feat: ENG-179 Cashu NFC card top-up

__tests__/card/cashu-topup-helpers.spec.ts

@@ -0,0 +1,116 @@
+/**
+ * cashu-topup-helpers.spec.ts
+ *
+ * Unit tests for the Cashu card top-up helper functions.
+ * These are pure logic functions with no RN/NFC dependencies.
+ */
+
+import {
+  extractNonceFromSecret,
+  toCardWriteProof,
+} from "@app/screens/card-screen/cashu-topup.helpers"
+
+// ── Fixtures ──────────────────────────────────────────────────────────────
+
+// NUT-XX worked example from spec/NUT-XX.md
+const EXAMPLE_NONCE = "916c21b8c67da71e9d02f4e3adc6f30700c152e01a07ae30e3bcc6b55b0c9e5e"
+const EXAMPLE_PUBKEY = "02a9acc1e48c25eeeb9289b5031cc57da9fe72f3fe2861d264bdc074209b107ba2"
+
+/** Build a P2PK secret JSON string from (nonce, pubkey) matching the on-card format */
+function makeP2PKSecret(nonce: string, pubkey: string): string {
+  return JSON.stringify([
+    "P2PK",
+    {
+      nonce,
+      data: pubkey,
+      tags: [["sigflag", "SIG_ALL"]],
+    },
+  ])
+}
+
+const EXAMPLE_SECRET = makeP2PKSecret(EXAMPLE_NONCE, EXAMPLE_PUBKEY)
+
+const EXAMPLE_PROOF = {
+  id: "0059534ce0bfa19a",
+  amount: 100,
+  secret: EXAMPLE_SECRET,
+  C: "024a43eddcf0e42dad32ca5c0e82e51d7a38e7a48b80e89d2e17cc94abb02c04c3",
+}
+
+// ── extractNonceFromSecret ────────────────────────────────────────────────
+
+describe("extractNonceFromSecret", () => {
+  it("extracts nonce from a valid P2PK secret", () => {
+    expect(extractNonceFromSecret(EXAMPLE_SECRET)).toBe(EXAMPLE_NONCE)
+  })
+
+  it("extracts nonce regardless of other fields", () => {
+    const secretWithExtras = JSON.stringify([
+      "P2PK",
+      {
+        nonce: "aabbcc",
+        data: EXAMPLE_PUBKEY,
+        tags: [["sigflag", "SIG_ALL"], ["locktime", "9999999999"]],
+      },
+    ])
+    expect(extractNonceFromSecret(secretWithExtras)).toBe("aabbcc")
+  })
+
+  it("throws for non-P2PK secrets", () => {
+    const htlcSecret = JSON.stringify([
+      "HTLC",
+      { nonce: "deadbeef", data: "something" },
+    ])
+    expect(() => extractNonceFromSecret(htlcSecret)).toThrow("Invalid P2PK secret")
+  })
+
+  it("throws for missing nonce field", () => {
+    const noNonce = JSON.stringify(["P2PK", { data: EXAMPLE_PUBKEY }])
+    expect(() => extractNonceFromSecret(noNonce)).toThrow("Invalid P2PK secret")
+  })
+
+  it("throws for invalid JSON", () => {
+    expect(() => extractNonceFromSecret("not-json")).toThrow("Invalid P2PK secret")
+  })
+
+  it("throws for plain string secrets (non-P2PK)", () => {
+    expect(() => extractNonceFromSecret("deadbeefdeadbeef")).toThrow(
+      "Invalid P2PK secret",
+    )
+  })
+})
+
+// ── toCardWriteProof ──────────────────────────────────────────────────────
+
+describe("toCardWriteProof", () => {
+  it("maps a GQL proof to the card write format", () => {
+    const result = toCardWriteProof(EXAMPLE_PROOF)
+    expect(result).toEqual({
+      keysetId: "0059534ce0bfa19a",
+      amount: 100,
+      nonce: EXAMPLE_NONCE,
+      C: "024a43eddcf0e42dad32ca5c0e82e51d7a38e7a48b80e89d2e17cc94abb02c04c3",
+    })
+  })
+
+  it("propagates nonce extraction errors", () => {
+    const badProof = { ...EXAMPLE_PROOF, secret: "not-a-p2pk-secret" }
+    expect(() => toCardWriteProof(badProof)).toThrow("Invalid P2PK secret")
+  })
+
+  it("preserves amount exactly (no rounding)", () => {
+    const proofs = [1, 2, 4, 8, 16, 32, 64].map((amount) => ({
+      ...EXAMPLE_PROOF,
+      amount,
+    }))
+    proofs.forEach((proof) => {
+      expect(toCardWriteProof(proof).amount).toBe(proof.amount)
+    })
+  })
+
+  it("uses proof.id as keysetId (not amount or C)", () => {
+    const result = toCardWriteProof(EXAMPLE_PROOF)
+    expect(result.keysetId).toBe(EXAMPLE_PROOF.id)
+    expect(result.keysetId).not.toBe(EXAMPLE_PROOF.C)
+  })
+})

