From b8db7ae6b7d8bd187d901d9136d4f8f33c4ac85b Mon Sep 17 00:00:00 2001
From: Claude <noreply@anthropic.com>
Date: Fri, 19 Jun 2026 17:26:48 +0000
Subject: [PATCH] perf(cashu): dispatch token prefixes via DualCase startsWith
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Replace startsWith(..., ignoreCase = true) — which case-folds on every
call — with the precomputed DualCase prefixes and the new
String.startsWith(DualCase) helper, so the cashuA/cashuB dispatch only
compares against already-cased strings.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013UMNKix4qEfiAPP9s2a4gB
---
 .../ui/screen/loggedIn/wallet/CashuWalletViewModel.kt  |  3 ++-
 .../quartz/nip60Cashu/token/CashuTokenB64Parser.kt     | 10 ++++++++--
 .../com/vitorpamplona/quartz/utils/StringUtils.kt      |  2 ++
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/wallet/CashuWalletViewModel.kt b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/wallet/CashuWalletViewModel.kt
index 8b1b677264..0d0cd0ce79 100644
--- a/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/wallet/CashuWalletViewModel.kt
+++ b/amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/wallet/CashuWalletViewModel.kt
@@ -34,6 +34,7 @@ import com.vitorpamplona.quartz.nip60Cashu.mintApi.MintHttpException
 import com.vitorpamplona.quartz.nip60Cashu.token.CashuTokenB64Parser
 import com.vitorpamplona.quartz.nip87Ecash.recommendation.MintRecommendationEvent
 import com.vitorpamplona.quartz.utils.Log
+import com.vitorpamplona.quartz.utils.startsWith
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.asStateFlow
@@ -838,7 +839,7 @@ class CashuWalletViewModel : ViewModel() {
             return
         }
 
-        if (!trimmed.startsWith("cashuA", ignoreCase = true) && !trimmed.startsWith("cashuB", ignoreCase = true)) {
+        if (!trimmed.startsWith(CashuTokenB64Parser.CashuAPrefix) && !trimmed.startsWith(CashuTokenB64Parser.CashuBPrefix)) {
             _redeemState.value =
                 CashuRedeemFlowState.Error("Not a Cashu token (must start with cashuA or cashuB)")
             return
diff --git a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip60Cashu/token/CashuTokenB64Parser.kt b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip60Cashu/token/CashuTokenB64Parser.kt
index 2889b4aaeb..eefe13a01f 100644
--- a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip60Cashu/token/CashuTokenB64Parser.kt
+++ b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/nip60Cashu/token/CashuTokenB64Parser.kt
@@ -21,6 +21,8 @@
 package com.vitorpamplona.quartz.nip60Cashu.token
 
 import com.vitorpamplona.quartz.nip01Core.core.toHexKey
+import com.vitorpamplona.quartz.utils.DualCase
+import com.vitorpamplona.quartz.utils.startsWith
 import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.decodeFromByteArray
@@ -45,6 +47,10 @@ object CashuTokenB64Parser {
     /** Both "cashuA" and "cashuB" prefixes are 6 chars. */
     private const val PREFIX_LENGTH = 6
 
+    /** Precomputed dual-case prefixes so dispatch avoids per-call case folding. */
+    val CashuAPrefix = DualCase("cashuA")
+    val CashuBPrefix = DualCase("cashuB")
+
     private val json =
         Json {
             ignoreUnknownKeys = true
@@ -53,8 +59,8 @@ object CashuTokenB64Parser {
 
     fun parse(token: String): List<CashuToken>? =
         when {
-            token.startsWith("cashuA", ignoreCase = true) -> parseCashuA(token)
-            token.startsWith("cashuB", ignoreCase = true) -> parseCashuB(token)
+            token.startsWith(CashuAPrefix) -> parseCashuA(token)
+            token.startsWith(CashuBPrefix) -> parseCashuB(token)
             else -> null
         }
 
diff --git a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/StringUtils.kt b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/StringUtils.kt
index 7a22427f21..e02e2227d6 100644
--- a/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/StringUtils.kt
+++ b/quartz/src/commonMain/kotlin/com/vitorpamplona/quartz/utils/StringUtils.kt
@@ -109,6 +109,8 @@ fun String.startsWithAny(terms: List<DualCase>): Boolean {
     return terms.any { startsWithIgnoreCase(it.lowercase, it.uppercase) }
 }
 
+fun String.startsWith(prefix: DualCase): Boolean = startsWithIgnoreCase(prefix.lowercase, prefix.uppercase)
+
 class DualCase(
     val lowercase: String,
     val uppercase: String,