Accounting A-2: neutrale Periodenabrechnung + BWA-Uebersicht + FX + CSV-Export

Alles laenderneutral, ohne steuerliche Einordnung (A-3 US-Steuerschicht bleibt bewusst offen,
haengt an den CPA-Fragebogen-Antworten). Konzept: docs/konzepte/KONZEPT-Modul-Accounting.md, A-2.

Pure Logik (unit-getestet):
- AccountingEngine.BuildStatement: aggregiert Ledger-Saetze eines Zeitraums (x Account/alle) zu
  Anfangs-/Endsaldo, Ein-/Auszahlungen, Handelsvolumen, Redeems, Rewards, Fees und
  Netto-Handelsergebnis (Cash-Basis, EXKL. Ein-/Auszahlungen); Invariante Endsaldo-Anfang =
  Ergebnis + Einz. - Ausz. BuildMonthlyBreakdown: Monatsvergleich mit verketteten Anfangssalden.
- FxConverter: USDC->USD (dokumentierte 1:1-Annahme) + USD->EUR ueber amtliche Tageskurse
  (acc_fx_rates, Nearest-on-or-before fuer Wochenend-/Feiertage).
- CsvExporter: Ledger + Statement als RFC-4180-CSV, kulturinvariant (Punkt-Dezimal, ISO-Datum).

Infrastruktur:
- acc_fx_rates (FxRate, PK Datum) + EfFxRateRepository (Upsert je Datum). Migration AddFxRates angewendet.
- ILedgerRepository.GetUpTo (alle Saetze <= to fuer die Abrechnung inkl. Anfangssaldo).
- AccountingReportService: baut Abrechnungen + Waehrungs-View (USDC/USD immer, EUR wenn Kurse geladen).

UI (designerfaehig, partial + .Designer.cs): neuer erster Tab 'Uebersicht / BWA' mit KPI-Kacheln
(Netto-Handelsergebnis gruen/rot, Endsaldo, Ein-/Auszahlungen, Fees, Rewards, Volumen, #Trades),
Monatsvergleich-Grid, Zeitraum-Picker (Standard laufender Monat), Konto- und Waehrungswahl, CSV-Export
via SaveFileDialog.

Tests: +6 (Periodenaggregation+Invariante, Monatsverkettung, FX-Umrechnung/Nearest-Kurs, CSV-Quoting).
Build 0 Fehler, 385 Tests gruen, --smoke-ui alle 6 Views gruen.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

docs/konzepte/KONZEPT-Modul-Accounting.md

@@ -214,6 +214,14 @@ Sync-/Buchungsfehler unserer Trading-Seite. Bericht in der UI + Export.
 - **A-2 Abrechnung + Übersicht + FX:** `AccountingEngine` + BWA-UI + Periodenabrechnung je Account/alle,
   Werte in USDC/USD/EUR (Tageskurse in `acc_fx_rates`). **Akzeptanz:** Monatsabrechnung stimmt gegen
   Balance-Anker; Kennzahlen plausibel; FX nachvollziehbar.
+  **✅ UMGESETZT (2026-07-20):** `AccountingEngine` (pur): `BuildStatement` (Anfangs-/Endsaldo,
+  Ein-/Auszahlungen, Handelsvolumen, Redeems, Rewards, Fees, Netto-Handelsergebnis Cash-Basis exkl.
+  Ein-/Auszahlungen; Invariante Endsaldo−Anfang = Ergebnis+Einz.−Ausz.) + `BuildMonthlyBreakdown`
+  (verkettete Monats-Anfangssalden). `FxConverter` (pur, USDC≈USD-1:1-Annahme dokumentiert; USD→EUR
+  über `acc_fx_rates`, Nearest-on-or-before). `CsvExporter` (pur, RFC-4180, kulturinvariant).
+  `AccountingReportService` (Abrechnung + Währungs-View USDC/USD/EUR). UI-Tab „Übersicht/BWA"
+  (designerfähig): KPI-Kacheln + Monatsvergleich + Zeitraum-/Konto-/Währungswahl + CSV-Export. +6 Tests.
+  **Offen für Zielland:** EZB-Kurs-Ingest (acc_fx_rates füllen) → dann ist EUR verfügbar (USDC/USD sofort).
 - **A-3 US-Steuerschicht:** `UsTaxEngine` (FIFO-Lot-Matching, Haltefristen, Gain/Loss) + Form-8949-/
   Schedule-D-Ansicht + Annahmen-Dokumentation. **Akzeptanz:** Summe realisierter Gain/Loss stimmt gegen
   die neutrale Abrechnung; Annahmen ausgewiesen.

src/PolyTrader.Modules.Accounting/AccountingModule.cs

@@ -32,6 +32,10 @@ namespace PolyTrader.Modules.Accounting
             services.AddSingleton<ILedgerRepository, EfLedgerRepository>();
             services.AddSingleton<IIngestRunRepository, EfIngestRunRepository>();
             services.AddSingleton<IRawSnapshotRepository, EfRawSnapshotRepository>();
+            services.AddSingleton<IFxRateRepository, EfFxRateRepository>();
+
+            // A-2: neutrale Periodenabrechnung/BWA + Währungs-View (USDC/USD/EUR).
+            services.AddSingleton<Services.AccountingReportService>();
 
             // Ingest-Quellen: offline Null-Stubs (das Modul läuft ohne Live-Anbindung und bucht korrekt
             // nichts). Im Zielland werden die echten Quellen (Polymarket /activity, Alchemy-Transfers,

src/PolyTrader.Modules.Accounting/Logic/AccountingEngine.cs

@@ -0,0 +1,91 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using PolyTrader.Modules.Accounting.Models;
+
+namespace PolyTrader.Modules.Accounting.Logic
+{
+    /// <summary>
+    /// Neutrale Periodenabrechnung (A-2): aggregiert die Ledger-Sätze eines Zeitraums (× Account oder
+    /// alle) zu einer prüfbaren Aufstellung — länderneutral, ohne steuerliche Einordnung (die kommt
+    /// getrennt in der US-Steuerschicht A-3). Alle Beträge in USDC (native Buchungswährung); die
+    /// FX-Umrechnung nach USD/EUR liegt separat im <see cref="FxConverter"/>.
+    /// </summary>
+    public sealed record PeriodStatement(
+        int? AccountId,
+        DateTime From,
+        DateTime To,
+        decimal OpeningBalanceUsdc,
+        decimal ClosingBalanceUsdc,
+        decimal Deposits,
+        decimal Withdrawals,
+        decimal TradeVolume,
+        decimal Redeems,
+        decimal Rewards,
+        decimal Fees,
+        decimal NetTradingResultUsdc,   // operatives Ergebnis (Cash-Basis, EXKL. Ein-/Auszahlungen)
+        int TradeCount,
+        int EntryCount)
+    {
+        /// <summary>Invariante: Endsaldo − Anfangssaldo = Handelsergebnis + Einzahlungen − Auszahlungen.</summary>
+        public decimal BalanceChange => ClosingBalanceUsdc - OpeningBalanceUsdc;
+    }
+
+    public static class AccountingEngine
+    {
+        private static bool IsCashflowType(LedgerEventType t) =>
+            t is LedgerEventType.Deposit or LedgerEventType.Withdrawal;
+
+        /// <summary>
+        /// Baut die Abrechnung für [<paramref name="from"/>, <paramref name="to"/>]. <paramref name="allUpToTo"/>
+        /// enthält ALLE Ledger-Sätze des Scopes bis <paramref name="to"/> (für den Anfangssaldo werden die
+        /// Sätze vor <paramref name="from"/> kumuliert). Grenzen inklusive.
+        /// </summary>
+        public static PeriodStatement BuildStatement(
+            IEnumerable<LedgerEntry> allUpToTo, DateTime from, DateTime to, int? accountId)
+        {
+            var list = allUpToTo.Where(e => e.Timestamp <= to).ToList();
+
+            decimal opening = list.Where(e => e.Timestamp < from).Sum(e => e.NetUsdc);
+            var period = list.Where(e => e.Timestamp >= from && e.Timestamp <= to).ToList();
+
+            decimal Sum(Func<LedgerEntry, bool> pred, Func<LedgerEntry, decimal> sel) =>
+                period.Where(pred).Sum(sel);
+
+            decimal deposits = Sum(e => e.EventType == LedgerEventType.Deposit, e => e.GrossUsdc);
+            decimal withdrawals = Sum(e => e.EventType == LedgerEventType.Withdrawal, e => e.GrossUsdc);
+            decimal tradeVolume = Sum(e => e.EventType is LedgerEventType.TradeBuy or LedgerEventType.TradeSell, e => e.GrossUsdc);
+            decimal redeems = Sum(e => e.EventType == LedgerEventType.Redeem, e => e.GrossUsdc);
+            decimal rewards = Sum(e => e.EventType == LedgerEventType.Reward, e => e.GrossUsdc);
+            decimal fees = period.Sum(e => e.FeeUsdc);
+            decimal netTrading = period.Where(e => !IsCashflowType(e.EventType)).Sum(e => e.NetUsdc);
+            decimal closing = opening + period.Sum(e => e.NetUsdc);
+            int tradeCount = period.Count(e => e.EventType is LedgerEventType.TradeBuy or LedgerEventType.TradeSell);
+
+            return new PeriodStatement(accountId, from, to, opening, closing, deposits, withdrawals,
+                tradeVolume, redeems, rewards, fees, netTrading, tradeCount, period.Count);
+        }
+
+        /// <summary>
+        /// Zerlegt den Zeitraum in Kalendermonate und liefert je Monat eine Abrechnung (für den
+        /// BWA-Perioden-/Monatsvergleich). Anfangssaldo jedes Monats = Endsaldo des Vormonats.
+        /// </summary>
+        public static List<PeriodStatement> BuildMonthlyBreakdown(
+            IEnumerable<LedgerEntry> allUpToTo, DateTime from, DateTime to, int? accountId)
+        {
+            var list = allUpToTo.ToList();
+            var result = new List<PeriodStatement>();
+            var monthStart = new DateTime(from.Year, from.Month, 1, 0, 0, 0, DateTimeKind.Utc);
+
+            while (monthStart <= to)
+            {
+                DateTime monthEnd = monthStart.AddMonths(1).AddTicks(-1);
+                DateTime windowFrom = monthStart < from ? from : monthStart;
+                DateTime windowTo = monthEnd > to ? to : monthEnd;
+                result.Add(BuildStatement(list, windowFrom, windowTo, accountId));
+                monthStart = monthStart.AddMonths(1);
+            }
+            return result;
+        }
+    }
+}

