fix(invoices): send invoice amounts as exact cent-rounded decimals

Stornorechnung saves still failed: the VAT amount was formatted invariantly
("-615.3757999999999") and re-parsed under the server's de-DE culture as
-6153757999999999, overflowing numeric(10,3) in fds__setInvoice.

- FdsInvoiceData.BuildInvoiceParams: amount params are decimal(10,x) via
  AmountParam/ParseAmount (culture-independent, rounded to cents); amounts
  beyond +/-9,999,999.99 throw InvoiceAmountOutOfRangeException.
- InvoiceService.RegisterInvoiceAsync: refuses such an invoice with a logged
  error (EventId InvoiceAmountRejected) instead of storing a wrong amount.
- Invoice editor: vat_val is cent-rounded decimal, no float noise.
- Tests: InvoiceAmountParamTests replaces the float-based Storno test.
- Bump Azure.Storage.Blobs 12.30.0; OCORE/OCORE_web submodules (AngleSharp
  1.8.3, Azure.Storage.Files.Shares 12.28.0).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Fuchs.Tests/InvoiceAmountParamTests.cs

@@ -0,0 +1,165 @@
+using System;
+using System.Collections.Generic;
+using System.Data;
+using System.Globalization;
+using System.Linq;
+using Fuchs.intranet;
+using Microsoft.Data.SqlClient;
+using Newtonsoft.Json.Linq;
+using Xunit;
+
+namespace Fuchs.Tests;
+
+/// <summary>
+/// Invoice amounts reach the procs as exact, cent-rounded decimals, independent of the server
+/// culture. Regression for the Stornorechnung save failure: the VAT amount was formatted
+/// invariantly ("-615.3757999999999", unrounded double from a reloaded Storno line) and re-parsed
+/// under de-DE as -6153757999999999 → "Error converting data type float to numeric".
+/// </summary>
+public class InvoiceAmountParamTests : IDisposable
+{
+    private readonly CultureInfo _culture = CultureInfo.CurrentCulture;
+    public void Dispose() => CultureInfo.CurrentCulture = _culture;
+
+    private static readonly string[] AmountParams =
+        { "@InvoiceBalance", "@InvoiceBalance_net", "@InvoiceVAT_net1", "@InvoiceService_net", "@InvoiceService_VAT" };
+
+    /// <summary>The exact shape InvoiceDraftEditService.BuildFdsData produces: decimal sums, VAT map by rate.</summary>
+    private static FdsInvoiceData StornoDraft(object vatAmount) => new(new JObject
+    {
+        ["admin"] = new JObject { ["type"] = "c", ["customerid"] = "7" },
+        ["new"]   = new JObject { ["title"] = "Stornorechnung", ["total_net"] = -3238.82m, ["total_gross"] = -3854.20m },
+        ["sms"]   = new JObject
+        {
+            ["tscn"] = -1234.56m, ["tscvat"] = -234.57m,
+            ["vat"]  = new JObject { ["19"] = JToken.FromObject(vatAmount) }
+        }
+    });
+
+    private static decimal Val(List<SqlParameter> pl, string name)
+    {
+        var p = pl.Single(x => x.ParameterName == name);
+        Assert.Equal(SqlDbType.Decimal, p.SqlDbType);
+        return Assert.IsType<decimal>(p.Value);
+    }
+
+    public static TheoryData<string, object> CulturesAndVat => new()
+    {
+        { "de-DE", -615.38m },
+        { "en-US", -615.38m },
+        { "de-DE", -615.3757999999999 },    // unrounded double from a reloaded Storno line (net * vat * 0.01)
+        { "en-US", -615.3757999999999 },
+        { "de-DE", -615.3800000000001 },
+        { "", -615.38m },                   // invariant
+    };
+
+    [Theory]
+    [MemberData(nameof(CulturesAndVat))]
+    public void BuildInvoiceParams_StornoDraft_AmountsExactInEveryCulture(string culture, object vatAmount)
+    {
+        CultureInfo.CurrentCulture = new CultureInfo(culture);
+
+        var pl = StornoDraft(vatAmount).BuildInvoiceParams(change: true, invId: "abc");
+
+        Assert.Equal(-3854.20m, Val(pl, "@InvoiceBalance"));
+        Assert.Equal(-3238.82m, Val(pl, "@InvoiceBalance_net"));
+        Assert.Equal(-615.38m,  Val(pl, "@InvoiceVAT_net1"));
+        Assert.Equal(-1234.56m, Val(pl, "@InvoiceService_net"));
+        Assert.Equal(-234.57m,  Val(pl, "@InvoiceService_VAT"));
+    }
+
+    [Fact]
+    public void BuildInvoiceParams_AmountParams_MatchProcPrecisionAndScale()
+    {
