Refactor code structure for improved readability and maintainability

2026-07-10 14:29:51 +02:00
parent af445c015e
commit 42997c4f49
18 changed files with 1237 additions and 615 deletions
@@ -1,4 +1,3 @@
-using System.Linq;
 using Fuchs.intranet;
 using Newtonsoft.Json.Linq;
 using Xunit;
@@ -6,9 +5,11 @@ using Xunit;
 namespace Fuchs.Tests;

 /// <summary>
-/// Verifies the server-side port of the former client-side invoice math
-/// (<c>quantChange</c> + <c>invSumUpdate</c>). Because the truth now lives in the
-/// backend (ADR 0006), this logic is finally unit-testable directly.
+/// Verifies the server-side aggregation of invoice draft totals (the port of the
+/// former client-side <c>invSumUpdate</c> footer math). The truth now lives in the
+/// backend (ADR 0006), so this is unit-testable directly. Line values are read from
+/// each block's <c>itm</c> array (the editor's <c>co</c> objects: <c>vt</c>=net,
+/// <c>vv</c>=VAT, <c>vs</c>=service-net, <c>vsv</c>=service-VAT, <c>vat</c>=rate).
 /// </summary>
 public class InvoiceDraftCalculatorTests
 {
@@ -21,16 +22,15 @@ public class InvoiceDraftCalculatorTests
        return s;
    }

-    // ── RecomputeTotals ──────────────────────────────────────────────────────
    [Fact]
    public void RecomputeTotals_SumsNetVatServiceAndPerBlock()
    {
        var s = SessionWith(@"[
-          { 'Id':'10','items':[
-             {'net_val':100,'vat_val':19,'svcnet_val':0,'svcvat_val':0,'vat':'19%','Type':'material'},
-             {'net_val':50,'vat_val':9.5,'svcnet_val':50,'svcvat_val':9.5,'vat':'19%','Type':'Service'} ] },
-          { 'Id':'11','items':[
-             {'net_val':200,'vat_val':14,'svcnet_val':0,'svcvat_val':0,'vat':'7%','Type':'material'} ] }
+          { 'Id':'10','itm':[
+             {'vt':100,'vv':19,'vs':0,'vsv':0,'vat':'19%'},
+             {'vt':50,'vv':9.5,'vs':50,'vsv':9.5,'vat':'19%'} ] },
+          { 'Id':'11','itm':[
+             {'vt':200,'vv':14,'vs':0,'vsv':0,'vat':'7%'} ] }
        ]");

        InvoiceDraftCalculator.RecomputeTotals(s);
@@ -49,8 +49,7 @@ public class InvoiceDraftCalculatorTests
    [Fact]
    public void RecomputeTotals_ReverseCharge_SuppressesVatAndGrossEqualsNet()
    {
-        var s = SessionWith(@"[{ 'Id':'1','items':[
-            {'net_val':100,'vat_val':19,'vat':'19%','Type':'material'} ] }]", p13b: true);
+        var s = SessionWith(@"[{ 'Id':'1','itm':[ {'vt':100,'vv':19,'vat':'19%'} ] }]", p13b: true);

        InvoiceDraftCalculator.RecomputeTotals(s);

@@ -70,41 +69,6 @@ public class InvoiceDraftCalculatorTests
        Assert.Empty(s.Sums.VatByRate);
    }

-    // ── RecomputeItem (quantChange port) ─────────────────────────────────────
-    [Theory]
-    [InlineData("Service", true)]
-    [InlineData("material", false)]
-    public void RecomputeItem_DerivesLineValuesFromQtyPriceVat(string type, bool isService)
-    {
-        var item = new JObject
-        {
-            ["quantityhours"] = 5, ["net"] = "10", ["vat"] = "19", ["Type"] = type
-        };
-
-        InvoiceDraftCalculator.RecomputeItem(item);
-
-        Assert.Equal(50m, item["net_val"]!.Value<decimal>());
-        Assert.Equal(9.5m, item["vat_val"]!.Value<decimal>());
-        if (isService)
-        {
-            Assert.Equal(50m, item["svcnet_val"]!.Value<decimal>());
-            Assert.Equal(9.5m, item["svcvat_val"]!.Value<decimal>());
-        }
-        else
-        {
-            Assert.Null(item["svcnet_val"]);
-        }
-    }
-
-    [Fact]
-    public void RecomputeItem_ZeroQuantity_LeavesValuesUntouched()
-    {
-        var item = new JObject { ["quantityhours"] = 0, ["net"] = "10", ["vat"] = "19", ["Type"] = "material" };
-        InvoiceDraftCalculator.RecomputeItem(item);
-        Assert.Null(item["net_val"]);   // guard qty>0 && price>0 not met → no derivation
-    }
-
-    // ── NormalizeRate ────────────────────────────────────────────────────────
    [Theory]
    [InlineData("19,0%", "19")]
    [InlineData("7%", "7")]
@@ -115,23 +79,21 @@ public class InvoiceDraftCalculatorTests
    public void NormalizeRate_CanonicalisesRateStrings(string raw, string expected)
        => Assert.Equal(expected, InvoiceDraftCalculator.NormalizeRate(raw));

-    // ── Validate ─────────────────────────────────────────────────────────────
    [Fact]
    public void Validate_ValidDraft_NoErrors()
    {
-        var s = SessionWith(@"[{ 'Id':'1','items':[
-            {'net_val':100,'vat_val':19,'vat':'19%','Type':'material'} ] }]");
+        var s = SessionWith(@"[{ 'Id':'1','itm':[ {'vt':100,'vv':19,'vat':'19%'} ] }]");
        InvoiceDraftCalculator.RecomputeTotals(s);
        InvoiceDraftCalculator.Validate(s);
        Assert.DoesNotContain(s.ValidationMessages, m => m.Severity == "error");
    }

    [Theory]
-    [InlineData("", "warning")]      // missing email → advisory
+    [InlineData("", "warning")]
    [InlineData("not-an-email", "error")]
    public void Validate_EmailProblems_AreFlagged(string email, string severity)
    {
-        var s = SessionWith(@"[{ 'Id':'1','items':[{'net_val':10,'vat':'19%','Type':'material'}] }]");
+        var s = SessionWith(@"[{ 'Id':'1','itm':[{'vt':10,'vat':'19%'}] }]");
        s.New["invoiceemail"] = email;
        InvoiceDraftCalculator.RecomputeTotals(s);
        InvoiceDraftCalculator.Validate(s);
@@ -150,9 +112,28 @@ public class InvoiceDraftCalculatorTests
    [Fact]
    public void Validate_UnknownVatRate_IsWarning()
    {
-        var s = SessionWith(@"[{ 'Id':'1','items':[{'net_val':10,'vat_val':0.5,'vat':'5%','Type':'material'}] }]");
+        var s = SessionWith(@"[{ 'Id':'1','itm':[{'vt':10,'vv':0.5,'vat':'5%'}] }]");
        InvoiceDraftCalculator.RecomputeTotals(s);
        InvoiceDraftCalculator.Validate(s);
        Assert.Contains(s.ValidationMessages, m => m.Field == "vat" && m.Severity == "warning");
    }
+
+    [Fact]
+    public void Validate_MissingAddress_IsWarning()
+    {
+        var s = SessionWith(@"[{ 'Id':'1','itm':[{'vt':10,'vat':'19%'}] }]");
+        s.New["invoiceaddress"] = "";
+        InvoiceDraftCalculator.RecomputeTotals(s);
+        InvoiceDraftCalculator.Validate(s);
+        Assert.Contains(s.ValidationMessages, m => m.Field == "address" && m.Severity == "warning");
+    }
+
+    [Fact]
+    public void Validate_NegativeTotal_IsWarning()
+    {
+        var s = SessionWith(@"[{ 'Id':'1','itm':[{'vt':-50,'vv':0,'vat':''}] }]");
+        InvoiceDraftCalculator.RecomputeTotals(s);
+        InvoiceDraftCalculator.Validate(s);
+        Assert.Contains(s.ValidationMessages, m => m.Field == "total" && m.Severity == "warning");
+    }
 }
@@ -0,0 +1,126 @@
+using System;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Fuchs.Notifications;
+using Microsoft.AspNetCore.SignalR;
+using Microsoft.Extensions.Logging.Abstractions;
+using Newtonsoft.Json.Linq;
+using Xunit;
+
+namespace Fuchs.Tests;
+
+/// <summary>
+/// Verifies <see cref="DraftNotifier"/> targets the draft's SignalR group (keyed by
+/// session token, ADR 0007) with the right method/payload, and — like the other
+/// notification path — swallows hub failures so a missed coordination ping never
+/// fails the underlying operation.
+/// </summary>
+public class InvoiceDraftNotifierTests
+{
+    private sealed class CapturingClientProxy : IClientProxy
+    {
+        private readonly bool _throw;
+        public string? Method { get; private set; }
+        public object?[]? Args { get; private set; }
+        public CapturingClientProxy(bool doThrow = false) => _throw = doThrow;
+        public Task SendCoreAsync(string method, object?[] args, CancellationToken cancellationToken = default)
+        {
+            if (_throw) throw new InvalidOperationException("hub down");
+            Method = method;
+            Args = args;
+            return Task.CompletedTask;
+        }
+    }
+
+    private sealed class StubHubClients : IHubClients
+    {
+        private readonly IClientProxy _proxy;
+        public string? RequestedGroup { get; private set; }
+        public StubHubClients(IClientProxy proxy) => _proxy = proxy;
+        public IClientProxy Group(string groupName) { RequestedGroup = groupName; return _proxy; }
+        public IClientProxy All => throw new NotImplementedException();
+        public IClientProxy AllExcept(IReadOnlyList<string> e) => throw new NotImplementedException();
+        public IClientProxy Client(string c) => throw new NotImplementedException();
+        public IClientProxy Clients(IReadOnlyList<string> c) => throw new NotImplementedException();
+        public IClientProxy Groups(IReadOnlyList<string> g) => throw new NotImplementedException();
+        public IClientProxy GroupExcept(string g, IReadOnlyList<string> e) => throw new NotImplementedException();
+        public IClientProxy User(string u) => throw new NotImplementedException();
+        public IClientProxy Users(IReadOnlyList<string> u) => throw new NotImplementedException();
+    }
+
+    private sealed class StubHubContext : IHubContext<DraftPreviewHub>
+    {
+        public StubHubContext(IHubClients clients) => Clients = clients;
+        public IHubClients Clients { get; }
+        public IGroupManager Groups => throw new NotImplementedException();
+    }
+
+    private static (DraftNotifier notifier, StubHubClients clients, CapturingClientProxy proxy) Create(bool doThrow = false)
+    {
+        var proxy = new CapturingClientProxy(doThrow);
+        var clients = new StubHubClients(proxy);
+        var notifier = new DraftNotifier(new StubHubContext(clients), NullLogger<DraftNotifier>.Instance);
+        return (notifier, clients, proxy);
+    }
+
+    [Fact]
+    public async Task SignalDraftReadyAsync_SendsToTokenGroupWithVersion()
+    {
+        var (notifier, clients, proxy) = Create();
+
+        await notifier.SignalDraftReadyAsync("tok-1", 7);
+
+        Assert.Equal("tok-1", clients.RequestedGroup);
+        Assert.Equal("draftReady", proxy.Method);
+        var payload = JObject.FromObject(proxy.Args![0]!);
+        Assert.Equal("tok-1", payload["token"]!.Value<string>());
+        Assert.Equal(7, payload["version"]!.Value<int>());
+    }
+
+    [Fact]
+    public async Task SignalExpiringAsync_SendsSecondsLeft()
+    {
+        var (notifier, _, proxy) = Create();
+
+        await notifier.SignalExpiringAsync("tok-2", 120);
+
+        Assert.Equal("draftExpiring", proxy.Method);
+        var payload = JObject.FromObject(proxy.Args![0]!);
+        Assert.Equal(120, payload["secondsLeft"]!.Value<int>());
+    }
+
+    [Fact]
+    public async Task SignalClosedAsync_SendsReason()
+    {
+        var (notifier, _, proxy) = Create();
+
+        await notifier.SignalClosedAsync("tok-3", "expired");
+
+        Assert.Equal("draftClosed", proxy.Method);
+        var payload = JObject.FromObject(proxy.Args![0]!);
+        Assert.Equal("expired", payload["reason"]!.Value<string>());
+    }
+
+    [Fact]
+    public async Task EmptyToken_DoesNotSend()
+    {
+        var (notifier, clients, proxy) = Create();
+
+        await notifier.SignalDraftReadyAsync("", 1);
+
+        Assert.Null(clients.RequestedGroup);
+        Assert.Null(proxy.Method);
+    }
+
+    [Fact]
+    public async Task HubFailure_IsSwallowed()
+    {
+        var (notifier, _, _) = Create(doThrow: true);
+
+        // Must not throw — a failed coordination ping cannot fail the caller's operation.
+        await notifier.SignalDraftReadyAsync("tok", 1);
+        await notifier.SignalExpiringAsync("tok", 60);
+        await notifier.SignalClosedAsync("tok", "expired");
+    }
+}
@@ -2,7 +2,6 @@ using System.Linq;
 using System.Threading.Tasks;
 using Fuchs.intranet;
 using Fuchs.Services;
-using Microsoft.Data.SqlClient;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Logging.Abstractions;
 using MigraDoc.DocumentObjectModel;
@@ -15,8 +14,8 @@ namespace Fuchs.Tests;

 /// <summary>
 /// Exercises the draft edit orchestrator's pure paths (open/patch/history/flush)
-/// without any database, proving the backend-authoritative model behaves correctly
-/// end-to-end at the service seam (ADR 0006).
+/// without a database, proving the backend-authoritative model behaves correctly at
+/// the service seam (ADR 0006). Blocks use the editor's <c>itm</c>/<c>items</c> shape.
 /// </summary>
 public class InvoiceDraftServiceTests
 {
@@ -32,8 +31,10 @@ public class InvoiceDraftServiceTests
            invoice.InvoiceRegistration = new GenericObjectDictionary(new System.Collections.Generic.Dictionary<string, object> { ["Id"] = "INV42" });
            return Task.FromResult(invoice);
        }
+        public FdsInvoiceData? PreviewInvoice;
+        public bool? PreviewDraft;
        public Task<FdsInvoiceData> LoadInvoiceAsync(string id, string u, DatabaseSecurity s) => throw new System.NotSupportedException();
-        public Document GenerateInvoicePdf(FdsInvoiceData i, bool d) => throw new System.NotSupportedException();
+        public Document GenerateInvoicePdf(FdsInvoiceData i, bool d) { PreviewInvoice = i; PreviewDraft = d; return new Document(); }
        public Task<byte[]> RenderInvoicePdfBytesAsync(FdsInvoiceData i, bool d) => throw new System.NotSupportedException();
        public Task<byte[]> StoreInvoiceDocumentFileAsync(FdsInvoiceData i, bool d, string u, DatabaseSecurity s) => throw new System.NotSupportedException();
        public Task<byte[]?> GetInvoiceFileAsync(FdsInvoiceData i, bool d, fds.IFdsMfr m) => throw new System.NotSupportedException();
@@ -41,18 +42,17 @@ public class InvoiceDraftServiceTests

    private static (InvoiceDraftEditService svc, FakeInvoiceService inv, InvoiceDraftCache cache) NewService()
    {
-        var cfg = new ConfigurationBuilder().Build();
-        var cache = new InvoiceDraftCache(cfg);
+        var cache = new InvoiceDraftCache(new ConfigurationBuilder().Build());
        var inv = new FakeInvoiceService();
-        var svc = new InvoiceDraftEditService(cache, inv, intranet: null!, NullLogger<InvoiceDraftEditService>.Instance);
+        var svc = new InvoiceDraftEditService(cache, inv, NullLogger<InvoiceDraftEditService>.Instance);
        return (svc, inv, cache);
    }

    private static JObject Payload() => JObject.Parse(@"{
        'admin':{'p13b':false,'type':'r','paymentterms':'10wd'},
        'new':{'invoiceemail':'a@b.de','invoiceaddress':'Weg 1','invoicetitle':'Rechnung'},
-        'req':[{'Id':'1','items':[
-            {'Id':'900','net_val':100,'vat_val':19,'vat':'19%','Type':'material','net':'10','quantityhours':10} ]}]
+        'req':[{'Id':'1','text':'Auftrag','itm':[{'id':'900','typ':'material','vt':100,'vv':19,'vs':0,'vsv':0,'vat':'19%'}],
+                'items':[{'id':'900','type':'material','total_net':100,'vat':'19%'}]}]
    }");

