fix: guard calculator refresh writes

Port the Android calculator follow-up behavior so external refreshes skip no-op persisted writes and do not clear BTC when the active fiat input is empty. Also keep calculator value storage scoped/named for the in-app widget preview instead of OS home screen wording.

Author: ovitrif

Bitkit/Components/Widgets/CalculatorWidget.swift

@@ -63,22 +63,25 @@ struct CalculatorWidget: View {
             hydrateValuesIfNeeded()
         }
         .onChange(of: currency.selectedCurrency) {
+            let previousValues = values
             refreshCurrencyFields()
             refreshDerivedValue(preferredSource: calculatorInput.activeInput)
             refreshNumberPadConfiguration()
-            persistValues()
+            persistValuesIfNeeded(previousValues: previousValues)
         }
         .onChange(of: currency.displayUnit) { _, newUnit in
+            let previousValues = values
             convertBitcoinValue(to: newUnit)
             refreshCurrencyFields()
             refreshDerivedValue(preferredSource: calculatorInput.activeInput)
             refreshNumberPadConfiguration()
-            persistValues()
+            persistValuesIfNeeded(previousValues: previousValues)
         }
         .onChange(of: currency.rates) {
+            let previousValues = values
             refreshCurrencyFields()
             refreshDerivedValue(preferredSource: calculatorInput.activeInput)
-            persistValues()
+            persistValuesIfNeeded(previousValues: previousValues)
         }
         .onChange(of: calculatorInput.submittedKey?.id) {
             guard let key = calculatorInput.submittedKey?.value else { return }
@@ -151,7 +154,7 @@ struct CalculatorWidget: View {
         guard !hasHydrated else { return }
         hasHydrated = true
 
-        let saved = CalculatorHomeScreenWidgetOptionsStore.load()
+        let saved = CalculatorWidgetOptionsStore.load()
         let savedSats = CalculatorWidgetFormatter.bitcoinValueToSats(saved.bitcoinValue, displayUnit: saved.displayUnit)
 
         values = CalculatorWidgetValues(
@@ -265,7 +268,9 @@ struct CalculatorWidget: View {
     }
 
     private func refreshDerivedValue(preferredSource: CalculatorMoneyType? = nil) {
-        if values.refreshSource(activeInput: preferredSource) == .fiat {
+        guard let source = values.refreshSource(activeInput: preferredSource) else { return }
+
+        if source == .fiat {
             refreshBitcoinFromFiat()
         } else {
             refreshFiatFromBitcoin()
@@ -322,7 +327,12 @@ struct CalculatorWidget: View {
 
     private func persistValues() {
         guard hasHydrated else { return }
-        CalculatorHomeScreenWidgetOptionsStore.save(currentValues)
+        CalculatorWidgetOptionsStore.save(currentValues)
+    }
+
+    private func persistValuesIfNeeded(previousValues: CalculatorWidgetValues) {
+        guard values != previousValues else { return }
+        persistValues()
     }
 
     private func showInputError(for key: String) {

Bitkit/Models/CalculatorWidgetData.swift

@@ -25,7 +25,8 @@ struct CalculatorWidgetValues: Codable, Equatable {
         bitcoinValue.isEmpty && !fiatValue.isEmpty
     }
 
-    func refreshSource(activeInput: CalculatorMoneyType?) -> CalculatorMoneyType {
+    func refreshSource(activeInput: CalculatorMoneyType?) -> CalculatorMoneyType? {
+        if activeInput == .fiat, fiatValue.isEmpty { return nil }
         if let activeInput { return activeInput }
         return shouldRefreshBitcoinFromFiat ? .fiat : .bitcoin
     }

Bitkit/Resources/Localization/en.lproj/Localizable.strings

@@ -1387,9 +1387,6 @@
 "widgets__list__button" = "Enable In Settings";
 "widgets__delete__title" = "Delete Widget?";
 "widgets__delete__description" = "Are you sure you want to delete '{name}' from your widgets?";
-"widgets__widget__size_small" = "Small";
-"widgets__widget__size_wide" = "Wide";
-"widgets__widget__save_widget" = "Save Widget";
 "widgets__price__name" = "Bitcoin Price";
 "widgets__price__description" = "Check the latest Bitcoin exchange rates for a variety of fiat currencies.";
 "widgets__price__error" = "Couldn\'t get price data";

Bitkit/Services/Widgets/CalculatorHomeScreenWidgetOptionsStore.swift

@@ -0,0 +1,21 @@
+import Foundation
+
+/// Stores the latest calculator values for Bitkit's in-app widget row and preview screen.
+enum CalculatorWidgetOptionsStore {
+    private static let key = "calculator_widget_values_v1"
+
+    static func save(_ values: CalculatorWidgetValues) {
+        guard let data = try? JSONEncoder().encode(values)
+        else { return }
+        UserDefaults.standard.set(data, forKey: key)
+    }
+
+    static func load() -> CalculatorWidgetValues {
+        guard let data = UserDefaults.standard.data(forKey: key),
+              let values = try? JSONDecoder().decode(CalculatorWidgetValues.self, from: data)
+        else {
+            return CalculatorWidgetValues()
+        }
+        return values
+    }
+}

Bitkit/Services/Widgets/CalculatorWidgetOptionsStore.swift

@@ -157,7 +157,7 @@ struct CalculatorWidgetPreviewView: View {
     }
 
     private func hydrateValues() {
-        let saved = CalculatorHomeScreenWidgetOptionsStore.load()
+        let saved = CalculatorWidgetOptionsStore.load()
         let bitcoinValue = Self.previewBitcoinValue(saved: saved, displayUnit: currency.displayUnit)
 
         values = CalculatorWidgetValues(

Bitkit/Views/Widgets/CalculatorWidgetPreviewView.swift

@@ -112,6 +112,12 @@ final class CalculatorWidgetTests: XCTestCase {
         XCTAssertEqual(values.refreshSource(activeInput: .bitcoin), .bitcoin)
     }
 
+    func testEmptyFiatActiveInputSkipsRefreshSource() {
+        let values = CalculatorWidgetValues(bitcoinValue: "10000", fiatValue: "")
+
+        XCTAssertNil(values.refreshSource(activeInput: .fiat))
+    }
+
     func testRefreshSourceFallsBackToFiatOnlyValue() {
         let values = CalculatorWidgetValues(bitcoinValue: "", fiatValue: "12.34")