src/PolyTrader.Modules.Accounting/Logic/CsvExporter.cs

@@ -0,0 +1,75 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Linq;
+using System.Text;
+using PolyTrader.Modules.Accounting.Models;
+
+namespace PolyTrader.Modules.Accounting.Logic
+{
+    /// <summary>
+    /// Reiner CSV-Export (A-2/A-4-neutral): erzeugt maschinen-/prüfbare CSV-Strings aus Ledger und
+    /// Abrechnung. Kulturinvariant (Punkt-Dezimal, ISO-Datum), RFC-4180-Quoting. Der Dateizugriff
+    /// liegt in der UI; die Formatierung ist hier pur + testbar.
+    /// </summary>
+    public static class CsvExporter
+    {
+        private static string F(decimal d) => d.ToString("0.######", CultureInfo.InvariantCulture);
+        private static string T(DateTime d) => d.ToString("yyyy-MM-dd HH:mm:ss", CultureInfo.InvariantCulture);
+
+        private static string Q(string s)
+        {
+            s ??= string.Empty;
+            bool needsQuote = s.Contains(',') || s.Contains('"') || s.Contains('\n') || s.Contains('\r');
+            if (needsQuote) s = "\"" + s.Replace("\"", "\"\"") + "\"";
+            return s;
+        }
+
+        /// <summary>Vollständiger Ledger-Export (eine Zeile je Buchungssatz, inkl. Nachweisspalten).</summary>
+        public static string Ledger(IEnumerable<LedgerEntry> entries)
+        {
+            var sb = new StringBuilder();
+            sb.AppendLine("Timestamp,AccountId,EventType,Side,MarketSlug,Outcome,Size,PriceUsdc,GrossUsdc,FeeUsdc,NetUsdc,TxHash,LogIndex,Source,IdempotencyKey");
+            foreach (var e in entries.OrderBy(e => e.Timestamp))
+            {
+                sb.Append(T(e.Timestamp)).Append(',')
+                  .Append(e.AccountId).Append(',')
+                  .Append(e.EventType).Append(',')
+                  .Append(Q(e.Side)).Append(',')
+                  .Append(Q(e.MarketSlug)).Append(',')
+                  .Append(Q(e.Outcome)).Append(',')
+                  .Append(F(e.Size)).Append(',')
+                  .Append(F(e.PriceUsdc)).Append(',')
+                  .Append(F(e.GrossUsdc)).Append(',')
+                  .Append(F(e.FeeUsdc)).Append(',')
+                  .Append(F(e.NetUsdc)).Append(',')
+                  .Append(Q(e.TxHash)).Append(',')
+                  .Append(e.LogIndex).Append(',')
+                  .Append(Q(e.Source)).Append(',')
+                  .Append(Q(e.IdempotencyKey)).Append('\n');
+            }
+            return sb.ToString();
+        }
+
+        /// <summary>Aggregat-Export einer Abrechnung (Kennzahl,USDC) – prüfbare Zusammenfassung.</summary>
+        public static string Statement(PeriodStatement s)
+        {
+            var sb = new StringBuilder();
+            sb.AppendLine("Kennzahl,USDC");
+            void Row(string k, decimal v) => sb.Append(Q(k)).Append(',').Append(F(v)).Append('\n');
+            sb.AppendLine(Q($"Zeitraum {T(s.From)} .. {T(s.To)}" + (s.AccountId.HasValue ? $" | Konto {s.AccountId}" : " | alle Konten")) + ",");
+            Row("Anfangssaldo", s.OpeningBalanceUsdc);
+            Row("Einzahlungen", s.Deposits);
+            Row("Auszahlungen", s.Withdrawals);
+            Row("Handelsvolumen", s.TradeVolume);
+            Row("Redeems", s.Redeems);
+            Row("Rewards", s.Rewards);
+            Row("Fees", s.Fees);
+            Row("Netto-Handelsergebnis (Cash)", s.NetTradingResultUsdc);
+            Row("Endsaldo", s.ClosingBalanceUsdc);
+            sb.Append(Q("Anzahl Trades")).Append(',').Append(s.TradeCount).Append('\n');
+            sb.Append(Q("Anzahl Buchungen")).Append(',').Append(s.EntryCount).Append('\n');
+            return sb.ToString();
+        }
+    }
+}

src/PolyTrader.Modules.Accounting/Logic/FxConverter.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using PolyTrader.Modules.Accounting.Models;
+
+namespace PolyTrader.Modules.Accounting.Logic
+{
+    /// <summary>
+    /// Reine Währungsumrechnung (A-2): jede Transaktion/Aufstellung ist in USDC (nativ). USD ergibt sich
+    /// über die (dokumentierte, umstellbare) USDC≈USD-Annahme; EUR über amtliche USD→EUR-Tageskurse
+    /// (EZB, versioniert in acc_fx_rates). Seiteneffektfrei + unit-getestet.
+    /// </summary>
+    public static class FxConverter
+    {
+        /// <summary>Dokumentierte Vereinfachung: 1 USDC = 1 USD (im Export ausgewiesen, in Settings umstellbar).</summary>
+        public const decimal DefaultUsdcToUsd = 1.0m;
+
+        public static decimal UsdcToUsd(decimal usdc, decimal usdcToUsd) =>
+            Math.Round(usdc * usdcToUsd, 6, MidpointRounding.AwayFromZero);
+
+        public static decimal UsdToEur(decimal usd, decimal usdToEur) =>
+            Math.Round(usd * usdToEur, 6, MidpointRounding.AwayFromZero);
+
+        public static decimal UsdcToEur(decimal usdc, decimal usdToEur, decimal usdcToUsd) =>
+            Math.Round(usdc * usdcToUsd * usdToEur, 6, MidpointRounding.AwayFromZero);
+
+        /// <summary>
+        /// Amtlicher Kurs am oder vor dem Stichtag (Wochenend-/Feiertagskurse gibt es nicht → letzter
+        /// gültiger davor). null, wenn kein Kurs am/vor dem Datum vorliegt.
+        /// </summary>
+        public static FxRate? NearestOnOrBefore(IEnumerable<FxRate> rates, DateTime date)
+        {
+            DateTime day = date.Date;
+            return rates.Where(r => r.Date.Date <= day)
+                        .OrderByDescending(r => r.Date)
+                        .FirstOrDefault();
+        }
+    }
+}

src/PolyTrader.Modules.Accounting/Models/FxRate.cs

@@ -0,0 +1,17 @@
+using System;
+
+namespace PolyTrader.Modules.Accounting.Models
+{
+    /// <summary>
+    /// Amtlicher Tages-FX-Kurs (Tabelle acc_fx_rates): USD→EUR je Datum (z. B. EZB-Referenzkurs),
+    /// versioniert für nachvollziehbare, reproduzierbare Umrechnung. USDC→USD wird als dokumentierte
+    /// 1:1-Annahme separat behandelt (nicht je Tag gespeichert).
+    /// </summary>
+    public class FxRate
+    {
+        /// <summary>Kurs-Datum (nur Datum; PK).</summary>
+        public DateTime Date { get; set; }
+        public decimal UsdToEur { get; set; }
+        public string Source { get; set; } = string.Empty;   // z. B. "ECB" / "manual"
+    }
+}

src/PolyTrader.Modules.Accounting/Persistence/AccountingDbContext.cs

@@ -17,6 +17,7 @@ namespace PolyTrader.Modules.Accounting.Persistence
         public DbSet<LedgerEntry> Ledger => Set<LedgerEntry>();
         public DbSet<IngestRun> IngestRuns => Set<IngestRun>();
         public DbSet<RawSnapshot> RawSnapshots => Set<RawSnapshot>();
+        public DbSet<FxRate> FxRates => Set<FxRate>();
 
         protected override void OnModelCreating(ModelBuilder b)
         {
@@ -64,6 +65,15 @@ namespace PolyTrader.Modules.Accounting.Persistence
                 e.Property(x => x.Json).HasColumnType("longtext");
                 e.HasIndex(x => x.IngestRunId);
             });
+
+            b.Entity<FxRate>(e =>
+            {
+                e.ToTable("acc_fx_rates");
+                e.HasKey(x => x.Date);
+                e.Property(x => x.Date).HasColumnType("date");
+                e.Property(x => x.UsdToEur).HasPrecision(18, 8);
+                e.Property(x => x.Source).HasMaxLength(40);
+            });
         }
     }
 

src/PolyTrader.Modules.Accounting/Persistence/Migrations/20260720100910_AddFxRates.Designer.cs