    [Fact]
@@ -85,18 +85,31 @@ public class InvoiceDraftServiceTests
    }

    [Fact]
-    public void ApplyPatch_ItemQty_RecomputesLineAndTotals()
+    public void ApplyPatch_BlockReplace_RecomputesTotals()
    {
        var (svc, _, _) = NewService();
        var s = svc.OpenFromPayload(Payload(), "user1");

-        var s2 = svc.ApplyPatch(s.Token, new InvoiceDraftDelta { Target = "item.qty", Ref = "900", Value = JToken.FromObject(5) });
+        var newBlock = JObject.Parse(@"{'Id':'1','text':'Auftrag','itm':[{'id':'900','typ':'material','vt':50,'vv':9.5,'vat':'19%'}],
+                                        'items':[{'id':'900','type':'material','total_net':50,'vat':'19%'}]}");
+        var s2 = svc.ApplyPatch(s.Token, new InvoiceDraftDelta { Target = "block.replace", Ref = "1", Value = newBlock });

-        // qty 5 × price 10 = 50 net, 19% → 9.5 VAT.
        Assert.Equal(50m, s2!.Sums.TotalNet);
        Assert.Equal(9.5m, s2.Sums.VatByRate["19"]);
    }

+    [Fact]
+    public void ApplyPatch_BlockRemove_EmptiesDraftAndFlagsNoItems()
+    {
+        var (svc, _, _) = NewService();
+        var s = svc.OpenFromPayload(Payload(), "user1");
+
+        var s2 = svc.ApplyPatch(s.Token, new InvoiceDraftDelta { Target = "block.remove", Ref = "1" });
+
+        Assert.Equal(0m, s2!.Sums.TotalNet);
+        Assert.Contains(s2.ValidationMessages, m => m.Field == "items" && m.Severity == "error");
+    }
+
    [Fact]
    public void ApplyPatch_P13bToggle_FlipsAndSuppressesVat()
    {
@@ -129,7 +142,6 @@ public class InvoiceDraftServiceTests
        Assert.False(inv.LastChange);   // new draft (no prior InvId) → create, not update
        Assert.Equal("INV42", svc.Get(s.Token)!.InvId);

-        // The FdsInvoiceData handed to registration carries the session's server-computed totals.
        var prms = inv.Registered!.BuildInvoiceParams(change: false, invId: "");
        var balance = prms.First(p => p.ParameterName == "@InvoiceBalance");
        Assert.Equal("119", System.Convert.ToString(balance.Value, System.Globalization.CultureInfo.InvariantCulture));
@@ -137,19 +149,207 @@ public class InvoiceDraftServiceTests
        Assert.Equal("19", vatRate.Value);
    }

-    [Fact]
-    public async Task DiscardAsync_NeverSaved_ReturnsSessionUnchanged()
-    {
-        var (svc, _, _) = NewService();
-        var s = svc.OpenFromPayload(Payload(), "user1");
-        var back = await svc.DiscardAsync(s.Token, "user1", null!);
-        Assert.Same(s, back);   // no InvId → nothing to reload from the DB
-    }
-
    [Fact]
    public void GetHistory_UnknownToken_IsEmpty()
    {
        var (svc, _, _) = NewService();
        Assert.Empty(svc.GetHistory("ghost"));
    }
+
+    [Theory]
+    [InlineData("address", "invoiceaddress")]
+    [InlineData("title", "invoicetitle")]
+    [InlineData("provisionperiod", "provisionperiod")]
+    public void ApplyPatch_ScalarFieldDeltas_UpdateNew(string target, string newKey)
+    {
+        var (svc, _, _) = NewService();
+        var s = svc.OpenFromPayload(Payload(), "user1");
+
+        var s2 = svc.ApplyPatch(s.Token, new InvoiceDraftDelta { Target = target, Value = JToken.FromObject("X-VALUE") });
+
+        Assert.Equal("X-VALUE", s2!.New[newKey]!.Value<string>());
+    }
+
+    [Fact]
+    public void ApplyPatch_ProvisionLocation_MirrorsLocAndProvisionlocation()
+    {
+        var (svc, _, _) = NewService();
+        var s = svc.OpenFromPayload(Payload(), "user1");
+
+        var s2 = svc.ApplyPatch(s.Token, new InvoiceDraftDelta { Target = "provisionlocation", Value = JToken.FromObject("Baustelle 7") });
+
+        Assert.Equal("Baustelle 7", s2!.New["provisionlocation"]!.Value<string>());
+        Assert.Equal("Baustelle 7", s2.New["loc"]!.Value<string>());
+    }
+
+    [Fact]
+    public void ApplyPatch_Contact_BuildsCustomValuesJson()
+    {
+        var (svc, _, _) = NewService();
+        var s = svc.OpenFromPayload(Payload(), "user1");
+
+        var s2 = svc.ApplyPatch(s.Token, new InvoiceDraftDelta
+        {
+            Target = "contact",
+            Value = JObject.Parse(@"{'name':'Max Mustermann','email':'max@kunde.de'}")
+        });
+
+        var cv = JObject.Parse(s2!.New["CustomValues"]!.Value<string>()!);
+        Assert.Equal("Max Mustermann", cv["contactName"]!.Value<string>());
+        Assert.Equal("max@kunde.de", cv["contactEmail"]!.Value<string>());
+    }
+
+    [Fact]
+    public void ApplyPatch_SetmodeDelta_UpdatesAdmin()
+    {
+        var (svc, _, _) = NewService();
+        var s = svc.OpenFromPayload(Payload(), "user1");
+
+        var s2 = svc.ApplyPatch(s.Token, new InvoiceDraftDelta { Target = "setmode", Value = JToken.FromObject("itemprices") });
+
+        Assert.Equal("itemprices", s2!.Admin["setmode"]!.Value<string>());
+    }
+
+    [Fact]
+    public void ApplyPatch_P13bExplicitFalse_TurnsOffAndRestoresVat()
+    {
+        var (svc, _, _) = NewService();
+        var payload = Payload();
+        payload["admin"]!["p13b"] = true;                    // start reverse-charge
+        var s = svc.OpenFromPayload(payload, "user1");
+        Assert.Empty(s.Sums.VatByRate);
+
+        var s2 = svc.ApplyPatch(s.Token, new InvoiceDraftDelta { Target = "p13b", Value = JToken.FromObject(false) });
+
+        Assert.Equal(119m, s2!.Sums.TotalGross);             // VAT restored
+        Assert.Equal(19m, s2.Sums.VatByRate["19"]);
+    }
+
+    [Fact]
+    public void ApplyPatch_BlockReplace_InsertsWhenBlockIsNew()
+    {
+        var (svc, _, _) = NewService();
+        var s = svc.OpenFromPayload(Payload(), "user1");
+
+        var newBlock = JObject.Parse(@"{'Id':'2','text':'Zusatz','itm':[{'id':'950','typ':'material','vt':30,'vv':5.7,'vat':'19%'}],
+                                        'items':[{'id':'950','type':'material','total_net':30,'vat':'19%'}]}");
+        var s2 = svc.ApplyPatch(s.Token, new InvoiceDraftDelta { Target = "block.replace", Ref = "2", Value = newBlock });
+
+        Assert.Equal(2, s2!.Req.Count);
+        Assert.Equal(130m, s2.Sums.TotalNet);                // 100 (block 1) + 30 (new block 2)
+        Assert.Equal(30m, s2.Sums.NetByBlock["2"]);
+    }
+
+    [Fact]
+    public void ApplyPatch_UnknownTarget_IsNoOp_NoVersionBumpNoHistory()
+    {
+        var (svc, _, _) = NewService();
+        var s = svc.OpenFromPayload(Payload(), "user1");
+
+        var s2 = svc.ApplyPatch(s.Token, new InvoiceDraftDelta { Target = "nonsense", Value = JToken.FromObject("x") });
+
+        Assert.NotNull(s2);
+        Assert.Equal(0, s2!.Version);
+        Assert.Empty(s2.History);
+    }
+
+    [Fact]
+    public void ApplyPatch_MultipleEdits_AccumulateHistoryInOrder()
+    {
+        var (svc, _, _) = NewService();
+        var s = svc.OpenFromPayload(Payload(), "user1");
+
+        svc.ApplyPatch(s.Token, new InvoiceDraftDelta { Target = "email", Value = JToken.FromObject("a1@x.de") });
+        svc.ApplyPatch(s.Token, new InvoiceDraftDelta { Target = "title", Value = JToken.FromObject("Titel 2") });
+        var s3 = svc.ApplyPatch(s.Token, new InvoiceDraftDelta { Target = "address", Value = JToken.FromObject("Adr 3") });
+
+        Assert.Equal(3, s3!.Version);
+        Assert.Equal(3, s3.History.Count);
+        Assert.Equal(new[] { "email", "title", "address" }, s3.History.Select(h => h.Target).ToArray());
+        Assert.Equal(new[] { 1, 2, 3 }, s3.History.Select(h => h.Version).ToArray());
+    }
+
+    [Fact]
+    public void BuildState_ExposesPayloadSumsValidationAndVersion()
+    {
+        var (svc, _, _) = NewService();
+        var s = svc.OpenFromPayload(Payload(), "user1");
+        svc.ApplyPatch(s.Token, new InvoiceDraftDelta { Target = "email", Value = JToken.FromObject("x@y.de") });
+
+        var state = JObject.FromObject(svc.BuildState(svc.Get(s.Token)!));
+
+        Assert.Equal(1, state["version"]!.Value<int>());
+        Assert.Equal(100m, state["sums"]!["total_net"]!.Value<decimal>());
+        Assert.Equal(119m, state["sums"]!["total_gross"]!.Value<decimal>());
+        Assert.Equal(19m, state["sums"]!["vat"]!["19"]!.Value<decimal>());
+        Assert.Single((JArray)state["req"]!);
+        Assert.Equal(1, state["historyCount"]!.Value<int>());
+        Assert.NotNull(state["validation"]);
+    }
+
+    [Fact]
+    public async Task FlushToDbAsync_ExistingInvId_UpdatesInsteadOfCreates()
+    {
+        var (svc, inv, _) = NewService();
+        var payload = Payload();
+        payload["invid"] = "INV7";
+        var s = svc.OpenFromPayload(payload, "user1");
+
+        await svc.FlushToDbAsync(s.Token, "user1", null!);
+
+        Assert.True(inv.LastChange);   // prior InvId → update path
+    }
+
+    [Fact]
+    public async Task FlushToDbAsync_MapsInvoiceOptionsFrom13bAndSetmode()
+    {
+        var (svc, inv, _) = NewService();
+        var payload = Payload();
+        payload["admin"]!["p13b"] = true;
+        payload["admin"]!["setmode"] = "itemprices";
+        var s = svc.OpenFromPayload(payload, "user1");
+
+        await svc.FlushToDbAsync(s.Token, "user1", null!);
+
+        var options = inv.Registered!.BuildInvoiceParams(change: false, invId: "")
+            .First(p => p.ParameterName == "@InvoiceOptions").Value?.ToString() ?? "";
+        Assert.Contains("§13b", options);
+        Assert.Contains("setmode:itemprices", options);
+    }
+
+    [Fact]
+    public void RenderPreview_SynthesizesDraftRegistrationFromSession()
+    {
+        var (svc, inv, _) = NewService();
+        var s = svc.OpenFromPayload(Payload(), "user1");
+
+        var doc = svc.RenderPreview(s.Token);
+
+        Assert.NotNull(doc);
+        Assert.True(inv.PreviewDraft);                          // always rendered as a draft
+        var reg = inv.PreviewInvoice!.InvoiceRegistration!;
+        Assert.Equal("Rechnung", reg.getString("InvoiceTitle"));
+        Assert.Equal("Weg 1", reg.getString("SendToAddress"));
+        Assert.Equal("a@b.de", reg.getString("SendToEmail"));
+        Assert.Equal("19", reg.getString("InvoiceVAT_1"));     // rate synthesised from server sums
+        Assert.True(inv.PreviewInvoice.IsDraft);
+    }
+
+    [Fact]
+    public void RenderPreview_UnknownToken_ReturnsNull()
+    {
+        var (svc, _, _) = NewService();
+        Assert.Null(svc.RenderPreview("ghost"));
+    }
+
+    [Fact]
+    public void Close_RemovesSession_ThenReportsFalse()
+    {
+        var (svc, _, _) = NewService();
+        var s = svc.OpenFromPayload(Payload(), "user1");
+
+        Assert.True(svc.Close(s.Token));
+        Assert.Null(svc.Get(s.Token));
+        Assert.False(svc.Close(s.Token));
+    }
 }
@@ -17,32 +17,26 @@ public partial class IntranetController
    /// <summary>Standard 410 when a session token is unknown/expired — the client re-opens the draft.</summary>
    private IActionResult DraftGone() => StatusCode(410, new { error = "expired" });

-    // POST inv/dopen — { id? | payload? } → { token, version }
+    // POST inv/dopen — { payload } → { token, version }
+    // The editor assembles the initial draft (from a service request or a reloaded DB draft
+    // via the existing render paths) and seeds the authoritative session here. Reload/discard
+    // is the client re-fetching + re-seeding, so there is no server-side DB reshaping.
    private async Task<IActionResult> HandleDraftOpen(string fn, string id, string code)
    {
-        InvoiceDraftSession session;
-        if (HasForm("id") && !string.IsNullOrEmpty(Form("id")))
+        if (!HasForm("payload"))
        {
-            _logger.LogInformation("Draft dopen: from DB draft {InvId} user={User}", Form("id"), UserAccountID);
-            session = await _invoiceDrafts.OpenFromDraftAsync(Form("id"), UserAccountID, DbSec);
-        }
-        else if (HasForm("payload"))
-        {
-            _logger.LogInformation("Draft dopen: from payload user={User}", UserAccountID);
-            JObject payload;
-            try { payload = JObject.Parse(Form("payload")); }
-            catch (JsonException ex)
-            {
-                _logger.LogWarning(ex, "Draft dopen: invalid payload JSON user={User}", UserAccountID);
-                return BadRequest400();
-            }
-            session = _invoiceDrafts.OpenFromPayload(payload, UserAccountID);
-        }
-        else
-        {
-            _logger.LogWarning("Draft dopen: neither 'id' nor 'payload' supplied user={User}", UserAccountID);
+            _logger.LogWarning("Draft dopen: 'payload' missing user={User}", UserAccountID);
            return BadRequest400();
        }
+        JObject payload;
+        try { payload = JObject.Parse(Form("payload")); }
+        catch (JsonException ex)
+        {
+            _logger.LogWarning(ex, "Draft dopen: invalid payload JSON user={User}", UserAccountID);
+            return BadRequest400();
+        }
+        var session = _invoiceDrafts.OpenFromPayload(payload, UserAccountID);
+        _logger.LogInformation("Draft dopen: session {Token} (invId={InvId}) user={User}", session.Token, session.InvId, UserAccountID);
        // The browser holds the token from this response and fetches dstate directly; there is
        // no server 'draftReady' on open (it would race the client's group-join). Signals drive
        // only subsequent server-side changes.
@@ -125,16 +119,6 @@ public partial class IntranetController
        return await JSONAsync(new { history });
    }