app/components/card/EmptyCard.tsx

@@ -17,7 +17,11 @@ import EmptyFlashcard from "@app/assets/icons/empty-flashcard.svg"
 
 const width = Dimensions.get("screen").width
 
-const EmptyCard = () => {
+type EmptyCardProps = {
+  onCashuTopup?: () => void
+}
+
+const EmptyCard = ({ onCashuTopup }: EmptyCardProps) => {
   const navigation = useNavigation<StackNavigationProp<RootStackParamList>>()
   const styles = useStyles()
   const { LL } = useI18nContext()
@@ -39,6 +43,13 @@ const EmptyCard = () => {
         onPress={() => readFlashcard(false)}
         btnStyle={{ marginBottom: 10 }}
       />
+      {onCashuTopup && (
+        <PrimaryBtn
+          label="💳  Top Up Flash Card"
+          onPress={onCashuTopup}
+          btnStyle={{ marginBottom: 10 }}
+        />
+      )}
       <PrimaryBtn type="outline" label="Find a Flashpoint" onPress={findFlashpoint} />
     </View>
   )

app/components/card/Flashcard.tsx

@@ -28,9 +28,10 @@ import { DisplayCurrency, toBtcMoneyAmount } from "@app/types/amounts"
 type Props = {
   onReload: () => void
   onTopup: () => void
+  onCashuTopup?: () => void
 }
 
-const Flashcard: React.FC<Props> = ({ onReload, onTopup }) => {
+const Flashcard: React.FC<Props> = ({ onReload, onTopup, onCashuTopup }) => {
   const isAuthed = useIsAuthed()
   const styles = useStyles()
   const { colors } = useTheme().theme
@@ -72,6 +73,14 @@ const Flashcard: React.FC<Props> = ({ onReload, onTopup }) => {
         <View style={styles.btns}>
           <IconBtn type="clear" icon="down" label={`Reload\nCard`} onPress={onReload} />
           <IconBtn type="clear" icon="qr" label={`Topup via\nQR`} onPress={onTopup} />
+          {onCashuTopup && (
+            <IconBtn
+              type="clear"
+              icon="cardAdd"
+              label={`Flash\nTop-Up`}
+              onPress={onCashuTopup}
+            />
+          )}
           <IconBtn
             type="clear"
             icon={"cardRemove"}

app/i18n/en/index.ts

@@ -835,7 +835,7 @@ const en: BaseTranslation = {
     showNostrSecret: "Chat Settings",
     beginnerMode: "Disable Bitcoin Account",
     advanceMode: "Enable Bitcoin Account (Advanced Mode)",
-    keysManagement: "Key management",
+    keysManagement: "Wallet backup",
 		showBtcAccount: "Show Bitcoin account",
 		hideBtcAccount: "Hide Bitcoin account"
   },

app/i18n/raw-i18n/source/en.json

@@ -772,7 +772,7 @@
         "showNostrSecret": "Chat Settings",
         "beginnerMode": "Disable Bitcoin Account",
         "advanceMode": "Enable Bitcoin Account (Advanced Mode)",
-        "keysManagement": "Key management",
+        "keysManagement": "Wallet backup",
         "showBtcAccount": "Show Bitcoin account",
         "hideBtcAccount": "Hide Bitcoin account"
     },

app/navigation/root-navigator.tsx

@@ -10,7 +10,7 @@ import {
 } from "../screens/authentication-screen"
 import { PinScreen } from "../screens/authentication-screen/pin-screen"
 import { ContactsDetailScreen, ContactsScreen } from "../screens/contacts-screen"
-import { CardScreen, FlashcardTopup } from "../screens/card-screen"
+import { CardScreen, FlashcardTopup, CashuTopup } from "../screens/card-screen"
 import { ChatList } from "@app/screens/chat"
 import { DeveloperScreen } from "../screens/developer-screen"
 import { EarnMapScreen } from "../screens/earns-map-screen"
@@ -269,6 +269,13 @@ export const RootStack = () => {
           title: LL.ReceiveScreen.topupFlashcard(),
         }}
       />
+      <RootNavigator.Screen
+        name="cashuTopup"
+        component={CashuTopup}
+        options={{
+          title: "Flash Card Top-Up",
+        }}
+      />
       <RootNavigator.Screen
         name="redeemBitcoinDetail"
         component={RedeemBitcoinDetailScreen}

app/navigation/stack-param-lists.ts

@@ -87,6 +87,7 @@ export type RootStackParamList = {
   priceHistory: undefined
   receiveBitcoin: undefined
   flashcardTopup: { flashcardLnurl: string }
+  cashuTopup: undefined
   redeemBitcoinDetail: {
     receiveDestination: ReceiveDestination
   }