=...                         # required; Bearer key for the SDP API
SDP_API_BASE_URL=http://127.0.0.1:8787  # SDP base URL (this is the default)
SDP_CUSTODY_PROVIDER=privy              # a managed provider; local custody can't do wallet-per-user

Then seed the rewards catalog and run it:

bin/rails db:seed    # starter catalog: Free coffee (50) · Sticker pack (100) · T-shirt (500)
bin/dev              # web · js · css · jobs · sdp_watcher

First run, in the browser:

1. Sign up with an email — your custody wallet provisions in the background.
2. Visit /token/new to create and deploy the points token (business setup; runs once).
3. Earn points on the dashboard, then redeem a reward — watch the balance update live.

Tests

bin/rails test       # Minitest; SDP HTTP stubbed with WebMock, no live stack

License

MIT