Initial commit for first version of project

GasTankAR.xcodeproj/project.pbxproj

@@ -200,11 +200,12 @@
 				};
 			};
 			buildConfigurationList = 95BEEDC83035F1C000D17653 /* Build configuration list for PBXProject "GasTankAR" */;
-			developmentRegion = en;
+			developmentRegion = de;
 			hasScannedForEncodings = 0;
 			knownRegions = (
 				en,
 				Base,
+				de,
 			);
 			mainGroup = 95BEEDC43035F1C000D17653;
 			minimizedProjectReferenceProxies = 1;
@@ -293,13 +294,16 @@
 				ENABLE_PREVIEWS = YES;
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_FILE = GasTankAR/Info.plist;
-				INFOPLIST_KEY_NSCameraUsageDescription = CAMERA_USAGE_DESCRIPTION;
+				INFOPLIST_KEY_LSApplicationCategoryType = "public.app-category.business";
+				INFOPLIST_KEY_NSCameraUsageDescription = "Die Kamera wird benötigt, um Gastanks im AR-Modus auf dem Grundstück zu visualisieren.";
+				INFOPLIST_KEY_NSLocationWhenInUseUsageDescription = "Der Standort wird verwendet, um aufgenommene Fotos mit ihrem Aufnahmeort zu verknüpfen und auf der Karte anzuzeigen.";
 				INFOPLIST_KEY_UIApplicationSupportsIndirectInputEvents = YES;
 				INFOPLIST_KEY_UILaunchScreen_Generation = YES;
 				INFOPLIST_KEY_UIRequiredDeviceCapabilities = arkit;
 				INFOPLIST_KEY_UIStatusBarHidden = YES;
 				INFOPLIST_KEY_UISupportedInterfaceOrientations_iPad = "UIInterfaceOrientationPortrait UIInterfaceOrientationPortraitUpsideDown UIInterfaceOrientationLandscapeLeft UIInterfaceOrientationLandscapeRight";
 				INFOPLIST_KEY_UISupportedInterfaceOrientations_iPhone = "UIInterfaceOrientationPortrait UIInterfaceOrientationLandscapeLeft UIInterfaceOrientationLandscapeRight";
+				IPHONEOS_DEPLOYMENT_TARGET = 26.0;
 				LD_RUNPATH_SEARCH_PATHS = (
 					"$(inherited)",
 					"@executable_path/Frameworks",
@@ -328,13 +332,16 @@
 				ENABLE_PREVIEWS = YES;
 				GENERATE_INFOPLIST_FILE = YES;
 				INFOPLIST_FILE = GasTankAR/Info.plist;
-				INFOPLIST_KEY_NSCameraUsageDescription = CAMERA_USAGE_DESCRIPTION;
+				INFOPLIST_KEY_LSApplicationCategoryType = "public.app-category.business";
+				INFOPLIST_KEY_NSCameraUsageDescription = "Die Kamera wird benötigt, um Gastanks im AR-Modus auf dem Grundstück zu visualisieren.";
+				INFOPLIST_KEY_NSLocationWhenInUseUsageDescription = "Der Standort wird verwendet, um aufgenommene Fotos mit ihrem Aufnahmeort zu verknüpfen und auf der Karte anzuzeigen.";
 				INFOPLIST_KEY_UIApplicationSupportsIndirectInputEvents = YES;
 				INFOPLIST_KEY_UILaunchScreen_Generation = YES;
 				INFOPLIST_KEY_UIRequiredDeviceCapabilities = arkit;
 				INFOPLIST_KEY_UIStatusBarHidden = YES;
 				INFOPLIST_KEY_UISupportedInterfaceOrientations_iPad = "UIInterfaceOrientationPortrait UIInterfaceOrientationPortraitUpsideDown UIInterfaceOrientationLandscapeLeft UIInterfaceOrientationLandscapeRight";
 				INFOPLIST_KEY_UISupportedInterfaceOrientations_iPhone = "UIInterfaceOrientationPortrait UIInterfaceOrientationLandscapeLeft UIInterfaceOrientationLandscapeRight";
+				IPHONEOS_DEPLOYMENT_TARGET = 26.0;
 				LD_RUNPATH_SEARCH_PATHS = (
 					"$(inherited)",
 					"@executable_path/Frameworks",

GasTankAR.xcodeproj/xcuserdata/dennis.xcuserdatad/xcdebugger/Breakpoints_v2.xcbkptlist

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Bucket
+   uuid = "49F4A6D3-C1CC-44A3-AC2F-F7F6C434BF73"
+   type = "1"
+   version = "2.0">
+   <Breakpoints>
+      <BreakpointProxy
+         BreakpointExtensionID = "Xcode.Breakpoint.FileBreakpoint">
+         <BreakpointContent
+            uuid = "74309E53-14CD-4936-BF18-C77CB66EA2E1"
+            shouldBeEnabled = "Yes"
+            ignoreCount = "0"
+            continueAfterRunningActions = "No"
+            filePath = "GasTankAR/ContentView.swift"
+            startingColumnNumber = "9223372036854775807"
+            endingColumnNumber = "9223372036854775807"
+            startingLineNumber = "20"
+            endingLineNumber = "20"
+            landmarkName = "unknown"
+            landmarkType = "0">
+         </BreakpointContent>
+      </BreakpointProxy>
+   </Breakpoints>
+</Bucket>

GasTankAR/AppDelegate.swift

@@ -10,8 +10,6 @@ import UIKit
 @main
 class AppDelegate: UIResponder, UIApplicationDelegate {
 
-
-
     func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
         // Override point for customization after application launch.
         return true
@@ -31,6 +29,5 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
         // Use this method to release any resources that were specific to the discarded scenes, as they will not return.
     }
 
-
 }
 

GasTankAR/Assets.xcassets/Image.imageset/Contents.json

@@ -0,0 +1,20 @@
+{
+  "images" : [
+    {
+      "idiom" : "universal",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "universal",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "universal",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

GasTankAR/Assets.xcassets/tank-lower.imageset/Contents.json

@@ -0,0 +1,21 @@
+{
+  "images" : [
+    {
+      "filename" : "ChatGPT Image 26. Aug. 2026, 00_01_42.png",
+      "idiom" : "universal",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "universal",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "universal",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

GasTankAR/Assets.xcassets/tank-upper.imageset/Contents.json

@@ -0,0 +1,21 @@
+{
+  "images" : [
+    {
+      "filename" : "ChatGPT Image 26. Aug. 2026, 00_01_57.png",
+      "idiom" : "universal",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "universal",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "universal",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "author" : "xcode",
+    "version" : 1
+  }
+}

GasTankAR/ContentView.swift

@@ -6,35 +6,16 @@
 //
 
 import SwiftUI
-import RealityKit
+import SwiftData
-
-struct ContentView : View {
 
+struct ContentView: View {
     var body: some View {
-        RealityView { content in
+        ProjectListView()
-
+            .modelContainer(for: Project.self)
-            // Create a cube model
-            let model = Entity()
-            let mesh = MeshResource.generateBox(size: 0.1, cornerRadius: 0.005)
-            let material = SimpleMaterial(color: .gray, roughness: 0.15, isMetallic: true)
-            model.components.set(ModelComponent(mesh: mesh, materials: [material]))
-            model.position = [0, 0.05, 0]
-
-            // Create horizontal plane anchor for the content
-            let anchor = AnchorEntity(.plane(.horizontal, classification: .any, minimumBounds: SIMD2<Float>(0.2, 0.2)))
-            anchor.addChild(model)
-
-            // Add the horizontal plane anchor to the scene
-            content.add(anchor)
-
-            content.camera = .spatialTracking
-
-        }
-        .edgesIgnoringSafeArea(.all)
     }
-
 }
 
 #Preview {
-    ContentView()
+    ProjectListView()
+        .modelContainer(PreviewSupport.container)
 }

GasTankAR/Info.plist

@@ -2,6 +2,11 @@
 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 <plist version="1.0">
 <dict>
+	<key>CFBundleLocalizations</key>
+	<array>
+		<string>de</string>
+		<string>en</string>
+	</array>
 	<key>UIApplicationSceneManifest</key>
 	<dict>
 		<key>UIApplicationSupportsMultipleScenes</key>

GasTankAR/Model/Project.swift

@@ -0,0 +1,81 @@
+//
+//  Project.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 25.08.26.
+//
+
+import Foundation
+import SwiftData
+import ARKit
+
+@Model
+final class Project {
+    /// Identifier given by the user for the project. In DOCUframe terms
+    /// it is the LeadID.
+    var leadID: String
+
+    /// Customer name to link the project to.
+    var customerName: String
+
+    var creationDate: Date
+
+    /// Der für das Projekt ausgewählte Tank. Jedes Projekt hat genau einen Tank.
+    /// `Tank` ist `Codable`, daher persistiert SwiftData das direkt als Attribut.
+    var tank: Tank
+
+    /// Archivierte `ARWorldMap` (via `NSKeyedArchiver`). Wegen der Größe extern gespeichert.
+    @Attribute(.externalStorage) var worldMapData: Data?
+
+    /// Welt-Transform des platzierten Tanks (Position, Rotation, Skalierung) als
+    /// 16 Floats (spaltenweise). Zusammen mit der WorldMap wird der Tank so wiederhergestellt.
+    var tankTransform: [Float]?
+
+    /// Im AR-Modus aufgenommene Fotos. Werden beim Löschen des Projekts mitentfernt.
+    @Relationship(deleteRule: .cascade, inverse: \ProjectPhoto.project)
+    var photos: [ProjectPhoto] = []
+
+    init(
+        leadID: String,
+        customerName: String,
+        creationDate: Date,
+        tank: Tank = Tank(),
+        worldMapData: Data? = nil,
+        tankTransform: [Float]? = nil
+    ) {
+        self.leadID = leadID
+        self.customerName = customerName
+        self.creationDate = creationDate
+        self.tank = tank
+        self.worldMapData = worldMapData
+        self.tankTransform = tankTransform
+    }
+
+    /// Human-readable title combining the lead identifier and customer name.
+    var title: String {
+        "\(leadID) – \(customerName)"
+    }
+
+    /// Up to two uppercased initials derived from the customer name, for use as an avatar.
+    var initials: String {
+        let letters = customerName
+            .split(whereSeparator: { $0 == " " || $0 == "&" })
+            .prefix(2)
+            .compactMap { $0.first }
+        return String(letters).uppercased()
+    }
+
+    /// Gespeicherte Session der getrackten Welt. (De-)serialisiert `worldMapData`.
+    /// Berechnete Property – wird von SwiftData nicht persistiert.
+    var worldMap: ARWorldMap? {
+        get {
+            guard let worldMapData else { return nil }
+            return try? NSKeyedUnarchiver.unarchivedObject(ofClass: ARWorldMap.self, from: worldMapData)
+        }
+        set {
+            worldMapData = newValue.flatMap {
+                try? NSKeyedArchiver.archivedData(withRootObject: $0, requiringSecureCoding: true)
+            }
+        }
+    }
+}

GasTankAR/Model/ProjectPhoto.swift

@@ -0,0 +1,49 @@
+//
+//  ProjectPhoto.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 27.08.26.
+//
+
+import Foundation
+import SwiftData
+import CoreLocation
+
+/// Ein im AR-Modus aufgenommenes Foto (Snapshot der Kamera-Sicht), das zu einem Projekt gehört.
+/// Die Bilddaten liegen wegen ihrer Größe extern (`.externalStorage`).
+@Model
+final class ProjectPhoto {
+    /// Aufnahmezeitpunkt – Grundlage für die Gruppierung in der Galerie.
+    var creationDate: Date
+
+    /// JPEG-kodierte Bilddaten.
+    @Attribute(.externalStorage) var imageData: Data
+
+    /// Geografische Breite des Aufnahmeorts, sofern beim Aufnehmen ein Standort vorlag.
+    var latitude: Double?
+    /// Geografische Länge des Aufnahmeorts, sofern beim Aufnehmen ein Standort vorlag.
+    var longitude: Double?
+
+    /// Zugehöriges Projekt (Rückbeziehung zu `Project.photos`).
+    var project: Project?
+
+    init(
+        creationDate: Date,
+        imageData: Data,
+        latitude: Double? = nil,
+        longitude: Double? = nil,
+        project: Project? = nil
+    ) {
+        self.creationDate = creationDate
+        self.imageData = imageData
+        self.latitude = latitude
+        self.longitude = longitude
+        self.project = project
+    }
+
+    /// Aufnahmeort als Koordinate – `nil`, wenn kein Standort gespeichert wurde.
+    var coordinate: CLLocationCoordinate2D? {
+        guard let latitude, let longitude else { return nil }
+        return CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
+    }
+}