@@ -0,0 +1,233 @@
+// <auto-generated />
+using System;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Metadata;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using PolyTrader.Modules.Accounting.Persistence;
+
+#nullable disable
+
+namespace PolyTrader.Modules.Accounting.Persistence.Migrations
+{
+    [DbContext(typeof(AccountingDbContext))]
+    [Migration("20260720100910_AddFxRates")]
+    partial class AddFxRates
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder
+                .HasAnnotation("ProductVersion", "8.0.13")
+                .HasAnnotation("Relational:MaxIdentifierLength", 64);
+
+            MySqlModelBuilderExtensions.AutoIncrementColumns(modelBuilder);
+
+            modelBuilder.Entity("PolyTrader.Modules.Accounting.Models.FxRate", b =>
+                {
+                    b.Property<DateTime>("Date")
+                        .HasColumnType("date");
+
+                    b.Property<string>("Source")
+                        .IsRequired()
+                        .HasMaxLength(40)
+                        .HasColumnType("varchar(40)");
+
+                    b.Property<decimal>("UsdToEur")
+                        .HasPrecision(18, 8)
+                        .HasColumnType("decimal(18,8)");
+
+                    b.HasKey("Date");
+
+                    b.ToTable("acc_fx_rates", (string)null);
+                });
+
+            modelBuilder.Entity("PolyTrader.Modules.Accounting.Models.IngestRun", b =>
+                {
+                    b.Property<long>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("bigint");
+
+                    MySqlPropertyBuilderExtensions.UseMySqlIdentityColumn(b.Property<long>("Id"));
+
+                    b.Property<int>("AccountId")
+                        .HasColumnType("int");
+
+                    b.Property<bool>("Backfill")
+                        .HasColumnType("tinyint(1)");
+
+                    b.Property<decimal?>("BalanceAnchorUsdc")
+                        .HasPrecision(28, 8)
+                        .HasColumnType("decimal(28,8)");
+
+                    b.Property<decimal?>("BalanceDeltaUsdc")
+                        .HasPrecision(28, 8)
+                        .HasColumnType("decimal(28,8)");
+
+                    b.Property<int>("DuplicateEntries")
+                        .HasColumnType("int");
+
+                    b.Property<DateTime?>("FinishedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<DateTime?>("FromTimestamp")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<decimal?>("LedgerNetUsdc")
+                        .HasPrecision(28, 8)
+                        .HasColumnType("decimal(28,8)");
+
+                    b.Property<string>("Message")
+                        .IsRequired()
+                        .HasMaxLength(1000)
+                        .HasColumnType("varchar(1000)");
+
+                    b.Property<int>("NewEntries")
+                        .HasColumnType("int");
+
+                    b.Property<DateTime>("StartedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<bool>("Success")
+                        .HasColumnType("tinyint(1)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("AccountId", "StartedAt");
+
+                    b.ToTable("acc_ingest_runs", (string)null);
+                });
+
+            modelBuilder.Entity("PolyTrader.Modules.Accounting.Models.LedgerEntry", b =>
+                {
+                    b.Property<long>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("bigint");
+
+                    MySqlPropertyBuilderExtensions.UseMySqlIdentityColumn(b.Property<long>("Id"));
+
+                    b.Property<int>("AccountId")
+                        .HasColumnType("int");
+
+                    b.Property<string>("EventType")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("varchar(20)");
+
+                    b.Property<decimal>("FeeUsdc")
+                        .HasPrecision(28, 8)
+                        .HasColumnType("decimal(28,8)");
+
+                    b.Property<decimal>("GrossUsdc")
+                        .HasPrecision(28, 8)
+                        .HasColumnType("decimal(28,8)");
+
+                    b.Property<string>("IdempotencyKey")
+                        .IsRequired()
+                        .HasMaxLength(200)
+                        .HasColumnType("varchar(200)");
+
+                    b.Property<long>("IngestBatchId")
+                        .HasColumnType("bigint");
+
+                    b.Property<DateTime>("IngestedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<int>("LogIndex")
+                        .HasColumnType("int");
+
+                    b.Property<string>("MarketSlug")
+                        .IsRequired()
+                        .HasMaxLength(300)
+                        .HasColumnType("varchar(300)");
+
+                    b.Property<decimal>("NetUsdc")
+                        .HasPrecision(28, 8)
+                        .HasColumnType("decimal(28,8)");
+
+                    b.Property<string>("Outcome")
+                        .IsRequired()
+                        .HasMaxLength(200)
+                        .HasColumnType("varchar(200)");
+
+                    b.Property<decimal>("PriceUsdc")
+                        .HasPrecision(18, 6)
+                        .HasColumnType("decimal(18,6)");
+
+                    b.Property<string>("Side")
+                        .IsRequired()
+                        .HasMaxLength(10)
+                        .HasColumnType("varchar(10)");
+
+                    b.Property<decimal>("Size")
+                        .HasPrecision(28, 8)
+                        .HasColumnType("decimal(28,8)");
+
+                    b.Property<string>("Source")
+                        .IsRequired()
+                        .HasMaxLength(40)
+                        .HasColumnType("varchar(40)");
+
+                    b.Property<DateTime>("Timestamp")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<string>("TokenId")
+                        .IsRequired()
+                        .HasMaxLength(120)
+                        .HasColumnType("varchar(120)");
+
+                    b.Property<string>("TxHash")
+                        .IsRequired()
+                        .HasMaxLength(80)
+                        .HasColumnType("varchar(80)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("EventType");
+
+                    b.HasIndex("IdempotencyKey")
+                        .IsUnique();
+
+                    b.HasIndex("AccountId", "Timestamp");
+
+                    b.ToTable("acc_ledger", (string)null);
+                });
+
+            modelBuilder.Entity("PolyTrader.Modules.Accounting.Models.RawSnapshot", b =>
+                {
+                    b.Property<long>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("bigint");
+
+                    MySqlPropertyBuilderExtensions.UseMySqlIdentityColumn(b.Property<long>("Id"));
+
+                    b.Property<int>("AccountId")
+                        .HasColumnType("int");
+
+                    b.Property<DateTime>("CapturedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<long>("IngestRunId")
+                        .HasColumnType("bigint");
+
+                    b.Property<string>("Json")
+                        .IsRequired()
+                        .HasColumnType("longtext");
+
+                    b.Property<string>("SourceKind")
+                        .IsRequired()
+                        .HasMaxLength(20)
+                        .HasColumnType("varchar(20)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("IngestRunId");
+
+                    b.ToTable("acc_raw", (string)null);
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

src/PolyTrader.Modules.Accounting/Persistence/Migrations/20260720100910_AddFxRates.cs

@@ -0,0 +1,37 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace PolyTrader.Modules.Accounting.Persistence.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddFxRates : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "acc_fx_rates",
+                columns: table => new
+                {
+                    Date = table.Column<DateTime>(type: "date", nullable: false),
+                    UsdToEur = table.Column<decimal>(type: "decimal(18,8)", precision: 18, scale: 8, nullable: false),
+                    Source = table.Column<string>(type: "varchar(40)", maxLength: 40, nullable: false)
+                        .Annotation("MySql:CharSet", "utf8mb4")
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_acc_fx_rates", x => x.Date);
+                })
+                .Annotation("MySql:CharSet", "utf8mb4");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "acc_fx_rates");
+        }
+    }
+}

src/PolyTrader.Modules.Accounting/Persistence/Migrations/AccountingDbContextModelSnapshot.cs

@@ -22,6 +22,25 @@ namespace PolyTrader.Modules.Accounting.Persistence.Migrations
 
             MySqlModelBuilderExtensions.AutoIncrementColumns(modelBuilder);
 
+            modelBuilder.Entity("PolyTrader.Modules.Accounting.Models.FxRate", b =>
+                {
+                    b.Property<DateTime>("Date")
+                        .HasColumnType("date");
+
+                    b.Property<string>("Source")
+                        .IsRequired()
+                        .HasMaxLength(40)
+                        .HasColumnType("varchar(40)");
+
+                    b.Property<decimal>("UsdToEur")
+                        .HasPrecision(18, 8)
+                        .HasColumnType("decimal(18,8)");
+
+                    b.HasKey("Date");
+
+                    b.ToTable("acc_fx_rates", (string)null);
+                });
+
             modelBuilder.Entity("PolyTrader.Modules.Accounting.Models.IngestRun", b =>
                 {
                     b.Property<long>("Id")

src/PolyTrader.Modules.Accounting/Persistence/Repositories.cs

@@ -15,6 +15,8 @@ namespace PolyTrader.Modules.Accounting.Persistence
         decimal SumNet(int accountId);
         int Count(int accountId);
         List<LedgerEntry> Query(int? accountId, DateTime? from, DateTime? to, int limit);
+        /// <summary>ALLE Sätze des Scopes bis <paramref name="to"/> (für die Abrechnung inkl. Anfangssaldo).</summary>
+        List<LedgerEntry> GetUpTo(int? accountId, DateTime to);
     }
 
     public interface IIngestRunRepository
@@ -29,6 +31,13 @@ namespace PolyTrader.Modules.Accounting.Persistence
         void Insert(RawSnapshot snapshot);
     }
 