+        var pl = StornoDraft(-615.38m).BuildInvoiceParams(change: false, invId: "");
+
+        foreach (var name in AmountParams)
+        {
+            var p = pl.Single(x => x.ParameterName == name);
+            Assert.Equal(10, p.Precision);
+            // fds__setInvoice/fds__createInvoice: numeric(10,3); fds__createInvoice_Details: numeric(10,2).
+            Assert.Equal(name.StartsWith("@InvoiceService_") ? 2 : 3, p.Scale);
+        }
+    }
+
+    [Theory]
+    [InlineData(-10_000_000.00)]
+    [InlineData(10_000_000.00)]
+    [InlineData(-6153757999999999.0)]
+    public void BuildInvoiceParams_AmountOutOfProcRange_Throws(double vat)
+    {
+        var ex = Assert.Throws<InvoiceAmountOutOfRangeException>(() =>
+            StornoDraft(vat).BuildInvoiceParams(change: true, invId: "abc"));
+
+        Assert.Equal("@InvoiceVAT_net1", ex.Parameter);
+    }
+
+    [Theory]
+    [InlineData(9_999_999.99)]
+    [InlineData(-9_999_999.99)]
+    [InlineData(0.0)]
+    public void BuildInvoiceParams_AmountAtProcRangeBoundary_Accepted(double vat)
+    {
+        var pl = StornoDraft(vat).BuildInvoiceParams(change: true, invId: "abc");
+
+        Assert.Equal((decimal)vat, Val(pl, "@InvoiceVAT_net1"));
+    }
+
+    [Fact]
+    public void BuildInvoiceParams_MissingAmounts_KeepPreviousNullAndZeroSemantics()
+    {
+        var noSms = new FdsInvoiceData(new JObject { ["admin"] = new JObject(), ["new"] = new JObject() })
+            .BuildInvoiceParams(change: false, invId: "");
+        Assert.Equal(DBNull.Value, noSms.Single(p => p.ParameterName == "@InvoiceBalance").Value);
+        Assert.Equal(0m, noSms.Single(p => p.ParameterName == "@InvoiceService_net").Value);   // no sms block → 0
+        Assert.Equal(0m, noSms.Single(p => p.ParameterName == "@InvoiceVAT_net1").Value);      // HighestVat → "0"
+
+        var emptySms = new FdsInvoiceData(new JObject { ["new"] = new JObject(), ["sms"] = new JObject() })
+            .BuildInvoiceParams(change: false, invId: "");
+        Assert.Equal(DBNull.Value, emptySms.Single(p => p.ParameterName == "@InvoiceService_net").Value);  // key missing → NULL
+
+        // No "new" block at all: the legacy SQL_Float(nz(...) ?? "0") sent 0, not NULL.
+        var noNew = new FdsInvoiceData(new JObject { ["admin"] = new JObject(), ["sms"] = new JObject() })
+            .BuildInvoiceParams(change: false, invId: "");
+        Assert.Equal(0m, noNew.Single(p => p.ParameterName == "@InvoiceBalance").Value);
+        Assert.Equal(0m, noNew.Single(p => p.ParameterName == "@InvoiceBalance_net").Value);
+    }
+
+    [Theory]
+    [InlineData("-19.95", "-19.95")]
+    [InlineData("-19,95", "-19.95")]
+    [InlineData("-1234.5600000000002", "-1234.56")]
+    [InlineData("-615.3757999999999", "-615.38")]
+    [InlineData("1234,565", "1234.57")]        // rounded half away from zero
+    [InlineData("-1234,565", "-1234.57")]
+    [InlineData("-1.5E-05", "0")]
+    [InlineData(" 42 ", "42")]
+    public void ParseAmount_Strings_ParsedCultureIndependentlyAndRoundedToCents(string raw, string expected)
+    {
+        foreach (var c in new[] { "de-DE", "en-US" })
+        {
+            CultureInfo.CurrentCulture = new CultureInfo(c);
+            Assert.Equal(decimal.Parse(expected, CultureInfo.InvariantCulture), FdsInvoiceData.ParseAmount(raw));
+        }
+    }
+
+    [Theory]
+    [InlineData(null)]
+    [InlineData("")]
+    [InlineData("NaN")]
+    [InlineData("abc")]
+    [InlineData(double.NaN)]
+    [InlineData(double.PositiveInfinity)]
+    public void ParseAmount_EmptyOrInvalid_IsNull(object? raw) =>
+        Assert.Null(FdsInvoiceData.ParseAmount(raw));
+
+    [Fact]
+    public void ParseAmount_NumbersAndJValues_TakenAsIs()
+    {
+        Assert.Equal(-3238.82m, FdsInvoiceData.ParseAmount(-3238.82m));
+        Assert.Equal(-3238.82m, FdsInvoiceData.ParseAmount(-3238.82));
+        Assert.Equal(-12m,      FdsInvoiceData.ParseAmount(-12));
+        Assert.Equal(-3238.82m, FdsInvoiceData.ParseAmount(new JValue(-3238.82m)));
+        Assert.Null(FdsInvoiceData.ParseAmount(JValue.CreateNull()));
+    }
+}