GasTankAR/Model/Tank.swift

@@ -0,0 +1,80 @@
+//
+//  Tank.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 25.08.26.
+//
+
+import Foundation
+
+/// Verfügbare Tankgrößen laut Projektplan Phase 4 (Modell + korrekter Maßstab).
+enum TankSize: String, CaseIterable, Identifiable, Codable, Hashable {
+    case t1_2
+    case t2_1
+    case t2_9
+
+    var id: String { rawValue }
+
+    var displayName: String {
+        switch self {
+        case .t1_2: "1,2 t"
+        case .t2_1: "2,1 t"
+        case .t2_9: "2,9 t"
+        }
+    }
+}
+
+/// Verfügbare Tankfarben (Farbvariante mit Logo).
+enum TankColor: String, CaseIterable, Identifiable, Codable, Hashable {
+    case white
+    case green
+
+    var id: String { rawValue }
+
+    var displayName: String {
+        switch self {
+        case .white: "Weiß"
+        case .green: "Grün"
+        }
+    }
+}
+
+/// Aufstellungsart des Tanks.
+enum TankPlacement: String, CaseIterable, Identifiable, Codable, Hashable {
+    case aboveGround
+    case belowGround
+
+    var id: String { rawValue }
+
+    var displayName: String {
+        switch self {
+        case .aboveGround: "Oberirdisch"
+        case .belowGround: "Unterirdisch"
+        }
+    }
+
+    /// Name des Asset-Icons für diese Aufstellungsart.
+    var imageName: String {
+        switch self {
+        case .aboveGround: "tank-upper"
+        case .belowGround: "tank-lower"
+        }
+    }
+}
+
+/// Ein für ein Projekt ausgewählter Tank. Kombiniert die in Phase 4 des
+/// Projektplans vorgesehenen Auswahlmöglichkeiten: Größe, Farbe und
+/// Aufstellungsart sowie die optionale halbtransparente Darstellung.
+struct Tank: Hashable, Codable {
+    var size: TankSize = .t1_2
+    var color: TankColor = .white
+    var placement: TankPlacement = .aboveGround
+
+    /// Optionale Darstellung, bei der nur der Deckel sichtbar ist.
+    var showLidOnly: Bool = false
+
+    /// Kurzbeschreibung für Listen und Detailanzeigen.
+    var displayName: String {
+        "\(size.displayName) · \(color.displayName) · \(placement.displayName)"
+    }
+}

GasTankAR/PreviewSupport.swift

@@ -0,0 +1,134 @@
+//
+//  PreviewSupport.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+#if DEBUG
+import Foundation
+import SwiftData
+import UIKit
+
+/// Beispieldaten und In-Memory-Container ausschließlich für SwiftUI-Previews.
+/// Wird über `#if DEBUG` aus Release-Builds ausgeschlossen.
+@MainActor
+enum PreviewSupport {
+    /// Container mit einer Reihe an Beispielprojekten.
+    static let container: ModelContainer = {
+        let container = makeEmptyContainer()
+        for project in sampleProjects() {
+            container.mainContext.insert(project)
+        }
+        return container
+    }()
+
+    /// Leerer In-Memory-Container (z. B. für den „Leer"-Zustand).
+    static func makeEmptyContainer() -> ModelContainer {
+        let configuration = ModelConfiguration(isStoredInMemoryOnly: true)
+        // swiftlint:disable:next force_try
+        return try! ModelContainer(for: Project.self, configurations: configuration)
+    }
+
+    /// Ein einzelnes Beispielprojekt inklusive Container (für Detail-Previews).
+    static func singleProjectContainer() -> (container: ModelContainer, project: Project) {
+        let container = makeEmptyContainer()
+        let project = Project(
+            leadID: "LEAD-1001",
+            customerName: "Müller Heizungsbau",
+            creationDate: .now,
+            tank: Tank()
+        )
+        container.mainContext.insert(project)
+        return (container, project)
+    }
+
+    /// Projekt inklusive Beispiel-Fotos (mit generierten Test-Bildern) für die Galerie-Preview.
+    /// Deckt mehrere Aufnahmetage sowie Fotos mit und ohne Standort ab.
+    static func galleryProjectContainer() -> (container: ModelContainer, project: Project) {
+        let container = makeEmptyContainer()
+        let project = Project(
+            leadID: "LEAD-1042",
+            customerName: "Müller Heizungsbau",
+            creationDate: .now
+        )
+        container.mainContext.insert(project)
+
+        let day: TimeInterval = 86_400
+        let samples: [(color: UIColor, label: String, offset: TimeInterval, lat: Double?, lon: Double?)] = [
+            (.systemBlue, "1", 0, 52.5200, 13.4050),
+            (.systemGreen, "2", -3_600, 48.1372, 11.5756),
+            (.systemOrange, "3", -day, nil, nil),
+            (.systemPurple, "4", -3 * day, 50.1109, 8.6821),
+        ]
+        for sample in samples {
+            let photo = ProjectPhoto(
+                creationDate: Date.now.addingTimeInterval(sample.offset),
+                imageData: sampleImageData(color: sample.color, label: sample.label),
+                latitude: sample.lat,
+                longitude: sample.lon,
+                project: project
+            )
+            container.mainContext.insert(photo)
+        }
+        return (container, project)
+    }
+
+    /// Einzelnes Beispiel-Foto (mit Standort) für die Detail-Preview.
+    static func samplePhoto() -> ProjectPhoto {
+        ProjectPhoto(
+            creationDate: .now,
+            imageData: sampleImageData(color: .systemTeal, label: "AR"),
+            latitude: 52.5200,
+            longitude: 13.4050
+        )
+    }
+
+    /// Erzeugt ein einfarbiges Test-Bild mit zentrierter Beschriftung als JPEG-Daten.
+    static func sampleImageData(color: UIColor, label: String) -> Data {
+        let size = CGSize(width: 1200, height: 900)
+        let image = UIGraphicsImageRenderer(size: size).image { context in
+            color.setFill()
+            context.fill(CGRect(origin: .zero, size: size))
+
+            let text = label as NSString
+            let attributes: [NSAttributedString.Key: Any] = [
+                .font: UIFont.boldSystemFont(ofSize: 240),
+                .foregroundColor: UIColor.white,
+            ]
+            let textSize = text.size(withAttributes: attributes)
+            let origin = CGPoint(
+                x: (size.width - textSize.width) / 2,
+                y: (size.height - textSize.height) / 2
+            )
+            text.draw(at: origin, withAttributes: attributes)
+        }
+        return image.jpegData(compressionQuality: 0.8) ?? Data()
+    }
+
+    /// Erzeugt eine Reihe von Beispielprojekten.
+    static func sampleProjects(count: Int = 40) -> [Project] {
+        let names: [String] = [
+            "Müller Heizungsbau", "Schmidt GmbH", "Weber & Söhne", "Fischer Sanitär",
+            "Becker Klimatechnik", "Hoffmann Anlagenbau", "Wagner & Partner", "Schulz Energie",
+            "Koch Gasversorgung", "Richter Industrie", "Klein Tankbau", "Wolf Technik",
+            "Neumann GmbH", "Schwarz Heizsysteme", "Zimmermann AG", "Braun Installationen",
+        ]
+
+        var projects: [Project] = []
+        for index in 0..<count {
+            let leadNumber: Int = 1001 + index
+            let leadID: String = "LEAD-" + String(leadNumber)
+            let offset: TimeInterval = TimeInterval(-index) * 86_400
+            let project = Project(
+                leadID: leadID,
+                customerName: names[index % names.count],
+                creationDate: Date.now.addingTimeInterval(offset),
+                tank: Tank()
+            )
+            projects.append(project)
+        }
+        return projects
+    }
+}
+#endif

GasTankAR/Services/DocuframeService.swift

@@ -0,0 +1,71 @@
+//
+//  DocuframeService.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import Foundation
+
+/// Foto-Übergabeobjekt für DOCUframe-Vorgänge – bewusst unabhängig von der
+/// Persistenzschicht (SwiftData), damit die Domäne keine Speicher-Details kennt.
+struct DocuframePhoto: Sendable {
+    let imageData: Data
+    let creationDate: Date
+    let latitude: Double?
+    let longitude: Double?
+}
+
+/// Fehler bei DOCUframe-Vorgängen.
+enum DocuframeError: LocalizedError, Equatable {
+    case noPhotosSelected
+    /// Der Server hat mit einem 4xx-Status geantwortet (fehlerhafte Anfrage).
+    case clientError(statusCode: Int)
+    /// Der Server hat mit einem 5xx-Status geantwortet (Serverproblem).
+    case serverError(statusCode: Int)
+    /// Netzwerk-/Transportfehler (z. B. keine Verbindung).
+    case transport(String)
+
+    var errorDescription: String? {
+        switch self {
+        case .noPhotosSelected:
+            "Es wurden keine Fotos ausgewählt."
+        case .clientError(let statusCode):
+            "Die Anfrage wurde von DOCUframe abgelehnt (Fehler \(statusCode)). Bitte prüfe die Daten und versuche es erneut."
+        case .serverError(let statusCode):
+            "DOCUframe ist derzeit nicht erreichbar (Serverfehler \(statusCode)). Bitte versuche es später erneut."
+        case .transport(let message):
+            message
+        }
+    }
+
+    /// Bildet einen HTTP-Statuscode auf den passenden Fehler ab – `nil` bei Erfolg (2xx/3xx).
+    static func from(statusCode: Int) -> DocuframeError? {
+        switch statusCode {
+        case 400..<500: .clientError(statusCode: statusCode)
+        case 500..<600: .serverError(statusCode: statusCode)
+        default: nil
+        }
+    }
+}
+
+extension HTTPURLResponse {
+    /// Wirft einen ``DocuframeError``, wenn der Statuscode einen 4xx-/5xx-Fehler darstellt.
+    func validateDocuframeStatus() throws {
+        if let error = DocuframeError.from(statusCode: statusCode) {
+            throw error
+        }
+    }
+}
+
+/// Abstraktion des DOCUframe-Zugriffs (Upload & Mailversand).
+///
+/// Clean-Architecture-Grenze: Die Präsentationsschicht hängt nur von diesem Protokoll ab,
+/// nicht von der konkreten DOCUframe-Anbindung. Konkrete Implementierungen (Stub, echte
+/// Anbindung, Mock für Tests) liegen in der Infrastruktur- bzw. Testschicht.
+protocol DocuframeService: Sendable {
+    /// Lädt die übergebenen Fotos zum Projekt (Lead) in DOCUframe hoch.
+    func uploadPhotos(_ photos: [DocuframePhoto], projectLeadID: String) async throws
+    /// Versendet die übergebenen Fotos als E-Mail über DOCUframe.
+    func sendEmail(_ photos: [DocuframePhoto], projectLeadID: String) async throws
+}

GasTankAR/Services/StubDocuframeService.swift

@@ -0,0 +1,44 @@
+//
+//  StubDocuframeService.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import Foundation
+import OSLog
+
+/// Platzhalter-Implementierung des ``DocuframeService``. Simuliert Latenz und protokolliert
+/// die Aufrufe, führt aber noch keinen echten Upload/Mailversand aus. Die konkrete
+/// DOCUframe-Anbindung ersetzt diesen Stub später, ohne dass die Präsentationsschicht sich ändert.
+struct StubDocuframeService: DocuframeService {
+    private static let logger = Logger(subsystem: "GasTankAR", category: "DOCUframe")
+
+    /// Optionaler HTTP-Statuscode, den der Stub simuliert. Bei 4xx/5xx wirft er den
+    /// entsprechenden ``DocuframeError`` – so lässt sich die Fehlerbehandlung durchspielen.
+    /// Standard `nil` = erfolgreicher Vorgang.
+    private let simulatedStatusCode: Int?
+
+    init(simulatedStatusCode: Int? = nil) {
+        self.simulatedStatusCode = simulatedStatusCode
+    }
+
+    func uploadPhotos(_ photos: [DocuframePhoto], projectLeadID: String) async throws {
+        try await simulate(operation: "Upload", photoCount: photos.count, projectLeadID: projectLeadID)
+    }
+
+    func sendEmail(_ photos: [DocuframePhoto], projectLeadID: String) async throws {
+        try await simulate(operation: "Mailversand", photoCount: photos.count, projectLeadID: projectLeadID)
+    }
+
+    private func simulate(operation: String, photoCount: Int, projectLeadID: String) async throws {
+        Self.logger.info("Stub-\(operation, privacy: .public) von \(photoCount) Foto(s) für Lead \(projectLeadID, privacy: .public)")
+        try await Task.sleep(for: .seconds(1))
+
+        // Simuliert eine Server-Antwort: Bei 4xx/5xx wird der passende Fehler geworfen.
+        if let simulatedStatusCode, let error = DocuframeError.from(statusCode: simulatedStatusCode) {
+            Self.logger.error("DOCUframe-\(operation, privacy: .public) fehlgeschlagen (HTTP \(simulatedStatusCode))")
+            throw error
+        }
+    }
+}