+    /// <summary>Amtliche FX-Tageskurse (USD→EUR), versioniert. Upsert je Datum.</summary>
+    public interface IFxRateRepository
+    {
+        void Upsert(FxRate rate);
+        List<FxRate> GetAll();
+    }
+
     // ---------------- EF-Implementierungen ----------------
 
     public class EfLedgerRepository : ILedgerRepository
@@ -77,6 +86,14 @@ namespace PolyTrader.Modules.Accounting.Persistence
             if (to.HasValue) q = q.Where(x => x.Timestamp <= to.Value);
             return q.OrderByDescending(x => x.Timestamp).Take(limit).ToList();
         }
+
+        public List<LedgerEntry> GetUpTo(int? accountId, DateTime to)
+        {
+            using var ctx = _factory.CreateDbContext();
+            var q = ctx.Ledger.AsNoTracking().Where(x => x.Timestamp <= to);
+            if (accountId.HasValue) q = q.Where(x => x.AccountId == accountId.Value);
+            return q.OrderBy(x => x.Timestamp).ToList();
+        }
     }
 
     public class EfIngestRunRepository : IIngestRunRepository
@@ -119,4 +136,25 @@ namespace PolyTrader.Modules.Accounting.Persistence
             ctx.SaveChanges();
         }
     }
+
+    public class EfFxRateRepository : IFxRateRepository
+    {
+        private readonly IDbContextFactory<AccountingDbContext> _factory;
+        public EfFxRateRepository(IDbContextFactory<AccountingDbContext> factory) => _factory = factory;
+
+        public void Upsert(FxRate rate)
+        {
+            using var ctx = _factory.CreateDbContext();
+            var existing = ctx.FxRates.Find(rate.Date.Date);
+            if (existing == null) ctx.FxRates.Add(new FxRate { Date = rate.Date.Date, UsdToEur = rate.UsdToEur, Source = rate.Source });
+            else { existing.UsdToEur = rate.UsdToEur; existing.Source = rate.Source; }
+            ctx.SaveChanges();
+        }
+
+        public List<FxRate> GetAll()
+        {
+            using var ctx = _factory.CreateDbContext();
+            return ctx.FxRates.AsNoTracking().OrderBy(x => x.Date).ToList();
+        }
+    }
 }

src/PolyTrader.Modules.Accounting/Services/AccountingReportService.cs

@@ -0,0 +1,61 @@
+using System;
+using System.Collections.Generic;
+using PolyTrader.Modules.Accounting.Logic;
+using PolyTrader.Modules.Accounting.Models;
+using PolyTrader.Modules.Accounting.Persistence;
+
+namespace PolyTrader.Modules.Accounting.Services
+{
+    /// <summary>
+    /// Anzeige-Währung einer Abrechnung. USDC/USD sind immer verfügbar (USD über die dokumentierte
+    /// 1:1-Annahme), EUR nur, wenn ein amtlicher Tageskurs geladen ist.
+    /// </summary>
+    public sealed record CurrencyContext(string Code, decimal Factor, bool Available, string Note);
+
+    /// <summary>
+    /// Report-Service (A-2): baut neutrale Periodenabrechnungen aus dem Ledger und stellt die
+    /// Währungs-Umrechnung (USDC/USD/EUR) bereit. Reine Aggregation liegt im <see cref="AccountingEngine"/>,
+    /// FX im <see cref="FxConverter"/> – der Service verdrahtet nur Persistenz + pure Logik.
+    /// </summary>
+    public class AccountingReportService
+    {
+        private readonly ILedgerRepository _ledger;
+        private readonly IFxRateRepository _fx;
+
+        /// <summary>USDC→USD-Faktor (dokumentierte 1:1-Annahme; Zielland ggf. über Settings umstellbar).</summary>
+        public decimal UsdcToUsd { get; set; } = FxConverter.DefaultUsdcToUsd;
+
+        public AccountingReportService(ILedgerRepository ledger, IFxRateRepository fx)
+        {
+            _ledger = ledger;
+            _fx = fx;
+        }
+
+        public PeriodStatement BuildStatement(int? accountId, DateTime from, DateTime to) =>
+            AccountingEngine.BuildStatement(_ledger.GetUpTo(accountId, to), from, to, accountId);
+
+        public List<PeriodStatement> BuildMonthly(int? accountId, DateTime from, DateTime to) =>
+            AccountingEngine.BuildMonthlyBreakdown(_ledger.GetUpTo(accountId, to), from, to, accountId);
+
+        /// <summary>Löst die Anzeige-Währung zum Stichtag auf (für EUR wird der EZB-Kurs am/vor dem Datum genutzt).</summary>
+        public CurrencyContext ResolveCurrency(string code, DateTime asOf)
+        {
+            switch ((code ?? "USDC").Trim().ToUpperInvariant())
+            {
+                case "USD":
+                    return new CurrencyContext("USD", UsdcToUsd, true, $"USDC≈USD (1:1-Annahme, Faktor {UsdcToUsd}).");
+                case "EUR":
+                    var rate = FxConverter.NearestOnOrBefore(_fx.GetAll(), asOf);
+                    if (rate == null)
+                        return new CurrencyContext("EUR", 0m, false, "Keine EZB-Tageskurse geladen – EUR nicht verfügbar.");
+                    return new CurrencyContext("EUR", UsdcToUsd * rate.UsdToEur, true,
+                        $"USD→EUR {rate.UsdToEur} ({rate.Date:yyyy-MM-dd}, {rate.Source}); USDC≈USD 1:1.");
+                default:
+                    return new CurrencyContext("USDC", 1.0m, true, "Native Buchungswährung.");
+            }
+        }
+
+        public static decimal Convert(decimal usdc, CurrencyContext ctx) =>
+            Math.Round(usdc * ctx.Factor, 2, MidpointRounding.AwayFromZero);
+    }
+}