Fuchs.Tests/InvoiceRegisterSqlTests.cs

@@ -0,0 +1,62 @@
+using System;
+using Fuchs.Services;
+using Xunit;
+
+namespace Fuchs.Tests;
+
+/// <summary>
+/// The invoice header save batch must stop as soon as fds__createInvoice / fds__setInvoice fails:
+/// previously a parameter conversion error left @Id NULL and the batch went on to
+/// fds__createInvoice_Details, whose "Cannot insert NULL into InvId" buried the real error.
+/// </summary>
+public class InvoiceRegisterSqlTests
+{
+    [Theory]
+    [InlineData(false, "[dbo].[fds__createInvoice] ", "fds__createInvoice did not return")]
+    [InlineData(true, "[dbo].[fds__setInvoice] ", "fds__setInvoice did not return")]
+    public void BuildRegisterInvoiceSql_GuardSitsBetweenHeaderProcAndDetails(bool change, string headerProc, string guardText)
+    {
+        string sql = InvoiceService.BuildRegisterInvoiceSql(change, hasProvisionLocation: true);
+
+        int header  = sql.IndexOf(headerProc, StringComparison.Ordinal);
+        int guard   = sql.IndexOf("IF @Id IS NULL THROW", StringComparison.Ordinal);
+        int details = sql.IndexOf("[dbo].[fds__createInvoice_Details]", StringComparison.Ordinal);
+        int update  = sql.IndexOf("UPDATE [dbo].[fds__invoices]", StringComparison.Ordinal);
+
+        Assert.True(header >= 0, "header proc missing");
+        Assert.True(header < guard && guard < details && details < update, sql);
+        Assert.Contains(guardText, sql);
+    }
+
+    [Theory]
+    [InlineData(false)]
+    [InlineData(true)]
+    public void BuildRegisterInvoiceSql_ExactlyOneHeaderProcPerMode(bool change)
+    {
+        string sql = InvoiceService.BuildRegisterInvoiceSql(change, hasProvisionLocation: false);
+
+        Assert.Equal(change, sql.Contains("[dbo].[fds__setInvoice] @InvId,"));
+        Assert.Equal(!change, sql.Contains("[dbo].[fds__createInvoice] @InvoiceType,"));
+        Assert.Equal(change, sql.Contains("@InvId"));
+    }
+
+    [Theory]
+    [InlineData(false, false)]
+    [InlineData(true, true)]
+    public void BuildRegisterInvoiceSql_ProvisionLocationUpdateOnlyWhenPresent(bool hasProvisionLocation, bool expected)
+    {
+        string sql = InvoiceService.BuildRegisterInvoiceSql(change: true, hasProvisionLocation);
+
+        Assert.Equal(expected, sql.Contains("@ProvisionLocation"));
+    }
+
+    [Fact]
+    public void BuildRegisterInvoiceSql_EveryStatementIsSemicolonTerminated()
+    {
+        // THROW requires the preceding statement to be terminated with ';'.
+        string sql = InvoiceService.BuildRegisterInvoiceSql(change: true, hasProvisionLocation: true);
+
+        foreach (var line in sql.Split('\n'))
+            Assert.EndsWith(";", line.TrimEnd());
+    }
+}