GasTankAR/Views/Docuframe/DocuframeView.swift

@@ -0,0 +1,126 @@
+//
+//  DocuframeView.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import SwiftUI
+import SwiftData
+
+/// DOCUframe-Tab: Auswahl aufgenommener Fotos und Übergabe an DOCUframe (Upload) bzw. Mailversand.
+struct DocuframeView: View {
+    let project: Project
+
+    @State private var viewModel = DocuframeViewModel()
+
+    private let columns = [GridItem(.adaptive(minimum: 110), spacing: 2)]
+
+    private var photos: [ProjectPhoto] {
+        project.photos.sorted { $0.creationDate > $1.creationDate }
+    }
+
+    var body: some View {
+        Group {
+            if photos.isEmpty {
+                ContentUnavailableView(
+                    "Keine Fotos",
+                    systemImage: "photo.on.rectangle.angled",
+                    description: Text("Nimm im AR-Modus Fotos auf, um sie an DOCUframe zu übergeben.")
+                )
+            } else {
+                ScrollView {
+                    LazyVGrid(columns: columns, spacing: 2) {
+                        ForEach(photos) { photo in
+                            selectableThumbnail(photo)
+                        }
+                    }
+                    .padding(2)
+                }
+            }
+        }
+        .safeAreaInset(edge: .bottom) {
+            if !photos.isEmpty { actionBar }
+        }
+        .alert(
+            viewModel.result?.title ?? "",
+            isPresented: resultBinding,
+            presenting: viewModel.result
+        ) { _ in
+            Button("OK", role: .cancel) {}
+        } message: { result in
+            Text(result.message)
+        }
+    }
+
+    private func selectableThumbnail(_ photo: ProjectPhoto) -> some View {
+        let selected = viewModel.isSelected(photo)
+        return PhotoThumbnail(imageData: photo.imageData)
+            .aspectRatio(1, contentMode: .fit)
+            .clipped()
+            .overlay(alignment: .topTrailing) {
+                Image(systemName: selected ? "checkmark.circle.fill" : "circle")
+                    .font(.title3)
+                    .symbolRenderingMode(.palette)
+                    .foregroundStyle(.white, selected ? Color.accentColor : Color.black.opacity(0.35))
+                    .padding(6)
+                    .shadow(radius: 2)
+            }
+            .overlay {
+                if selected {
+                    Rectangle().strokeBorder(Color.accentColor, lineWidth: 3)
+                }
+            }
+            .contentShape(.rect)
+            .onTapGesture { viewModel.toggleSelection(photo) }
+    }
+
+    private var actionBar: some View {
+        VStack(spacing: 10) {
+            Text(viewModel.hasSelection ? "\(viewModel.selectionCount) ausgewählt" : "Fotos zum Übertragen auswählen")
+                .font(.footnote)
+                .foregroundStyle(.secondary)
+
+            VStack(spacing: 8) {
+                Button {
+                    Task { await viewModel.upload(from: photos, leadID: project.leadID) }
+                } label: {
+                    Label("In DOCUframe hochladen", systemImage: "arrow.up.doc")
+                        .frame(maxWidth: .infinity)
+                }
+                .buttonStyle(.borderedProminent)
+
+                Button {
+                    Task { await viewModel.sendEmail(from: photos, leadID: project.leadID) }
+                } label: {
+                    Label("E-Mail senden", systemImage: "envelope")
+                        .frame(maxWidth: .infinity)
+                }
+                .buttonStyle(.bordered)
+            }
+            .controlSize(.large)
+            .disabled(!viewModel.hasSelection || viewModel.isProcessing)
+
+            if viewModel.isProcessing {
+                ProgressView()
+            }
+        }
+        .padding()
+        .background(.bar)
+    }
+
+    private var resultBinding: Binding<Bool> {
+        Binding(
+            get: { viewModel.result != nil },
+            set: { if !$0 { viewModel.result = nil } }
+        )
+    }
+}
+
+#Preview {
+    let sample = PreviewSupport.galleryProjectContainer()
+    return NavigationStack {
+        DocuframeView(project: sample.project)
+    }
+    .modelContainer(sample.container)
+}

GasTankAR/Views/Docuframe/DocuframeViewModel.swift

@@ -0,0 +1,118 @@
+//
+//  DocuframeViewModel.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import Foundation
+import SwiftData
+
+/// Präsentationslogik für den DOCUframe-Tab: verwaltet die Fotoauswahl und stößt Upload bzw.
+/// Mailversand über den injizierten ``DocuframeService`` an. Kennt keine UI-Details.
+@MainActor
+@Observable
+final class DocuframeViewModel {
+    /// Auswahl anhand der stabilen SwiftData-Identität der Fotos.
+    var selectedIDs: Set<PersistentIdentifier> = []
+    /// Läuft gerade ein Upload/Mailversand?
+    private(set) var isProcessing = false
+    /// Ergebnis des letzten Vorgangs für die Anzeige (nil = kein Hinweis).
+    var result: DocuframeActionResult?
+
+    @ObservationIgnored private let service: DocuframeService
+
+    /// Der Service wird injiziert (Default: Stub) – austauschbar für echte Anbindung oder Tests.
+    init(service: DocuframeService = StubDocuframeService()) {
+        self.service = service
+    }
+
+    var hasSelection: Bool { !selectedIDs.isEmpty }
+    var selectionCount: Int { selectedIDs.count }
+
+    func isSelected(_ photo: ProjectPhoto) -> Bool {
+        selectedIDs.contains(photo.persistentModelID)
+    }
+
+    func toggleSelection(_ photo: ProjectPhoto) {
+        let id = photo.persistentModelID
+        if selectedIDs.contains(id) {
+            selectedIDs.remove(id)
+        } else {
+            selectedIDs.insert(id)
+        }
+    }
+
+    func upload(from photos: [ProjectPhoto], leadID: String) async {
+        await perform(from: photos, leadID: leadID, successText: "in DOCUframe hochgeladen") {
+            try await service.uploadPhotos($0, projectLeadID: $1)
+        }
+    }
+
+    func sendEmail(from photos: [ProjectPhoto], leadID: String) async {
+        await perform(from: photos, leadID: leadID, successText: "per E-Mail versendet") {
+            try await service.sendEmail($0, projectLeadID: $1)
+        }
+    }
+
+    // MARK: - Gemeinsame Ausführung
+
+    private func perform(
+        from photos: [ProjectPhoto],
+        leadID: String,
+        successText: String,
+        action: ([DocuframePhoto], String) async throws -> Void
+    ) async {
+        let selected = photos.filter { selectedIDs.contains($0.persistentModelID) }
+        guard !selected.isEmpty else {
+            result = .failure(message: DocuframeError.noPhotosSelected.localizedDescription)
+            return
+        }
+
+        isProcessing = true
+        defer { isProcessing = false }
+
+        let payload = selected.map(Self.makeDTO)
+        do {
+            try await action(payload, leadID)
+            result = .success(message: "\(selected.count) Foto(s) \(successText).")
+        } catch {
+            // Bei HTTP 4xx/5xx (und anderen Fehlern) den Nutzer informieren.
+            result = .failure(message: error.localizedDescription)
+        }
+    }
+
+    /// Bildet das Persistenz-Model auf ein persistenzunabhängiges Domänen-DTO ab.
+    private static func makeDTO(_ photo: ProjectPhoto) -> DocuframePhoto {
+        DocuframePhoto(
+            imageData: photo.imageData,
+            creationDate: photo.creationDate,
+            latitude: photo.latitude,
+            longitude: photo.longitude
+        )
+    }
+}
+
+/// Ergebnis eines DOCUframe-Vorgangs für die Anzeige (Erfolg oder Fehler).
+enum DocuframeActionResult {
+    case success(message: String)
+    case failure(message: String)
+
+    var title: String {
+        switch self {
+        case .success: "Erledigt"
+        case .failure: "Fehler"
+        }
+    }
+
+    var message: String {
+        switch self {
+        case .success(let message), .failure(let message): message
+        }
+    }
+
+    var isError: Bool {
+        if case .failure = self { return true }
+        return false
+    }
+}

GasTankAR/Views/GalleryView.swift

@@ -0,0 +1,263 @@
+//
+//  GalleryView.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 27.08.26.
+//
+
+import SwiftUI
+import SwiftData
+import MapKit
+import CoreLocation
+
+/// Galerie der im AR-Modus aufgenommenen Fotos eines Projekts.
+/// Anzeige wie in der Fotos-App (Raster), gruppiert nach Aufnahmedatum mit
+/// angehefteten Abschnitts-Überschriften – analog zur Buchstaben-Gruppierung der Kontakte-App.
+struct GalleryView: View {
+    @Bindable var project: Project
+    @Environment(\.modelContext) private var modelContext
+
+    @State private var selectedPhoto: ProjectPhoto?
+
+    private let columns = [GridItem(.adaptive(minimum: 110), spacing: 2)]
+
+    /// Fotos nach Tag gruppiert und absteigend sortiert (neueste zuerst).
+    private var sections: [(date: Date, photos: [ProjectPhoto])] {
+        let groups = Dictionary(grouping: project.photos) { photo in
+            Calendar.current.startOfDay(for: photo.creationDate)
+        }
+        return groups
+            .map { (date: $0.key, photos: $0.value.sorted { $0.creationDate > $1.creationDate }) }
+            .sorted { $0.date > $1.date }
+    }
+
+    var body: some View {
+        Group {
+            if project.photos.isEmpty {
+                ContentUnavailableView(
+                    "Keine Fotos",
+                    systemImage: "photo.on.rectangle.angled",
+                    description: Text("Nimm im AR-Modus über den Kamera-Button ein Foto auf.")
+                )
+            } else {
+                ScrollView {
+                    LazyVGrid(columns: columns, spacing: 2, pinnedViews: [.sectionHeaders]) {
+                        ForEach(sections, id: \.date) { section in
+                            Section {
+                                ForEach(section.photos) { photo in
+                                    thumbnail(for: photo)
+                                }
+                            } header: {
+                                sectionHeader(for: section.date)
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        .fullScreenCover(item: $selectedPhoto) { photo in
+            PhotoViewer(photo: photo) {
+                delete(photo)
+            }
+        }
+    }
+
+    private func thumbnail(for photo: ProjectPhoto) -> some View {
+        PhotoThumbnail(imageData: photo.imageData)
+            .aspectRatio(1, contentMode: .fit)
+            .clipped()
+            .contentShape(.rect)
+            .onTapGesture { selectedPhoto = photo }
+            .contextMenu {
+                Button("Löschen", systemImage: "trash", role: .destructive) {
+                    delete(photo)
+                }
+            }
+    }
+
+    private func sectionHeader(for date: Date) -> some View {
+        Text(Self.headerTitle(for: date))
+            .font(.headline)
+            .frame(maxWidth: .infinity, alignment: .leading)
+            .padding(.horizontal)
+            .padding(.vertical, 8)
+            .background(.bar)
+    }
+
+    private func delete(_ photo: ProjectPhoto) {
+        if selectedPhoto == photo { selectedPhoto = nil }
+        modelContext.delete(photo)
+        try? modelContext.save()
+    }
+
+    /// Überschrift wie in der Fotos-App: „Heute"/„Gestern", sonst das ausgeschriebene Datum.
+    private static func headerTitle(for date: Date) -> String {
+        let calendar = Calendar.current
+        if calendar.isDateInToday(date) { return "Heute" }
+        if calendar.isDateInYesterday(date) { return "Gestern" }
+        return date.formatted(.dateTime.day().month(.wide).year())
+    }
+}
+
+/// Lädt und dekodiert die Bilddaten außerhalb des Main-Threads und zeigt das Ergebnis quadratisch.
+struct PhotoThumbnail: View {
+    let imageData: Data
+
+    @State private var image: UIImage?
+
+    var body: some View {
+        GeometryReader { geometry in
+            ZStack {
+                Color(.secondarySystemBackground)
+                if let image {
+                    Image(uiImage: image)
+                        .resizable()
+                        .scaledToFill()
+                        .frame(width: geometry.size.width, height: geometry.size.height)
+                        .clipped()
+                }
+            }
+        }
+        .task(id: imageData) {
+            image = await decode(imageData)
+        }
+    }
+
+    private func decode(_ data: Data) async -> UIImage? {
+        await Task.detached(priority: .userInitiated) {
+            UIImage(data: data)
+        }.value
+    }
+}
+
+/// Vollbild-Betrachter für ein einzelnes Foto mit Schließen- und Löschen-Aktion.
+private struct PhotoViewer: View {
+    let photo: ProjectPhoto
+    let onDelete: () -> Void
+
+    @Environment(\.dismiss) private var dismiss
+
+    var body: some View {
+        NavigationStack {
+            ScrollView {
+                VStack(spacing: 0) {
+                    if let image = UIImage(data: photo.imageData) {
+                        Image(uiImage: image)
+                            .resizable()
+                            .scaledToFit()
+                            .frame(maxWidth: .infinity)
+                    }
+
+                    if let coordinate = photo.coordinate {
+                        VStack(alignment: .leading, spacing: 8) {
+                            Text("Karte")
+                                .font(.headline)
+                            PhotoLocationCard(coordinate: coordinate)
+                        }
+                        .frame(maxWidth: .infinity, alignment: .leading)
+                        .padding()
+                    }
+                }
+            }
+            .background(Color(.systemGroupedBackground))
+            .toolbar {
+                ToolbarItem(placement: .topBarLeading) {
+                    Button("Fertig") { dismiss() }
+                }
+                ToolbarItem(placement: .topBarTrailing) {
+                    Button("Löschen", systemImage: "trash", role: .destructive) {
+                        onDelete()
+                        dismiss()
+                    }
+                }
+            }
+            .toolbarBackground(.visible, for: .navigationBar)
+            .navigationTitle(photo.creationDate.formatted(.dateTime.day().month().year().hour().minute()))
+            .navigationBarTitleDisplayMode(.inline)
+        }
+    }
+}
+
+/// Schwebende Karte, die den Aufnahmeort eines Fotos zeigt: Karten-Vorschau plus
+/// (rückwärts-geokodierte) Adresse. Tippen öffnet den Ort in Apple Karten.
+private struct PhotoLocationCard: View {
+    let coordinate: CLLocationCoordinate2D
+
+    @State private var address: String?
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 0) {
+            Map(
+                initialPosition: .region(
+                    MKCoordinateRegion(center: coordinate, latitudinalMeters: 350, longitudinalMeters: 350)
+                )
+            ) {
+                Marker("Aufnahmeort", coordinate: coordinate)
+                    .tint(.red)
+            }
+            .frame(height: 140)
+            .allowsHitTesting(false)
+
+            HStack(spacing: 12) {
+                Image(systemName: "mappin.circle.fill")
+                    .font(.title2)
+                    .foregroundStyle(.red)
+                VStack(alignment: .leading, spacing: 2) {
+                    Text("Aufnahmeort")
+                        .font(.subheadline.weight(.semibold))
+                    Text(address ?? Self.coordinateText(coordinate))
+                        .font(.caption)
+                        .foregroundStyle(.secondary)
+                        .lineLimit(2)
+                }
+                Spacer(minLength: 0)
+                Image(systemName: "arrow.up.forward.app.fill")
+                    .font(.title3)
+                    .foregroundStyle(.secondary)
+            }
+            .padding(12)
+        }
+        .background(Color(.secondarySystemGroupedBackground))
+        .clipShape(.rect(cornerRadius: 12))
+        .contentShape(.rect)
+        .onTapGesture { openInMaps() }
+        .accessibilityElement(children: .combine)
+        .accessibilityLabel("Aufnahmeort, in Apple Karten öffnen")
+        .task(id: coordinate.latitude + coordinate.longitude) { await reverseGeocode() }
+    }
+
+    private func openInMaps() {
+        let mapItem = MKMapItem(placemark: MKPlacemark(coordinate: coordinate))
+        mapItem.name = address ?? "Aufnahmeort"
+        mapItem.openInMaps()
+    }
+
+    private func reverseGeocode() async {
+        let location = CLLocation(latitude: coordinate.latitude, longitude: coordinate.longitude)
+        guard let placemark = try? await CLGeocoder().reverseGeocodeLocation(location).first else { return }
+        let street = [placemark.thoroughfare, placemark.subThoroughfare]
+            .compactMap { $0 }
+            .joined(separator: " ")
+        let city = [placemark.postalCode, placemark.locality]
+            .compactMap { $0 }
+            .joined(separator: " ")
+        let composed = [street, city].filter { !$0.isEmpty }.joined(separator: ", ")
+        if !composed.isEmpty { address = composed }
+    }
+
+    private static func coordinateText(_ coordinate: CLLocationCoordinate2D) -> String {
+        String(format: "%.5f, %.5f", coordinate.latitude, coordinate.longitude)
+    }
+}
+
+#Preview("Galerie") {
+    let sample = PreviewSupport.galleryProjectContainer()
+    return NavigationStack {
+        GalleryView(project: sample.project)
+    }
+    .modelContainer(sample.container)
+}
+
+#Preview("Foto-Detail") {
+    PhotoViewer(photo: PreviewSupport.samplePhoto()) {}
+}

