Cashing out was the least approachable thing here: open your wallet,
create an invoice for exactly the right amount, copy it, come back, paste
it. That is the step people abandon, leaving sats behind.
LNURL-withdraw replaces it with a scan. The arcade shows a code, the
wallet pulls the funds, and the player never handles an invoice or types
an amount. The paste path is kept for wallets without LNURL support, but
folded away.
The withdraw token is a bearer instrument, so it is random, single-use,
bound to one account and one amount, and expires in five minutes. Sixteen
goroutines racing one code yield exactly one payment. Funds are debited
when the code is issued — otherwise a player could cash out and bet the
same sats before the wallet claimed them — and a sweep refunds any code
that is never scanned.
bech32 is verified against the BIP-173 vectors, including the invalid
ones. Getting this wrong produces codes that silently fail to scan with
no useful error for the player.
Adds a three-card first-run walkthrough, an explanation of what a
multiplier target means, and a one-time confirmation before a player's
first real-money action — the interface is deliberately frictionless, and
that is the one place a moment of friction is worth it.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The node is an interface, so the code where money is actually at risk is
tested against a fake that can be made to fail, stall, or lie. Plugging
in Alby Hub is configuration, not new code.
Crediting a deposit is idempotent by payment hash: a node reporting the
same settlement twice must not mint money. Withdrawals debit before they
pay, because a payment that succeeds while the ledger write fails loses
money permanently, whereas the reverse is recoverable. Withdrawals above
a threshold wait for a human, which bounds what a stolen session token
can remove.
17 tests including concurrent settlement, concurrent double-spend,
concurrent processors, failed payment refunds, fee caps, and solvency.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