Fuchs.Tests/SqlNumberParameterTests.cs

@@ -0,0 +1,86 @@
+using System;
+using System.Globalization;
+using System.Linq;
+using Fuchs.intranet;
+using Newtonsoft.Json.Linq;
+using Xunit;
+using static OCORE.SQL.sql;
+
+namespace Fuchs.Tests;
+
+/// <summary>
+/// Regression tests for the OCORE string → number SQL parameter helpers. Saving a Stornorechnung
+/// failed in production with "Error converting data type float to numeric": the negative totals
+/// did not parse in the first (sign-less) attempt and fell back to the server's de-DE culture,
+/// where "." is a group separator — "-19.95" became -1995 and JS float noise
+/// ("-1234.5600000000002") overflowed numeric(10,3), so fds__setInvoice never ran.
+/// Every test runs under de-DE, the production server culture.
+/// </summary>
+public class SqlNumberParameterTests : IDisposable
+{
+    private readonly CultureInfo _culture = CultureInfo.CurrentCulture;
+
+    public SqlNumberParameterTests() => CultureInfo.CurrentCulture = new CultureInfo("de-DE");
+
+    public void Dispose() => CultureInfo.CurrentCulture = _culture;
+
+    [Theory]
+    [InlineData("-19.95", -19.95)]
+    [InlineData("-1234.56", -1234.56)]
+    [InlineData("-1234.5600000000002", -1234.56)]
+    [InlineData("-0.5", -0.5)]
+    [InlineData("1234.56", 1234.56)]
+    [InlineData("1234.5600000000002", 1234.56)]
+    [InlineData("-1,5", -1.5)]
+    [InlineData("-1.234,56", -1234.56)]
+    [InlineData("1.234,56", 1234.56)]
+    [InlineData("1,234.56", 1234.56)]
+    [InlineData(" -42 ", -42)]
+    [InlineData("-1.5E-05", -0.000015)]
+    [InlineData("0", 0)]
+    public void SQL_Float_StringValue_ParsesSignedAndCultureFormattedNumbers(string input, double expected)
+    {
+        var p = SQL_Float("@v", stringvalue: input);
+
+        var value = Assert.IsType<float>(p.Value);
+        Assert.Equal(expected, value, 0.01);
+    }
+
+    [Theory]
+    [InlineData("-19.95", -19.95)]
+    [InlineData("-1234.56", -1234.56)]
+    [InlineData("-1.234,56", -1234.56)]
+    [InlineData("1.234,56", 1234.56)]
+    [InlineData("-1,5", -1.5)]
+    public void SQL_Decimal_StringValue_ParsesSignedAndCultureFormattedNumbers(string input, double expected)
+    {
+        var p = SQL_Decimal("@v", input, precision: 10, scale: 3);
+
+        var value = Assert.IsType<decimal>(p.Value);
+        Assert.Equal((decimal)expected, value);
+    }
+
+    [Theory]
+    [InlineData("")]
+    [InlineData("NaN")]
+    [InlineData("abc")]
+    [InlineData("--5")]
+    public void SQL_Float_StringValue_InvalidOrEmpty_IsDbNull(string input)
+    {
+        var p = SQL_Float("@v", stringvalue: input);
+
+        Assert.Equal(DBNull.Value, p.Value);
+    }
+
+    [Theory]
+    [InlineData("")]
+    [InlineData("NaN")]
+    [InlineData("abc")]
+    public void SQL_Decimal_StringValue_InvalidOrEmpty_IsDbNull(string input)
+    {
+        var p = SQL_Decimal("@v", input);
+
+        Assert.Equal(DBNull.Value, p.Value);
+    }
+
+}