-    // POST inv/ddiscard — { token } → { ok, version }; reload from DB + draftReady
-    private async Task<IActionResult> HandleDraftDiscard(string fn, string id, string code)
-    {
-        if (!HasForm("token")) return BadRequest400();
-        var session = await _invoiceDrafts.DiscardAsync(Form("token"), UserAccountID, DbSec);
-        if (session == null) return DraftGone();
-        await _draftNotifier.SignalDraftReadyAsync(session.Token, session.Version);
-        return await JSONAsync(new { ok = true, version = session.Version });
-    }
-
    // POST inv/dclose — { token } → { ok }
    private async Task<IActionResult> HandleDraftClose(string fn, string id, string code)
    {
@@ -165,7 +165,6 @@ public partial class IntranetController
            case "dpreview": return await HandleDraftPreview(fn, id, code);
            case "dsave":    return await HandleDraftSave(fn, id, code);
            case "dhistory": return await HandleDraftHistory(fn, id, code);
-            case "ddiscard": return await HandleDraftDiscard(fn, id, code);
            case "dclose":   return await HandleDraftClose(fn, id, code);

            default:
@@ -9,32 +9,31 @@ namespace Fuchs.Services;
 /// Orchestrates a live, backend-authoritative invoice draft editing session
 /// (ADR 0006). Owns the lifecycle around an <see cref="InvoiceDraftSession"/>:
 /// open (seed the cache), apply single edits, build the view state, render a PDF
-/// preview from the cache, flush to the DB ("Zwischenspeichern"), discard (reload
-/// from the DB) and expose the change history. All totals/VAT are computed by
-/// <see cref="InvoiceDraftCalculator"/> — the browser never calculates.
+/// preview from the cache, flush to the DB ("Zwischenspeichern") and expose the
+/// change history. All totals/VAT are aggregated by <see cref="InvoiceDraftCalculator"/>
+/// — the browser never sums.
+///
+/// Reload/discard is handled by the client (re-fetch the DB draft via the existing
+/// <c>inv/get</c> render path and re-seed), so there is no server-side DB reshaping here.
 /// </summary>
 public interface IInvoiceDraftService
 {
    /// <summary>
-    /// Seeds a new cache session for a brand-new draft from the editor's initially
-    /// assembled payload (<c>admin</c> / <c>new</c> / <c>req</c> blocks). Computes
-    /// totals + validation and returns the session (with its fresh token/version).
+    /// Seeds a new cache session from the editor's assembled payload
+    /// (<c>admin</c> / <c>new</c> / <c>req</c> blocks, each block carrying the editor's
+    /// <c>itm</c>/<c>items</c> line arrays). Computes totals + validation and returns the
+    /// session (with its fresh token/version). An <c>invid</c> in the payload marks it as
+    /// an update of an existing DB draft.
    /// </summary>
    InvoiceDraftSession OpenFromPayload(JObject payload, string userAccountId);

-    /// <summary>
-    /// Seeds a cache session by loading an existing DB draft (<c>fds__getInvoice</c>)
-    /// and reshaping it into the editor's block/item structure. Computes + caches.
-    /// </summary>
-    Task<InvoiceDraftSession> OpenFromDraftAsync(string invId, string userAccountId, DatabaseSecurity dbSec);
-
    /// <summary>Returns the cached session for the token (touching its TTL), or null if absent/expired.</summary>
    InvoiceDraftSession? Get(string token);

    /// <summary>
-    /// Applies one editor change to the cached session: mutates the payload,
-    /// re-derives affected item math + totals, re-validates, appends a history entry
-    /// and bumps the version. Returns the mutated session, or null if the token is unknown.
+    /// Applies one editor change to the cached session: mutates the payload, re-aggregates
+    /// totals, re-validates, appends a history entry and bumps the version. Returns the
+    /// mutated session, or null if the token is unknown.
    /// </summary>
    InvoiceDraftSession? ApplyPatch(string token, InvoiceDraftDelta delta);

@@ -45,8 +44,8 @@ public interface IInvoiceDraftService
    IReadOnlyList<ChangeHistoryEntry> GetHistory(string token);

    /// <summary>
-    /// Persists the cached session to the DB via the existing invoice registration
-    /// path ("Zwischenspeichern"). Sets <see cref="InvoiceDraftSession.InvId"/> on success.
+    /// Persists the cached session to the DB via the existing invoice registration path
+    /// ("Zwischenspeichern"). Sets <see cref="InvoiceDraftSession.InvId"/> on success.
    /// Returns the registered invoice data (for the success event), or null if the token is unknown.
    /// </summary>
    Task<FdsInvoiceData?> FlushToDbAsync(string token, string userAccountId, DatabaseSecurity dbSec);
@@ -54,21 +53,15 @@ public interface IInvoiceDraftService
    /// <summary>Renders a draft PDF straight from the cached session (no client upload). Null if token unknown.</summary>
    Document? RenderPreview(string token);

-    /// <summary>
-    /// Discards the session's in-memory changes by reloading it from the DB draft
-    /// (requires a prior flush / an existing <c>InvId</c>). Bumps the version so the
-    /// client refetches. Returns the reloaded session, or null if the token is unknown.
-    /// </summary>
-    Task<InvoiceDraftSession?> DiscardAsync(string token, string userAccountId, DatabaseSecurity dbSec);
-
-    /// <summary>Removes the session from the cache (explicit close/finalise). Returns true if one was present.</summary>
+    /// <summary>Removes the session from the cache (explicit close/discard/finalise). Returns true if one was present.</summary>
    bool Close(string token);
 }

 /// <summary>
 /// A single editor change posted to <c>inv/dpatch</c>. <see cref="Target"/> names the
-/// field/operation (e.g. "email", "p13b", "item.qty"); <see cref="Ref"/> is the item or
-/// block id it applies to (when relevant); <see cref="Value"/> is the new value.
+/// field/operation (e.g. "email", "p13b", "block.replace"); <see cref="Ref"/> is the block
+/// id it applies to (when relevant); <see cref="Value"/> is the new value (a scalar for
+/// fields, or a full block object for <c>block.replace</c>).
 /// </summary>
 public sealed class InvoiceDraftDelta
 {
@@ -1,44 +1,37 @@
 using System.Globalization;
-using System.Web;
 using Fuchs.intranet;
-using Microsoft.Data.SqlClient;
 using Microsoft.Extensions.Logging;
 using MigraDoc.DocumentObjectModel;
 using Newtonsoft.Json.Linq;
 using OCORE.security;
-using OCORE.SQL;
 using static OCORE.commons;
 using static OCORE.OCORE_dictionaries;
-using static OCORE.SQL.sql;

 namespace Fuchs.Services;

 /// <summary>
 /// Backend-authoritative invoice draft editing (ADR 0006). Holds the truth in an
 /// <see cref="InvoiceDraftSession"/> (via <see cref="IInvoiceDraftCache"/>), applies
-/// single edits, computes totals with <see cref="InvoiceDraftCalculator"/>, renders
+/// single edits, aggregates totals with <see cref="InvoiceDraftCalculator"/>, renders
 /// previews and flushes to the DB by reusing the existing <see cref="IInvoiceService"/>
-/// registration path — no new persistence. Deliberately I/O-thin so the calculation
-/// remains unit-testable.
+/// registration path — no new persistence. The session stores the editor's own block
+/// shape (<c>itm</c>/<c>items</c> line arrays), which the PDF/persistence already consume,
+/// so nothing is re-shaped server-side.
 /// </summary>
 public sealed class InvoiceDraftEditService : IInvoiceDraftService
 {
    private readonly IInvoiceDraftCache _cache;
    private readonly IInvoiceService _invoices;
-    private readonly Fuchs_intranet _intranet;
    private readonly ILogger<InvoiceDraftEditService> _logger;

    public InvoiceDraftEditService(IInvoiceDraftCache cache, IInvoiceService invoices,
-        Fuchs_intranet intranet, ILogger<InvoiceDraftEditService> logger)
+        ILogger<InvoiceDraftEditService> logger)
    {
        _cache = cache;
        _invoices = invoices;
-        _intranet = intranet;
        _logger = logger;
    }

-    private string Conn => _intranet.Intranet__SQLConnectionString;
-
    // ── Open ─────────────────────────────────────────────────────────────────
    public InvoiceDraftSession OpenFromPayload(JObject payload, string userAccountId)
    {
@@ -58,17 +51,6 @@ public sealed class InvoiceDraftEditService : IInvoiceDraftService
        return session;
    }

-    public async Task<InvoiceDraftSession> OpenFromDraftAsync(string invId, string userAccountId, DatabaseSecurity dbSec)
-    {
-        var session = new InvoiceDraftSession { Token = NewToken(), UserAccountId = userAccountId, InvId = invId };
-        await LoadDraftIntoAsync(session, invId, userAccountId, dbSec);
-        Refresh(session);
-        _cache.Set(session);
-        _logger.LogInformation("Draft session {Token} opened from DB draft {InvId} (user={User})",
-            session.Token, invId, userAccountId);
-        return session;
-    }
-
    public InvoiceDraftSession? Get(string token) => _cache.Get(token);

    // ── Patch ──────────────────────────────────────────────────────────────────
@@ -118,17 +100,10 @@ public sealed class InvoiceDraftEditService : IInvoiceDraftService
            case "setmode":           return SetAdmin(s, "setmode", d, ref oldValue);
            case "p13b":
                oldValue = Str(s.Admin["p13b"]);
-                bool next = d.Value != null && d.Value.Type != JTokenType.Null
-                    ? AsBool(d.Value)
-                    : !AsBool(s.Admin["p13b"]);          // toggle when no explicit value
-                s.Admin["p13b"] = next;
+                s.Admin["p13b"] = d.Value != null && d.Value.Type != JTokenType.Null
+                    ? AsBool(d.Value) : !AsBool(s.Admin["p13b"]);   // toggle when no explicit value
                return true;
-            case "item.qty":          return SetItem(s, d, "quantityhours", recompute: true, ref oldValue);
-            case "item.price":        return SetItem(s, d, "net", recompute: true, ref oldValue);
-            case "item.note":         return SetItem(s, d, "Note", recompute: false, ref oldValue);
-            case "item.remove":       return RemoveItem(s, d, ref oldValue);
-            case "block.combine":
-            case "item.combine":      return SetBlockFlag(s, d, "onesum", ref oldValue);
+            case "block.replace":     return ReplaceBlock(s, d, ref oldValue);
            case "block.remove":      return RemoveBlock(s, d, ref oldValue);
            default:                  return false;
        }
@@ -161,31 +136,22 @@ public sealed class InvoiceDraftEditService : IInvoiceDraftService
        return true;
    }

-    private static bool SetItem(InvoiceDraftSession s, InvoiceDraftDelta d, string key, bool recompute, ref string oldValue)
+    /// <summary>Replaces (or inserts) a whole block — the editor re-emits an edited block's line arrays as one delta.</summary>
+    private static bool ReplaceBlock(InvoiceDraftSession s, InvoiceDraftDelta d, ref string oldValue)
    {
-        var item = FindItem(s, d.Ref);
-        if (item == null) return false;
-        oldValue = Str(item[key]);
-        item[key] = d.Value ?? JValue.CreateString(d.ValueString);
-        if (recompute) InvoiceDraftCalculator.RecomputeItem(item);
-        return true;
-    }
-
-    private static bool RemoveItem(InvoiceDraftSession s, InvoiceDraftDelta d, ref string oldValue)
-    {
-        var item = FindItem(s, d.Ref);
-        if (item == null) return false;
-        oldValue = Str(item["NameOrNumber"]).ne(Str(item["htmltext"]));
-        item.Remove();
-        return true;
-    }
-
-    private static bool SetBlockFlag(InvoiceDraftSession s, InvoiceDraftDelta d, string key, ref string oldValue)
-    {
-        var block = FindBlock(s, d.Ref);
-        if (block == null) return false;
-        oldValue = Str(block[key]);
-        block[key] = d.Value != null && d.Value.Type != JTokenType.Null ? AsBool(d.Value) : !AsBool(block[key]);
+        if (d.Value is not JObject nb) return false;
+        string bid = !string.IsNullOrEmpty(d.Ref) ? d.Ref : Str(nb["Id"]);
+        var existing = FindBlock(s, bid);
+        if (existing != null)
+        {
+            oldValue = Str(existing["text"]);
+            existing.Replace(nb);
+        }
+        else
+        {
+            oldValue = "";
+            s.Req.Add(nb);
+        }
        return true;
    }

@@ -229,7 +195,7 @@ public sealed class InvoiceDraftEditService : IInvoiceDraftService
    public IReadOnlyList<ChangeHistoryEntry> GetHistory(string token) =>
        _cache.Get(token)?.History ?? (IReadOnlyList<ChangeHistoryEntry>)Array.Empty<ChangeHistoryEntry>();

-    // ── Flush / preview / discard ─────────────────────────────────────────────
+    // ── Flush / preview ────────────────────────────────────────────────────────
    public async Task<FdsInvoiceData?> FlushToDbAsync(string token, string userAccountId, DatabaseSecurity dbSec)
    {
        var session = _cache.Get(token);
@@ -258,30 +224,6 @@ public sealed class InvoiceDraftEditService : IInvoiceDraftService
        return _invoices.GenerateInvoicePdf(fds, draft: true);
    }

-    public async Task<InvoiceDraftSession?> DiscardAsync(string token, string userAccountId, DatabaseSecurity dbSec)
-    {
-        var session = _cache.Get(token);
-        if (session == null) return null;
-        if (string.IsNullOrEmpty(session.InvId))
-        {
-            _logger.LogInformation("Draft {Token} discard requested but never saved — nothing to reload (user={User})", token, userAccountId);
-            return session;
-        }
-        await LoadDraftIntoAsync(session, session.InvId, userAccountId, dbSec);
-        Refresh(session);
-        session.Version++;
-        session.History.Add(new ChangeHistoryEntry
-        {
-            UserAccountId = userAccountId,
-            Target = "discard",
-            NewValue = "Änderungen verworfen",
-            Version = session.Version
-        });
-        _cache.Set(session);
-        _logger.LogInformation("Draft {Token} discarded, reloaded from DB invoice {InvId} (user={User})", token, session.InvId, userAccountId);
-        return session;
-    }
-
    public bool Close(string token) => _cache.Remove(token) != null;

    // ── Internals ──────────────────────────────────────────────────────────────
@@ -300,16 +242,12 @@ public sealed class InvoiceDraftEditService : IInvoiceDraftService
        return null;
    }

-    private static JObject? FindItem(InvoiceDraftSession s, string itemId)
-    {
-        foreach (var b in s.Req)
-            if (b is JObject bo && bo["items"] is JArray items)
-                foreach (var it in items)
-                    if (it is JObject io && Str(io["Id"]) == itemId) return io;
-        return null;
-    }
-
-    /// <summary>Builds the <see cref="FdsInvoiceData"/> from the session — the server-side port of <c>invcPayload</c>.</summary>
+    /// <summary>
+    /// Builds the <see cref="FdsInvoiceData"/> from the session — the server-side equivalent
+    /// of <c>invcPayload</c>. The session already holds the editor's <c>req</c> block shape
+    /// (<c>itm</c>/<c>items</c> line arrays) that registration and the PDF consume, so the
+    /// blocks pass through unchanged; only the header/total normalisation is applied.
+    /// </summary>
    private FdsInvoiceData BuildFdsData(InvoiceDraftSession session)
    {
        var adm = (JObject)session.Admin.DeepClone();
@@ -375,8 +313,8 @@ public sealed class InvoiceDraftEditService : IInvoiceDraftService
        {
            idx++;
            if (idx > 2) break;
-            d[$"InvoiceVAT_{idx}"]     = kv.Key;
-            d[$"InvoiceVAT_net{idx}"]  = kv.Value;
+            d[$"InvoiceVAT_{idx}"]    = kv.Key;
+            d[$"InvoiceVAT_net{idx}"] = kv.Value;
        }
        return new GenericObjectDictionary(d);
    }
@@ -391,96 +329,6 @@ public sealed class InvoiceDraftEditService : IInvoiceDraftService
        return string.Join(",", tokens);
    }

