ζ-3.6: Drop-Notification-Banner für Submission-Conflicts

Auto-Flush hat 4xx-Errors (duplicate, validation_failed, unauthorized)
bisher stillschweigend gedroppt — User offline einreichen, im Web
denselben Text posten, Online gehen → die Native-Submission war weg
ohne Hinweis.

SubmissionQueue:
- struct DropRecord (textPreview, authorName, code, message, droppedAt)
- private(set) var dropNotifications: [DropRecord]
- tryFlush sammelt jetzt einen Pre-Delete-Snapshot in dropNotifications
- consumeDropNotifications() leert die Liste — UI ruft beim
  Banner-Quittieren auf

SubmitQuoteView:
- droppedBanner zeigt alle gedroppten Drafts mit Text-Preview +
  lokalisierter Error-Message
- "Quittieren"-Button leert nur die UI-State (Server-Drop ist final)
- harvestDropNotifications() läuft nach jedem flushPending

iOS + macOS BUILD SUCCEEDED.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Sources/Core/Submit/SubmissionQueue.swift

@@ -21,10 +21,33 @@ final class SubmissionQueue {
     let container: ModelContainer
     private var inFlight: Bool = false
 
+    /// Sammelt Drop-Records vom letzten tryFlush — eine UI-Schicht kann
+    /// sie als "diese N Submissions wurden permanent verworfen"-Banner
+    /// anzeigen, statt dass der User stumm verliert.
+    struct DropRecord: Identifiable, Sendable {
+        let id = UUID()
+        let textPreview: String
+        let authorName: String?
+        let code: String?
+        let message: String
+        let droppedAt: Date
+    }
+
+    /// Drop-Notifications der letzten Session — UI liest und konsumiert
+    /// via `consumeDropNotifications()`.
+    private(set) var dropNotifications: [DropRecord] = []
+
     init(container: ModelContainer) {
         self.container = container
     }
 
+    /// Leert die Liste — Caller hat sie gerade angezeigt.
+    func consumeDropNotifications() -> [DropRecord] {
+        let snapshot = dropNotifications
+        dropNotifications.removeAll()
+        return snapshot
+    }
+
     /// Hängt einen Draft an die Queue.
     func deposit(_ draft: QuoteDraft, error: String? = nil) {
         let ctx = ModelContext(container)
@@ -91,6 +114,15 @@ final class SubmissionQueue {
             } catch let error as ZitareAPIError where shouldDrop(error) {
                 Log.app.warning("Dropping pending submission (permanent error: \(error.code ?? "?", privacy: .public))")
                 entry.lastError = error.errorDescription
+                // Notify UI: dieser Draft wurde verworfen. Pre-Snapshot
+                // der Daten vor dem Delete machen.
+                dropNotifications.append(DropRecord(
+                    textPreview: String(entry.text.prefix(120)),
+                    authorName: entry.authorName,
+                    code: error.code,
+                    message: error.errorDescription ?? "Fehler",
+                    droppedAt: Date()
+                ))
                 ctx.delete(entry)
             } catch let error as LocalizedError {
                 entry.lastError = error.errorDescription

Sources/Features/Submit/SubmitQuoteView.swift

@@ -29,6 +29,7 @@ struct SubmitQuoteView: View {
     @State private var lastSuccessSlug: String?
     @State private var queuedForRetry: Bool = false
     @State private var pendingCount: Int = 0
+    @State private var droppedNotifications: [SubmissionQueue.DropRecord] = []
     @FocusState private var textFocused: Bool
 
     var body: some View {
@@ -38,6 +39,9 @@ struct SubmitQuoteView: View {
                 authorSection
                 sourceSection
                 licenseSection
+                if !droppedNotifications.isEmpty {
+                    Section { droppedBanner }
+                }
                 if pendingCount > 0 {
                     Section { pendingBanner }
                 }
@@ -166,6 +170,35 @@ struct SubmitQuoteView: View {
             .font(.callout)
     }
 
+    private var droppedBanner: some View {
+        VStack(alignment: .leading, spacing: 8) {
+            Label(
+                "\(droppedNotifications.count) Submission(s) wurden verworfen",
+                systemImage: "exclamationmark.octagon"
+            )
+            .foregroundStyle(ZitareTheme.error)
+            .font(.callout)
+            .fontWeight(.medium)
+            ForEach(droppedNotifications) { record in
+                VStack(alignment: .leading, spacing: 2) {
+                    Text("„\(record.textPreview)…\"")
+                        .font(.caption)
+                        .foregroundStyle(ZitareTheme.foreground)
+                        .lineLimit(2)
+                    Text(record.message)
+                        .font(.caption2)
+                        .foregroundStyle(ZitareTheme.mutedForeground)
+                }
+            }
+            Button {
+                droppedNotifications = []
+            } label: {
+                Label("Quittieren", systemImage: "checkmark")
+                    .font(.caption)
+            }
+        }
+    }
+
     private var pendingBanner: some View {
         VStack(alignment: .leading, spacing: 4) {
             Label("\(pendingCount) Submission(s) in der Warteschlange", systemImage: "tray.and.arrow.up")
@@ -294,19 +327,30 @@ struct SubmitQuoteView: View {
 
     @MainActor
     private func flushPending() async {
-        guard pendingCount > 0 else { return }
+        guard pendingCount > 0 else {
+            harvestDropNotifications()
+            return
+        }
         let api = ZitareAPI(auth: auth)
         let sent = await submissionQueue.tryFlush(api: api)
         if sent > 0 {
             Log.app.info("Foreground-Flush: \(sent) Submission(s) nachgereicht")
         }
         refreshPendingCount()
+        harvestDropNotifications()
     }
 
     private func refreshPendingCount() {
         pendingCount = submissionQueue.queueDepth()
     }
 
+    private func harvestDropNotifications() {
+        let drops = submissionQueue.consumeDropNotifications()
+        if !drops.isEmpty {
+            droppedNotifications.append(contentsOf: drops)
+        }
+    }
+
     private func label(for kind: QuoteDraft.SourceKind) -> LocalizedStringKey {
         switch kind {
         case .book: "Buch"