Fuchs/Controllers/IntranetController.Invoices2.cs

@@ -475,7 +475,9 @@ public partial class IntranetController
                     {
                         ["Id"]         = d["Id"],
                         ["net_val"]    = net,
-                        ["vat_val"]    = net * vat * 0.01,
+                        // Cent-rounded in decimal like InvoiceDraftCalculator; the former double product
+                        // (e.g. -615.3757999999999) carried float noise into the draft's VAT sums.
+                        ["vat_val"]    = Math.Round((decimal)net * (decimal)vat / 100m, 2, MidpointRounding.AwayFromZero),
                         ["vat"]        = vat == 0 ? "" : vat.ToString("0.00", FuchsPdf.DeCulture) + "%",
                         ["svcnet_val"] = d.no("value_service", 0),
                         ["net"]        = d.no("value", 0),

Fuchs/Fuchs.csproj

@@ -54,7 +54,7 @@
     <PackageReference Include="SixLabors.ImageSharp" Version="4.1.2" />
     <PackageReference Include="System.Configuration.ConfigurationManager" Version="10.0.12" />
     <PackageReference Include="System.Drawing.Common" Version="10.0.12" />
-    <PackageReference Include="Azure.Storage.Blobs" Version="12.29.2" />
+    <PackageReference Include="Azure.Storage.Blobs" Version="12.30.0" />
   </ItemGroup>
   <ItemGroup>
     <Folder Include="App_Data\cache\" />

Fuchs/Services/InvoiceService.cs

@@ -70,6 +70,8 @@ public class InvoiceService : IInvoiceService
 
     private string Conn => _intranet.Intranet__SQLConnectionString;
 
+    private static readonly EventId InvoiceAmountRejected = new(0, "InvoiceAmountRejected");
+
     public async Task<FdsInvoiceData> LoadInvoiceAsync(string id, string userAccountId, DatabaseSecurity dbSec)
     {
         _logger.LogDebug("LoadInvoiceAsync id={Id} user={User}", id, userAccountId);
@@ -151,6 +153,27 @@ public class InvoiceService : IInvoiceService
         return blocks;
     }
 
+    /// <summary>
+    /// The header save batch for <see cref="RegisterInvoiceAsync"/>. If the create/set proc fails
+    /// (e.g. a parameter conversion error) the batch would otherwise carry on with a NULL
+    /// <c>@Id</c> and fail again in <c>fds__createInvoice_Details</c> ("Cannot insert NULL into
+    /// InvId"), burying the real error; the guard stops the batch right after the first failure.
+    /// </summary>
+    internal static string BuildRegisterInvoiceSql(bool change, bool hasProvisionLocation)
+    {
+        var sqlParts = new List<string> { "DECLARE @Id varchar(10);" };
+        sqlParts.Add(change
+            ? "EXECUTE [dbo].[fds__setInvoice] @InvId, @InvoiceType, @InvoiceTitle, @InvoiceBalance, @InvoiceBalance_net, @InvoiceVAT_net1, @InvoiceVAT_1, @PaymentTerm, @CustomerId, @SendToAddress, @SendToEmail, @SendToEmailCc, @ProvisionPeriod, @CustomValues, @authuser, @Id OUTPUT, @SendToAddressJson;"
+            : "EXECUTE [dbo].[fds__createInvoice] @InvoiceType, @InvoiceTitle, @InvoiceBalance, @InvoiceBalance_net, @InvoiceVAT_net1, @InvoiceVAT_1, @PaymentTerm, @CustomerId, @SendToAddress, @SendToEmail, @SendToEmailCc, @ProvisionPeriod, @CustomValues, @authuser, @Id OUTPUT, @SendToAddressJson;");
+        sqlParts.Add(change
+            ? "IF @Id IS NULL THROW 50001, N'fds__setInvoice did not return an invoice id - invoice header not saved.', 1;"
+            : "IF @Id IS NULL THROW 50001, N'fds__createInvoice did not return an invoice id - invoice header not saved.', 1;");
+        sqlParts.Add("EXECUTE [dbo].[fds__createInvoice_Details] @Id, @InvoiceService_net, @InvoiceService_VAT, @InvoiceOptions, @authuser;");
+        if (hasProvisionLocation)
+            sqlParts.Add("UPDATE [dbo].[fds__invoices] SET [ProvisionLocation] = LEFT(@ProvisionLocation,1000) WHERE [Id] = @Id AND [isFinal] = 0;");
+        return string.Join("\n", sqlParts);
+    }
+
     public async Task<FdsInvoiceData> RegisterInvoiceAsync(FdsInvoiceData invoice, bool change, string invId,
         string userAccountId, DatabaseSecurity dbSec)
     {
@@ -158,28 +181,26 @@ public class InvoiceService : IInvoiceService
         if (invoice.NewValues == null) { _logger.LogWarning("RegisterInvoiceAsync: no form values supplied (user={User})", userAccountId); return invoice; }
 