-    /// <summary>Loads the DB draft (<c>fds__getInvoice</c>) into the session's payload — the port of HandleInvoiceGet + BuildInvoiceRequestList.</summary>
-    private async Task LoadDraftIntoAsync(InvoiceDraftSession session, string invId, string userAccountId, DatabaseSecurity dbSec)
-    {
-        var pl = new List<SqlParameter> { SQL_VarChar("@authuser", userAccountId), SQL_VarChar("@Id", invId) };
-        var dset = await getSQLDataSet_async(
-            "EXECUTE [dbo].[fds__getInvoice] @Id, @authuser;",
-            Conn, pl, tablenames: new[] { "admin", "inv", "req", "itm" },
-            Security: dbSec, options: new FIS_SQLOptions());
-        if (!string.IsNullOrEmpty(dset.Exception))
-            _logger.LogError("LoadDraftIntoAsync sql exception for {InvId}: {Ex}", invId, dset.Exception);
-
-        var adminDic = dset.Table("admin").FirstRow.toObjectDictionary();
-        var invDic   = dset.Table("inv").FirstRow.toObjectDictionary();
-        string invoiceOptions = invDic.nz("InvoiceOptions", "");
-        bool p13b = invoiceOptions.Split(',').Contains("§13b");
-        string setmode = invoiceOptions.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
-            .FirstOrDefault(t => t.StartsWith("setmode:", StringComparison.OrdinalIgnoreCase))?["setmode:".Length..] ?? "";
-
-        var admin = JObject.FromObject(adminDic);
-        admin["type"] = admin["type"] ?? JValue.CreateString(invDic.nz("InvoiceType").Substr(0, 1));
-        admin["p13b"] = p13b;
-        if (!string.IsNullOrEmpty(setmode)) admin["setmode"] = setmode;
-
-        var nw = new JObject
-        {
-            ["invoicetitle"]      = invDic.nz("InvoiceTitle"),
-            ["title"]             = invDic.nz("InvoiceTitle"),
-            ["invoiceaddress"]    = invDic.nz("SendToAddress"),
-            ["invoiceemail"]      = invDic.nz("SendToEmail"),
-            ["provisionlocation"] = invDic.nz("ProvisionLocation"),
-            ["loc"]               = invDic.nz("ProvisionLocation"),
-            ["provisionperiod"]   = invDic.nz("ProvisionPeriod"),
-            ["CustomValues"]      = invDic.nz("CustomValues"),
-            ["paymentterm"]       = invDic.nz("PaymentTerm")
-        };
-
-        session.Admin = admin;
-        session.New = nw;
-        session.Req = BuildDraftBlocks(dset);
-        session.IsDraft = invDic.getItem("IsFinal", false) is not true;
-    }
-
-    /// <summary>Reshapes the <c>fds__getInvoice</c> req/itm tables into the editor's block/item JSON (port of BuildInvoiceRequestList).</summary>
-    private static JArray BuildDraftBlocks(SQLDataSet dset)
-    {
-        var blocks = new JArray();
-        foreach (System.Data.DataRow rq in dset.Tables("req").Select("",
-            dset.Tables("req").Columns.Contains("order") ? "order" : ""))
-        {
-            var rdic = rq.toObjectDictionary();
-            var block = new JObject
-            {
-                ["Id"]      = rdic["mfr__servicerequest"]?.ToString() ?? "",
-                ["InvRqId"] = rdic["Id"]?.ToString() ?? "",
-                ["text"]    = HttpUtility.HtmlDecode(rdic["title"]?.ToString() ?? "")
-            };
-            var items = new JArray();
-            if (dset.Contains("itm"))
-            {
-                foreach (System.Data.DataRow sitm in dset.Tables("itm").Select(
-                    $"[InvRqId] = '{rdic["Id"]}'",
-                    dset.Tables("itm").Columns.Contains("order") ? "order" : ""))
-                {
-                    var di    = sitm.toObjectDictionary();
-                    double net = Convert.ToDouble(di.no("value_total", 0));
-                    double vat = Convert.ToDouble(di.no("vat", 0));
-                    items.Add(new JObject
-                    {
-                        ["Id"]         = di["Id"]?.ToString() ?? "",
-                        ["net_val"]    = net,
-                        ["vat_val"]    = net * vat * 0.01,
-                        ["vat"]        = vat == 0 ? "" : vat.ToString("0.00", FuchsPdf.DeCulture) + "%",
-                        ["svcnet_val"] = Convert.ToDouble(di.no("value_service", 0)),
-                        ["svcvat_val"] = 0,
-                        ["net"]        = Convert.ToDouble(di.no("value", 0)),
-                        ["quantity"]   = di.nz("Quantity"),
-                        ["Type"]       = di.nz("Type"),
-                        ["Note"]       = di.nz("Text"),
-                        ["htmltext"]   = di.nz("Text"),
-                        ["position"]   = di.nz("Position"),
-                        ["SortOrder"]  = di.nz("SortOrder")
-                    });
-                }
-            }
-            block["items"] = items;
-            blocks.Add(block);
-        }
-        return blocks;
-    }
-
    // ── token helpers ─────────────────────────────────────────────────────────
    private static string Str(JToken? t) =>
        t == null || t.Type == JTokenType.Null ? "" : t.Type == JTokenType.String ? t.Value<string>() ?? "" : t.ToString();
@@ -4,49 +4,22 @@ using Newtonsoft.Json.Linq;
 namespace Fuchs.intranet;

 /// <summary>
-/// Server-side, pure port of the invoice totals/VAT math that used to live in the
-/// browser (<c>quantChange</c> + <c>invSumUpdate</c> in <c>fis.inv_shared.js</c>).
-/// This is the authoritative calculation for a live draft (ADR 0006): given the
-/// editable payload of an <see cref="InvoiceDraftSession"/>, it (re)computes each
-/// item's line values, aggregates block/rate totals into
-/// <see cref="InvoiceDraftSession.Sums"/>, and runs the plausibility/consistency
-/// checks into <see cref="InvoiceDraftSession.ValidationMessages"/>.
+/// Server-side, pure aggregation of an invoice draft's totals/VAT — the authoritative
+/// replacement for the browser's <c>invSumUpdate</c> footer math (ADR 0006). The user's
+/// requirement is that the <b>sums</b> live in the backend cache, not the frontend.
 ///
-/// Kept static and free of I/O so it is exhaustively unit-testable — the payoff the
-/// old <c>EVAL_live_invoice_editing.md</c> predicted once the truth moved server-side.
+/// It reads each block's persisted line contract (<c>block.itm</c> = the editor's <c>co</c>
+/// objects: <c>vt</c>=net, <c>vv</c>=VAT, <c>vs</c>=service-net, <c>vsv</c>=service-VAT,
+/// <c>vat</c>=rate) — exactly the shape the editor already posts and the PDF/persistence
+/// already consume — so no line data is re-derived or re-shaped. It then applies the §13b
+/// reverse-charge rule and validates. Static/pure, hence exhaustively unit-testable.
 /// </summary>
 public static class InvoiceDraftCalculator
 {
    /// <summary>
-    /// Re-derives a single item's line values from quantity × net price × VAT rate —
-    /// the port of the editor's <c>quantChange</c>. Only applied when an item's
-    /// quantity/price actually changes (osum/set/text lines keep their stored values,
-    /// exactly as the client only ran <c>quantChange</c> on edited quantity rows).
-    /// Mirrors the guard <c>qty &gt; 0 &amp;&amp; price &gt; 0</c>.
-    /// </summary>
-    public static void RecomputeItem(JObject item)
-    {
-        int qty      = (int)Dec(item["quantityhours"]);
-        decimal net  = Dec(item["net"]);
-        decimal vat  = RatePercent(Str(item["vat"])) * 0.01m;   // "19%"/"19,0%" → 0.19
-        if (qty > 0 && net > 0)
-        {
-            decimal netVal = decimal.Round(qty * net, 2, MidpointRounding.AwayFromZero);
-            decimal vatVal = decimal.Round(qty * net * vat, 2, MidpointRounding.AwayFromZero);
-            item["net_val"] = netVal;
-            item["vat_val"] = vatVal;
-            if (string.Equals(Str(item["Type"]), "service", StringComparison.OrdinalIgnoreCase))
-            {
-                item["svcnet_val"] = netVal;
-                item["svcvat_val"] = vatVal;
-            }
-        }
-    }
-
-    /// <summary>
-    /// Aggregates all line items into the draft's totals — the port of <c>invSumUpdate</c>'s
-    /// <c>csms</c> accumulation plus the §13b reverse-charge rule (VAT suppressed → gross = net).
-    /// VAT is grouped by the item's rate string (matching the editor's <c>sms.vat</c> map).
+    /// Aggregates every block's line values into the draft's totals — the port of
+    /// <c>invSumUpdate</c>'s <c>csms</c> accumulation plus §13b (VAT suppressed → gross = net).
+    /// VAT is grouped by the line's rate string (matching the editor's <c>sms.vat</c> map).
    /// </summary>
    public static void RecomputeTotals(InvoiceDraftSession session)
    {
@@ -58,15 +31,15 @@ public static class InvoiceDraftCalculator
            if (blockTok is not JObject block) continue;
            decimal blockNet = 0;
            string blockId = Str(block["Id"]);
-            if (block["items"] is JArray items)
+            if (block["itm"] is JArray lines)
            {
-                foreach (var itemTok in items)
+                foreach (var lineTok in lines)
                {
-                    if (itemTok is not JObject item) continue;
-                    decimal netVal = Dec(item["net_val"]);
-                    decimal vatVal = Dec(item["vat_val"]);
-                    decimal svcNet = Dec(item["svcnet_val"]);
-                    decimal svcVat = Dec(item["svcvat_val"]);
+                    if (lineTok is not JObject co) continue;
+                    decimal netVal = Dec(co["vt"]);
+                    decimal vatVal = Dec(co["vv"]);
+                    decimal svcNet = Dec(co["vs"]);
+                    decimal svcVat = Dec(co["vsv"]);

                    sums.ServiceNet += svcNet;
                    sums.ServiceVat += svcVat;
@@ -75,7 +48,7 @@ public static class InvoiceDraftCalculator
                    sums.TotalGross += netVal + vatVal;
                    blockNet        += netVal;

-                    string rate = NormalizeRate(Str(item["vat"]));
+                    string rate = NormalizeRate(Str(co["vat"]));
                    if (rate.Length > 0)
                        sums.VatByRate[rate] = sums.VatByRate.GetValueOrDefault(rate) + vatVal;
                }
@@ -106,30 +79,23 @@ public static class InvoiceDraftCalculator
        void Add(string field, string sev, string msg) =>
            session.ValidationMessages.Add(new InvoiceDraftValidationMessage(field, sev, msg));

-        // Recipient email
        string email = Str(session.New["invoiceemail"]).Trim();
        if (email.Length == 0)
            Add("email", "warning", "Es ist keine E-Mail-Adresse hinterlegt — die Rechnung kann nicht per E-Mail versandt werden.");
        else if (!IsValidEmail(email))
            Add("email", "error", "Die E-Mail-Adresse ist ungültig.");

-        // Recipient address
        if (Str(session.New["invoiceaddress"]).Trim().Length == 0)
            Add("address", "warning", "Es ist keine Rechnungsanschrift hinterlegt.");

-        // At least one priced line
        if (!HasAnyItem(session))
            Add("items", "error", "Die Rechnung enthält keine Positionen.");

-        // VAT rate sanity (only when not reverse-charge)
        if (!Flag(session.Admin, "p13b"))
-        {
            foreach (var rate in session.Sums.VatByRate.Keys)
                if (!IsKnownVatRate(rate))
                    Add("vat", "warning", $"Ungewöhnlicher Umsatzsteuersatz: {rate}%.");
-        }

-        // Negative total
        if (session.Sums.TotalGross < 0)
            Add("total", "warning", "Der Rechnungsbetrag ist negativ.");
    }
@@ -138,7 +104,7 @@ public static class InvoiceDraftCalculator
    private static bool HasAnyItem(InvoiceDraftSession session)
    {
        foreach (var blockTok in session.Req)
-            if (blockTok is JObject block && block["items"] is JArray items && items.Count > 0)
+            if (blockTok is JObject block && block["itm"] is JArray lines && lines.Count > 0)
                return true;
        return false;
    }
@@ -152,7 +118,7 @@ public static class InvoiceDraftCalculator
    }

    private static string Str(JToken? token) =>
-        token == null || token.Type == JTokenType.Null ? "" : token.Value<string>() ?? "";
+        token == null || token.Type == JTokenType.Null ? "" : token.Type == JTokenType.String ? token.Value<string>() ?? "" : token.ToString();

    private static bool Flag(JObject obj, string key)
    {
@@ -176,13 +142,6 @@ public static class InvoiceDraftCalculator

    private static bool IsKnownVatRate(string rate) => rate is "0" or "7" or "19";

