Receipts were only being checked for a valid event signature — anyone could
sign a kind:9735 and have it counted toward another user's zap totals. NIP-57
Appendix F mandates three additional checks: receipt.pubkey == LNURL
provider's nostrPubkey (MUST), bolt11 invoice amount == zap request "amount"
tag (MUST), and lnurl tag == recipient's lnurl (SHOULD).
- Adds LnZapReceiptValidator + LnurlForm in quartz commonMain (pure logic).
- Adds LnurlEndpointCache (jvmAndroid) and the LnurlEndpointResolver
interface for async lookup. The cache is primed by outbound zaps (existing
LightningAddressResolver fetches now extract nostrPubkey) and on demand for
inbound receipts when no entry is present.
- Adds OkHttpLnurlEndpointResolver in commons, wired into LocalCache via
AppModules using the existing money-tier OkHttp builder (so Tor settings
apply).
- LocalCache.consume(LnZapEvent) now: drops receipts that fail MUST checks
synchronously when the cache is warm, defers credit until async resolution
finishes on cache miss, and falls back to legacy signature-only behavior
when no resolver is wired (tests).
- LnZapRequestEvent.create() now accepts amountMillisats + lnurl; both are
threaded through Account.createZapRequestFor and emitted as tags so future
receipts can be validated against them.
21 new tests cover validator reasons, lnurl form canonicalization across
lud16/URL/bech32, and cache eviction.
Claude
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