         var pl = new List<SqlParameter> { SQL_VarChar("@authuser", userAccountId) };
+        try
+        {
             pl.AddRange(invoice.BuildInvoiceParams(change, invId));
+        }
+        catch (InvoiceAmountOutOfRangeException ex)
+        {
+            // Refuse rather than store a wrong amount; an empty registration makes the caller report the save as failed.
+            _logger.LogError(InvoiceAmountRejected, ex,
+                "RegisterInvoiceAsync: refused invoice {InvId} - amount {Parameter} = {Value} is out of range (user={User})",
+                invId, ex.Parameter, ex.Value, userAccountId);
+            return invoice;
+        }
 
-        var sqlParts = new List<string> { "DECLARE @Id varchar(10);" };
-        if (!change)
-        {
-            sqlParts.Add("EXECUTE [dbo].[fds__createInvoice] @InvoiceType, @InvoiceTitle, @InvoiceBalance, @InvoiceBalance_net, @InvoiceVAT_net1, @InvoiceVAT_1, @PaymentTerm, @CustomerId, @SendToAddress, @SendToEmail, @SendToEmailCc, @ProvisionPeriod, @CustomValues, @authuser, @Id OUTPUT, @SendToAddressJson;");
-            sqlParts.Add("EXECUTE [dbo].[fds__createInvoice_Details] @Id, @InvoiceService_net, @InvoiceService_VAT, @InvoiceOptions, @authuser;");
-        }
-        else
-        {
-            pl.Add(SQL_VarChar("@InvId", invId));
-            sqlParts.Add("EXECUTE [dbo].[fds__setInvoice] @InvId, @InvoiceType, @InvoiceTitle, @InvoiceBalance, @InvoiceBalance_net, @InvoiceVAT_net1, @InvoiceVAT_1, @PaymentTerm, @CustomerId, @SendToAddress, @SendToEmail, @SendToEmailCc, @ProvisionPeriod, @CustomValues, @authuser, @Id OUTPUT, @SendToAddressJson;");
-            sqlParts.Add("EXECUTE [dbo].[fds__createInvoice_Details] @Id, @InvoiceService_net, @InvoiceService_VAT, @InvoiceOptions, @authuser;");
-        }
-        if (invoice.RawProvisionLocation.Length > 0)
-        {
+        if (change) pl.Add(SQL_VarChar("@InvId", invId));
+        bool hasProvisionLocation = invoice.RawProvisionLocation.Length > 0;
+        if (hasProvisionLocation)
             pl.Add(SQL_NVarChar("@ProvisionLocation",
                 string.Join("\n", invoice.RawProvisionLocation).LeftToFirst("<!--", emptyIfNotFound: false)));
-            sqlParts.Add("UPDATE [dbo].[fds__invoices] SET [ProvisionLocation] = LEFT(@ProvisionLocation,1000) WHERE [Id] = @Id AND [isFinal] = 0;");
-        }
 
-        var invdset = await getSQLDataSet_async(string.Join("\n", sqlParts),
+        var invdset = await getSQLDataSet_async(BuildRegisterInvoiceSql(change, hasProvisionLocation),
             Conn, pl, tablenames: new[] { "inv", "det" },
             Security: dbSec, options: new FIS_SQLOptions());
         if (!string.IsNullOrEmpty(invdset.Exception))