-    /// <summary>Parses a VAT rate string ("19%", "19,0%", "7") to its numeric percent (German/invariant tolerant).</summary>
-    internal static decimal RatePercent(string? raw)
-    {
-        string s = (raw ?? "").Replace("%", "").Trim().Replace(',', '.');
-        return decimal.TryParse(s, NumberStyles.Any, CultureInfo.InvariantCulture, out decimal d) ? d : 0;
-    }
-
    private static bool IsValidEmail(string email)
    {
        int at = email.IndexOf('@');
@@ -99,11 +99,202 @@ $inv.eM = (r, re, opt) => {
    if ((opt || '').split(',').includes('setm') === true) {
        m.push({ lbl: $ict.setm, fnc: $inv.ssetmode });
    }
+    if ((opt || '').split(',').includes('iss') === true) {  /* backend-authoritative draft (ADR 0006) */
+        m.push({ lbl: 'Änderungshistorie', fnc: () => $inv.d.history() });
+        m.push({ lbl: 'Änderungen verwerfen', fnc: () => $inv.d.discard() });
+    }
    if (booln(r, false) === true) {
        m.push({ lbl: $ict.rel, fnc: $inv.rReload });
    }
    return $('#topbar').ocmsmenu(m);  /* empty Array => empty menu */
 };
+/* ── Backend-authoritative draft editing controller (ADR 0006/0007) ───────────
+   The server holds the truth for an invoice draft in an in-memory session; this
+   object seeds it, sends single edits as deltas, and renders the totals footer +
+   validation from the authoritative server state. It is invoice-only: reminders
+   never obtain a token (invSumUpdate, the seed trigger, is only bound for invoices),
+   so they keep the legacy stateless flow untouched. */
+$inv.d = {
+    tbl: () => $('div.invoice_layout table.invi'),
+    layout: () => $('div.invoice_layout'),
+    token: function () { return $inv.d.tbl().data('dtoken') || ''; },
+    /* Hash each assembled block so only genuinely-changed blocks are sent as deltas. */
+    hashes: function () {
+        let bai = $inv.d.tbl().data('bai') || [], h = {};
+        $.each(bai, (i, b) => { h[(b.Id || '').toString()] = JSON.stringify(b); });
+        return h;
+    },
+    /* Seed the authoritative server session from the assembled editor payload. Called
+       once from invSumUpdate on open; thereafter the backend is the source of truth. */
+    seed: function (payload) {
+        let l = $inv.d.layout(); l.aC('freeze');
+        $ocms.postXT({
+            url: $ocms.url('inv/dopen'), data: { payload: JSON.stringify(payload) }, success: (r) => {
+                $inv.d.tbl().data('dtoken', r.token).data('dver', r.version).data('dhashes', $inv.d.hashes());
+                $fis.draft.bind(r.token, {
+                    onReady: () => $inv.d.refresh(),
+                    onExpiring: (s) => $inv.d.warnExpiry(s),
+                    onClosed: (reason) => $inv.d.closed(reason)
+                });
+                $inv.d.refresh();
+            }, error: () => { l.rC('freeze'); }, complete: () => { $inv.d.tbl().removeData('dseeding'); }
+        });
+    },
+    /* Re-fetch the authoritative state and render the totals footer + validation from it. */
+    refresh: function (cb) {
+        let t = $inv.d.token(); if (t === '') { return; }
+        $ocms.postXT({
+            url: $ocms.url('inv/dstate'), data: { token: t }, success: (state) => {
+                $inv.d.applyState(state); if (typeof cb === 'function') { cb(state); }
+            }, error: (xhr) => { if (xhr && xhr.status === 410) { $inv.d.closed('expired'); } },
+            complete: () => { $inv.d.layout().rC('freeze'); }
+        });
+    },
+    applyState: function (state) {
+        let tbl = $inv.d.tbl(); if (tbl.length < 1) { return; }
+        tbl.data('dver', state.version).data('serverSums', state.sums);
+        $inv.d.footer(tbl, state.sums || {}, state.admin || {});
+        $inv.d.validation(state.validation || []);
+    },
+    /* Send one change to the server; the draftReady signal and this success both refresh. */
+    sync: function (delta) {
+        let t = $inv.d.token(); if (t === '') { return; }
+        $inv.d.layout().aC('freeze');
+        $ocms.postXT({
+            url: $ocms.url('inv/dpatch'), data: { token: t, delta: JSON.stringify(delta) },
+            success: () => { $inv.d.refresh(); },
+            error: (xhr) => { $inv.d.layout().rC('freeze'); if (xhr && xhr.status === 410) { $inv.d.closed('expired'); } }
+        });
+    },
+    /* Diff the freshly-rebuilt blocks against the last-synced state and send only the
+       changed/removed blocks as granular block.replace / block.remove deltas. */
+    syncChanged: function (tbl) {
+        if (($inv.d.token()) === '') { return; }
+        let bai = tbl.data('bai') || [], prev = tbl.data('dhashes') || {}, next = {}, changed = [], removed = [];
+        $.each(bai, (i, b) => { let id = (b.Id || '').toString(), h = JSON.stringify(b); next[id] = h; if (prev[id] !== h) { changed.push(b); } });
+        $.each(prev, (id) => { if (next[id] === undefined) { removed.push(id); } });
+        tbl.data('dhashes', next);
+        changed.forEach((b) => $inv.d.sync({ Target: 'block.replace', Ref: (b.Id || '').toString(), Value: b }));
+        removed.forEach((id) => $inv.d.sync({ Target: 'block.remove', Ref: id }));
+    },
+    /* Map an inline recipient field to its delta target and send it. */
+    syncField: function (nme, val) {
+        if ($inv.d.token() === '') { return; }
+        let map = { invoicetitle: 'title', invoiceaddress: 'address', invoiceemail: 'email', loc: 'provisionlocation', provisionlocation: 'provisionlocation', provisionperiod: 'provisionperiod' };
+        let target = map[nme]; if (!target) { return; }
+        $inv.d.sync({ Target: target, Value: val });
+    },
+    /* Render the totals footer from the server sums (port of invSumUpdate's footer half). */
+    footer: function (tbl, sums, admin) {
+        let ft = tbl.children('tfoot').empty(); tbl.nextAll('.fnote').remove();
+        let p13b = bool(admin.p13b, false);
+        let rwcy = (lbl, val, cls) => $$.tdc('currency', $$.tr(ft, { class: cls || 'tsum' }).append([$$.tdc('aux'), $$.td({ colspan: 4 }).text(lbl)]), fnum(val, $rct.cst));
+        let fn = (t) => $$.dc('fnote').insertAfter(tbl).rwText(t);
+        rwcy('Netto', sums.total_net || 0);
+        if (p13b === false) { $.each(sums.vat || {}, (rate, amt) => rwcy($rct.vat + ' ' + rate + '%', amt, 'tvat')); }
+        rwcy('Summe', sums.total_gross || 0);
+        let itype = (admin.type || '');
+        if (itype === 'i') { fn($rct.note2); fn($rct.note4); }
+        else if (itype === 'c') { fn($rct.note2); }
+        else {
+            fn(string($rct.note3, [fnum(((sums.service_net || 0) + (sums.service_vat || 0)) * (admin.tax_servicerefund || 0), $rct.cst)])).aC('ntax');
+            fn($rct.note2);
+            fn(string($rct.note1, [fnum((sums.service_net || 0) + (sums.service_vat || 0), $rct.cst), fnum(sums.service_net || 0, $rct.cst), fnum(sums.service_vat || 0, $rct.cst)]));
+        }
+        if (p13b === true) { fn($rct.note13b); }
+    },
+    validation: function (msgs) {
+        let frm = $('div.invoice_layout'); if (frm.length < 1) { return; }
+        let box = frm.children('.dvalidation');
+        if (box.length < 1) { box = $$.dc('dvalidation'); frm.prepend(box); }
+        box.empty().tC('hidden', (msgs || []).length < 1);
+        $.each(msgs || [], (i, m) => $$.dc('dvmsg', box).aC(m.severity).text(m.message));
+    },
+    /* PDF preview straight from the cache; confirm = flush + finalise, cancel = discard. */
+    preview: function () {
+        let t = $inv.d.token(); if (t === '') { return; }
+        let l = $inv.d.layout();
+        let email = ($inv.d.tbl().data('new') || {}).invoiceemail || '';
+        if ($fis.ValidateEmail(email) === false) { if (bool(confirm($ict.ivE + $ict.ivEc), false) === false) { return; } }
+        l.aC('freeze');
+        $ocms.postXT({
+            url: $ocms.url('inv/dpreview'), data: { token: t }, success: (response) => {
+                l.rC('freeze');
+                let c = $$.dc('imagecollection pdfpreview'), vhr = Math.round(vh() * 0.88), total = response.total;
+                if (total > 10) { $$.dc('note warn', c).text($ict.tpe); }
+                $.each(response.img || [], (ii, img) => { $$.dc('pdfp', c).append($$.img(img).css('max-height', (vhr - rpx(6)).toString() + 'px')); });
+                for (let ic = (response.img || []).length + 1; ic <= total; ic++) { $$.dc('pdfp ph', c).append($$.dc('note', $ict.pna)); }
+                $ocms.dlg(c, {
+                    size: [vhr, Math.round(vw() * 0.88)], zindex: 50, form: false, button: $rct.crI,
+                    confirm: function (e) {
+                        let ct = $(this); l.aC('freeze');
+                        $ocms.postXT({
+                            url: $ocms.url('inv/dsave'), data: { token: t }, success: (sv) => {
+                                $ocms.postXT({
+                                    url: $ocms.url('req/sconf'), data: { id: sv.invid }, success: (cresp) => {
+                                        ct.trigger('modal_close');
+                                        if (cresp.hasFile === true) { window.open($ocms.url('req/idoc') + '?id=' + sv.invid, '_blank'); }
+                                        $inv.d.close();
+                                        $ocms.init('req'); $inv.rReload();
+                                    }, error: () => { alert($t.f1); ct.trigger('modal_close'); }, complete: () => { l.rC('freeze'); }
+                                });
+                            }, error: () => { l.rC('freeze'); alert($ict.eis); }
+                        });
+                    },
+                    cancel: function (e) { if (confirm($ict.cdI)) { $inv.d.close(); $inv.rReload(); } }
+                });
+            }, error: () => { l.rC('freeze'); alert($ict.eis); }
+        });
+    },
+    /* Zwischenspeichern: flush the cache to the DB (no re-upload); stay in the editor. */
+    save: function () {
+        let t = $inv.d.token(); if (t === '') { return; }
+        let l = $inv.d.layout(); l.aC('freeze');
+        $ocms.postXT({
+            url: $ocms.url('inv/dsave'), data: { token: t }, success: (r) => { $inv.d.tbl().data('invid', r.invid); },
+            error: () => { alert($ict.eis); }, complete: () => { l.rC('freeze'); }
+        });
+    },
+    history: function () {
+        let t = $inv.d.token(); if (t === '') { return; }
+        $ocms.postXT({
+            url: $ocms.url('inv/dhistory'), data: { token: t }, success: (r) => {
+                let c = $$.dc('dhist');
+                if ((r.history || []).length < 1) { $$.dc('note', c).text('Noch keine Änderungen erfasst.'); }
+                else {
+                    let ts = $$.tblset({ class: 'invtbl fullwidth' }, c);
+                    $$.tr(ts.hd).append([$$.th().text('Zeit'), $$.th().text('Feld'), $$.th().text('Alt'), $$.th().text('Neu')]);
+                    $.each(r.history, (i, h) => $$.tr(ts.bdy).append([$$.tdc('keep', fdt(h.timestamp)), $$.td().text(h.target), $$.td().text(h.oldValue), $$.td().text(h.newValue)]));
+                }
+                $ocms.dlg(c, { width: 800, form: false });
+            }
+        });
+    },
+    discard: function () {
+        let invid = $inv.d.tbl().data('invid') || '';
+        if (invid === '') { alert('Es wurde noch kein Zwischenstand gespeichert, der wiederhergestellt werden könnte.'); return; }
+        if (confirm('Alle Änderungen verwerfen und den zuletzt gespeicherten Stand neu laden?') === false) { return; }
+        $inv.d.close();
+        $inv.cntInv({ id: invid });
+    },
+    warnExpiry: function (secondsLeft) {
+        let mins = Math.max(1, Math.round((secondsLeft || 0) / 60));
+        $fis.notifications.push({ severity: 'info', title: 'Entwurf läuft ab', message: 'Der Rechnungsentwurf läuft in etwa ' + mins + ' Minute(n) ab. Bitte zwischenspeichern, sonst gehen die Änderungen verloren.' });
+    },
+    closed: function (reason) {
+        let t = $inv.d.token();
+        $inv.d.tbl().removeData('dtoken');
+        if (t !== '') { $fis.draft.release(t); }
+        $fis.frm_edit().remove(); $fis.lf(true);
+        $fis.notifications.push({ severity: 'error', title: 'Entwurf geschlossen', message: reason === 'expired' ? 'Der Rechnungsentwurf ist wegen Inaktivität abgelaufen. Nicht gespeicherte Änderungen sind verloren.' : 'Der Rechnungsentwurf wurde geschlossen.' });
+        try { $inv.rReload(); } catch (e) { }
+    },
+    close: function () {
+        let t = $inv.d.token();
+        if (t !== '') { $ocms.postXT({ url: $ocms.url('inv/dclose'), data: { token: t } }); $fis.draft.release(t); }
+        $inv.d.tbl().removeData('dtoken');
+    }
+};
 $inv.cInv2 = function (data) {
    let fr = $$.dc('rfrm').ldng(1);
    let o = $ocms.dlg(fr, { width: 1000 });
@@ -499,6 +690,8 @@ $inv.eHtml = function (ev) {
            if (typeof change === 'function') {
                change(response.txt);
            }
+            /* backend-authoritative: mirror the inline recipient-field edit to the server session */
+            $inv.d.syncField(ev.data.nme, isPlainText ? (response.txt || '') : response.txt);
        },
        tinymce: { valid_elements: 'br', hidemenu: true, hidetoolbar: true }
    }
@@ -713,6 +906,13 @@ $inv.invSumUpdate = function () {
    }
    tbl.data('sms', sms);
    tbl.data('bai', ba);
+    /* Backend-authoritative seeding (ADR 0006): on the first calculation of an invoice
+       draft (invSumUpdate is only bound for invoices, never reminders), hand the assembled
+       model to the server session and switch to server-driven totals from then on. */
+    if ((tbl.data('dtoken') || '') === '' && bool(tbl.data('dseeding'), false) === false && ((tbl.data('admin') || {}).type != null)) {
+        tbl.data('dseeding', true);
+        $inv.d.seed($.extend($inv.invcPayload(tbl.data()), { invid: tbl.data('invid') || '' }));
+    }
 };
 $inv.worknotes = function (rx) {
    let wn = '';
@@ -800,7 +1000,13 @@ $inv.rendersrq = function () {
        $$.tdc('currency isumval', istr);
    }
 };
-$inv.t_fds_inv = () => { $('div.invoice_layout table.invi').trigger('fds.inv'); };
+$inv.t_fds_inv = () => {
+    let tbl = $('div.invoice_layout table.invi');
+    tbl.trigger('fds.inv');
+    /* After any local item mutation, push the changed block(s) to the authoritative
+       server session as granular deltas (invoice drafts only — reminders have no token). */
+    if ((tbl.data('dtoken') || '') !== '') { $inv.d.syncChanged(tbl); }
+};
 $inv.sedit = () => {
    $inv.sprev(true);
 };
@@ -855,6 +1061,7 @@ $inv.sp13b = () => {
    } else {
    }
    tbl.trigger('fds.inv');
+    $inv.d.sync({ Target: 'p13b', Value: d.admin.p13b });
 };
 /* Maps an item row's data to the backend item contract consumed by InvoiceSetPricing
   / FuchsPdf.ApplyInvoice: { id, type, title (plain), desc (html), qty, price_net,
@@ -909,6 +1116,7 @@ $inv.setSetmode = (mode) => {
    let opts = (d.inv.InvoiceOptions || '').split(',').filter(x => x !== '' && x.indexOf('setmode:') !== 0);
    if (mode && mode !== 'setprice') { opts.push('setmode:' + mode); }
    d.inv.InvoiceOptions = opts.join(',');
+    $inv.d.sync({ Target: 'setmode', Value: mode });
 };
 $inv.sctp = () => {
    let flds = $invcol.ctp;
@@ -925,6 +1133,7 @@ $inv.sctp = () => {
            cvo.contactEmail = response.email;
            d.new.CustomValues = JSON.stringify(cvo);  //Assign it to new Values so that this is submitted also
            l.find('.ctpfrm').text(ne(response.name, response.email));
+            $inv.d.sync({ Target: 'contact', Value: { name: response.name, email: response.email } });