GasTankAR/Views/ProjectCreate.swift

@@ -0,0 +1,82 @@
+//
+//  ProjectCreate.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 25.08.26.
+//
+
+import SwiftUI
+import SwiftData
+
+struct ProjectCreateView: View {
+    @Environment(\.modelContext) private var modelContext
+    @Environment(\.dismiss) private var dismiss
+
+    @State private var leadID: String = ""
+    @State private var customerName: String = ""
+    @State private var creationDate: Date = .now
+    @State private var tank: Tank = Tank()
+
+    /// Whether the entered values are sufficient to create a project.
+    private var canSave: Bool {
+        !leadID.trimmingCharacters(in: .whitespaces).isEmpty
+            && !customerName.trimmingCharacters(in: .whitespaces).isEmpty
+    }
+
+    var body: some View {
+        NavigationStack {
+            Form {
+                Section("Projektdaten") {
+                    TextField("Lead-ID", text: $leadID)
+                        .textInputAutocapitalization(.characters)
+                        .autocorrectionDisabled()
+
+                    TextField("Kundenname", text: $customerName)
+                        .textInputAutocapitalization(.words)
+                    
+                    DatePicker(
+                        "Erstellungsdatum",
+                        selection: $creationDate,
+                        displayedComponents: [.date]
+                    )
+                }
+
+                Section("Tankauswahl") {
+                    TankEditor(tank: $tank)
+                }
+            }
+            .navigationTitle("Projekt erstellen")
+            .navigationBarTitleDisplayMode(.inline)
+            .toolbar {
+                ToolbarItem(placement: .cancellationAction) {
+                    Button("Abbrechen", systemImage: "xmark") {
+                        dismiss()
+                    }
+                }
+                ToolbarItem(placement: .confirmationAction) {
+                    Button("Speichern", systemImage: "checkmark") {
+                        save()
+                    }
+                    .buttonStyle(.borderedProminent)
+                    .disabled(!canSave)
+                }
+            }
+        }
+    }
+
+    private func save() {
+        let project = Project(
+            leadID: leadID.trimmingCharacters(in: .whitespaces),
+            customerName: customerName.trimmingCharacters(in: .whitespaces),
+            creationDate: creationDate,
+            tank: tank
+        )
+        modelContext.insert(project)
+        dismiss()
+    }
+}
+
+#Preview {
+    ProjectCreateView()
+        .modelContainer(for: Project.self, inMemory: true)
+}

GasTankAR/Views/ProjectDetailView.swift

@@ -0,0 +1,66 @@
+//
+//  ProjectDetailView.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 25.08.26.
+//
+
+import SwiftUI
+import SwiftData
+
+struct ProjectDetailView: View {
+    @Bindable var project: Project
+
+    var body: some View {
+        TabView {
+            detailsTab
+                .tabItem { Label("Details", systemImage: "info.circle") }
+
+            GalleryView(project: project)
+                .tabItem { Label("Galerie", systemImage: "photo.on.rectangle") }
+
+            DocuframeView(project: project)
+                .tabItem { Label("DOCUframe", systemImage: "arrow.up.doc.on.clipboard") }
+        }
+        .navigationTitle(project.customerName)
+        .navigationBarTitleDisplayMode(.inline)
+    }
+
+    private var detailsTab: some View {
+        List {
+            Section("Projektdaten") {
+                LabeledContent("Kunde", value: project.customerName)
+                LabeledContent("Lead-ID", value: project.leadID)
+                LabeledContent(
+                    "Erstellt am",
+                    value: project.creationDate.formatted(.dateTime.day().month().year())
+                )
+            }
+
+            Section("Tankauswahl") {
+                TankEditor(tank: $project.tank)
+            }
+        }
+        .safeAreaInset(edge: .bottom) {
+            NavigationLink {
+                ARExperienceView(project: project)
+            } label: {
+                Label("AR-Modus starten", systemImage: "arkit")
+                    .font(.headline)
+                    .frame(maxWidth: .infinity)
+                    .frame(height: 50)
+            }
+            .buttonStyle(.borderedProminent)
+            .padding()
+        }
+    }
+}
+
+#Preview {
+    let sample = PreviewSupport.singleProjectContainer()
+
+    return NavigationStack {
+        ProjectDetailView(project: sample.project)
+    }
+    .modelContainer(sample.container)
+}

GasTankAR/Views/ProjectListItem.swift

@@ -0,0 +1,58 @@
+//
+//  ProjectListItem.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 25.08.26.
+//
+
+import SwiftUI
+
+struct ProjectListItem: View {
+    let project: Project
+
+    var body: some View {
+        HStack(spacing: 12) {
+            Circle()
+                .fill(.tint)
+                .frame(width: 40, height: 40)
+                .overlay {
+                    Text(project.initials)
+                        .font(.subheadline.weight(.semibold))
+                        .foregroundStyle(.white)
+                }
+
+            VStack(alignment: .leading, spacing: 2) {
+                Text(project.customerName)
+                    .font(.body)
+                Text(project.leadID)
+                    .font(.caption)
+                    .foregroundStyle(.secondary)
+            }
+
+            Spacer()
+
+            Text(project.creationDate, format: .dateTime.day().month().year())
+                .font(.caption)
+                .foregroundStyle(.secondary)
+        }
+    }
+}
+
+#Preview {
+    List {
+        ProjectListItem(
+            project: Project(
+                leadID: "LEAD-1001",
+                customerName: "Müller Heizungsbau",
+                creationDate: .now
+            )
+        )
+        ProjectListItem(
+            project: Project(
+                leadID: "LEAD-1002",
+                customerName: "Weber & Söhne",
+                creationDate: .now
+            )
+        )
+    }
+}

GasTankAR/Views/ProjectListView.swift

@@ -0,0 +1,99 @@
+//
+//  ProjectListView.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 25.08.26.
+//
+
+import SwiftUI
+import SwiftData
+
+struct ProjectListView: View {
+    @Environment(\.modelContext) private var modelContext
+    @Query(sort: \Project.creationDate, order: .reverse) private var projects: [Project]
+
+    @State private var selectedProject: Project?
+    @State private var isCreatingProject = false
+    @State private var isShowingSettings = false
+
+    var body: some View {
+        NavigationSplitView {
+            List(selection: $selectedProject) {
+                ForEach(projects) { project in
+                    ProjectListItem(project: project)
+                        .tag(project)
+                }
+                .onDelete(perform: deleteProjects)
+            }
+            .overlay {
+                if projects.isEmpty {
+                    ContentUnavailableView(
+                        "Keine Projekte",
+                        systemImage: "tray",
+                        description: Text("Tippe auf +, um dein erstes Projekt zu erstellen.")
+                    )
+                }
+            }
+            .navigationTitle(Text("Projekte"))
+            .toolbar {
+                ToolbarItem(placement: .topBarTrailing) {
+                    Button("Einstellungen", systemImage: "gearshape") {
+                        isShowingSettings = true
+                    }
+                }
+            }
+            .sheet(isPresented: $isShowingSettings) {
+                SettingsView()
+            }
+            .overlay(alignment: .bottomTrailing) {
+                GlassEffectContainer {
+                    Button {
+                        isCreatingProject = true
+                    } label: {
+                        Image(systemName: "plus")
+                            .font(.title2.weight(.semibold))
+                            .frame(width: 56, height: 56)
+                            .contentShape(.circle)
+                    }
+                    .buttonStyle(.plain)
+                    .glassEffect(.regular.interactive(), in: .circle)
+                }
+                .padding()
+                .accessibilityLabel("Projekt erstellen")
+            }
+            .sheet(isPresented: $isCreatingProject) {
+                ProjectCreateView()
+            }
+        } detail: {
+            NavigationStack {
+                if let selectedProject {
+                    ProjectDetailView(project: selectedProject)
+                } else {
+                    ContentUnavailableView(
+                        "Kein Projekt ausgewählt",
+                        systemImage: "hand.point.up.left",
+                        description: Text("Wähle links ein Projekt aus, um die Details zu sehen.")
+                    )
+                }
+            }
+        }
+    }
+
+    private func deleteProjects(at offsets: IndexSet) {
+        for index in offsets {
+            let project = projects[index]
+            if project == selectedProject { selectedProject = nil }
+            modelContext.delete(project)
+        }
+    }
+}
+
+#Preview("Gefüllt") {
+    ProjectListView()
+        .modelContainer(PreviewSupport.container)
+}
+
+#Preview("Leer") {
+    ProjectListView()
+        .modelContainer(PreviewSupport.makeEmptyContainer())
+}

GasTankAR/Views/SettingsView.swift

@@ -0,0 +1,54 @@
+//
+//  SettingsView.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import SwiftUI
+import ARKit
+
+/// Zentraler Schlüssel für die LiDAR-Einstellung (in AppStorage/UserDefaults).
+enum SettingsKeys {
+    static let lidarFeaturesEnabled = "lidarFeaturesEnabled"
+}
+
+struct SettingsView: View {
+    @AppStorage(SettingsKeys.lidarFeaturesEnabled) private var lidarEnabled = false
+    @Environment(\.dismiss) private var dismiss
+
+    /// LiDAR ist verfügbar, wenn das Gerät Scene-Reconstruction (Mesh) unterstützt.
+    private var lidarSupported: Bool {
+        ARWorldTrackingConfiguration.supportsSceneReconstruction(.mesh)
+    }
+
+    var body: some View {
+        NavigationStack {
+            Form {
+                Section {
+                    Toggle("LiDAR-Funktionen aktivieren", isOn: $lidarEnabled)
+                        .disabled(!lidarSupported)
+                } header: {
+                    Text("Augmented Reality")
+                } footer: {
+                    if lidarSupported {
+                        Text("Nutzt den LiDAR-Scanner für präzisere Flächenerkennung, Tiefe und realistische Verdeckung. Änderungen greifen beim nächsten Start des AR-Modus.")
+                    } else {
+                        Text("Dieses Gerät hat keinen LiDAR-Scanner. Die App nutzt automatisch das Verfahren ohne LiDAR.")
+                    }
+                }
+            }
+            .navigationTitle("Einstellungen")
+            .navigationBarTitleDisplayMode(.inline)
+            .toolbar {
+                ToolbarItem(placement: .confirmationAction) {
+                    Button("Fertig") { dismiss() }
+                }
+            }
+        }
+    }
+}
+
+#Preview {
+    SettingsView()
+}

GasTankAR/Views/TankAR/ARControlOverlay.swift

@@ -0,0 +1,83 @@
+//
+//  ARControlOverlay.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 27.08.26.
+//
+
+import SwiftUI
+
+/// Runde Werkzeug-Buttons oben rechts über der AR-View. Untereinander angeordnet;
+/// weitere Funktionen lassen sich als zusätzliche `roundButton` ergänzen.
+struct ARControlOverlay: View {
+    let controller: ARSessionController
+    /// Öffnet die Strecken-Liste (Ausmessen).
+    let onMeasure: () -> Void
+
+    var body: some View {
+        VStack {
+            HStack {
+                Spacer()
+                VStack(spacing: 12) {
+                    roundButton(
+                        systemImage: "shield.lefthalf.filled",
+                        isActive: controller.showSafetyZones,
+                        label: "Sicherheitsabstand"
+                    ) {
+                        controller.toggleSafetyZones()
+                    }
+
+                    roundButton(
+                        systemImage: "ruler",
+                        isActive: controller.measurementPhase != .idle,
+                        label: "Ausmessen"
+                    ) {
+                        onMeasure()
+                    }
+
+                    roundButton(
+                        systemImage: "point.3.connected.trianglepath.dotted",
+                        isActive: controller.pipeRoutingPhase != .idle,
+                        label: "Rohrführung"
+                    ) {
+                        if controller.pipeRoutingPhase == .idle {
+                            controller.startPipeRouting()
+                        }
+                    }
+
+                    roundButton(
+                        systemImage: "camera.fill",
+                        isActive: false,
+                        label: "Foto aufnehmen"
+                    ) {
+                        controller.captureSnapshot()
+                    }
+                }
+            }
+            Spacer()
+        }
+        .padding()
+    }
+
+    private func roundButton(
+        systemImage: String,
+        isActive: Bool,
+        label: String,
+        action: @escaping () -> Void
+    ) -> some View {
+        Button(action: action) {
+            Image(systemName: systemImage)
+                .font(.title3)
+                .frame(width: 52, height: 52)
+                .foregroundStyle(isActive ? Color.white : Color.primary)
+                .background(
+                    isActive ? AnyShapeStyle(Color.accentColor) : AnyShapeStyle(.ultraThinMaterial),
+                    in: .circle
+                )
+                .shadow(radius: 3)
+        }
+        .buttonStyle(.plain)
+        .accessibilityLabel(label)
+        .accessibilityAddTraits(isActive ? .isSelected : [])
+    }
+}