Fuchs/code/FdsInvoiceData.cs

@@ -173,9 +173,9 @@ public class FdsInvoiceData
         {
             SQL_VarChar("@InvoiceType",        Admin?.nz("type") ?? ""),
             SQL_NVarChar("@InvoiceTitle",       NewValues?.nz("title") ?? ""),
-            SQL_Float("@InvoiceBalance",        stringvalue: NewValues?.nz("total_gross") ?? "0"),
-            SQL_Float("@InvoiceBalance_net",    stringvalue: NewValues?.nz("total_net") ?? "0"),
-            SQL_Float("@InvoiceVAT_net1",       stringvalue: vatNet),
+            AmountParam("@InvoiceBalance",      NewValues is null ? 0m : NewValues.getItem("total_gross"), scale: 3),
+            AmountParam("@InvoiceBalance_net",  NewValues is null ? 0m : NewValues.getItem("total_net"), scale: 3),
+            AmountParam("@InvoiceVAT_net1",     vatNet, scale: 3),
             SQL_VarChar("@InvoiceVAT_1",        vatRate),
             SQL_VarChar("@PaymentTerm",         NewValues?.nz("paymentterm") ?? "", dbNull_IfEmpty: true),
             SQL_BigInt("@CustomerId",           Admin?.nz("customerid") ?? ""),
@@ -185,12 +185,63 @@ public class FdsInvoiceData
             SQL_NVarChar("@ProvisionPeriod",    RawProvisionPeriod, dbNull_IfEmpty: true),
             SQL_NVarChar("@CustomValues",       RawCustomValues, dbNull_IfEmpty: true),
             SQL_NVarChar("@SendToAddressJson",  SendToAddressJsonForPersist(), dbNull_IfEmpty: true),
-            SQL_Float("@InvoiceService_net",    stringvalue: Sms?.nz("tscn") ?? "0"),
-            SQL_Float("@InvoiceService_VAT",    stringvalue: Sms?.nz("tscvat") ?? "0"),
+            AmountParam("@InvoiceService_net",  Sms is null ? 0m : Sms.getItem("tscn"), scale: 2),
+            AmountParam("@InvoiceService_VAT",  Sms is null ? 0m : Sms.getItem("tscvat"), scale: 2),
             SQL_VarChar("@InvoiceOptions", BuildInvoiceOptions(), dbNull_IfEmpty: true)
         };
     }
 
+    /// <summary>Largest magnitude the <c>numeric(10,x)</c> amount parameters of the invoice procs accept.</summary>
+    internal const decimal MaxAmount = 9_999_999.99m;
+
+    /// <summary>
+    /// Invoice amounts go to SQL as exact <c>decimal</c> parameters rounded to cents — never through
+    /// a culture-dependent string → float round trip. That round trip once parsed negative amounts
+    /// with the server's de-DE culture ("-615.3758" → -6153758, with float noise beyond numeric(10,3)),
+    /// so Stornorechnungen could not be saved. An amount outside the procs' range is refused here
+    /// (<see cref="InvoiceAmountOutOfRangeException"/>) instead of being stored wrongly or failing in SQL.
+    /// </summary>
+    internal static SqlParameter AmountParam(string name, object? raw, byte scale)
+    {
+        decimal? value = ParseAmount(raw);
+        if (value is { } v && Math.Abs(v) > MaxAmount)
+            throw new InvoiceAmountOutOfRangeException(name, v);
+        return new SqlParameter(name, System.Data.SqlDbType.Decimal)
+        {
+            Precision = 10,
+            Scale = scale,
+            Value = value.HasValue ? value.Value : DBNull.Value
+        };
+    }
+
+    /// <summary>
+    /// Reads an amount the draft session or editor supplied: numbers are taken as-is; strings may be
+    /// German ("-1234,56") or invariant ("-1234.56", "-1.5E-05") — a comma marks German formatting.
+    /// The result is rounded to cents. Empty / "NaN" / unparseable → null (stored as NULL).
+    /// </summary>
+    internal static decimal? ParseAmount(object? raw)
+    {
+        if (raw is JValue jv) raw = jv.Value;
+        decimal d;
+        switch (raw)
+        {
+            case null: return null;
+            case decimal m: d = m; break;
+            case double dbl when double.IsFinite(dbl): d = (decimal)dbl; break;
+            case float flt when float.IsFinite(flt): d = (decimal)flt; break;
+            case int or long or short or byte: d = Convert.ToDecimal(raw, CultureInfo.InvariantCulture); break;
+            case double or float: return null;
+            default:
+                string s = (Convert.ToString(raw, CultureInfo.InvariantCulture) ?? "").Trim();
+                var culture = s.Contains(',') ? GermanCulture : CultureInfo.InvariantCulture;
+                if (!decimal.TryParse(s, NumberStyles.Float, culture, out d)) return null;
+                break;
+        }
+        return Math.Round(d, 2, MidpointRounding.AwayFromZero);
+    }
+
+    private static readonly CultureInfo GermanCulture = new("de-DE");
+
     /// <summary>
     /// Builds the InvoiceOptions CSV from the posted admin flags.
     /// <c>§13b</c> is the existing reverse-charge flag; <c>setmode:&lt;mode&gt;</c>
@@ -253,6 +304,14 @@ public class FdsInvoiceData
     }
 }
 