        }, typedvalues: true
    });
@@ -949,82 +1158,12 @@ $inv.invcPayload = function (d) {
    adm.customerid = (adm.customerid != null ? adm.customerid : adm.CustomerId);
    return { admin: adm, req: d.bai, sms: d.sms, new: nw };
 };
-$inv.ssave = () => {
-    var l = $('div.invoice_layout'), d = l.find('table.invi').data();
-    $inv.t_fds_inv();
-    l.aC('freeze');
-    $ocms.postXT({
-        url: $ocms.url('req/save'), data: { invc: JSON.stringify($inv.invcPayload(d)), id: d.invid || '' }, success: (response) => {
-            $inv.cntInv({ id: response.id });
-        }, error: () => {
-            alert($ict.eis);
-        }, complete: () => {
-            l.rC('freeze');
-        }
-    });
-};
-$inv.sprev = (change) => {
-    var l = $('div.invoice_layout'), d = l.find('table.invi').data();
-    change = bool(change, false);
-    $inv.t_fds_inv();
-    l.aC('freeze');
-    //console.debug({ admin: d.admin, req: d.bai, sms: d.sms, new: d.new });
-    if ($fis.ValidateEmail(d.new.invoiceemail || '') === false) {
-        if (bool(confirm($ict.ivE + $ict.ivEc),false) === false) {
-            l.rC('freeze');
-            return;
-        }
-    }
-    $ocms.postXT({
-        url: $ocms.url('req/' + (change === true ?'sedit':'sprep')), data: { invc: JSON.stringify($inv.invcPayload(d)), id: d.invid ||'' }, success: (response) => {
-            let c = $$.dc('imagecollection pdfpreview'), vhr = Math.round(vh() * 0.88), invid = response.id, invtp = response.total;
-            if (invtp > 10) {
-                $$.dc('note warn', c).text($ict.tpe);
-            }
-            $.each(response.img || [], function (ii, img) {
-                $$.dc('pdfp', c).append($$.img(img).css('max-height', (vhr - rpx(6)).toString() + 'px'));
-            });
-            for (let ic = (response.img || []).length + 1; ic <= invtp; ic++) {
-                $$.dc('pdfp ph', c).append($$.dc('note', $ict.pna));
-            }
-            $ocms.dlg(c, {
-                size: [vhr, Math.round(vw() * 0.88)], zindex: 50, form: false, button: $rct.crI, confirm: function (e) {
-                    let ct = $(this);
-                    l.aC('freeze');  /* spinner while the invoice is finalized/emailed on the backend */
-                    $ocms.postXT({
-                        url: $ocms.url('req/sconf'), data: { id: invid }, success: (cresp) => {
-                            ct.trigger('modal_close');
-                            if (cresp.hasFile === true) {
-                                window.open($ocms.url('req/idoc') + '?id=' + invid, '_blank');  /* open pdf in new tab, only if a file was actually created */
-                            }
-                            $ocms.init('req');   /* go back to request list */
-                            $inv.rReload();
-                        }, error: () => {
-                            alert($t.f1);
-                            ct.trigger('modal_close');
-                        }, complete: () => {
-                            l.rC('freeze');
-                        }
-                    });
-                }, cancel: function (e) {
-                    let ct = $(this);
-                    if (confirm($ict.cdI)) {
-                        $ocms.postXT({
-                            url: $ocms.url('req/sdel'), data: {
-                                id: invid
-                            }
-                        });
-                    }
-                    $inv.rReload();
-                }
-            });
-        }, error: () => {
-            alert($ict.eis);
-        }, complete: () => {
-            l.rC('freeze');
-        }
-    });
-};
+/* Zwischenspeichern and preview now run against the backend-authoritative session
+   (ADR 0006): no full-invoice re-upload — the cached draft is flushed / rendered by
+   token. See $inv.d.save / $inv.d.preview. The finalise + email path (req/sconf) is
+   unchanged and is invoked from the preview modal's confirm handler. */
+$inv.ssave = () => { $inv.d.save(); };
+$inv.sprev = (change) => { $inv.d.preview(); };
 $inv.rReload = () => {
    try {
        let s = $('#listframe ul.rql:first').data();
@@ -399,6 +399,33 @@
 	}
 }

+/* Backend-authoritative draft editing (ADR 0006): server-side plausibility findings
+   rendered above the editor, and the change-history dialog table. */
+.edit_frm .invoice_layout .dvalidation {
+	margin: 0 0 1rem 0;
+
+	&.hidden { display: none; }
+
+	.dvmsg {
+		padding: 0.4rem 0.7rem;
+		margin: 0.25rem 0;
+		border-radius: 0.2rem;
+		font-size: 0.9rem;
+		border-left: 4px solid #999;
+		background: #f5f5f5;
+
+		&.error   { border-left-color: #c0392b; background: #fdecea; color: #922; }
+		&.warning { border-left-color: #e0a800; background: #fff8e1; color: #7a5c00; }
+		&.info    { border-left-color: #3498db; background: #eaf4fb; color: #1c5a82; }
+	}
+}
+
+.dhist {
+	.invtbl { width: 100%; }
+	td, th { padding: 0.3rem 0.6rem; text-align: left; vertical-align: top; }
+	tbody tr:nth-child(even) { background: #fafafa; }
+}
+
 .modal-body .lstfrm {
 	display: block;
 	position: relative;
@@ -405,6 +405,50 @@ table.if td.num {
  animation: fis_spin 0.8s linear infinite;
 }

+/* Backend-authoritative draft editing (ADR 0006): server-side plausibility findings
+   rendered above the editor, and the change-history dialog table. */
+.edit_frm .invoice_layout .dvalidation {
+  margin: 0 0 1rem 0;
+}
+.edit_frm .invoice_layout .dvalidation.hidden {
+  display: none;
+}
+.edit_frm .invoice_layout .dvalidation .dvmsg {
+  padding: 0.4rem 0.7rem;
+  margin: 0.25rem 0;
+  border-radius: 0.2rem;
+  font-size: 0.9rem;
+  border-left: 4px solid #999;
+  background: #f5f5f5;
+}
+.edit_frm .invoice_layout .dvalidation .dvmsg.error {
+  border-left-color: #c0392b;
+  background: #fdecea;
+  color: #922;
+}
+.edit_frm .invoice_layout .dvalidation .dvmsg.warning {
+  border-left-color: #e0a800;
+  background: #fff8e1;
+  color: #7a5c00;
+}
+.edit_frm .invoice_layout .dvalidation .dvmsg.info {
+  border-left-color: #3498db;
+  background: #eaf4fb;
+  color: #1c5a82;
+}
+
+.dhist .invtbl {
+  width: 100%;
+}
+.dhist td, .dhist th {
+  padding: 0.3rem 0.6rem;
+  text-align: left;
+  vertical-align: top;
+}
+.dhist tbody tr:nth-child(even) {
+  background: #fafafa;
+}
+
 .modal-body .lstfrm {
  display: block;
  position: relative;
@@ -646,11 +646,202 @@ $inv.eM = (r, re, opt) => {
    if ((opt || '').split(',').includes('setm') === true) {
        m.push({ lbl: $ict.setm, fnc: $inv.ssetmode });
    }
+    if ((opt || '').split(',').includes('iss') === true) {  /* backend-authoritative draft (ADR 0006) */
+        m.push({ lbl: 'Änderungshistorie', fnc: () => $inv.d.history() });
+        m.push({ lbl: 'Änderungen verwerfen', fnc: () => $inv.d.discard() });
+    }
    if (booln(r, false) === true) {
        m.push({ lbl: $ict.rel, fnc: $inv.rReload });
    }
    return $('#topbar').ocmsmenu(m);  /* empty Array => empty menu */
 };
+/* ── Backend-authoritative draft editing controller (ADR 0006/0007) ───────────
+   The server holds the truth for an invoice draft in an in-memory session; this
+   object seeds it, sends single edits as deltas, and renders the totals footer +
+   validation from the authoritative server state. It is invoice-only: reminders
+   never obtain a token (invSumUpdate, the seed trigger, is only bound for invoices),
+   so they keep the legacy stateless flow untouched. */
+$inv.d = {
+    tbl: () => $('div.invoice_layout table.invi'),
+    layout: () => $('div.invoice_layout'),
+    token: function () { return $inv.d.tbl().data('dtoken') || ''; },
+    /* Hash each assembled block so only genuinely-changed blocks are sent as deltas. */
+    hashes: function () {
+        let bai = $inv.d.tbl().data('bai') || [], h = {};
+        $.each(bai, (i, b) => { h[(b.Id || '').toString()] = JSON.stringify(b); });
+        return h;
+    },
+    /* Seed the authoritative server session from the assembled editor payload. Called
+       once from invSumUpdate on open; thereafter the backend is the source of truth. */
+    seed: function (payload) {
+        let l = $inv.d.layout(); l.aC('freeze');
+        $ocms.postXT({
+            url: $ocms.url('inv/dopen'), data: { payload: JSON.stringify(payload) }, success: (r) => {
+                $inv.d.tbl().data('dtoken', r.token).data('dver', r.version).data('dhashes', $inv.d.hashes());
+                $fis.draft.bind(r.token, {
+                    onReady: () => $inv.d.refresh(),
+                    onExpiring: (s) => $inv.d.warnExpiry(s),
+                    onClosed: (reason) => $inv.d.closed(reason)
+                });
+                $inv.d.refresh();
+            }, error: () => { l.rC('freeze'); }, complete: () => { $inv.d.tbl().removeData('dseeding'); }
+        });
+    },
+    /* Re-fetch the authoritative state and render the totals footer + validation from it. */
+    refresh: function (cb) {
+        let t = $inv.d.token(); if (t === '') { return; }
+        $ocms.postXT({
+            url: $ocms.url('inv/dstate'), data: { token: t }, success: (state) => {
+                $inv.d.applyState(state); if (typeof cb === 'function') { cb(state); }
+            }, error: (xhr) => { if (xhr && xhr.status === 410) { $inv.d.closed('expired'); } },
+            complete: () => { $inv.d.layout().rC('freeze'); }
+        });
+    },
+    applyState: function (state) {
+        let tbl = $inv.d.tbl(); if (tbl.length < 1) { return; }
+        tbl.data('dver', state.version).data('serverSums', state.sums);
+        $inv.d.footer(tbl, state.sums || {}, state.admin || {});
+        $inv.d.validation(state.validation || []);
+    },
+    /* Send one change to the server; the draftReady signal and this success both refresh. */
+    sync: function (delta) {
+        let t = $inv.d.token(); if (t === '') { return; }
+        $inv.d.layout().aC('freeze');
+        $ocms.postXT({
+            url: $ocms.url('inv/dpatch'), data: { token: t, delta: JSON.stringify(delta) },
+            success: () => { $inv.d.refresh(); },
+            error: (xhr) => { $inv.d.layout().rC('freeze'); if (xhr && xhr.status === 410) { $inv.d.closed('expired'); } }
+        });
+    },
+    /* Diff the freshly-rebuilt blocks against the last-synced state and send only the
+       changed/removed blocks as granular block.replace / block.remove deltas. */
+    syncChanged: function (tbl) {
+        if (($inv.d.token()) === '') { return; }
+        let bai = tbl.data('bai') || [], prev = tbl.data('dhashes') || {}, next = {}, changed = [], removed = [];
+        $.each(bai, (i, b) => { let id = (b.Id || '').toString(), h = JSON.stringify(b); next[id] = h; if (prev[id] !== h) { changed.push(b); } });
+        $.each(prev, (id) => { if (next[id] === undefined) { removed.push(id); } });
+        tbl.data('dhashes', next);
+        changed.forEach((b) => $inv.d.sync({ Target: 'block.replace', Ref: (b.Id || '').toString(), Value: b }));
+        removed.forEach((id) => $inv.d.sync({ Target: 'block.remove', Ref: id }));
+    },
+    /* Map an inline recipient field to its delta target and send it. */
+    syncField: function (nme, val) {
+        if ($inv.d.token() === '') { return; }
+        let map = { invoicetitle: 'title', invoiceaddress: 'address', invoiceemail: 'email', loc: 'provisionlocation', provisionlocation: 'provisionlocation', provisionperiod: 'provisionperiod' };
+        let target = map[nme]; if (!target) { return; }
+        $inv.d.sync({ Target: target, Value: val });
+    },
+    /* Render the totals footer from the server sums (port of invSumUpdate's footer half). */
+    footer: function (tbl, sums, admin) {
+        let ft = tbl.children('tfoot').empty(); tbl.nextAll('.fnote').remove();
+        let p13b = bool(admin.p13b, false);
+        let rwcy = (lbl, val, cls) => $$.tdc('currency', $$.tr(ft, { class: cls || 'tsum' }).append([$$.tdc('aux'), $$.td({ colspan: 4 }).text(lbl)]), fnum(val, $rct.cst));
+        let fn = (t) => $$.dc('fnote').insertAfter(tbl).rwText(t);
+        rwcy('Netto', sums.total_net || 0);
+        if (p13b === false) { $.each(sums.vat || {}, (rate, amt) => rwcy($rct.vat + ' ' + rate + '%', amt, 'tvat')); }
+        rwcy('Summe', sums.total_gross || 0);
+        let itype = (admin.type || '');
+        if (itype === 'i') { fn($rct.note2); fn($rct.note4); }
+        else if (itype === 'c') { fn($rct.note2); }
+        else {
+            fn(string($rct.note3, [fnum(((sums.service_net || 0) + (sums.service_vat || 0)) * (admin.tax_servicerefund || 0), $rct.cst)])).aC('ntax');
+            fn($rct.note2);
+            fn(string($rct.note1, [fnum((sums.service_net || 0) + (sums.service_vat || 0), $rct.cst), fnum(sums.service_net || 0, $rct.cst), fnum(sums.service_vat || 0, $rct.cst)]));
+        }
+        if (p13b === true) { fn($rct.note13b); }
+    },
+    validation: function (msgs) {
+        let frm = $('div.invoice_layout'); if (frm.length < 1) { return; }
+        let box = frm.children('.dvalidation');
+        if (box.length < 1) { box = $$.dc('dvalidation'); frm.prepend(box); }
+        box.empty().tC('hidden', (msgs || []).length < 1);
+        $.each(msgs || [], (i, m) => $$.dc('dvmsg', box).aC(m.severity).text(m.message));
+    },
+    /* PDF preview straight from the cache; confirm = flush + finalise, cancel = discard. */
+    preview: function () {
+        let t = $inv.d.token(); if (t === '') { return; }
+        let l = $inv.d.layout();
+        let email = ($inv.d.tbl().data('new') || {}).invoiceemail || '';
+        if ($fis.ValidateEmail(email) === false) { if (bool(confirm($ict.ivE + $ict.ivEc), false) === false) { return; } }
+        l.aC('freeze');
+        $ocms.postXT({
+            url: $ocms.url('inv/dpreview'), data: { token: t }, success: (response) => {
+                l.rC('freeze');
+                let c = $$.dc('imagecollection pdfpreview'), vhr = Math.round(vh() * 0.88), total = response.total;
+                if (total > 10) { $$.dc('note warn', c).text($ict.tpe); }
+                $.each(response.img || [], (ii, img) => { $$.dc('pdfp', c).append($$.img(img).css('max-height', (vhr - rpx(6)).toString() + 'px')); });
+                for (let ic = (response.img || []).length + 1; ic <= total; ic++) { $$.dc('pdfp ph', c).append($$.dc('note', $ict.pna)); }
+                $ocms.dlg(c, {
+                    size: [vhr, Math.round(vw() * 0.88)], zindex: 50, form: false, button: $rct.crI,
+                    confirm: function (e) {
+                        let ct = $(this); l.aC('freeze');
+                        $ocms.postXT({
+                            url: $ocms.url('inv/dsave'), data: { token: t }, success: (sv) => {
+                                $ocms.postXT({
+                                    url: $ocms.url('req/sconf'), data: { id: sv.invid }, success: (cresp) => {
+                                        ct.trigger('modal_close');
+                                        if (cresp.hasFile === true) { window.open($ocms.url('req/idoc') + '?id=' + sv.invid, '_blank'); }
+                                        $inv.d.close();
+                                        $ocms.init('req'); $inv.rReload();
+                                    }, error: () => { alert($t.f1); ct.trigger('modal_close'); }, complete: () => { l.rC('freeze'); }
+                                });
+                            }, error: () => { l.rC('freeze'); alert($ict.eis); }
+                        });
+                    },
+                    cancel: function (e) { if (confirm($ict.cdI)) { $inv.d.close(); $inv.rReload(); } }
+                });
+            }, error: () => { l.rC('freeze'); alert($ict.eis); }
+        });
+    },
+    /* Zwischenspeichern: flush the cache to the DB (no re-upload); stay in the editor. */
+    save: function () {
+        let t = $inv.d.token(); if (t === '') { return; }
+        let l = $inv.d.layout(); l.aC('freeze');
+        $ocms.postXT({
+            url: $ocms.url('inv/dsave'), data: { token: t }, success: (r) => { $inv.d.tbl().data('invid', r.invid); },
+            error: () => { alert($ict.eis); }, complete: () => { l.rC('freeze'); }
+        });
+    },
+    history: function () {
+        let t = $inv.d.token(); if (t === '') { return; }
+        $ocms.postXT({
+            url: $ocms.url('inv/dhistory'), data: { token: t }, success: (r) => {
+                let c = $$.dc('dhist');
+                if ((r.history || []).length < 1) { $$.dc('note', c).text('Noch keine Änderungen erfasst.'); }
+                else {
+                    let ts = $$.tblset({ class: 'invtbl fullwidth' }, c);
+                    $$.tr(ts.hd).append([$$.th().text('Zeit'), $$.th().text('Feld'), $$.th().text('Alt'), $$.th().text('Neu')]);
+                    $.each(r.history, (i, h) => $$.tr(ts.bdy).append([$$.tdc('keep', fdt(h.timestamp)), $$.td().text(h.target), $$.td().text(h.oldValue), $$.td().text(h.newValue)]));
+                }
+                $ocms.dlg(c, { width: 800, form: false });
+            }
+        });
+    },
+    discard: function () {
+        let invid = $inv.d.tbl().data('invid') || '';
+        if (invid === '') { alert('Es wurde noch kein Zwischenstand gespeichert, der wiederhergestellt werden könnte.'); return; }
+        if (confirm('Alle Änderungen verwerfen und den zuletzt gespeicherten Stand neu laden?') === false) { return; }
+        $inv.d.close();
+        $inv.cntInv({ id: invid });
+    },
+    warnExpiry: function (secondsLeft) {
+        let mins = Math.max(1, Math.round((secondsLeft || 0) / 60));
+        $fis.notifications.push({ severity: 'info', title: 'Entwurf läuft ab', message: 'Der Rechnungsentwurf läuft in etwa ' + mins + ' Minute(n) ab. Bitte zwischenspeichern, sonst gehen die Änderungen verloren.' });
+    },
+    closed: function (reason) {
+        let t = $inv.d.token();
+        $inv.d.tbl().removeData('dtoken');
+        if (t !== '') { $fis.draft.release(t); }
+        $fis.frm_edit().remove(); $fis.lf(true);
+        $fis.notifications.push({ severity: 'error', title: 'Entwurf geschlossen', message: reason === 'expired' ? 'Der Rechnungsentwurf ist wegen Inaktivität abgelaufen. Nicht gespeicherte Änderungen sind verloren.' : 'Der Rechnungsentwurf wurde geschlossen.' });
+        try { $inv.rReload(); } catch (e) { }
+    },
+    close: function () {
+        let t = $inv.d.token();
+        if (t !== '') { $ocms.postXT({ url: $ocms.url('inv/dclose'), data: { token: t } }); $fis.draft.release(t); }
+        $inv.d.tbl().removeData('dtoken');
+    }
+};
 $inv.cInv2 = function (data) {
    let fr = $$.dc('rfrm').ldng(1);
    let o = $ocms.dlg(fr, { width: 1000 });
@@ -1046,6 +1237,8 @@ $inv.eHtml = function (ev) {
            if (typeof change === 'function') {
                change(response.txt);
            }
+            /* backend-authoritative: mirror the inline recipient-field edit to the server session */
+            $inv.d.syncField(ev.data.nme, isPlainText ? (response.txt || '') : response.txt);
        },
        tinymce: { valid_elements: 'br', hidemenu: true, hidetoolbar: true }
    }
@@ -1260,6 +1453,13 @@ $inv.invSumUpdate = function () {
    }
    tbl.data('sms', sms);
    tbl.data('bai', ba);
+    /* Backend-authoritative seeding (ADR 0006): on the first calculation of an invoice
+       draft (invSumUpdate is only bound for invoices, never reminders), hand the assembled
+       model to the server session and switch to server-driven totals from then on. */
+    if ((tbl.data('dtoken') || '') === '' && bool(tbl.data('dseeding'), false) === false && ((tbl.data('admin') || {}).type != null)) {
+        tbl.data('dseeding', true);
+        $inv.d.seed($.extend($inv.invcPayload(tbl.data()), { invid: tbl.data('invid') || '' }));
+    }
 };
 $inv.worknotes = function (rx) {
    let wn = '';
@@ -1347,7 +1547,13 @@ $inv.rendersrq = function () {
        $$.tdc('currency isumval', istr);
    }
 };
-$inv.t_fds_inv = () => { $('div.invoice_layout table.invi').trigger('fds.inv'); };
+$inv.t_fds_inv = () => {
+    let tbl = $('div.invoice_layout table.invi');
+    tbl.trigger('fds.inv');
+    /* After any local item mutation, push the changed block(s) to the authoritative
+       server session as granular deltas (invoice drafts only — reminders have no token). */
+    if ((tbl.data('dtoken') || '') !== '') { $inv.d.syncChanged(tbl); }
+};
 $inv.sedit = () => {
    $inv.sprev(true);
 };
@@ -1402,6 +1608,7 @@ $inv.sp13b = () => {
    } else {
    }
    tbl.trigger('fds.inv');
+    $inv.d.sync({ Target: 'p13b', Value: d.admin.p13b });
 };
 /* Maps an item row's data to the backend item contract consumed by InvoiceSetPricing
   / FuchsPdf.ApplyInvoice: { id, type, title (plain), desc (html), qty, price_net,
@@ -1456,6 +1663,7 @@ $inv.setSetmode = (mode) => {
    let opts = (d.inv.InvoiceOptions || '').split(',').filter(x => x !== '' && x.indexOf('setmode:') !== 0);
    if (mode && mode !== 'setprice') { opts.push('setmode:' + mode); }
    d.inv.InvoiceOptions = opts.join(',');
+    $inv.d.sync({ Target: 'setmode', Value: mode });
 };
 $inv.sctp = () => {
    let flds = $invcol.ctp;
@@ -1472,6 +1680,7 @@ $inv.sctp = () => {
            cvo.contactEmail = response.email;
            d.new.CustomValues = JSON.stringify(cvo);  //Assign it to new Values so that this is submitted also
            l.find('.ctpfrm').text(ne(response.name, response.email));
+            $inv.d.sync({ Target: 'contact', Value: { name: response.name, email: response.email } });