src/PolyTrader.Modules.Accounting/Ui/AccountingMainForm.Designer.cs

@@ -18,6 +18,28 @@ namespace PolyTrader.Modules.Accounting.Ui
         private void InitializeComponent()
         {
             this.tabControlAcc = new System.Windows.Forms.TabControl();
+            this.tabUebersicht = new System.Windows.Forms.TabPage();
+            this.dgvMonthly = new System.Windows.Forms.DataGridView();
+            this.flpKpis = new System.Windows.Forms.FlowLayoutPanel();
+            this.lblKpiNet = new System.Windows.Forms.Label();
+            this.lblKpiClosing = new System.Windows.Forms.Label();
+            this.lblKpiDeposits = new System.Windows.Forms.Label();
+            this.lblKpiWithdrawals = new System.Windows.Forms.Label();
+            this.lblKpiFees = new System.Windows.Forms.Label();
+            this.lblKpiRewards = new System.Windows.Forms.Label();
+            this.lblKpiVolume = new System.Windows.Forms.Label();
+            this.lblKpiTrades = new System.Windows.Forms.Label();
+            this.pnlOverviewTop = new System.Windows.Forms.Panel();
+            this.btnExportCsv = new System.Windows.Forms.Button();
+            this.btnCalc = new System.Windows.Forms.Button();
+            this.cbCurrency = new System.Windows.Forms.ComboBox();
+            this.lblWaehrung = new System.Windows.Forms.Label();
+            this.dtTo = new System.Windows.Forms.DateTimePicker();
+            this.lblBis = new System.Windows.Forms.Label();
+            this.dtFrom = new System.Windows.Forms.DateTimePicker();
+            this.lblVon = new System.Windows.Forms.Label();
+            this.cbOvAccount = new System.Windows.Forms.ComboBox();
+            this.lblOvKonto = new System.Windows.Forms.Label();
             this.tabLedger = new System.Windows.Forms.TabPage();
             this.dgvLedger = new System.Windows.Forms.DataGridView();
             this.toolStripLedger = new System.Windows.Forms.ToolStrip();
@@ -37,6 +59,10 @@ namespace PolyTrader.Modules.Accounting.Ui
             this.btnStatusRefresh = new System.Windows.Forms.ToolStripButton();
             this.lblAccStatus = new System.Windows.Forms.Label();
             this.tabControlAcc.SuspendLayout();
+            this.tabUebersicht.SuspendLayout();
+            ((System.ComponentModel.ISupportInitialize)(this.dgvMonthly)).BeginInit();
+            this.flpKpis.SuspendLayout();
+            this.pnlOverviewTop.SuspendLayout();
             this.tabLedger.SuspendLayout();
             ((System.ComponentModel.ISupportInitialize)(this.dgvLedger)).BeginInit();
             this.toolStripLedger.SuspendLayout();
@@ -47,6 +73,7 @@ namespace PolyTrader.Modules.Accounting.Ui
             //
             // tabControlAcc
             //
+            this.tabControlAcc.Controls.Add(this.tabUebersicht);
             this.tabControlAcc.Controls.Add(this.tabLedger);
             this.tabControlAcc.Controls.Add(this.tabStatus);
             this.tabControlAcc.Dock = System.Windows.Forms.DockStyle.Fill;
@@ -56,6 +83,259 @@ namespace PolyTrader.Modules.Accounting.Ui
             this.tabControlAcc.Size = new System.Drawing.Size(1100, 618);
             this.tabControlAcc.TabIndex = 0;
             //
+            // tabUebersicht
+            //
+            this.tabUebersicht.Controls.Add(this.dgvMonthly);
+            this.tabUebersicht.Controls.Add(this.flpKpis);
+            this.tabUebersicht.Controls.Add(this.pnlOverviewTop);
+            this.tabUebersicht.Location = new System.Drawing.Point(4, 24);
+            this.tabUebersicht.Name = "tabUebersicht";
+            this.tabUebersicht.Padding = new System.Windows.Forms.Padding(3);
+            this.tabUebersicht.Size = new System.Drawing.Size(1092, 590);
+            this.tabUebersicht.TabIndex = 0;
+            this.tabUebersicht.Text = "Übersicht / BWA";
+            this.tabUebersicht.UseVisualStyleBackColor = true;
+            //
+            // dgvMonthly
+            //
+            this.dgvMonthly.AllowUserToAddRows = false;
+            this.dgvMonthly.AllowUserToDeleteRows = false;
+            this.dgvMonthly.ColumnHeadersHeightSizeMode = System.Windows.Forms.DataGridViewColumnHeadersHeightSizeMode.AutoSize;
+            this.dgvMonthly.Dock = System.Windows.Forms.DockStyle.Fill;
+            this.dgvMonthly.Location = new System.Drawing.Point(3, 133);
+            this.dgvMonthly.Name = "dgvMonthly";
+            this.dgvMonthly.ReadOnly = true;
+            this.dgvMonthly.RowHeadersVisible = false;
+            this.dgvMonthly.SelectionMode = System.Windows.Forms.DataGridViewSelectionMode.FullRowSelect;
+            this.dgvMonthly.Size = new System.Drawing.Size(1086, 454);
+            this.dgvMonthly.TabIndex = 2;
+            //
+            // flpKpis
+            //
+            this.flpKpis.Controls.Add(this.lblKpiNet);
+            this.flpKpis.Controls.Add(this.lblKpiClosing);
+            this.flpKpis.Controls.Add(this.lblKpiDeposits);
+            this.flpKpis.Controls.Add(this.lblKpiWithdrawals);
+            this.flpKpis.Controls.Add(this.lblKpiFees);
+            this.flpKpis.Controls.Add(this.lblKpiRewards);
+            this.flpKpis.Controls.Add(this.lblKpiVolume);
+            this.flpKpis.Controls.Add(this.lblKpiTrades);
+            this.flpKpis.Dock = System.Windows.Forms.DockStyle.Top;
+            this.flpKpis.Location = new System.Drawing.Point(3, 39);
+            this.flpKpis.Name = "flpKpis";
+            this.flpKpis.Padding = new System.Windows.Forms.Padding(4);
+            this.flpKpis.Size = new System.Drawing.Size(1086, 94);
+            this.flpKpis.TabIndex = 1;
+            //
+            // lblKpiNet
+            //
+            this.lblKpiNet.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
+            this.lblKpiNet.Font = new System.Drawing.Font("Segoe UI", 10F, System.Drawing.FontStyle.Bold);
+            this.lblKpiNet.Margin = new System.Windows.Forms.Padding(4);
+            this.lblKpiNet.MinimumSize = new System.Drawing.Size(200, 74);
+            this.lblKpiNet.Name = "lblKpiNet";
+            this.lblKpiNet.Padding = new System.Windows.Forms.Padding(8);
+            this.lblKpiNet.Size = new System.Drawing.Size(200, 74);
+            this.lblKpiNet.TabIndex = 0;
+            this.lblKpiNet.Text = "Netto-Handelsergebnis\n—";
+            this.lblKpiNet.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
+            //
+            // lblKpiClosing
+            //
+            this.lblKpiClosing.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
+            this.lblKpiClosing.Font = new System.Drawing.Font("Segoe UI", 10F, System.Drawing.FontStyle.Bold);
+            this.lblKpiClosing.Margin = new System.Windows.Forms.Padding(4);
+            this.lblKpiClosing.MinimumSize = new System.Drawing.Size(180, 74);
+            this.lblKpiClosing.Name = "lblKpiClosing";
+            this.lblKpiClosing.Padding = new System.Windows.Forms.Padding(8);
+            this.lblKpiClosing.Size = new System.Drawing.Size(180, 74);
+            this.lblKpiClosing.TabIndex = 1;
+            this.lblKpiClosing.Text = "Endsaldo\n—";
+            this.lblKpiClosing.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
+            //
+            // lblKpiDeposits
+            //
+            this.lblKpiDeposits.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
+            this.lblKpiDeposits.Font = new System.Drawing.Font("Segoe UI", 10F, System.Drawing.FontStyle.Bold);
+            this.lblKpiDeposits.Margin = new System.Windows.Forms.Padding(4);
+            this.lblKpiDeposits.MinimumSize = new System.Drawing.Size(150, 74);
+            this.lblKpiDeposits.Name = "lblKpiDeposits";
+            this.lblKpiDeposits.Padding = new System.Windows.Forms.Padding(8);
+            this.lblKpiDeposits.Size = new System.Drawing.Size(150, 74);
+            this.lblKpiDeposits.TabIndex = 2;
+            this.lblKpiDeposits.Text = "Einzahlungen\n—";
+            this.lblKpiDeposits.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
+            //
+            // lblKpiWithdrawals
+            //
+            this.lblKpiWithdrawals.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
+            this.lblKpiWithdrawals.Font = new System.Drawing.Font("Segoe UI", 10F, System.Drawing.FontStyle.Bold);
+            this.lblKpiWithdrawals.Margin = new System.Windows.Forms.Padding(4);
+            this.lblKpiWithdrawals.MinimumSize = new System.Drawing.Size(150, 74);
+            this.lblKpiWithdrawals.Name = "lblKpiWithdrawals";
+            this.lblKpiWithdrawals.Padding = new System.Windows.Forms.Padding(8);
+            this.lblKpiWithdrawals.Size = new System.Drawing.Size(150, 74);
+            this.lblKpiWithdrawals.TabIndex = 3;
+            this.lblKpiWithdrawals.Text = "Auszahlungen\n—";
+            this.lblKpiWithdrawals.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
+            //
+            // lblKpiFees
+            //
+            this.lblKpiFees.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
+            this.lblKpiFees.Font = new System.Drawing.Font("Segoe UI", 10F, System.Drawing.FontStyle.Bold);
+            this.lblKpiFees.Margin = new System.Windows.Forms.Padding(4);
+            this.lblKpiFees.MinimumSize = new System.Drawing.Size(140, 74);
+            this.lblKpiFees.Name = "lblKpiFees";
+            this.lblKpiFees.Padding = new System.Windows.Forms.Padding(8);
+            this.lblKpiFees.Size = new System.Drawing.Size(140, 74);
+            this.lblKpiFees.TabIndex = 4;
+            this.lblKpiFees.Text = "Fees\n—";
+            this.lblKpiFees.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
+            //
+            // lblKpiRewards
+            //
+            this.lblKpiRewards.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
+            this.lblKpiRewards.Font = new System.Drawing.Font("Segoe UI", 10F, System.Drawing.FontStyle.Bold);
+            this.lblKpiRewards.Margin = new System.Windows.Forms.Padding(4);
+            this.lblKpiRewards.MinimumSize = new System.Drawing.Size(140, 74);
+            this.lblKpiRewards.Name = "lblKpiRewards";
+            this.lblKpiRewards.Padding = new System.Windows.Forms.Padding(8);
+            this.lblKpiRewards.Size = new System.Drawing.Size(140, 74);
+            this.lblKpiRewards.TabIndex = 5;
+            this.lblKpiRewards.Text = "Rewards\n—";
+            this.lblKpiRewards.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
+            //
+            // lblKpiVolume
+            //
+            this.lblKpiVolume.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
+            this.lblKpiVolume.Font = new System.Drawing.Font("Segoe UI", 10F, System.Drawing.FontStyle.Bold);
+            this.lblKpiVolume.Margin = new System.Windows.Forms.Padding(4);
+            this.lblKpiVolume.MinimumSize = new System.Drawing.Size(160, 74);
+            this.lblKpiVolume.Name = "lblKpiVolume";
+            this.lblKpiVolume.Padding = new System.Windows.Forms.Padding(8);
+            this.lblKpiVolume.Size = new System.Drawing.Size(160, 74);
+            this.lblKpiVolume.TabIndex = 6;
+            this.lblKpiVolume.Text = "Handelsvolumen\n—";
+            this.lblKpiVolume.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
+            //
+            // lblKpiTrades
+            //
+            this.lblKpiTrades.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;
+            this.lblKpiTrades.Font = new System.Drawing.Font("Segoe UI", 10F, System.Drawing.FontStyle.Bold);
+            this.lblKpiTrades.Margin = new System.Windows.Forms.Padding(4);
+            this.lblKpiTrades.MinimumSize = new System.Drawing.Size(120, 74);
+            this.lblKpiTrades.Name = "lblKpiTrades";
+            this.lblKpiTrades.Padding = new System.Windows.Forms.Padding(8);
+            this.lblKpiTrades.Size = new System.Drawing.Size(120, 74);
+            this.lblKpiTrades.TabIndex = 7;
+            this.lblKpiTrades.Text = "Trades\n—";
+            this.lblKpiTrades.TextAlign = System.Drawing.ContentAlignment.MiddleLeft;
+            //
+            // pnlOverviewTop
+            //
+            this.pnlOverviewTop.Controls.Add(this.btnExportCsv);
+            this.pnlOverviewTop.Controls.Add(this.btnCalc);
+            this.pnlOverviewTop.Controls.Add(this.cbCurrency);
+            this.pnlOverviewTop.Controls.Add(this.lblWaehrung);
+            this.pnlOverviewTop.Controls.Add(this.dtTo);
+            this.pnlOverviewTop.Controls.Add(this.lblBis);
+            this.pnlOverviewTop.Controls.Add(this.dtFrom);
+            this.pnlOverviewTop.Controls.Add(this.lblVon);
+            this.pnlOverviewTop.Controls.Add(this.cbOvAccount);
+            this.pnlOverviewTop.Controls.Add(this.lblOvKonto);
+            this.pnlOverviewTop.Dock = System.Windows.Forms.DockStyle.Top;
+            this.pnlOverviewTop.Location = new System.Drawing.Point(3, 3);
+            this.pnlOverviewTop.Name = "pnlOverviewTop";
+            this.pnlOverviewTop.Size = new System.Drawing.Size(1086, 36);
+            this.pnlOverviewTop.TabIndex = 0;
+            //
+            // btnExportCsv
+            //
+            this.btnExportCsv.Location = new System.Drawing.Point(838, 5);
+            this.btnExportCsv.Name = "btnExportCsv";
+            this.btnExportCsv.Size = new System.Drawing.Size(110, 26);
+            this.btnExportCsv.TabIndex = 9;
+            this.btnExportCsv.Text = "CSV-Export";
+            this.btnExportCsv.UseVisualStyleBackColor = true;
+            //
+            // btnCalc
+            //
+            this.btnCalc.Location = new System.Drawing.Point(732, 5);
+            this.btnCalc.Name = "btnCalc";
+            this.btnCalc.Size = new System.Drawing.Size(100, 26);
+            this.btnCalc.TabIndex = 8;
+            this.btnCalc.Text = "Berechnen";
+            this.btnCalc.UseVisualStyleBackColor = true;
+            //
+            // cbCurrency
+            //
+            this.cbCurrency.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
+            this.cbCurrency.Items.AddRange(new object[] { "USDC", "USD", "EUR" });
+            this.cbCurrency.Location = new System.Drawing.Point(645, 6);
+            this.cbCurrency.Name = "cbCurrency";
+            this.cbCurrency.Size = new System.Drawing.Size(80, 23);
+            this.cbCurrency.TabIndex = 7;
+            //
+            // lblWaehrung
+            //
+            this.lblWaehrung.AutoSize = true;
+            this.lblWaehrung.Location = new System.Drawing.Point(575, 9);
+            this.lblWaehrung.Name = "lblWaehrung";
+            this.lblWaehrung.Size = new System.Drawing.Size(64, 15);
+            this.lblWaehrung.TabIndex = 6;
+            this.lblWaehrung.Text = "Währung:";
+            //
+            // dtTo
+            //
+            this.dtTo.Format = System.Windows.Forms.DateTimePickerFormat.Short;
+            this.dtTo.Location = new System.Drawing.Point(445, 6);
+            this.dtTo.Name = "dtTo";
+            this.dtTo.Size = new System.Drawing.Size(110, 23);
+            this.dtTo.TabIndex = 5;
+            //
+            // lblBis
+            //
+            this.lblBis.AutoSize = true;
+            this.lblBis.Location = new System.Drawing.Point(415, 9);
+            this.lblBis.Name = "lblBis";
+            this.lblBis.Size = new System.Drawing.Size(26, 15);
+            this.lblBis.TabIndex = 4;
+            this.lblBis.Text = "Bis:";
+            //
+            // dtFrom
+            //
+            this.dtFrom.Format = System.Windows.Forms.DateTimePickerFormat.Short;
+            this.dtFrom.Location = new System.Drawing.Point(300, 6);
+            this.dtFrom.Name = "dtFrom";
+            this.dtFrom.Size = new System.Drawing.Size(110, 23);
+            this.dtFrom.TabIndex = 3;
+            //
+            // lblVon
+            //
+            this.lblVon.AutoSize = true;
+            this.lblVon.Location = new System.Drawing.Point(267, 9);
+            this.lblVon.Name = "lblVon";
+            this.lblVon.Size = new System.Drawing.Size(31, 15);
+            this.lblVon.TabIndex = 2;
+            this.lblVon.Text = "Von:";
+            //
+            // cbOvAccount
+            //
+            this.cbOvAccount.DropDownStyle = System.Windows.Forms.ComboBoxStyle.DropDownList;
+            this.cbOvAccount.Location = new System.Drawing.Point(55, 6);
+            this.cbOvAccount.Name = "cbOvAccount";
+            this.cbOvAccount.Size = new System.Drawing.Size(200, 23);
+            this.cbOvAccount.TabIndex = 1;
+            //
+            // lblOvKonto
+            //
+            this.lblOvKonto.AutoSize = true;
+            this.lblOvKonto.Location = new System.Drawing.Point(6, 9);
+            this.lblOvKonto.Name = "lblOvKonto";
+            this.lblOvKonto.Size = new System.Drawing.Size(43, 15);
+            this.lblOvKonto.TabIndex = 0;
+            this.lblOvKonto.Text = "Konto:";
+            //
             // tabLedger
             //
             this.tabLedger.Controls.Add(this.dgvLedger);
@@ -64,7 +344,7 @@ namespace PolyTrader.Modules.Accounting.Ui
             this.tabLedger.Name = "tabLedger";
             this.tabLedger.Padding = new System.Windows.Forms.Padding(3);
             this.tabLedger.Size = new System.Drawing.Size(1092, 590);
-            this.tabLedger.TabIndex = 0;
+            this.tabLedger.TabIndex = 1;
             this.tabLedger.Text = "Ledger";
             this.tabLedger.UseVisualStyleBackColor = true;
             //
@@ -120,7 +400,7 @@ namespace PolyTrader.Modules.Accounting.Ui
             this.tabStatus.Name = "tabStatus";
             this.tabStatus.Padding = new System.Windows.Forms.Padding(3);
             this.tabStatus.Size = new System.Drawing.Size(1092, 590);
-            this.tabStatus.TabIndex = 1;
+            this.tabStatus.TabIndex = 2;
             this.tabStatus.Text = "Abruf / Status";
             this.tabStatus.UseVisualStyleBackColor = true;
             //
@@ -207,6 +487,11 @@ namespace PolyTrader.Modules.Accounting.Ui
             this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
             this.Text = "Accounting";
             this.tabControlAcc.ResumeLayout(false);
+            this.tabUebersicht.ResumeLayout(false);
+            ((System.ComponentModel.ISupportInitialize)(this.dgvMonthly)).EndInit();
+            this.flpKpis.ResumeLayout(false);
+            this.pnlOverviewTop.ResumeLayout(false);
+            this.pnlOverviewTop.PerformLayout();
             this.tabLedger.ResumeLayout(false);
             this.tabLedger.PerformLayout();
             ((System.ComponentModel.ISupportInitialize)(this.dgvLedger)).EndInit();
@@ -223,6 +508,28 @@ namespace PolyTrader.Modules.Accounting.Ui
         #endregion
 