GasTankAR/Views/TankAR/ARExperienceView.swift

@@ -0,0 +1,284 @@
+//
+//  ARExperienceView.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import SwiftUI
+import SwiftData
+
+/// Vollbild-AR-Erlebnis für ein Projekt: komponiert AR-View + Status-Overlay und
+/// besitzt den `ARSessionController`.
+struct ARExperienceView: View {
+    @Environment(\.modelContext) private var modelContext
+    @Environment(\.dismiss) private var dismiss
+    @AppStorage(SettingsKeys.lidarFeaturesEnabled) private var lidarEnabled = false
+
+    let project: Project
+
+    @State private var controller: ARSessionController?
+    @State private var flashOpacity = 0.0
+    @State private var showMeasurements = false
+    @State private var measurementName = ""
+
+    var body: some View {
+        ZStack {
+            if let controller {
+                ARViewContainer(controller: controller)
+                    .ignoresSafeArea()
+                ARStatusOverlay(controller: controller, onCancel: { dismiss() })
+                if controller.state == .immersive {
+                    ARControlOverlay(controller: controller) {
+                        showMeasurements = true
+                    }
+                    .transition(.opacity)
+                }
+                if controller.measurementPhase == .awaitingFirstPoint
+                    || controller.measurementPhase == .awaitingSecondPoint {
+                    measuringOverlay(controller: controller)
+                }
+                if controller.pipeRoutingPhase == .placing {
+                    pipeRoutingOverlay(controller: controller)
+                }
+                Color.white
+                    .opacity(flashOpacity)
+                    .ignoresSafeArea()
+                    .allowsHitTesting(false)
+                    .onChange(of: controller.snapshotFlashCounter) {
+                        flashOpacity = 0.9
+                        withAnimation(.easeOut(duration: 0.35)) { flashOpacity = 0 }
+                    }
+            }
+        }
+        .navigationTitle(project.customerName)
+        .navigationBarTitleDisplayMode(.inline)
+        .sheet(isPresented: $showMeasurements) {
+            if let controller {
+                MeasurementListView(controller: controller) {
+                    showMeasurements = false
+                    controller.startMeasurement()
+                }
+            }
+        }
+        .alert("Strecke benennen", isPresented: namingBinding) {
+            TextField("Bezeichnung", text: $measurementName)
+            Button("Speichern") {
+                controller?.finishMeasurement(name: measurementName)
+                measurementName = ""
+            }
+            Button("Abbrechen", role: .cancel) {
+                controller?.cancelMeasurement()
+                measurementName = ""
+            }
+        } message: {
+            Text("Gib der Strecke eine Bezeichnung. Sie erscheint auf der Linie.")
+        }
+        .task {
+            guard controller == nil else { return }
+            let persistence = ProjectPersistenceAdapter(project: project, modelContext: modelContext)
+            controller = ARSessionController(persistence: persistence, useLiDAR: lidarEnabled)
+        }
+    }
+
+    /// Präsentiert den Benennungs-Alert, sobald beide Punkte gesetzt sind.
+    private var namingBinding: Binding<Bool> {
+        Binding(
+            get: { controller?.measurementPhase == .naming },
+            set: { isPresented in
+                // Wird der Alert ohne Button-Aktion geschlossen, Messvorgang abbrechen.
+                if !isPresented, controller?.measurementPhase == .naming {
+                    controller?.cancelMeasurement()
+                }
+            }
+        )
+    }
+
+    /// Vollständiges Mess-Overlay: Fadenkreuz in der Mitte, Hinweis-/Distanz-Banner oben,
+    /// Auslöser-Button unten (wie beim Platzieren des Tanks).
+    private func measuringOverlay(controller: ARSessionController) -> some View {
+        ZStack {
+            // Fadenkreuz exakt in der Vollbild-Mitte – deckt sich mit dem Raycast-Punkt
+            // (arView.bounds-Mitte), der die Safe Area ignoriert.
+            measuringCrosshair
+                .frame(maxWidth: .infinity, maxHeight: .infinity)
+                .ignoresSafeArea()
+
+            VStack {
+                measuringBanner(for: controller)
+                Spacer()
+                measuringShutter(for: controller)
+            }
+            .padding()
+        }
+        .transition(.opacity)
+    }
+
+    private var measuringCrosshair: some View {
+        ZStack {
+            Circle()
+                .stroke(.yellow.opacity(0.9), lineWidth: 2)
+                .frame(width: 44, height: 44)
+            Circle()
+                .fill(.yellow)
+                .frame(width: 5, height: 5)
+        }
+        .shadow(radius: 2)
+        .allowsHitTesting(false)
+    }
+
+    private func measuringBanner(for controller: ARSessionController) -> some View {
+        HStack(spacing: 8) {
+            Image(systemName: "ruler")
+            Text(measuringBannerText(for: controller))
+                .font(.subheadline.weight(.medium))
+                .monospacedDigit()
+            Spacer(minLength: 0)
+            Button("Abbrechen") { controller.cancelMeasurement() }
+                .buttonStyle(.bordered)
+                .controlSize(.small)
+        }
+        .padding(.horizontal, 14)
+        .padding(.vertical, 10)
+        .background(.ultraThinMaterial, in: .capsule)
+    }
+
+    private func measuringBannerText(for controller: ARSessionController) -> String {
+        switch controller.measurementPhase {
+        case .awaitingFirstPoint:
+            return "Ziele auf den Startpunkt."
+        case .awaitingSecondPoint:
+            if let distance = controller.liveDistance {
+                return String(format: "Abstand: %.2f m", distance)
+            }
+            return "Ziele auf den Endpunkt."
+        default:
+            return ""
+        }
+    }
+
+    private func measuringShutter(for controller: ARSessionController) -> some View {
+        let title = controller.measurementPhase == .awaitingFirstPoint ? "Startpunkt setzen" : "Endpunkt setzen"
+        return VStack(spacing: 10) {
+            Text(title)
+                .font(.subheadline.weight(.medium))
+                .padding(.horizontal, 12)
+                .padding(.vertical, 6)
+                .background(.ultraThinMaterial, in: .capsule)
+
+            Button {
+                controller.captureMeasurementPoint()
+            } label: {
+                ZStack {
+                    Circle()
+                        .stroke(.white, lineWidth: 4)
+                        .frame(width: 74, height: 74)
+                    Circle()
+                        .fill(.yellow)
+                        .frame(width: 60, height: 60)
+                }
+                .shadow(radius: 4)
+                .contentShape(.circle)
+            }
+            .buttonStyle(.plain)
+            .accessibilityLabel(title)
+        }
+    }
+
+    // MARK: - Rohrführung-Overlay
+
+    /// Overlay für die Rohrführung: pinkes Fadenkreuz (Vollbild-Mitte), Info-Banner oben,
+    /// Auslöser + Aktionen unten (gleiche Bedienung wie beim Messen).
+    private func pipeRoutingOverlay(controller: ARSessionController) -> some View {
+        ZStack {
+            pipeCrosshair
+                .frame(maxWidth: .infinity, maxHeight: .infinity)
+                .ignoresSafeArea()
+
+            VStack {
+                pipeBanner(for: controller)
+                Spacer()
+                pipeControls(for: controller)
+            }
+            .padding()
+        }
+        .transition(.opacity)
+    }
+
+    private var pipeCrosshair: some View {
+        ZStack {
+            Circle()
+                .stroke(.pink.opacity(0.9), lineWidth: 2)
+                .frame(width: 44, height: 44)
+            Circle()
+                .fill(.pink)
+                .frame(width: 5, height: 5)
+        }
+        .shadow(radius: 2)
+        .allowsHitTesting(false)
+    }
+
+    private func pipeBanner(for controller: ARSessionController) -> some View {
+        HStack(spacing: 8) {
+            Image(systemName: "point.3.connected.trianglepath.dotted")
+            Text(pipeBannerText(for: controller))
+                .font(.subheadline.weight(.medium))
+                .monospacedDigit()
+            Spacer(minLength: 0)
+            Button("Abbrechen") { controller.cancelPipeRouting() }
+                .buttonStyle(.bordered)
+                .controlSize(.small)
+        }
+        .padding(.horizontal, 14)
+        .padding(.vertical, 10)
+        .background(.ultraThinMaterial, in: .capsule)
+    }
+
+    private func pipeBannerText(for controller: ARSessionController) -> String {
+        if controller.pipeWaypointCount == 0 {
+            return "Ziele auf den Startpunkt der Rohrführung."
+        }
+        return "Wegpunkte: \(controller.pipeWaypointCount) · Länge: \(controller.pipeRouteLengthText)"
+    }
+
+    private func pipeControls(for controller: ARSessionController) -> some View {
+        VStack(spacing: 12) {
+            Text("Wegpunkt setzen")
+                .font(.subheadline.weight(.medium))
+                .padding(.horizontal, 12)
+                .padding(.vertical, 6)
+                .background(.ultraThinMaterial, in: .capsule)
+
+            Button {
+                controller.addPipeWaypoint()
+            } label: {
+                ZStack {
+                    Circle()
+                        .stroke(.white, lineWidth: 4)
+                        .frame(width: 74, height: 74)
+                    Circle()
+                        .fill(.pink)
+                        .frame(width: 60, height: 60)
+                }
+                .shadow(radius: 4)
+                .contentShape(.circle)
+            }
+            .buttonStyle(.plain)
+            .accessibilityLabel("Wegpunkt setzen")
+
+            HStack(spacing: 12) {
+                Button("Rückgängig", systemImage: "arrow.uturn.backward") {
+                    controller.undoLastPipeWaypoint()
+                }
+                .buttonStyle(.bordered)
+                .disabled(controller.pipeWaypointCount == 0)
+
+                Button("Fertig", systemImage: "checkmark") {
+                    controller.finishPipeRouting()
+                }
+                .buttonStyle(.borderedProminent)
+                .disabled(controller.pipeWaypointCount < 2)
+            }
+        }
+    }
+}