+/// <summary>An invoice amount exceeds what the invoice procs' <c>numeric(10,x)</c> parameters can store.</summary>
+public sealed class InvoiceAmountOutOfRangeException(string parameter, decimal value)
+    : Exception($"Invoice amount {parameter} = {value.ToString(CultureInfo.InvariantCulture)} is outside ±{FdsInvoiceData.MaxAmount.ToString(CultureInfo.InvariantCulture)}.")
+{
+    public string Parameter { get; } = parameter;
+    public decimal Value { get; } = value;
+}
+
 /// <summary>A service-request group as it renders on the invoice: a heading plus its line items.</summary>
 public sealed class InvoiceBlock
 {

hlp/2026-10-01 check negative invoice amounts.sql

@@ -0,0 +1,22 @@
+-- Read-only check for amounts mangled by the SQL_Float culture bug (fixed 2026-10-01).
+-- No corrections are to be made from this: issued invoices are not changed retrospectively.
+--
+-- What was at risk: only the VAT amount of a negative invoice (Storno / Gutschrift / Korrektur).
+-- FdsInvoiceData.HighestVat formatted it invariantly ("-615.38"), and the old OCORE SQL_Float parsed a
+-- negative value with the server's de-DE culture ("." = thousands separator) -> -61538. When the VAT
+-- carried float noise ("-615.3757999999999") the result overflowed numeric(10,3) and the save failed
+-- (the reported error); without noise it would have been stored scaled by 10/100/1000.
+-- The header totals (InvoiceBalance / _net) and service totals were formatted and parsed in the same
+-- culture and were never affected. Negative amounts themselves are legitimate.
+--
+-- Bug signature: InvoiceVAT_net1 = (InvoiceBalance - InvoiceBalance_net) * 10 / 100 / 1000.
+SELECT  i.[Id], i.[InvoiceId], i.[InvoiceType], i.[IsFinal], i.[DateCreated], i.[DateModified],
+        i.[InvoiceBalance], i.[InvoiceBalance_net], i.[InvoiceVAT_net1],
+        vat_from_totals = i.[InvoiceBalance] - i.[InvoiceBalance_net],
+        vat_scaled_by_bug = CASE WHEN EXISTS (SELECT 1 FROM (VALUES (10), (100), (1000)) f(n)
+                                  WHERE i.[InvoiceBalance] - i.[InvoiceBalance_net] <> 0
+                                    AND ABS(i.[InvoiceVAT_net1] - (i.[InvoiceBalance] - i.[InvoiceBalance_net]) * f.n) <= 0.05 * f.n)
+                                 THEN 1 ELSE 0 END
+FROM    [dbo].[fds__invoices] i
+WHERE   i.[InvoiceBalance] < 0 OR i.[InvoiceBalance_net] < 0 OR i.[InvoiceVAT_net1] < 0
+ORDER BY vat_scaled_by_bug DESC, i.[DateModified] DESC;