         private System.Windows.Forms.TabControl tabControlAcc;
+        private System.Windows.Forms.TabPage tabUebersicht;
+        private System.Windows.Forms.Panel pnlOverviewTop;
+        private System.Windows.Forms.Label lblOvKonto;
+        private System.Windows.Forms.ComboBox cbOvAccount;
+        private System.Windows.Forms.Label lblVon;
+        private System.Windows.Forms.DateTimePicker dtFrom;
+        private System.Windows.Forms.Label lblBis;
+        private System.Windows.Forms.DateTimePicker dtTo;
+        private System.Windows.Forms.Label lblWaehrung;
+        private System.Windows.Forms.ComboBox cbCurrency;
+        private System.Windows.Forms.Button btnCalc;
+        private System.Windows.Forms.Button btnExportCsv;
+        private System.Windows.Forms.FlowLayoutPanel flpKpis;
+        private System.Windows.Forms.Label lblKpiNet;
+        private System.Windows.Forms.Label lblKpiClosing;
+        private System.Windows.Forms.Label lblKpiDeposits;
+        private System.Windows.Forms.Label lblKpiWithdrawals;
+        private System.Windows.Forms.Label lblKpiFees;
+        private System.Windows.Forms.Label lblKpiRewards;
+        private System.Windows.Forms.Label lblKpiVolume;
+        private System.Windows.Forms.Label lblKpiTrades;
+        private System.Windows.Forms.DataGridView dgvMonthly;
         private System.Windows.Forms.TabPage tabLedger;
         private System.Windows.Forms.ToolStrip toolStripLedger;
         private System.Windows.Forms.ToolStripLabel lblLedgerKonto;