GasTankAR/Views/TankAR/ARFlowStateMachine.swift

@@ -0,0 +1,252 @@
+//
+//  ARFlowStateMachine.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import Foundation
+
+/// Zustände des AR-Modus gemäß State-Machine (ohne den entfernten „Choose Tank"-State –
+/// stattdessen führt eine gefundene Location/ein erkannter Anker direkt in `immersive`).
+enum ARFlowState: Equatable {
+    case worldNotInitialized
+    case initializingWorld
+    case initializingNotPossible
+    case userMovesAround
+    case showOptions
+    case anchorDetection
+    case askToCancel
+    case selectLocation
+    case immersive
+    case relocating
+    case relocationFailed
+}
+
+/// Transparente ARKit-Statuslage (wird von der View in lokalisierten Text übersetzt).
+enum ARStatus: Equatable {
+    case relocalizing
+    case excessiveMotion
+    case insufficientFeatures
+    case unavailable
+}
+
+/// Quelle der Transform beim Platzieren des Tanks.
+enum PlacementSource: Equatable {
+    case storedTransform
+    case screenCenter
+    case imageAnchor
+}
+
+/// Eingaben in die State-Machine: ARKit-Events, Timer und Nutzeraktionen.
+enum ARFlowEvent: Equatable {
+    case started
+
+    // ARKit-Tracking
+    case trackingNormal
+    case trackingInitializing
+    case trackingRelocalizing
+    case trackingExcessiveMotion
+    case trackingInsufficientFeatures
+    case trackingUnavailable
+
+    // Coaching / Session
+    case coachingWillActivate
+    case coachingDidDeactivate
+    case sessionInterruptionEnded
+    case imageAnchorDetected
+
+    // Timer
+    case moveAroundTimerFired
+    case showOptionsTimerFired
+    case anchorDetectionTimerFired
+    case relocationTimerFired
+
+    // Nutzeraktionen
+    case captureConfirmed        // Raycast war erfolgreich (von der View vorgeprüft)
+    case keepMovingTapped
+    case placeAnchorMarkerTapped
+    case tryAgainAnchorTapped
+    case repositionTapped
+    case restartTapped
+    case retryRelocationTapped
+}
+
+/// Seiteneffekte, die der Controller (unreine Schale) ausführt.
+enum ARFlowCommand: Equatable {
+    case setStatus(ARStatus?)
+    case runConfiguration(useImages: Bool, useInitialMap: Bool, resetTracking: Bool)
+    case setCoachingAutomatic(Bool)
+    case startMoveAroundTimer
+    case startShowOptionsTimer
+    case cancelEscalationTimers
+    case startRelocationTimer
+    case cancelRelocationTimer
+    case startAnchorDetectionTimer
+    case cancelAnchorDetectionTimer
+    case placeTank(PlacementSource)
+    case removeTank
+    case persistWorldMap
+    case persistTankTransform
+    case clearStoredTransform
+}
+
+/// Reine, testbare State-Machine des AR-Flows. Enthält keinerlei ARKit-/UI-Abhängigkeiten:
+/// `reduce` verändert den Zustand und liefert die auszuführenden Kommandos zurück.
+struct ARFlowStateMachine {
+    private(set) var state: ARFlowState = .worldNotInitialized
+    private(set) var hasPlacedTank = false
+    private(set) var hasStoredTransform: Bool
+
+    init(hasStoredTransform: Bool) {
+        self.hasStoredTransform = hasStoredTransform
+    }
+
+    mutating func reduce(_ event: ARFlowEvent) -> [ARFlowCommand] {
+        switch event {
+        case .started:
+            state = .worldNotInitialized
+            return [.runConfiguration(useImages: false, useInitialMap: true, resetTracking: false)]
+
+        case .trackingNormal:
+            var commands: [ARFlowCommand] = [
+                .setStatus(nil), .cancelEscalationTimers, .cancelRelocationTimer, .setCoachingAutomatic(true),
+            ]
+            commands += resolvePlacedOrRestore()
+            return commands
+
+        case .trackingUnavailable:
+            return [.setStatus(.unavailable)]
+
+        case .trackingInitializing:
+            if !hasPlacedTank, state == .worldNotInitialized || state == .initializingWorld {
+                state = .initializingWorld
+            }
+            return [.setStatus(nil)]
+
+        case .trackingRelocalizing:
+            state = .relocating
+            return [.setStatus(.relocalizing), .cancelRelocationTimer, .startRelocationTimer]
+
+        case .trackingExcessiveMotion:
+            return [.setStatus(.excessiveMotion)]
+
+        case .trackingInsufficientFeatures:
+            var commands: [ARFlowCommand] = [.setStatus(.insufficientFeatures)]
+            let blockedStates: [ARFlowState] = [.anchorDetection, .showOptions, .askToCancel]
+            if !hasPlacedTank, !blockedStates.contains(state), state != .userMovesAround {
+                state = .initializingNotPossible
+                commands += [.cancelEscalationTimers, .startMoveAroundTimer]
+            }
+            return commands
+
+        case .moveAroundTimerFired:
+            guard state == .initializingNotPossible else { return [] }
+            state = .userMovesAround
+            return [.startShowOptionsTimer]
+
+        case .showOptionsTimerFired:
+            guard state == .userMovesAround else { return [] }
+            state = .showOptions
+            return [.setCoachingAutomatic(false)]
+
+        case .keepMovingTapped:
+            state = .userMovesAround
+            return [.setCoachingAutomatic(true), .cancelEscalationTimers, .startShowOptionsTimer]
+
+        case .placeAnchorMarkerTapped:
+            state = .anchorDetection
+            return [
+                .cancelEscalationTimers,
+                .setCoachingAutomatic(false),
+                .runConfiguration(useImages: true, useInitialMap: false, resetTracking: false),
+                .cancelAnchorDetectionTimer,
+                .startAnchorDetectionTimer,
+            ]
+
+        case .anchorDetectionTimerFired:
+            guard state == .anchorDetection else { return [] }
+            state = .askToCancel
+            return []
+
+        case .tryAgainAnchorTapped:
+            state = .showOptions
+            return [
+                .cancelAnchorDetectionTimer,
+                .runConfiguration(useImages: false, useInitialMap: false, resetTracking: false),
+                .setCoachingAutomatic(false),
+            ]
+
+        case .imageAnchorDetected:
+            guard state == .anchorDetection else { return [] }
+            state = .immersive
+            hasPlacedTank = true
+            return [.cancelAnchorDetectionTimer, .placeTank(.imageAnchor), .persistWorldMap, .persistTankTransform]
+
+        case .captureConfirmed:
+            guard state == .selectLocation else { return [] }
+            state = .immersive
+            hasPlacedTank = true
+            return [.placeTank(.screenCenter), .persistWorldMap, .persistTankTransform]
+
+        case .repositionTapped:
+            state = .selectLocation
+            hasPlacedTank = false
+            hasStoredTransform = false
+            return [.removeTank, .clearStoredTransform]
+
+        case .restartTapped:
+            state = .worldNotInitialized
+            hasPlacedTank = false
+            hasStoredTransform = false
+            return [
+                .cancelRelocationTimer,
+                .removeTank,
+                .clearStoredTransform,
+                .setStatus(nil),
+                .runConfiguration(useImages: false, useInitialMap: false, resetTracking: true),
+            ]
+
+        case .retryRelocationTapped:
+            state = .relocating
+            return [.setStatus(.relocalizing), .cancelRelocationTimer, .startRelocationTimer]
+
+        case .relocationTimerFired:
+            guard state == .relocating else { return [] }
+            state = .relocationFailed
+            return [.setStatus(nil)]
+
+        case .coachingWillActivate:
+            if !hasPlacedTank { state = .initializingWorld }
+            return []
+
+        case .coachingDidDeactivate:
+            return [.cancelEscalationTimers] + resolvePlacedOrRestore()
+
+        case .sessionInterruptionEnded:
+            var commands: [ARFlowCommand] = [.setStatus(nil)]
+            if hasPlacedTank {
+                state = .relocating
+                commands += [.cancelRelocationTimer, .startRelocationTimer]
+            }
+            return commands
+        }
+    }
+
+    /// Gemeinsame Logik für „Tracking normal / Coaching fertig": Tank wiederherstellen,
+    /// sonst in die Platzieren-UI wechseln (sofern nicht gerade Anker-Erkennung läuft).
+    private mutating func resolvePlacedOrRestore() -> [ARFlowCommand] {
+        if hasPlacedTank {
+            state = .immersive
+            return []
+        }
+        guard state != .anchorDetection else { return [] }
+        if hasStoredTransform {
+            state = .immersive
+            hasPlacedTank = true
+            return [.placeTank(.storedTransform)]
+        }
+        state = .selectLocation
+        return []
+    }
+}

GasTankAR/Views/TankAR/ARProjectPersisting.swift

@@ -0,0 +1,67 @@
+//
+//  ARProjectPersisting.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import ARKit
+import CoreLocation
+import SwiftData
+
+/// Abstraktion der Projekt-Persistenz für den AR-Modus (Dependency Inversion):
+/// Der Controller kennt so kein SwiftData und ist unit-testbar.
+@MainActor
+protocol ARProjectPersisting: AnyObject {
+    var tank: Tank { get }
+    var worldMap: ARWorldMap? { get }
+    var tankTransform: [Float]? { get }
+
+    func saveWorldMap(_ data: Data)
+    func saveTankTransform(_ transform: [Float])
+    func clearTankTransform()
+    func savePhoto(_ imageData: Data, date: Date, coordinate: CLLocationCoordinate2D?)
+}
+
+/// SwiftData-Adapter: verbindet das `Project`-Model mit dem `ARProjectPersisting`-Protokoll.
+@MainActor
+final class ProjectPersistenceAdapter: ARProjectPersisting {
+    private let project: Project
+    private let modelContext: ModelContext
+
+    init(project: Project, modelContext: ModelContext) {
+        self.project = project
+        self.modelContext = modelContext
+    }
+
+    var tank: Tank { project.tank }
+    var worldMap: ARWorldMap? { project.worldMap }
+    var tankTransform: [Float]? { project.tankTransform }
+
+    func saveWorldMap(_ data: Data) {
+        project.worldMapData = data
+        try? modelContext.save()
+    }
+
+    func saveTankTransform(_ transform: [Float]) {
+        project.tankTransform = transform
+        try? modelContext.save()
+    }
+
+    func clearTankTransform() {
+        project.tankTransform = nil
+        try? modelContext.save()
+    }
+
+    func savePhoto(_ imageData: Data, date: Date, coordinate: CLLocationCoordinate2D?) {
+        let photo = ProjectPhoto(
+            creationDate: date,
+            imageData: imageData,
+            latitude: coordinate?.latitude,
+            longitude: coordinate?.longitude,
+            project: project
+        )
+        modelContext.insert(photo)
+        try? modelContext.save()
+    }
+}

