Base fixes and test harness

PortfolioJournal/Utilities/CurrencyFormatter.swift

@@ -6,6 +6,16 @@ enum CurrencyFormatter {
         return AppSettings.getOrCreate(in: context).currency
     }
 
+    static func locale(for currencyCode: String?) -> Locale {
+        guard let currencyCode, !currencyCode.isEmpty else { return Locale.current }
+        if let match = Locale.availableIdentifiers.first(where: {
+            Locale(identifier: $0).currency?.identifier == currencyCode
+        }) {
+            return Locale(identifier: match)
+        }
+        return Locale.current
+    }
+
     static func format(_ decimal: Decimal, style: NumberFormatter.Style = .currency, maximumFractionDigits: Int = 2) -> String {
         let formatter = NumberFormatter()
         formatter.numberStyle = style
@@ -14,6 +24,21 @@ enum CurrencyFormatter {
         return formatter.string(from: decimal as NSDecimalNumber) ?? "\(decimal)"
     }
 
+    static func format(
+        _ decimal: Decimal,
+        currencyCode: String?,
+        style: NumberFormatter.Style = .currency,
+        maximumFractionDigits: Int = 2,
+        preferredLocale: Locale? = nil
+    ) -> String {
+        let formatter = NumberFormatter()
+        formatter.numberStyle = style
+        formatter.currencyCode = currencyCode ?? currentCurrencyCode()
+        formatter.maximumFractionDigits = maximumFractionDigits
+        formatter.locale = preferredLocale ?? locale(for: currencyCode)
+        return formatter.string(from: decimal as NSDecimalNumber) ?? "\(decimal)"
+    }
+
     static func symbol(for code: String) -> String {
         let formatter = NumberFormatter()
         formatter.numberStyle = .currency

PortfolioJournal/Utilities/MonthlyCheckInStore.swift

@@ -74,9 +74,39 @@ enum MonthlyCheckInStore {
     }
 
     static func setCompletionDate(_ completionDate: Date, for month: Date) {
-        updateEntry(for: month) { entry in
-            entry.completionTime = completionDate.timeIntervalSince1970
+        let targetMonth = month.startOfMonth
+        let targetKey = monthKey(for: targetMonth)
+        var entries = loadEntries()
+        var didChange = false
+
+        // Ensure the target month entry exists.
+        var targetEntry = entries[targetKey] ?? MonthlyCheckInEntry(
+            note: nil,
+            rating: nil,
+            mood: nil,
+            completionTime: legacyCompletion(for: targetKey),
+            createdAt: Date().timeIntervalSince1970
+        )
+        targetEntry.completionTime = completionDate.timeIntervalSince1970
+        entries[targetKey] = targetEntry
+        didChange = true
+
+        // Mark all previous pending entries as completed as well.
+        for (key, entry) in entries {
+            guard let entryMonth = monthFormatter.date(from: key)?.startOfMonth else { continue }
+            guard entryMonth < targetMonth else { continue }
+            guard entry.completionTime == nil else { continue }
+
+            var updated = entry
+            let fallbackCompletion = min(entryMonth.endOfMonth, completionDate)
+            updated.completionTime = fallbackCompletion.timeIntervalSince1970
+            entries[key] = updated
+            didChange = true
         }
+
+        guard didChange else { return }
+        saveEntries(entries)
+        persistLegacyMirrors(entries)
     }
 
     static func latestCompletionDate() -> Date? {