src/PolyTrader.Modules.Accounting/Ui/AccountingMainForm.cs

@@ -4,6 +4,7 @@ using System.Linq;
 using System.Threading;
 using System.Windows.Forms;
 using Microsoft.Extensions.DependencyInjection;
+using PolyTrader.Modules.Accounting.Logic;
 using PolyTrader.Modules.Accounting.Persistence;
 using PolyTrader.Modules.Accounting.Services;
 using PolyTraderSharp;
@@ -11,21 +12,31 @@ using PolyTraderSharp;
 namespace PolyTrader.Modules.Accounting.Ui
 {
     /// <summary>
-    /// Hauptfenster des Accounting-Moduls (A-1): Tab „Ledger" (unabhängig erhobene Buchungssätze,
+    /// Hauptfenster des Accounting-Moduls: Tab „Übersicht / BWA" (neutrale Periodenabrechnung + KPIs +
-    /// filterbar) und Tab „Abruf / Status" (Ingest-Läufe + Balance-Anker, manueller Backfill/Inkrement).
+    /// Monatsvergleich, Währung USDC/USD/EUR, CSV-Export), „Ledger" (Buchungssätze) und „Abruf / Status"
-    /// BWA-Übersicht, US-Steuerschicht und CSV/PDF-Export folgen A-2..A-4. Layout im Designer.
+    /// (Ingest-Läufe, manueller Backfill/Inkrement). Layout im Designer; Aggregation pur im
+    /// <see cref="AccountingEngine"/>. Die US-Steuerschicht (A-3) ist bewusst NICHT hier – sie hängt an
+    /// den CPA-Antworten.
     /// </summary>
     public partial class AccountingMainForm : Form
     {
         private ILedgerRepository? _ledger;
         private IIngestRunRepository? _runs;
         private AccountingIngestService? _ingest;
+        private AccountingReportService? _report;
         private TradingState? _state;
 
         public AccountingMainForm()
         {
             InitializeComponent();
 
+            // Übersicht / BWA
+            btnCalc.Click += (_, _) => Recalculate();
+            btnExportCsv.Click += (_, _) => ExportCsv();
+            cbOvAccount.SelectedIndexChanged += (_, _) => Recalculate();
+            cbCurrency.SelectedIndexChanged += (_, _) => Recalculate();
+
+            // Ledger + Status
             btnLedgerRefresh.Click += (_, _) => LoadLedger();
             cbLedgerAccount.SelectedIndexChanged += (_, _) => LoadLedger();
             btnStatusRefresh.Click += (_, _) => LoadRuns();
@@ -38,9 +49,17 @@ namespace PolyTrader.Modules.Accounting.Ui
             _ledger = services.GetRequiredService<ILedgerRepository>();
             _runs = services.GetRequiredService<IIngestRunRepository>();
             _ingest = services.GetRequiredService<AccountingIngestService>();
+            _report = services.GetRequiredService<AccountingReportService>();
             _state = services.GetRequiredService<TradingState>();
 
+            // Standard-Zeitraum: laufender Monat.
+            var now = DateTime.Now;
+            dtFrom.Value = new DateTime(now.Year, now.Month, 1);
+            dtTo.Value = now;
+            if (cbCurrency.Items.Count > 0) cbCurrency.SelectedIndex = 0;   // USDC
+
             PopulateAccounts();
+            Recalculate();
             LoadLedger();
             LoadRuns();
         }
@@ -56,6 +75,8 @@ namespace PolyTrader.Modules.Accounting.Ui
                     .OrderBy(a => a.AccountId)
                     .Select(a => new AccountItem(a.AccountId, string.IsNullOrEmpty(a.Name) ? $"#{a.AccountId}" : $"{a.Name} (#{a.AccountId})")));
 
+            cbOvAccount.DisplayMember = nameof(AccountItem.Label);
+            cbOvAccount.DataSource = new List<AccountItem>(items);
             foreach (var combo in new[] { cbLedgerAccount, cbStatusAccount })
             {
                 combo.ComboBox.DisplayMember = nameof(AccountItem.Label);
@@ -63,8 +84,80 @@ namespace PolyTrader.Modules.Accounting.Ui
             }
         }
 
-        private int? SelectedAccountId(ToolStripComboBox combo) =>
+        private static int? IdOf(object? item) => item is AccountItem it ? it.Id : null;
-            combo.SelectedItem is AccountItem it ? it.Id : null;
+
+        // ---------------- Übersicht / BWA ----------------
+
+        private void Recalculate()
+        {
+            if (_report == null) return;
+            try
+            {
+                DateTime from = dtFrom.Value.Date;
+                DateTime to = dtTo.Value.Date.AddDays(1).AddTicks(-1);   // inklusive gewählter Bis-Tag
+                int? accId = IdOf(cbOvAccount.SelectedItem);
+
+                var statement = _report.BuildStatement(accId, from, to);
+                var monthly = _report.BuildMonthly(accId, from, to);
+                var cur = _report.ResolveCurrency(cbCurrency.SelectedItem?.ToString() ?? "USDC", to);
+
+                UpdateKpis(statement, cur);
+                dgvMonthly.DataSource = monthly.Select(m => new MonthlyRow(m, cur)).ToList();
+
+                lblAccStatus.Text = cur.Available
+                    ? $"Währung {cur.Code}: {cur.Note}"
+                    : $"⚠️ {cur.Note} (Anzeige in USDC).";
+            }
+            catch (Exception ex)
+            {
+                lblAccStatus.Text = $"Abrechnung nicht möglich (acc_-Migration angewendet?): {ex.Message}";
+            }
+        }
+
+        private void UpdateKpis(PeriodStatement s, CurrencyContext cur)
+        {
+            CurrencyContext view = cur.Available ? cur : new CurrencyContext("USDC", 1m, true, "");
+            string unit = view.Code;
+            decimal V(decimal usdc) => AccountingReportService.Convert(usdc, view);
+
+            lblKpiNet.Text = $"Netto-Handelsergebnis\n{V(s.NetTradingResultUsdc):N2} {unit}";
+            lblKpiNet.ForeColor = s.NetTradingResultUsdc >= 0 ? System.Drawing.Color.ForestGreen : System.Drawing.Color.Firebrick;
+            lblKpiClosing.Text = $"Endsaldo\n{V(s.ClosingBalanceUsdc):N2} {unit}";
+            lblKpiDeposits.Text = $"Einzahlungen\n{V(s.Deposits):N2} {unit}";
+            lblKpiWithdrawals.Text = $"Auszahlungen\n{V(s.Withdrawals):N2} {unit}";
+            lblKpiFees.Text = $"Fees\n{V(s.Fees):N2} {unit}";
+            lblKpiRewards.Text = $"Rewards\n{V(s.Rewards):N2} {unit}";
+            lblKpiVolume.Text = $"Handelsvolumen\n{V(s.TradeVolume):N2} {unit}";
+            lblKpiTrades.Text = $"Trades\n{s.TradeCount}";
+        }
+
+        private void ExportCsv()
+        {
+            if (_ledger == null || _report == null) return;
+            DateTime from = dtFrom.Value.Date;
+            DateTime to = dtTo.Value.Date.AddDays(1).AddTicks(-1);
+            int? accId = IdOf(cbOvAccount.SelectedItem);
+
+            using var dlg = new SaveFileDialog
+            {
+                Filter = "CSV-Datei (*.csv)|*.csv",
+                FileName = $"accounting_{(accId?.ToString() ?? "alle")}_{from:yyyyMMdd}-{dtTo.Value:yyyyMMdd}.csv"
+            };
+            if (dlg.ShowDialog(this) != DialogResult.OK) return;
+
+            try
+            {
+                var statement = _report.BuildStatement(accId, from, to);
+                var entries = _ledger.Query(accId, from, to, 100000);
+                string csv = CsvExporter.Statement(statement) + Environment.NewLine + CsvExporter.Ledger(entries);
+                System.IO.File.WriteAllText(dlg.FileName, csv, new System.Text.UTF8Encoding(true));
+                lblAccStatus.Text = $"CSV exportiert: {dlg.FileName} ({entries.Count} Buchungen).";
+            }
+            catch (Exception ex)
+            {
+                lblAccStatus.Text = $"CSV-Export fehlgeschlagen: {ex.Message}";
+            }
+        }
 
         // ---------------- Ledger ----------------
 
@@ -73,7 +166,7 @@ namespace PolyTrader.Modules.Accounting.Ui
             if (_ledger == null) return;
             try
             {
-                var rows = _ledger.Query(SelectedAccountId(cbLedgerAccount), null, null, 1000);
+                var rows = _ledger.Query(IdOf(cbLedgerAccount.SelectedItem), null, null, 1000);
                 dgvLedger.DataSource = rows.Select(e => new LedgerRow(e)).ToList();
                 lblAccStatus.Text = rows.Count == 0
                     ? "Noch keine Buchungen. (Ingest-Quellen sind offline bis zur Live-Anbindung im Zielland.)"
@@ -92,7 +185,7 @@ namespace PolyTrader.Modules.Accounting.Ui
             if (_runs == null) return;
             try
             {
-                dgvRuns.DataSource = _runs.GetRecent(SelectedAccountId(cbStatusAccount), 100);
+                dgvRuns.DataSource = _runs.GetRecent(IdOf(cbStatusAccount.SelectedItem), 100);
             }
             catch (Exception ex)
             {
@@ -112,6 +205,7 @@ namespace PolyTrader.Modules.Accounting.Ui
                 lblAccStatus.Text = "Abruf abgeschlossen.";
                 LoadRuns();
                 LoadLedger();
+                Recalculate();
             }
             catch (Exception ex)
             {
@@ -126,7 +220,38 @@ namespace PolyTrader.Modules.Accounting.Ui
 
         private sealed record AccountItem(int? Id, string Label);
 
