Add search to the currency picker

Filters by code or display name, case-insensitively, across all three
sections (current, selected, and remaining currencies) — a section
disappears entirely once nothing in it matches. The matching logic
lives in shared code (matchesCurrencySearch) so Compose and SwiftUI
stay in sync; SwiftUI wires it into the native .searchable() field,
Compose gets a plain search text field with a clear button.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FXcrACM5sok3M1KQJ8kByy

shared/src/commonMain/kotlin/xyz/tyiu/satsprice/SystemCurrencies.kt

@@ -2,6 +2,16 @@ package xyz.tyiu.satsprice
 
 data class CurrencyInfo(val code: String, val displayName: String)
 
+/**
+ * Whether [info]'s code or display name contains [query], case-insensitively. A plain function
+ * (rather than a `CurrencyInfo` extension) so Kotlin/Native exports a predictable, positionally
+ * clear Swift signature, matching [currencyFlagEmoji]'s style.
+ */
+fun matchesCurrencySearch(info: CurrencyInfo, query: String): Boolean =
+    query.isBlank() ||
+        info.code.contains(query, ignoreCase = true) ||
+        info.displayName.contains(query, ignoreCase = true)
+
 /**
  * ISO 4217 codes for the precious metals actively traded today. These aren't tied to any
  * country, so a currently-used-currency filter derived from country/locale data (as the

shared/src/commonMain/kotlin/xyz/tyiu/satsprice/ui/PriceScreen.kt

@@ -27,6 +27,7 @@ import androidx.compose.material.icons.filled.KeyboardDoubleArrowDown
 import androidx.compose.material.icons.filled.KeyboardDoubleArrowUp
 import androidx.compose.material.icons.filled.MoreVert
 import androidx.compose.material.icons.filled.Refresh
+import androidx.compose.material.icons.filled.Search
 import androidx.compose.material3.Card
 import androidx.compose.material3.CardDefaults
 import androidx.compose.material3.CircularProgressIndicator
@@ -70,6 +71,7 @@ import xyz.tyiu.satsprice.domain.CurrencyConverter
 import xyz.tyiu.satsprice.domain.formatAmount
 import xyz.tyiu.satsprice.domain.groupDigits
 import xyz.tyiu.satsprice.domain.localizedDecimalSeparator
+import xyz.tyiu.satsprice.matchesCurrencySearch
 import xyz.tyiu.satsprice.shared.MR
 
 private val SectionColors
@@ -497,6 +499,28 @@ private fun CurrencyPickerScreen(
                 TextButton(onClick = onDone) { Text(stringResource(MR.strings.done)) }
             }
 
+            var searchQuery by remember { mutableStateOf("") }
+            OutlinedTextField(
+                value = searchQuery,
+                onValueChange = { searchQuery = it },
+                placeholder = { Text(stringResource(MR.strings.search_currencies_placeholder)) },
+                leadingIcon = { Icon(Icons.Default.Search, contentDescription = null) },
+                trailingIcon = if (searchQuery.isNotEmpty()) {
+                    {
+                        IconButton(onClick = { searchQuery = "" }) {
+                            Icon(
+                                Icons.Default.Close,
+                                contentDescription = stringResource(MR.strings.clear_search_content_description),
+                            )
+                        }
+                    }
+                } else {
+                    null
+                },
+                singleLine = true,
+                modifier = Modifier.fillMaxWidth().padding(horizontal = screenHorizontalPadding),
+            )
+
             Column(
                 modifier = Modifier
                     .fillMaxSize()
@@ -504,22 +528,26 @@ private fun CurrencyPickerScreen(
                     .padding(horizontal = screenHorizontalPadding, vertical = 8.dp),
                 verticalArrangement = Arrangement.spacedBy(16.dp),
             ) {
-                val selectedOthers = state.selectedOtherCurrencies()
+                val currentCurrency = state.currentCurrency()
+                val selectedOthers = state.selectedOtherCurrencies().filter { matchesCurrencySearch(it, searchQuery) }
+                val unselected = state.unselectedCurrencies().filter { matchesCurrencySearch(it, searchQuery) }
 