        }, typedvalues: true
    });
@@ -1496,82 +1705,12 @@ $inv.invcPayload = function (d) {
    adm.customerid = (adm.customerid != null ? adm.customerid : adm.CustomerId);
    return { admin: adm, req: d.bai, sms: d.sms, new: nw };
 };
-$inv.ssave = () => {
-    var l = $('div.invoice_layout'), d = l.find('table.invi').data();
-    $inv.t_fds_inv();
-    l.aC('freeze');
-    $ocms.postXT({
-        url: $ocms.url('req/save'), data: { invc: JSON.stringify($inv.invcPayload(d)), id: d.invid || '' }, success: (response) => {
-            $inv.cntInv({ id: response.id });
-        }, error: () => {
-            alert($ict.eis);
-        }, complete: () => {
-            l.rC('freeze');
-        }
-    });
-};
-$inv.sprev = (change) => {
-    var l = $('div.invoice_layout'), d = l.find('table.invi').data();
-    change = bool(change, false);
-    $inv.t_fds_inv();
-    l.aC('freeze');
-    //console.debug({ admin: d.admin, req: d.bai, sms: d.sms, new: d.new });
-    if ($fis.ValidateEmail(d.new.invoiceemail || '') === false) {
-        if (bool(confirm($ict.ivE + $ict.ivEc),false) === false) {
-            l.rC('freeze');
-            return;
-        }
-    }
-    $ocms.postXT({
-        url: $ocms.url('req/' + (change === true ?'sedit':'sprep')), data: { invc: JSON.stringify($inv.invcPayload(d)), id: d.invid ||'' }, success: (response) => {
-            let c = $$.dc('imagecollection pdfpreview'), vhr = Math.round(vh() * 0.88), invid = response.id, invtp = response.total;
-            if (invtp > 10) {
-                $$.dc('note warn', c).text($ict.tpe);
-            }
-            $.each(response.img || [], function (ii, img) {
-                $$.dc('pdfp', c).append($$.img(img).css('max-height', (vhr - rpx(6)).toString() + 'px'));
-            });
-            for (let ic = (response.img || []).length + 1; ic <= invtp; ic++) {
-                $$.dc('pdfp ph', c).append($$.dc('note', $ict.pna));
-            }
-            $ocms.dlg(c, {
-                size: [vhr, Math.round(vw() * 0.88)], zindex: 50, form: false, button: $rct.crI, confirm: function (e) {
-                    let ct = $(this);
-                    l.aC('freeze');  /* spinner while the invoice is finalized/emailed on the backend */
-                    $ocms.postXT({
-                        url: $ocms.url('req/sconf'), data: { id: invid }, success: (cresp) => {
-                            ct.trigger('modal_close');
-                            if (cresp.hasFile === true) {
-                                window.open($ocms.url('req/idoc') + '?id=' + invid, '_blank');  /* open pdf in new tab, only if a file was actually created */
-                            }
-                            $ocms.init('req');   /* go back to request list */
-                            $inv.rReload();
-                        }, error: () => {
-                            alert($t.f1);
-                            ct.trigger('modal_close');
-                        }, complete: () => {
-                            l.rC('freeze');
-                        }
-                    });
-                }, cancel: function (e) {
-                    let ct = $(this);
-                    if (confirm($ict.cdI)) {
-                        $ocms.postXT({
-                            url: $ocms.url('req/sdel'), data: {
-                                id: invid
-                            }
-                        });
-                    }
-                    $inv.rReload();
-                }
-            });
-        }, error: () => {
-            alert($ict.eis);
-        }, complete: () => {
-            l.rC('freeze');
-        }
-    });
-};
+/* Zwischenspeichern and preview now run against the backend-authoritative session
+   (ADR 0006): no full-invoice re-upload — the cached draft is flushed / rendered by
+   token. See $inv.d.save / $inv.d.preview. The finalise + email path (req/sconf) is
+   unchanged and is invoked from the preview modal's confirm handler. */
+$inv.ssave = () => { $inv.d.save(); };
+$inv.sprev = (change) => { $inv.d.preview(); };
 $inv.rReload = () => {
    try {
        let s = $('#listframe ul.rql:first').data();
@@ -542,6 +542,50 @@ table.if th.keep, table.if td.keep {
  animation: fis_spin 0.8s linear infinite;
 }