GasTankAR/Views/TankAR/ARSessionController.swift

@@ -0,0 +1,873 @@
+//
+//  ARSessionController.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import SwiftUI
+import RealityKit
+import ARKit
+import CoreLocation
+import Combine
+
+/// Orchestriert den AR-Modus: hält die `ARView`/Session, empfängt ARKit-Events,
+/// treibt die reine `ARFlowStateMachine` und führt deren Kommandos aus.
+/// Delegiert Konfiguration, Entity-Bau, Referenzbilder und Persistenz an Kollaborateure.
+@MainActor
+@Observable
+final class ARSessionController: NSObject, ARSessionDelegate, ARCoachingOverlayViewDelegate, CLLocationManagerDelegate {
+    // Von der UI beobachtete Zustände.
+    private(set) var state: ARFlowState = .worldNotInitialized
+    private(set) var statusMessage: String?
+    private(set) var worldMappingStatus: ARFrame.WorldMappingStatus = .notAvailable
+    private(set) var isTankSelected = false {
+        didSet { updateSelectionHighlight() }
+    }
+    /// Ob die Sicherheitsabstände (Ringe um den Tank) eingeblendet sind.
+    private(set) var showSafetyZones = false
+    /// Wird bei jedem erfolgreichen Foto erhöht – die UI nutzt das für ein kurzes Aufblitzen.
+    private(set) var snapshotFlashCounter = 0
+    /// Angelegte Strecken (nur für die laufende Sitzung gehalten).
+    private(set) var measurements: [Measurement] = []
+    /// Aktuelle Phase des Messvorgangs.
+    private(set) var measurementPhase: MeasurementPhase = .idle
+    /// Live-Distanz (Meter) zwischen erstem Punkt und aktueller Bildschirmmitte – für die UI.
+    private(set) var liveDistance: Float?
+
+    /// Aktuelle Rohrführung (Wegpunkt-Pfad) der laufenden Sitzung.
+    private(set) var pipeRoute = PipeRoute()
+    /// Aktuelle Phase des Rohr-Routings.
+    private(set) var pipeRoutingPhase: PipeRoutingPhase = .idle
+    /// Anzahl gesetzter Wegpunkte (für die UI).
+    var pipeWaypointCount: Int { pipeRoute.count }
+    /// Gesamtlänge der Rohrführung als Text (für die UI).
+    var pipeRouteLengthText: String { pipeRoute.formattedLength }
+
+    @ObservationIgnored private let persistence: ARProjectPersisting
+    @ObservationIgnored private let useLiDAR: Bool
+    @ObservationIgnored private let configFactory: SessionConfigurationFactory
+    @ObservationIgnored private let entityFactory = TankEntityFactory()
+    @ObservationIgnored private var machine: ARFlowStateMachine
+
+    @ObservationIgnored private weak var arView: ARView?
+    @ObservationIgnored private weak var coaching: ARCoachingOverlayView?
+
+    @ObservationIgnored private var tankAnchor: AnchorEntity?
+    @ObservationIgnored private var tankEntity: ModelEntity?
+    @ObservationIgnored private var safetyZoneEntity: Entity?
+
+    /// Anker für alle Mess-Visualisierungen (unabhängig vom Tank).
+    @ObservationIgnored private var measurementAnchor: AnchorEntity?
+    /// Container der fertigen Strecken, nach `Measurement.id`.
+    @ObservationIgnored private var measurementEntities: [UUID: Entity] = [:]
+    /// Label-Halter für das Billboarding (Ausrichtung zur Kamera).
+    @ObservationIgnored private var measurementLabels: [Entity] = []
+    /// Vorläufige Punkt-Kugeln während eines laufenden Messvorgangs.
+    @ObservationIgnored private var previewPointEntities: [Entity] = []
+    @ObservationIgnored private var pendingMeasurementStart: SIMD3<Float>?
+    @ObservationIgnored private var pendingMeasurementEnd: SIMD3<Float>?
+
+    /// Live-Vorschau (folgt der Bildschirmmitte): gezogene Linie und Distanz-Label.
+    /// Das Fadenkreuz stellt selbst das aktuelle Linienende dar (kein zusätzlicher Cursor).
+    @ObservationIgnored private var liveLineEntity: ModelEntity?
+    @ObservationIgnored private var liveLabelEntity: Entity?
+    /// Zuletzt gezeigte Live-Distanz in Zentimetern (drosselt die Label-/UI-Aktualisierung).
+    @ObservationIgnored private var lastLiveDistanceCm: Int?
+
+    /// Anker + Entities der Rohrführung.
+    @ObservationIgnored private var pipeAnchor: AnchorEntity?
+    @ObservationIgnored private var pipeWaypointEntities: [Entity] = []
+    @ObservationIgnored private var pipeSegmentEntities: [Entity] = []
+    /// Live-Segment vom letzten Wegpunkt zur aktuellen Bildschirmmitte.
+    @ObservationIgnored private var pipeLiveSegment: ModelEntity?
+    /// Per-Frame-Callback zum Ausrichten der Labels zur Kamera.
+    @ObservationIgnored private var sceneUpdateSubscription: (any Cancellable)?
+
+    /// Liefert den Standort für die Verortung aufgenommener Fotos.
+    @ObservationIgnored private let locationManager = CLLocationManager()
+    /// Zuletzt bekannter Standort (für die GPS-Verortung von Fotos).
+    @ObservationIgnored private var currentLocation: CLLocation?
+
+    @ObservationIgnored private lazy var initialWorldMap: ARWorldMap? = persistence.worldMap
+    @ObservationIgnored private lazy var storedTransform: simd_float4x4? =
+        persistence.tankTransform.flatMap { simd_float4x4(floatArray: $0) }
+    /// Transform für die nächste Platzierung aus Raycast/Bild-Anker.
+    @ObservationIgnored private var pendingTransform: simd_float4x4?
+
+    @ObservationIgnored private var moveAroundTask: Task<Void, Never>?
+    @ObservationIgnored private var showOptionsTask: Task<Void, Never>?
+    @ObservationIgnored private var anchorDetectionTask: Task<Void, Never>?
+    @ObservationIgnored private var relocationTask: Task<Void, Never>?
+    @ObservationIgnored private var mappingPollTask: Task<Void, Never>?
+
+    private static let moveAroundDelay: Duration = .seconds(3)
+    private static let showOptionsDelay: Duration = .seconds(6)
+    private static let anchorDetectionTimeout: Duration = .seconds(20)
+    private static let relocationTimeout: Duration = .seconds(15)
+
+    init(persistence: ARProjectPersisting, useLiDAR: Bool) {
+        self.persistence = persistence
+        self.useLiDAR = useLiDAR
+        self.configFactory = SessionConfigurationFactory(
+            useLiDAR: useLiDAR,
+            referenceImages: ReferenceImageProvider.load()
+        )
+        self.machine = ARFlowStateMachine(hasStoredTransform: persistence.tankTransform != nil)
+        super.init()
+        locationManager.delegate = self
+        locationManager.desiredAccuracy = kCLLocationAccuracyNearestTenMeters
+    }
+
+    // MARK: - Lifecycle (vom ARViewContainer)
+
+    func attach(to view: ARView) {
+        arView = view
+        view.session.delegate = self
+        view.automaticallyConfigureSession = false
+        view.environment.sceneUnderstanding.options = useLiDAR ? [.occlusion] : []
+
+        let coachingView = ARCoachingOverlayView()
+        coachingView.session = view.session
+        coachingView.goal = .horizontalPlane
+        coachingView.activatesAutomatically = true
+        coachingView.delegate = self
+        coachingView.translatesAutoresizingMaskIntoConstraints = false
+        view.addSubview(coachingView)
+        NSLayoutConstraint.activate([
+            coachingView.topAnchor.constraint(equalTo: view.topAnchor),
+            coachingView.bottomAnchor.constraint(equalTo: view.bottomAnchor),
+            coachingView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+            coachingView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+        ])
+        coaching = coachingView
+
+        let tap = UITapGestureRecognizer(target: self, action: #selector(handleTap(_:)))
+        view.addGestureRecognizer(tap)
+
+        // Pro Frame die Mess-Labels zur Kamera ausrichten (Billboarding).
+        sceneUpdateSubscription = view.scene.subscribe(to: SceneEvents.Update.self) { [weak self] _ in
+            guard let self else { return }
+            MainActor.assumeIsolated { self.onSceneUpdate() }
+        }
+
+        entityFactory.preload()
+        startMappingPoll()
+        startLocationUpdates()
+        send(.started)
+    }
+
+    func detach() {
+        [moveAroundTask, showOptionsTask, anchorDetectionTask, relocationTask, mappingPollTask]
+            .forEach { $0?.cancel() }
+        locationManager.stopUpdatingLocation()
+        sceneUpdateSubscription?.cancel()
+        arView?.session.pause()
+    }
+
+    // MARK: - Nutzeraktionen (von der Overlay-UI)
+
+    func capture() {
+        guard state == .selectLocation, let arView else { return }
+        let center = CGPoint(x: arView.bounds.midX, y: arView.bounds.midY)
+        guard let result = arView.raycast(from: center, allowing: .estimatedPlane, alignment: .horizontal).first
+        else { return }
+        pendingTransform = result.worldTransform
+        send(.captureConfirmed)
+    }
+
+    func keepMoving() { send(.keepMovingTapped) }
+    func placeAnchorMarker() { send(.placeAnchorMarkerTapped) }
+    func tryAgainAnchor() { send(.tryAgainAnchorTapped) }
+    func reposition() { send(.repositionTapped) }
+    func restart() { send(.restartTapped) }
+    func retryRelocation() { send(.retryRelocationTapped) }
+    func deselectTank() { isTankSelected = false }
+
+    // MARK: - Tank-Feinjustierung (über das Steuer-Panel)
+
+    private static let heightStep: Float = 0.05
+    private static let moveStep: Float = 0.05
+    private static let rotationStep: Float = .pi / 36   // 5°
+
+    /// Verändert die Höhe des Tanks (y-Achse). Ein Schritt pro Aufruf (auch beim Halten wiederholt).
+    func adjustTankHeight(up: Bool) {
+        guard let tankEntity else { return }
+        tankEntity.position.y += up ? Self.heightStep : -Self.heightStep
+        refreshAfterEdit()
+    }
+
+    /// Verschiebt den Tank auf dem Boden – links/rechts relativ zur Blickrichtung.
+    func moveTank(left: Bool) {
+        moveOnGround(right: left ? -1 : 1, forward: 0)
+    }
+
+    /// Verschiebt den Tank auf dem Boden – vor/zurück relativ zur Blickrichtung.
+    func moveTank(forward: Bool) {
+        moveOnGround(right: 0, forward: forward ? 1 : -1)
+    }
+
+    /// Dreht den Tank um die Hochachse.
+    func rotateTank(clockwise: Bool) {
+        guard let tankEntity else { return }
+        let angle = (clockwise ? -1 : 1) * Self.rotationStep
+        let rotation = simd_quatf(angle: angle, axis: SIMD3(0, 1, 0))
+        tankEntity.transform.rotation = rotation * tankEntity.transform.rotation
+        refreshAfterEdit()
+    }
+
+    /// Sichert die Transform nach Abschluss einer Anpassung (z. B. beim Loslassen des Buttons).
+    func commitTankEdit() {
+        persistTankTransform()
+    }
+
+    /// Verschiebt den Tank in der Bodenebene entlang der kamerarelativen Rechts-/Vorwärts-Achse.
+    private func moveOnGround(right rightAmount: Float, forward forwardAmount: Float) {
+        guard let tankEntity, let arView else { return }
+        let cameraMatrix = arView.cameraTransform.matrix
+
+        var right = SIMD3<Float>(cameraMatrix.columns.0.x, 0, cameraMatrix.columns.0.z)
+        right = length(right) > 1e-4 ? normalize(right) : SIMD3(1, 0, 0)
+
+        // Kamera-Vorwärts = -Z der Kamera, auf den Boden projiziert.
+        var forward = SIMD3<Float>(-cameraMatrix.columns.2.x, 0, -cameraMatrix.columns.2.z)
+        forward = length(forward) > 1e-4 ? normalize(forward) : SIMD3(0, 0, -1)
+
+        tankEntity.position += (right * rightAmount + forward * forwardAmount) * Self.moveStep
+        refreshAfterEdit()
+    }
+
+    /// Aktualisiert abhängige Visuals nach einer Anpassung – ohne zu persistieren
+    /// (das Speichern erfolgt gebündelt via ``commitTankEdit()``).
+    private func refreshAfterEdit() {
+        updateSafetyZones()
+        updateDepthFadeGroundY()
+    }
+
+    /// Blendet die Eck-Markierung passend zur Auswahl ein/aus.
+    private func updateSelectionHighlight() {
+        guard let tankEntity,
+              let highlight = tankEntity.findEntity(named: TankHighlightFactory.name) else { return }
+        highlight.isEnabled = isTankSelected
+    }
+
+    /// Blendet die Sicherheitsabstände um den Tank ein bzw. aus.
+    func toggleSafetyZones() {
+        showSafetyZones.toggle()
+        updateSafetyZones()
+    }
+
+    /// Nimmt einen Snapshot der aktuellen AR-Sicht auf und speichert ihn – samt aktuellem
+    /// Standort für die spätere Karten-Verortung – im Projekt.
+    func captureSnapshot() {
+        guard let arView else { return }
+        let coordinate = currentLocation?.coordinate
+        arView.snapshot(saveToHDR: false) { [weak self] image in
+            guard let image else { return }
+            let date = Date()
+            guard let data = PhotoEncoder.jpegData(from: image, coordinate: coordinate, date: date) else { return }
+            Task { @MainActor in
+                guard let self else { return }
+                self.persistence.savePhoto(data, date: date, coordinate: coordinate)
+                self.snapshotFlashCounter += 1
+            }
+        }
+    }
+
+    // MARK: - Ausmessen (Strecken)
+
+    /// Startet einen neuen Messvorgang; der Nutzer tippt danach zwei Punkte an.
+    func startMeasurement() {
+        clearMeasurementPreview()
+        pendingMeasurementStart = nil
+        pendingMeasurementEnd = nil
+        measurementPhase = .awaitingFirstPoint
+    }
+
+    /// Bricht den laufenden Messvorgang ab und entfernt vorläufige Punkte.
+    func cancelMeasurement() {
+        clearMeasurementPreview()
+        hideLivePreview()
+        pendingMeasurementStart = nil
+        pendingMeasurementEnd = nil
+        measurementPhase = .idle
+    }
+
+    /// Schließt den Messvorgang mit der eingegebenen Bezeichnung ab und rendert die Strecke.
+    func finishMeasurement(name: String) {
+        guard let start = pendingMeasurementStart, let end = pendingMeasurementEnd else {
+            cancelMeasurement()
+            return
+        }
+        let trimmed = name.trimmingCharacters(in: .whitespacesAndNewlines)
+        let measurement = Measurement(
+            name: trimmed.isEmpty ? "Strecke \(measurements.count + 1)" : trimmed,
+            start: start,
+            end: end
+        )
+        measurements.append(measurement)
+        renderMeasurement(measurement)
+
+        clearMeasurementPreview()
+        hideLivePreview()
+        pendingMeasurementStart = nil
+        pendingMeasurementEnd = nil
+        measurementPhase = .idle
+    }
+
+    /// Entfernt Strecken (aus der Liste per Swipe).
+    func deleteMeasurements(at offsets: IndexSet) {
+        for index in offsets {
+            let measurement = measurements[index]
+            if let entity = measurementEntities.removeValue(forKey: measurement.id) {
+                if let label = entity.findEntity(named: MeasurementEntityFactory.labelName) {
+                    measurementLabels.removeAll { $0 === label }
+                }
+                entity.removeFromParent()
+            }
+        }
+        measurements.remove(atOffsets: offsets)
+    }
+
+    /// Setzt den aktuellen Punkt aus der Bildschirmmitte (wie beim Platzieren des Tanks).
+    func captureMeasurementPoint() {
+        guard measurementPhase == .awaitingFirstPoint || measurementPhase == .awaitingSecondPoint else { return }
+        guard let position = raycastScreenCenter() else {
+            statusMessage = "Kein Punkt erkannt – ziele auf eine erkannte Fläche."
+            return
+        }
+        addMeasurementPreviewPoint(at: position)
+
+        if measurementPhase == .awaitingFirstPoint {
+            pendingMeasurementStart = position
+            measurementPhase = .awaitingSecondPoint
+        } else {
+            pendingMeasurementEnd = position
+            measurementPhase = .naming
+            hideLivePreview()
+        }
+    }
+
+    /// Raycast aus der Bildschirmmitte auf eine (geschätzte) Fläche.
+    private func raycastScreenCenter() -> SIMD3<Float>? {
+        guard let arView else { return nil }
+        let center = CGPoint(x: arView.bounds.midX, y: arView.bounds.midY)
+        guard let result = arView.raycast(from: center, allowing: .estimatedPlane, alignment: .any).first
+        else { return nil }
+        let column = result.worldTransform.columns.3
+        return SIMD3<Float>(column.x, column.y, column.z)
+    }
+
+    private func addMeasurementPreviewPoint(at position: SIMD3<Float>) {
+        let anchor = ensureMeasurementAnchor()
+        let point = MeasurementEntityFactory.makePoint(at: position)
+        anchor.addChild(point)
+        previewPointEntities.append(point)
+    }
+