-                Column {
-                    Text(
-                        stringResource(MR.strings.current_currency_section_title).uppercase(),
-                        style = SectionHeaderStyle,
-                        modifier = Modifier.padding(bottom = 4.dp),
-                    )
-                    CurrencyRow(
-                        info = state.currentCurrency(),
-                        isSelected = true,
-                        isPriced = state.isPriced(state.currentCurrency().code),
-                        sourceName = state.sourceName,
-                        localeCurrencyCode = state.localeCurrencyCode,
-                        onClick = null,
-                    )
+                if (matchesCurrencySearch(currentCurrency, searchQuery)) {
+                    Column {
+                        Text(
+                            stringResource(MR.strings.current_currency_section_title).uppercase(),
+                            style = SectionHeaderStyle,
+                            modifier = Modifier.padding(bottom = 4.dp),
+                        )
+                        CurrencyRow(
+                            info = currentCurrency,
+                            isSelected = true,
+                            isPriced = state.isPriced(currentCurrency.code),
+                            sourceName = state.sourceName,
+                            localeCurrencyCode = state.localeCurrencyCode,
+                            onClick = null,
+                        )
+                    }
                 }
 
                 if (selectedOthers.isNotEmpty()) {
@@ -544,22 +572,24 @@ private fun CurrencyPickerScreen(
                     }
                 }
 
-                Column {
-                    Text(
-                        stringResource(MR.strings.currencies_section_title).uppercase(),
-                        style = SectionHeaderStyle,
-                        modifier = Modifier.padding(bottom = 4.dp),
-                    )
-                    state.unselectedCurrencies().forEach { info ->
-                        key(info.code) {
-                            CurrencyRow(
-                                info = info,
-                                isSelected = false,
-                                isPriced = state.isPriced(info.code),
-                                sourceName = state.sourceName,
-                                localeCurrencyCode = state.localeCurrencyCode,
-                                onClick = { onToggle(info.code) },
-                            )
+                if (unselected.isNotEmpty()) {
+                    Column {
+                        Text(
+                            stringResource(MR.strings.currencies_section_title).uppercase(),
+                            style = SectionHeaderStyle,
+                            modifier = Modifier.padding(bottom = 4.dp),
+                        )
+                        unselected.forEach { info ->
+                            key(info.code) {
+                                CurrencyRow(
+                                    info = info,
+                                    isSelected = false,
+                                    isPriced = state.isPriced(info.code),
+                                    sourceName = state.sourceName,
+                                    localeCurrencyCode = state.localeCurrencyCode,
+                                    onClick = { onToggle(info.code) },
+                                )
+                            }
                         }
                     }
                 }

shared/src/commonMain/moko-resources/base/strings.xml

@@ -3,6 +3,7 @@
     <string name="bitcoin_section_title">Bitcoin</string>
     <string name="btc_label">BTC</string>
     <string name="btc_to_currency">1 BTC to %1$s</string>
+    <string name="clear_search_content_description">Clear search</string>
     <string name="currencies_section_title">Currencies</string>
     <string name="currencies_selected_count">%1$d selected</string>
     <string name="current_currency_section_title">Current Currency</string>
@@ -22,5 +23,6 @@
     <string name="remove_currency_content_description">Remove</string>
     <string name="retry">Retry</string>
     <string name="sats_label">Sats</string>
+    <string name="search_currencies_placeholder">Search currencies</string>
     <string name="selected_currencies_section_title">Selected Currencies</string>
 </resources>

shared/src/commonTest/kotlin/xyz/tyiu/satsprice/SystemCurrenciesTest.kt

@@ -2,6 +2,7 @@ package xyz.tyiu.satsprice
 
 import kotlin.test.Test
 import kotlin.test.assertEquals
+import kotlin.test.assertFalse
 import kotlin.test.assertTrue
 
 class SystemCurrenciesTest {
@@ -22,4 +23,17 @@ class SystemCurrenciesTest {
         assertEquals(0, currencyDecimalDigits("JPY"))
         assertEquals(3, currencyDecimalDigits("BHD"))
     }
+
+    @Test
+    fun matchesCurrencySearch_matchesByCodeOrDisplayNameCaseInsensitively() {
+        val usd = CurrencyInfo("USD", "US Dollar")
+
+        assertTrue(matchesCurrencySearch(usd, ""))
+        assertTrue(matchesCurrencySearch(usd, "usd"))
+        assertTrue(matchesCurrencySearch(usd, "USD"))
+        assertTrue(matchesCurrencySearch(usd, "dollar"))
+        assertTrue(matchesCurrencySearch(usd, "US Doll"))
+        assertFalse(matchesCurrencySearch(usd, "EUR"))
+        assertFalse(matchesCurrencySearch(usd, "Euro"))
+    }
 }