+/* Backend-authoritative draft editing (ADR 0006): server-side plausibility findings
+   rendered above the editor, and the change-history dialog table. */
+.edit_frm .invoice_layout .dvalidation {
+  margin: 0 0 1rem 0;
+}
+.edit_frm .invoice_layout .dvalidation.hidden {
+  display: none;
+}
+.edit_frm .invoice_layout .dvalidation .dvmsg {
+  padding: 0.4rem 0.7rem;
+  margin: 0.25rem 0;
+  border-radius: 0.2rem;
+  font-size: 0.9rem;
+  border-left: 4px solid #999;
+  background: #f5f5f5;
+}
+.edit_frm .invoice_layout .dvalidation .dvmsg.error {
+  border-left-color: #c0392b;
+  background: #fdecea;
+  color: #922;
+}
+.edit_frm .invoice_layout .dvalidation .dvmsg.warning {
+  border-left-color: #e0a800;
+  background: #fff8e1;
+  color: #7a5c00;
+}
+.edit_frm .invoice_layout .dvalidation .dvmsg.info {
+  border-left-color: #3498db;
+  background: #eaf4fb;
+  color: #1c5a82;
+}
+
+.dhist .invtbl {
+  width: 100%;
+}
+.dhist td, .dhist th {
+  padding: 0.3rem 0.6rem;
+  text-align: left;
+  vertical-align: top;
+}
+.dhist tbody tr:nth-child(even) {
+  background: #fafafa;
+}
+
 .modal-body .lstfrm {
  display: block;
  position: relative;
@@ -627,11 +627,202 @@ $inv.eM = (r, re, opt) => {
    if ((opt || '').split(',').includes('setm') === true) {
        m.push({ lbl: $ict.setm, fnc: $inv.ssetmode });
    }
+    if ((opt || '').split(',').includes('iss') === true) {  /* backend-authoritative draft (ADR 0006) */
+        m.push({ lbl: 'Änderungshistorie', fnc: () => $inv.d.history() });
+        m.push({ lbl: 'Änderungen verwerfen', fnc: () => $inv.d.discard() });
+    }
    if (booln(r, false) === true) {
        m.push({ lbl: $ict.rel, fnc: $inv.rReload });
    }
    return $('#topbar').ocmsmenu(m);  /* empty Array => empty menu */
 };
+/* ── Backend-authoritative draft editing controller (ADR 0006/0007) ───────────
+   The server holds the truth for an invoice draft in an in-memory session; this
+   object seeds it, sends single edits as deltas, and renders the totals footer +
+   validation from the authoritative server state. It is invoice-only: reminders
+   never obtain a token (invSumUpdate, the seed trigger, is only bound for invoices),
+   so they keep the legacy stateless flow untouched. */
+$inv.d = {
+    tbl: () => $('div.invoice_layout table.invi'),
+    layout: () => $('div.invoice_layout'),
+    token: function () { return $inv.d.tbl().data('dtoken') || ''; },
+    /* Hash each assembled block so only genuinely-changed blocks are sent as deltas. */
+    hashes: function () {
+        let bai = $inv.d.tbl().data('bai') || [], h = {};
+        $.each(bai, (i, b) => { h[(b.Id || '').toString()] = JSON.stringify(b); });
+        return h;
+    },
+    /* Seed the authoritative server session from the assembled editor payload. Called
+       once from invSumUpdate on open; thereafter the backend is the source of truth. */
+    seed: function (payload) {
+        let l = $inv.d.layout(); l.aC('freeze');
+        $ocms.postXT({
+            url: $ocms.url('inv/dopen'), data: { payload: JSON.stringify(payload) }, success: (r) => {
+                $inv.d.tbl().data('dtoken', r.token).data('dver', r.version).data('dhashes', $inv.d.hashes());
+                $fis.draft.bind(r.token, {
+                    onReady: () => $inv.d.refresh(),
+                    onExpiring: (s) => $inv.d.warnExpiry(s),
+                    onClosed: (reason) => $inv.d.closed(reason)
+                });
+                $inv.d.refresh();
+            }, error: () => { l.rC('freeze'); }, complete: () => { $inv.d.tbl().removeData('dseeding'); }
+        });
+    },
+    /* Re-fetch the authoritative state and render the totals footer + validation from it. */
+    refresh: function (cb) {
+        let t = $inv.d.token(); if (t === '') { return; }
+        $ocms.postXT({
+            url: $ocms.url('inv/dstate'), data: { token: t }, success: (state) => {
+                $inv.d.applyState(state); if (typeof cb === 'function') { cb(state); }
+            }, error: (xhr) => { if (xhr && xhr.status === 410) { $inv.d.closed('expired'); } },
+            complete: () => { $inv.d.layout().rC('freeze'); }
+        });
+    },
+    applyState: function (state) {
+        let tbl = $inv.d.tbl(); if (tbl.length < 1) { return; }
+        tbl.data('dver', state.version).data('serverSums', state.sums);
+        $inv.d.footer(tbl, state.sums || {}, state.admin || {});
+        $inv.d.validation(state.validation || []);
+    },
+    /* Send one change to the server; the draftReady signal and this success both refresh. */
+    sync: function (delta) {
+        let t = $inv.d.token(); if (t === '') { return; }
+        $inv.d.layout().aC('freeze');
+        $ocms.postXT({
+            url: $ocms.url('inv/dpatch'), data: { token: t, delta: JSON.stringify(delta) },
+            success: () => { $inv.d.refresh(); },
+            error: (xhr) => { $inv.d.layout().rC('freeze'); if (xhr && xhr.status === 410) { $inv.d.closed('expired'); } }
+        });
+    },
+    /* Diff the freshly-rebuilt blocks against the last-synced state and send only the
+       changed/removed blocks as granular block.replace / block.remove deltas. */
+    syncChanged: function (tbl) {
+        if (($inv.d.token()) === '') { return; }
+        let bai = tbl.data('bai') || [], prev = tbl.data('dhashes') || {}, next = {}, changed = [], removed = [];
+        $.each(bai, (i, b) => { let id = (b.Id || '').toString(), h = JSON.stringify(b); next[id] = h; if (prev[id] !== h) { changed.push(b); } });
+        $.each(prev, (id) => { if (next[id] === undefined) { removed.push(id); } });
+        tbl.data('dhashes', next);
+        changed.forEach((b) => $inv.d.sync({ Target: 'block.replace', Ref: (b.Id || '').toString(), Value: b }));
+        removed.forEach((id) => $inv.d.sync({ Target: 'block.remove', Ref: id }));
+    },
+    /* Map an inline recipient field to its delta target and send it. */
+    syncField: function (nme, val) {
+        if ($inv.d.token() === '') { return; }
+        let map = { invoicetitle: 'title', invoiceaddress: 'address', invoiceemail: 'email', loc: 'provisionlocation', provisionlocation: 'provisionlocation', provisionperiod: 'provisionperiod' };
+        let target = map[nme]; if (!target) { return; }
+        $inv.d.sync({ Target: target, Value: val });
+    },
+    /* Render the totals footer from the server sums (port of invSumUpdate's footer half). */
+    footer: function (tbl, sums, admin) {
+        let ft = tbl.children('tfoot').empty(); tbl.nextAll('.fnote').remove();
+        let p13b = bool(admin.p13b, false);
+        let rwcy = (lbl, val, cls) => $$.tdc('currency', $$.tr(ft, { class: cls || 'tsum' }).append([$$.tdc('aux'), $$.td({ colspan: 4 }).text(lbl)]), fnum(val, $rct.cst));
+        let fn = (t) => $$.dc('fnote').insertAfter(tbl).rwText(t);
+        rwcy('Netto', sums.total_net || 0);
+        if (p13b === false) { $.each(sums.vat || {}, (rate, amt) => rwcy($rct.vat + ' ' + rate + '%', amt, 'tvat')); }
+        rwcy('Summe', sums.total_gross || 0);
+        let itype = (admin.type || '');
+        if (itype === 'i') { fn($rct.note2); fn($rct.note4); }
+        else if (itype === 'c') { fn($rct.note2); }
+        else {
+            fn(string($rct.note3, [fnum(((sums.service_net || 0) + (sums.service_vat || 0)) * (admin.tax_servicerefund || 0), $rct.cst)])).aC('ntax');
+            fn($rct.note2);
+            fn(string($rct.note1, [fnum((sums.service_net || 0) + (sums.service_vat || 0), $rct.cst), fnum(sums.service_net || 0, $rct.cst), fnum(sums.service_vat || 0, $rct.cst)]));
+        }
+        if (p13b === true) { fn($rct.note13b); }
+    },
+    validation: function (msgs) {
+        let frm = $('div.invoice_layout'); if (frm.length < 1) { return; }
+        let box = frm.children('.dvalidation');
+        if (box.length < 1) { box = $$.dc('dvalidation'); frm.prepend(box); }
+        box.empty().tC('hidden', (msgs || []).length < 1);
+        $.each(msgs || [], (i, m) => $$.dc('dvmsg', box).aC(m.severity).text(m.message));
+    },
+    /* PDF preview straight from the cache; confirm = flush + finalise, cancel = discard. */
+    preview: function () {
+        let t = $inv.d.token(); if (t === '') { return; }
+        let l = $inv.d.layout();
+        let email = ($inv.d.tbl().data('new') || {}).invoiceemail || '';
+        if ($fis.ValidateEmail(email) === false) { if (bool(confirm($ict.ivE + $ict.ivEc), false) === false) { return; } }
+        l.aC('freeze');
+        $ocms.postXT({
+            url: $ocms.url('inv/dpreview'), data: { token: t }, success: (response) => {
+                l.rC('freeze');
+                let c = $$.dc('imagecollection pdfpreview'), vhr = Math.round(vh() * 0.88), total = response.total;
+                if (total > 10) { $$.dc('note warn', c).text($ict.tpe); }
+                $.each(response.img || [], (ii, img) => { $$.dc('pdfp', c).append($$.img(img).css('max-height', (vhr - rpx(6)).toString() + 'px')); });
+                for (let ic = (response.img || []).length + 1; ic <= total; ic++) { $$.dc('pdfp ph', c).append($$.dc('note', $ict.pna)); }
+                $ocms.dlg(c, {
+                    size: [vhr, Math.round(vw() * 0.88)], zindex: 50, form: false, button: $rct.crI,
+                    confirm: function (e) {
+                        let ct = $(this); l.aC('freeze');
+                        $ocms.postXT({
+                            url: $ocms.url('inv/dsave'), data: { token: t }, success: (sv) => {
+                                $ocms.postXT({
+                                    url: $ocms.url('req/sconf'), data: { id: sv.invid }, success: (cresp) => {
+                                        ct.trigger('modal_close');
+                                        if (cresp.hasFile === true) { window.open($ocms.url('req/idoc') + '?id=' + sv.invid, '_blank'); }
+                                        $inv.d.close();
+                                        $ocms.init('req'); $inv.rReload();
+                                    }, error: () => { alert($t.f1); ct.trigger('modal_close'); }, complete: () => { l.rC('freeze'); }
+                                });
+                            }, error: () => { l.rC('freeze'); alert($ict.eis); }
+                        });
+                    },
+                    cancel: function (e) { if (confirm($ict.cdI)) { $inv.d.close(); $inv.rReload(); } }
+                });
+            }, error: () => { l.rC('freeze'); alert($ict.eis); }
+        });
+    },
+    /* Zwischenspeichern: flush the cache to the DB (no re-upload); stay in the editor. */
+    save: function () {
+        let t = $inv.d.token(); if (t === '') { return; }
+        let l = $inv.d.layout(); l.aC('freeze');
+        $ocms.postXT({
+            url: $ocms.url('inv/dsave'), data: { token: t }, success: (r) => { $inv.d.tbl().data('invid', r.invid); },
+            error: () => { alert($ict.eis); }, complete: () => { l.rC('freeze'); }
+        });
+    },
+    history: function () {
+        let t = $inv.d.token(); if (t === '') { return; }
+        $ocms.postXT({
+            url: $ocms.url('inv/dhistory'), data: { token: t }, success: (r) => {
+                let c = $$.dc('dhist');
+                if ((r.history || []).length < 1) { $$.dc('note', c).text('Noch keine Änderungen erfasst.'); }
+                else {
+                    let ts = $$.tblset({ class: 'invtbl fullwidth' }, c);
+                    $$.tr(ts.hd).append([$$.th().text('Zeit'), $$.th().text('Feld'), $$.th().text('Alt'), $$.th().text('Neu')]);
+                    $.each(r.history, (i, h) => $$.tr(ts.bdy).append([$$.tdc('keep', fdt(h.timestamp)), $$.td().text(h.target), $$.td().text(h.oldValue), $$.td().text(h.newValue)]));
+                }
+                $ocms.dlg(c, { width: 800, form: false });
+            }
+        });
+    },
+    discard: function () {
+        let invid = $inv.d.tbl().data('invid') || '';
+        if (invid === '') { alert('Es wurde noch kein Zwischenstand gespeichert, der wiederhergestellt werden könnte.'); return; }
+        if (confirm('Alle Änderungen verwerfen und den zuletzt gespeicherten Stand neu laden?') === false) { return; }
+        $inv.d.close();
+        $inv.cntInv({ id: invid });
+    },
+    warnExpiry: function (secondsLeft) {
+        let mins = Math.max(1, Math.round((secondsLeft || 0) / 60));
+        $fis.notifications.push({ severity: 'info', title: 'Entwurf läuft ab', message: 'Der Rechnungsentwurf läuft in etwa ' + mins + ' Minute(n) ab. Bitte zwischenspeichern, sonst gehen die Änderungen verloren.' });
+    },
+    closed: function (reason) {
+        let t = $inv.d.token();
+        $inv.d.tbl().removeData('dtoken');
+        if (t !== '') { $fis.draft.release(t); }
+        $fis.frm_edit().remove(); $fis.lf(true);
+        $fis.notifications.push({ severity: 'error', title: 'Entwurf geschlossen', message: reason === 'expired' ? 'Der Rechnungsentwurf ist wegen Inaktivität abgelaufen. Nicht gespeicherte Änderungen sind verloren.' : 'Der Rechnungsentwurf wurde geschlossen.' });
+        try { $inv.rReload(); } catch (e) { }
+    },
+    close: function () {
+        let t = $inv.d.token();
+        if (t !== '') { $ocms.postXT({ url: $ocms.url('inv/dclose'), data: { token: t } }); $fis.draft.release(t); }
+        $inv.d.tbl().removeData('dtoken');
+    }
+};
 $inv.cInv2 = function (data) {
    let fr = $$.dc('rfrm').ldng(1);
    let o = $ocms.dlg(fr, { width: 1000 });
@@ -1027,6 +1218,8 @@ $inv.eHtml = function (ev) {
            if (typeof change === 'function') {
                change(response.txt);
            }
+            /* backend-authoritative: mirror the inline recipient-field edit to the server session */
+            $inv.d.syncField(ev.data.nme, isPlainText ? (response.txt || '') : response.txt);
        },
        tinymce: { valid_elements: 'br', hidemenu: true, hidetoolbar: true }
    }
@@ -1241,6 +1434,13 @@ $inv.invSumUpdate = function () {
    }
    tbl.data('sms', sms);
    tbl.data('bai', ba);
+    /* Backend-authoritative seeding (ADR 0006): on the first calculation of an invoice
+       draft (invSumUpdate is only bound for invoices, never reminders), hand the assembled
+       model to the server session and switch to server-driven totals from then on. */
+    if ((tbl.data('dtoken') || '') === '' && bool(tbl.data('dseeding'), false) === false && ((tbl.data('admin') || {}).type != null)) {
+        tbl.data('dseeding', true);
+        $inv.d.seed($.extend($inv.invcPayload(tbl.data()), { invid: tbl.data('invid') || '' }));
+    }
 };
 $inv.worknotes = function (rx) {
    let wn = '';
@@ -1328,7 +1528,13 @@ $inv.rendersrq = function () {
        $$.tdc('currency isumval', istr);
    }
 };
-$inv.t_fds_inv = () => { $('div.invoice_layout table.invi').trigger('fds.inv'); };
+$inv.t_fds_inv = () => {
+    let tbl = $('div.invoice_layout table.invi');
+    tbl.trigger('fds.inv');
+    /* After any local item mutation, push the changed block(s) to the authoritative
+       server session as granular deltas (invoice drafts only — reminders have no token). */
+    if ((tbl.data('dtoken') || '') !== '') { $inv.d.syncChanged(tbl); }
+};
 $inv.sedit = () => {
    $inv.sprev(true);
 };
@@ -1383,6 +1589,7 @@ $inv.sp13b = () => {
    } else {
    }
    tbl.trigger('fds.inv');
+    $inv.d.sync({ Target: 'p13b', Value: d.admin.p13b });
 };
 /* Maps an item row's data to the backend item contract consumed by InvoiceSetPricing
   / FuchsPdf.ApplyInvoice: { id, type, title (plain), desc (html), qty, price_net,
@@ -1437,6 +1644,7 @@ $inv.setSetmode = (mode) => {
    let opts = (d.inv.InvoiceOptions || '').split(',').filter(x => x !== '' && x.indexOf('setmode:') !== 0);
    if (mode && mode !== 'setprice') { opts.push('setmode:' + mode); }
    d.inv.InvoiceOptions = opts.join(',');
+    $inv.d.sync({ Target: 'setmode', Value: mode });
 };
 $inv.sctp = () => {
    let flds = $invcol.ctp;
@@ -1453,6 +1661,7 @@ $inv.sctp = () => {
            cvo.contactEmail = response.email;
            d.new.CustomValues = JSON.stringify(cvo);  //Assign it to new Values so that this is submitted also
            l.find('.ctpfrm').text(ne(response.name, response.email));
+            $inv.d.sync({ Target: 'contact', Value: { name: response.name, email: response.email } });

        }, typedvalues: true
    });
@@ -1477,82 +1686,12 @@ $inv.invcPayload = function (d) {
    adm.customerid = (adm.customerid != null ? adm.customerid : adm.CustomerId);
    return { admin: adm, req: d.bai, sms: d.sms, new: nw };
 };
-$inv.ssave = () => {
-    var l = $('div.invoice_layout'), d = l.find('table.invi').data();
-    $inv.t_fds_inv();
-    l.aC('freeze');
-    $ocms.postXT({
-        url: $ocms.url('req/save'), data: { invc: JSON.stringify($inv.invcPayload(d)), id: d.invid || '' }, success: (response) => {
-            $inv.cntInv({ id: response.id });
-        }, error: () => {
-            alert($ict.eis);
-        }, complete: () => {
-            l.rC('freeze');
-        }
-    });
-};
-$inv.sprev = (change) => {
-    var l = $('div.invoice_layout'), d = l.find('table.invi').data();
-    change = bool(change, false);
-    $inv.t_fds_inv();
-    l.aC('freeze');
-    //console.debug({ admin: d.admin, req: d.bai, sms: d.sms, new: d.new });
-    if ($fis.ValidateEmail(d.new.invoiceemail || '') === false) {
-        if (bool(confirm($ict.ivE + $ict.ivEc),false) === false) {
-            l.rC('freeze');
-            return;
-        }
-    }
-    $ocms.postXT({
-        url: $ocms.url('req/' + (change === true ?'sedit':'sprep')), data: { invc: JSON.stringify($inv.invcPayload(d)), id: d.invid ||'' }, success: (response) => {
-            let c = $$.dc('imagecollection pdfpreview'), vhr = Math.round(vh() * 0.88), invid = response.id, invtp = response.total;
-            if (invtp > 10) {
-                $$.dc('note warn', c).text($ict.tpe);
-            }
-            $.each(response.img || [], function (ii, img) {
-                $$.dc('pdfp', c).append($$.img(img).css('max-height', (vhr - rpx(6)).toString() + 'px'));
-            });
-            for (let ic = (response.img || []).length + 1; ic <= invtp; ic++) {
-                $$.dc('pdfp ph', c).append($$.dc('note', $ict.pna));
-            }
-            $ocms.dlg(c, {
-                size: [vhr, Math.round(vw() * 0.88)], zindex: 50, form: false, button: $rct.crI, confirm: function (e) {
-                    let ct = $(this);
-                    l.aC('freeze');  /* spinner while the invoice is finalized/emailed on the backend */
-                    $ocms.postXT({
-                        url: $ocms.url('req/sconf'), data: { id: invid }, success: (cresp) => {
-                            ct.trigger('modal_close');
-                            if (cresp.hasFile === true) {
-                                window.open($ocms.url('req/idoc') + '?id=' + invid, '_blank');  /* open pdf in new tab, only if a file was actually created */
-                            }
-                            $ocms.init('req');   /* go back to request list */
-                            $inv.rReload();
-                        }, error: () => {
-                            alert($t.f1);
-                            ct.trigger('modal_close');
-                        }, complete: () => {
-                            l.rC('freeze');
-                        }
-                    });
-                }, cancel: function (e) {
-                    let ct = $(this);
-                    if (confirm($ict.cdI)) {
-                        $ocms.postXT({
-                            url: $ocms.url('req/sdel'), data: {
-                                id: invid
-                            }
-                        });
-                    }
-                    $inv.rReload();
-                }
-            });
-        }, error: () => {
-            alert($ict.eis);
-        }, complete: () => {
-            l.rC('freeze');
-        }
-    });
-};
+/* Zwischenspeichern and preview now run against the backend-authoritative session
+   (ADR 0006): no full-invoice re-upload — the cached draft is flushed / rendered by
+   token. See $inv.d.save / $inv.d.preview. The finalise + email path (req/sconf) is
+   unchanged and is invoked from the preview modal's confirm handler. */
+$inv.ssave = () => { $inv.d.save(); };
+$inv.sprev = (change) => { $inv.d.preview(); };
 $inv.rReload = () => {
    try {
        let s = $('#listframe ul.rql:first').data();