-        /// <summary>Anzeige-Zeile fürs Ledger-Grid (kompakte, lesbare Spalten).</summary>
+        /// <summary>Anzeige-Zeile des Monatsvergleichs (Beträge in der gewählten Währung).</summary>
+        private sealed class MonthlyRow
+        {
+            public MonthlyRow(PeriodStatement m, CurrencyContext cur)
+            {
+                CurrencyContext view = cur.Available ? cur : new CurrencyContext("USDC", 1m, true, "");
+                decimal V(decimal usdc) => AccountingReportService.Convert(usdc, view);
+                Monat = m.From.ToString("yyyy-MM");
+                Anfangssaldo = V(m.OpeningBalanceUsdc);
+                Einzahlungen = V(m.Deposits);
+                Auszahlungen = V(m.Withdrawals);
+                Handelsvolumen = V(m.TradeVolume);
+                Rewards = V(m.Rewards);
+                Fees = V(m.Fees);
+                Handelsergebnis = V(m.NetTradingResultUsdc);
+                Endsaldo = V(m.ClosingBalanceUsdc);
+                Trades = m.TradeCount;
+            }
+
+            public string Monat { get; }
+            public decimal Anfangssaldo { get; }
+            public decimal Einzahlungen { get; }
+            public decimal Auszahlungen { get; }
+            public decimal Handelsvolumen { get; }
+            public decimal Rewards { get; }
+            public decimal Fees { get; }
+            public decimal Handelsergebnis { get; }
+            public decimal Endsaldo { get; }
+            public int Trades { get; }
+        }
+
+        /// <summary>Anzeige-Zeile fürs Ledger-Grid.</summary>
         private sealed class LedgerRow
         {
             public LedgerRow(Models.LedgerEntry e)

tests/PolyTrader.Tests/AccountingReportTests.cs

@@ -0,0 +1,131 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using PolyTrader.Modules.Accounting.Logic;
+using PolyTrader.Modules.Accounting.Models;
+using Xunit;
+
+namespace PolyTrader.Tests
+{
+    /// <summary>Sicherheitsnetz für die neutrale Abrechnung (A-2): Periodenaggregation, FX, CSV.</summary>
+    public class AccountingReportTests
+    {
+        private static readonly DateTime Jun = new(2026, 6, 15, 12, 0, 0, DateTimeKind.Utc);
+        private static readonly DateTime Jul = new(2026, 7, 10, 12, 0, 0, DateTimeKind.Utc);
+
+        private static LedgerEntry E(LedgerEventType type, decimal net, DateTime ts,
+            decimal gross = 0m, decimal fee = 0m) => new()
+        {
+            AccountId = 1, EventType = type, Timestamp = ts, NetUsdc = net,
+            GrossUsdc = gross == 0m ? Math.Abs(net) : gross, FeeUsdc = fee
+        };
+
+        // ---------------- AccountingEngine ----------------
+
+        [Fact]
+        public void Statement_aggregates_period_and_carries_opening_balance()
+        {
+            var entries = new List<LedgerEntry>
+            {
+                // VOR dem Zeitraum → nur Anfangssaldo
+                E(LedgerEventType.Deposit, 1000m, new DateTime(2026, 5, 1, 0, 0, 0, DateTimeKind.Utc), gross: 1000m),
+                // im Zeitraum (Juli)
+                E(LedgerEventType.TradeBuy, -100m, Jul, gross: 100m, fee: 1m),
+                E(LedgerEventType.TradeSell, 130m, Jul, gross: 130m, fee: 1m),
+                E(LedgerEventType.Reward, 5m, Jul, gross: 5m),
+                E(LedgerEventType.Deposit, 200m, Jul, gross: 200m),
+                E(LedgerEventType.Withdrawal, -50m, Jul, gross: 50m),
+            };
+
+            var from = new DateTime(2026, 7, 1, 0, 0, 0, DateTimeKind.Utc);
+            var to = new DateTime(2026, 7, 31, 23, 59, 59, DateTimeKind.Utc);
+            var s = AccountingEngine.BuildStatement(entries, from, to, 1);
+
+            Assert.Equal(1000m, s.OpeningBalanceUsdc);
+            Assert.Equal(200m, s.Deposits);
+            Assert.Equal(50m, s.Withdrawals);
+            Assert.Equal(230m, s.TradeVolume);              // 100 + 130
+            Assert.Equal(5m, s.Rewards);
+            Assert.Equal(2m, s.Fees);
+            Assert.Equal(35m, s.NetTradingResultUsdc);      // -100 +130 +5 (exkl. Ein-/Auszahlungen)
+            Assert.Equal(2, s.TradeCount);
+            // Invariante: Endsaldo − Anfangssaldo = Handelsergebnis + Einzahlungen − Auszahlungen
+            Assert.Equal(1185m, s.ClosingBalanceUsdc);      // 1000 + 35 + 200 - 50
+            Assert.Equal(s.NetTradingResultUsdc + s.Deposits - s.Withdrawals, s.BalanceChange);
+        }
+
+        [Fact]
+        public void Monthly_breakdown_chains_opening_balances()
+        {
+            var entries = new List<LedgerEntry>
+            {
+                E(LedgerEventType.Deposit, 100m, Jun, gross: 100m),   // Juni
+                E(LedgerEventType.TradeSell, 40m, Jul, gross: 40m),   // Juli
+            };
+            var from = new DateTime(2026, 6, 1, 0, 0, 0, DateTimeKind.Utc);
+            var to = new DateTime(2026, 7, 31, 23, 59, 59, DateTimeKind.Utc);
+
+            var months = AccountingEngine.BuildMonthlyBreakdown(entries, from, to, 1);
+
+            Assert.Equal(2, months.Count);
+            Assert.Equal(0m, months[0].OpeningBalanceUsdc);     // Juni startet bei 0
+            Assert.Equal(100m, months[0].ClosingBalanceUsdc);
+            Assert.Equal(100m, months[1].OpeningBalanceUsdc);   // Juli erbt Juni-Endsaldo
+            Assert.Equal(140m, months[1].ClosingBalanceUsdc);
+        }
+
+        // ---------------- FxConverter ----------------
+
+        [Fact]
+        public void Fx_conversions_usdc_usd_eur()
+        {
+            Assert.Equal(100m, FxConverter.UsdcToUsd(100m, 1.0m));
+            Assert.Equal(92m, FxConverter.UsdToEur(100m, 0.92m));
+            Assert.Equal(92m, FxConverter.UsdcToEur(100m, 0.92m, 1.0m));
+        }
+
+        [Fact]
+        public void Fx_nearest_on_or_before_picks_latest_valid_rate()
+        {
+            var rates = new List<FxRate>
+            {
+                new() { Date = new DateTime(2026, 7, 3), UsdToEur = 0.90m },
+                new() { Date = new DateTime(2026, 7, 5), UsdToEur = 0.92m },   // Freitag
+            };
+            // Sonntag 2026-07-05 gibt es keinen Kurs → letzter gültiger (Freitag).
+            var pick = FxConverter.NearestOnOrBefore(rates, new DateTime(2026, 7, 6));
+            Assert.NotNull(pick);
+            Assert.Equal(0.92m, pick!.UsdToEur);
+
+            Assert.Null(FxConverter.NearestOnOrBefore(rates, new DateTime(2026, 7, 1)));   // vor allen Kursen
+        }
+
+        // ---------------- CsvExporter ----------------
+
+        [Fact]
+        public void Csv_ledger_has_header_and_escapes_commas()
+        {
+            var entries = new List<LedgerEntry>
+            {
+                new() { AccountId = 1, EventType = LedgerEventType.TradeBuy, Timestamp = Jul,
+                        MarketSlug = "will-x-win, really?", Side = "BUY", Size = 10m, PriceUsdc = 0.5m,
+                        GrossUsdc = 5m, FeeUsdc = 0.1m, NetUsdc = -5.1m, TxHash = "0xabc", Source = "polymarket-activity" }
+            };
+            string csv = CsvExporter.Ledger(entries);
+            var lines = csv.Split('\n', StringSplitOptions.RemoveEmptyEntries);
+
+            Assert.StartsWith("Timestamp,AccountId,EventType", lines[0]);
+            Assert.Contains("\"will-x-win, really?\"", lines[1]);   // Komma-Feld gequotet
+            Assert.Contains("-5.1", lines[1]);                       // kulturinvariant (Punkt)
+        }
+
+        [Fact]
+        public void Csv_statement_lists_key_figures()
+        {
+            var s = new PeriodStatement(1, Jul, Jul, 100m, 135m, 0m, 0m, 230m, 0m, 5m, 2m, 35m, 2, 3);
+            string csv = CsvExporter.Statement(s);
+            Assert.Contains("Endsaldo,135", csv);
+            Assert.Contains("Netto-Handelsergebnis (Cash),35", csv);
+        }
+    }
+}