+    private func renderMeasurement(_ measurement: Measurement) {
+        let anchor = ensureMeasurementAnchor()
+        let entity = MeasurementEntityFactory.makeMeasurement(measurement)
+        anchor.addChild(entity)
+        measurementEntities[measurement.id] = entity
+        if let label = entity.findEntity(named: MeasurementEntityFactory.labelName) {
+            measurementLabels.append(label)
+        }
+    }
+
+    private func ensureMeasurementAnchor() -> AnchorEntity {
+        if let measurementAnchor { return measurementAnchor }
+        let anchor = AnchorEntity(world: matrix_identity_float4x4)
+        arView?.scene.addAnchor(anchor)
+        measurementAnchor = anchor
+        return anchor
+    }
+
+    private func clearMeasurementPreview() {
+        previewPointEntities.forEach { $0.removeFromParent() }
+        previewPointEntities.removeAll()
+    }
+
+    /// Pro-Frame-Aufgaben: Live-Vorschau aktualisieren und alle Labels zur Kamera ausrichten.
+    private func onSceneUpdate() {
+        updateLivePreview()
+        updatePipeLivePreview()
+        billboardLabels()
+    }
+
+    /// Aktualisiert Cursor, Live-Linie und Distanz-Label anhand der aktuellen Bildschirmmitte.
+    private func updateLivePreview() {
+        guard measurementPhase == .awaitingFirstPoint || measurementPhase == .awaitingSecondPoint,
+              let position = raycastScreenCenter() else {
+            return
+        }
+
+        ensureLivePreviewEntities()
+
+        guard measurementPhase == .awaitingSecondPoint, let start = pendingMeasurementStart else {
+            liveLineEntity?.isEnabled = false
+            liveLabelEntity?.isEnabled = false
+            liveDistance = nil
+            lastLiveDistanceCm = nil
+            return
+        }
+
+        if let liveLineEntity {
+            liveLineEntity.isEnabled = true
+            MeasurementEntityFactory.configureLine(liveLineEntity, from: start, to: position)
+        }
+
+        let distance = simd_distance(start, position)
+        liveLabelEntity?.isEnabled = true
+        liveLabelEntity?.position = MeasurementEntityFactory.labelPosition(from: start, to: position)
+
+        // Text/Distanz nur bei Änderung (auf cm gerundet) aktualisieren – spart Text-Neuaufbau.
+        let cm = Int((distance * 100).rounded())
+        if cm != lastLiveDistanceCm {
+            lastLiveDistanceCm = cm
+            liveDistance = distance
+            if let holder = liveLabelEntity {
+                holder.children.forEach { $0.removeFromParent() }
+                holder.addChild(MeasurementEntityFactory.makeText(String(format: "%.2f m", distance)))
+            }
+        }
+    }
+
+    private func ensureLivePreviewEntities() {
+        let anchor = ensureMeasurementAnchor()
+        if liveLineEntity == nil {
+            let line = MeasurementEntityFactory.makeLineBase()
+            line.isEnabled = false
+            anchor.addChild(line)
+            liveLineEntity = line
+        }
+        if liveLabelEntity == nil {
+            let label = MeasurementEntityFactory.makeLabelHolder()
+            label.isEnabled = false
+            anchor.addChild(label)
+            liveLabelEntity = label
+        }
+    }
+
+    private func hideLivePreview() {
+        liveLineEntity?.isEnabled = false
+        liveLabelEntity?.isEnabled = false
+        liveDistance = nil
+        lastLiveDistanceCm = nil
+    }
+
+    /// Richtet alle sichtbaren Labels (inkl. Live-Label) nur um die Gier-Achse zur Kamera aus.
+    private func billboardLabels() {
+        guard let arView else { return }
+        let camera = arView.cameraTransform.translation
+        var labels = measurementLabels
+        if let liveLabelEntity, liveLabelEntity.isEnabled { labels.append(liveLabelEntity) }
+        guard !labels.isEmpty else { return }
+
+        for label in labels {
+            let position = label.position(relativeTo: nil)
+            let direction = camera - position
+            let yaw = atan2(direction.x, direction.z)
+            label.setOrientation(simd_quatf(angle: yaw, axis: SIMD3(0, 1, 0)), relativeTo: nil)
+        }
+    }
+
+    // MARK: - Rohrführung (Wegpunkt-Pfad)
+
+    /// Startet eine neue Rohrführung. Beendet andere Interaktionsmodi und setzt den Pfad zurück.
+    func startPipeRouting() {
+        cancelMeasurement()
+        isTankSelected = false
+        clearPipeRoute()
+        pipeRoutingPhase = .placing
+    }
+
+    /// Setzt einen Wegpunkt aus der Bildschirmmitte und verbindet ihn mit dem vorherigen.
+    func addPipeWaypoint() {
+        guard pipeRoutingPhase == .placing else { return }
+        guard let position = raycastScreenCenter() else {
+            statusMessage = "Kein Punkt erkannt – ziele auf eine erkannte Fläche."
+            return
+        }
+        let anchor = ensurePipeAnchor()
+        if let previous = pipeRoute.waypoints.last {
+            let segment = PipeRouteEntityFactory.makeSegment(from: previous, to: position)
+            anchor.addChild(segment)
+            pipeSegmentEntities.append(segment)
+        }
+        let waypoint = PipeRouteEntityFactory.makeWaypoint(at: position)
+        anchor.addChild(waypoint)
+        pipeWaypointEntities.append(waypoint)
+        pipeRoute.add(position)
+    }
+
+    /// Entfernt den zuletzt gesetzten Wegpunkt (und sein Segment).
+    func undoLastPipeWaypoint() {
+        guard pipeRoute.removeLast() != nil else { return }
+        pipeWaypointEntities.popLast()?.removeFromParent()
+        pipeSegmentEntities.popLast()?.removeFromParent()
+    }
+
+    /// Beendet das Setzen; der fertige Pfad bleibt sichtbar.
+    func finishPipeRouting() {
+        pipeRoutingPhase = .idle
+        hidePipeLivePreview()
+    }
+
+    /// Verwirft die komplette Rohrführung.
+    func cancelPipeRouting() {
+        clearPipeRoute()
+        pipeRoutingPhase = .idle
+    }
+
+    private func ensurePipeAnchor() -> AnchorEntity {
+        if let pipeAnchor { return pipeAnchor }
+        let anchor = AnchorEntity(world: matrix_identity_float4x4)
+        arView?.scene.addAnchor(anchor)
+        pipeAnchor = anchor
+        return anchor
+    }
+
+    private func clearPipeRoute() {
+        pipeWaypointEntities.forEach { $0.removeFromParent() }
+        pipeSegmentEntities.forEach { $0.removeFromParent() }
+        pipeWaypointEntities.removeAll()
+        pipeSegmentEntities.removeAll()
+        hidePipeLivePreview()
+        pipeRoute.clear()
+    }
+
+    /// Zeichnet das Live-Segment vom letzten Wegpunkt zur aktuellen Bildschirmmitte.
+    private func updatePipeLivePreview() {
+        guard pipeRoutingPhase == .placing,
+              let last = pipeRoute.waypoints.last,
+              let position = raycastScreenCenter() else {
+            hidePipeLivePreview()
+            return
+        }
+        let segment = ensurePipeLiveSegment()
+        segment.isEnabled = true
+        PipeRouteEntityFactory.configureSegment(segment, from: last, to: position)
+    }
+
+    private func ensurePipeLiveSegment() -> ModelEntity {
+        if let pipeLiveSegment { return pipeLiveSegment }
+        let segment = PipeRouteEntityFactory.makeSegmentBase()
+        segment.isEnabled = false
+        ensurePipeAnchor().addChild(segment)
+        pipeLiveSegment = segment
+        return segment
+    }
+
+    private func hidePipeLivePreview() {
+        pipeLiveSegment?.isEnabled = false
+    }
+
+    // MARK: - Standort (für die GPS-Verortung von Fotos)
+
+    private func startLocationUpdates() {
+        switch locationManager.authorizationStatus {
+        case .notDetermined:
+            locationManager.requestWhenInUseAuthorization()
+        case .authorizedWhenInUse, .authorizedAlways:
+            locationManager.startUpdatingLocation()
+        default:
+            break
+        }
+    }
+
+    // MARK: - State-Machine
+
+    private func send(_ event: ARFlowEvent) {
+        let commands = machine.reduce(event)
+        state = machine.state
+        if state != .immersive { isTankSelected = false }
+        commands.forEach(execute)
+    }
+
+    private func execute(_ command: ARFlowCommand) {
+        switch command {
+        case .setStatus(let status):
+            statusMessage = status.map(Self.text(for:))
+        case .runConfiguration(let useImages, let useInitialMap, let resetTracking):
+            runConfiguration(useImages: useImages, useInitialMap: useInitialMap, resetTracking: resetTracking)
+        case .setCoachingAutomatic(let enabled):
+            setCoachingAutomatic(enabled)
+        case .startMoveAroundTimer:
+            moveAroundTask = schedule(Self.moveAroundDelay) { $0.send(.moveAroundTimerFired) }
+        case .startShowOptionsTimer:
+            showOptionsTask = schedule(Self.showOptionsDelay) { $0.send(.showOptionsTimerFired) }
+        case .cancelEscalationTimers:
+            moveAroundTask?.cancel()
+            showOptionsTask?.cancel()
+        case .startRelocationTimer:
+            relocationTask = schedule(Self.relocationTimeout) { $0.send(.relocationTimerFired) }
+        case .cancelRelocationTimer:
+            relocationTask?.cancel()
+        case .startAnchorDetectionTimer:
+            anchorDetectionTask = schedule(Self.anchorDetectionTimeout) { $0.send(.anchorDetectionTimerFired) }
+        case .cancelAnchorDetectionTimer:
+            anchorDetectionTask?.cancel()
+        case .placeTank(let source):
+            placeTank(from: source)
+        case .removeTank:
+            removeTank()
+        case .persistWorldMap:
+            persistWorldMap()
+        case .persistTankTransform:
+            persistTankTransform()
+        case .clearStoredTransform:
+            storedTransform = nil
+            persistence.clearTankTransform()
+        }
+    }
+
+    private func schedule(_ duration: Duration, _ action: @escaping (ARSessionController) -> Void) -> Task<Void, Never> {
+        Task { @MainActor [weak self] in
+            try? await Task.sleep(for: duration)
+            guard !Task.isCancelled, let self else { return }
+            action(self)
+        }
+    }
+
+    // MARK: - ARSessionDelegate
+
+    nonisolated func session(_ session: ARSession, cameraDidChangeTrackingState camera: ARCamera) {
+        let trackingState = camera.trackingState
+        Task { @MainActor in self.handleTrackingState(trackingState) }
+    }
+
+    nonisolated func session(_ session: ARSession, didFailWithError error: Error) {
+        let message = error.localizedDescription
+        Task { @MainActor in self.statusMessage = "AR-Fehler: \(message)" }
+    }
+
+    nonisolated func sessionWasInterrupted(_ session: ARSession) {
+        Task { @MainActor in self.statusMessage = "AR unterbrochen …" }
+    }
+
+    nonisolated func sessionInterruptionEnded(_ session: ARSession) {
+        Task { @MainActor in self.send(.sessionInterruptionEnded) }
+    }
+
+    nonisolated func session(_ session: ARSession, didAdd anchors: [ARAnchor]) {
+        let transform = anchors.compactMap { $0 as? ARImageAnchor }.first?.transform
+        guard let transform else { return }
+        Task { @MainActor in
+            self.pendingTransform = transform
+            self.send(.imageAnchorDetected)
+        }
+    }
+
+    private func handleTrackingState(_ trackingState: ARCamera.TrackingState) {
+        switch trackingState {
+        case .normal: send(.trackingNormal)
+        case .notAvailable: send(.trackingUnavailable)
+        case .limited(.initializing): send(.trackingInitializing)
+        case .limited(.relocalizing): send(.trackingRelocalizing)
+        case .limited(.excessiveMotion): send(.trackingExcessiveMotion)
+        case .limited(.insufficientFeatures): send(.trackingInsufficientFeatures)
+        case .limited: break
+        @unknown default: break
+        }
+    }
+
+    // MARK: - ARCoachingOverlayViewDelegate
+
+    func coachingOverlayViewWillActivate(_ coachingOverlayView: ARCoachingOverlayView) {
+        send(.coachingWillActivate)
+    }
+
+    func coachingOverlayViewDidDeactivate(_ coachingOverlayView: ARCoachingOverlayView) {
+        send(.coachingDidDeactivate)
+    }
+
+    // MARK: - CLLocationManagerDelegate
+
+    nonisolated func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
+        guard let location = locations.last else { return }
+        Task { @MainActor in self.currentLocation = location }
+    }
+
+    nonisolated func locationManagerDidChangeAuthorization(_ manager: CLLocationManager) {
+        Task { @MainActor in self.startLocationUpdates() }
+    }
+
+    // MARK: - Session-Konfiguration
+
+    private func runConfiguration(useImages: Bool, useInitialMap: Bool, resetTracking: Bool) {
+        let config = configFactory.make(
+            withImages: useImages,
+            initialWorldMap: useInitialMap ? initialWorldMap : nil
+        )
+        let options: ARSession.RunOptions = resetTracking ? [.resetTracking, .removeExistingAnchors] : []
+        arView?.session.run(config, options: options)
+    }
+
+    private func setCoachingAutomatic(_ enabled: Bool) {
+        coaching?.activatesAutomatically = enabled
+        if !enabled { coaching?.setActive(false, animated: true) }
+    }
+
+    // MARK: - Platzierung & Manipulation
+
+    private func placeTank(from source: PlacementSource) {
+        let transform: simd_float4x4?
+        switch source {
+        case .storedTransform: transform = storedTransform
+        case .screenCenter, .imageAnchor: transform = pendingTransform
+        }
+        guard let transform else { return }
+        placeTank(at: transform)
+    }
+
+    private func placeTank(at worldTransform: simd_float4x4) {
+        let anchor: AnchorEntity
+        if let tankAnchor {
+            anchor = tankAnchor
+        } else {
+            anchor = AnchorEntity(world: matrix_identity_float4x4)
+            arView?.scene.addAnchor(anchor)
+            tankAnchor = anchor
+        }
+
+        let container: ModelEntity
+        if let tankEntity {
+            container = tankEntity
+        } else {
+            container = entityFactory.makeContainer(for: persistence.tank)
+            anchor.addChild(container)
+            tankEntity = container
+            installManipulationGestures(on: container)
+        }
+
+        container.transform = Transform(matrix: worldTransform)
+        updateDepthFadeGroundY()
+        updateSceneOcclusion()
+        updateSafetyZones()
+    }
+
+    /// Baut die Sicherheitsabstände auf, aktualisiert ihre Bodenposition oder entfernt sie.
+    /// Die Ringe hängen am Tank-Anker (nicht am Tank selbst), damit Skalierung/Rotation
+    /// des Tanks sie nicht verzerrt; sie werden nur auf die Bodenmitte des Tanks gesetzt.
+    private func updateSafetyZones() {
+        guard showSafetyZones, let tankAnchor, let tankEntity else {
+            safetyZoneEntity?.removeFromParent()
+            safetyZoneEntity = nil
+            return
+        }
+
+        let entity: Entity
+        if let safetyZoneEntity {
+            entity = safetyZoneEntity
+        } else {
+            entity = SafetyZoneFactory.makeEntity()
+            tankAnchor.addChild(entity)
+            safetyZoneEntity = entity
+        }
+        entity.position = tankEntity.position(relativeTo: tankAnchor)
+    }
+
+    private func installManipulationGestures(on entity: ModelEntity) {
+        guard let arView else { return }
+        let recognizers = arView.installGestures([.translation, .rotation, .scale], for: entity)
+        for recognizer in recognizers {
+            recognizer.addTarget(self, action: #selector(handleManipulationChanged(_:)))
+        }
+    }
+
+    @objc private func handleManipulationChanged(_ recognizer: UIGestureRecognizer) {
+        updateSafetyZones()   // Ringe live mit dem Tank mitführen.
+        switch recognizer.state {
+        case .ended, .cancelled, .failed: persistTankTransform()
+        default: break
+        }
+    }
+
+    /// Einzel-Tap: den Tank an-/abwählen (blendet die „Neu platzieren"-Option ein).
+    @objc private func handleTap(_ gesture: UITapGestureRecognizer) {
+        guard state == .immersive, let arView else { return }
+
+        // Während Messen/Rohrführung erfolgt die Auswahl über Fadenkreuz + Button – Taps ignorieren.
+        guard measurementPhase == .idle, pipeRoutingPhase == .idle else { return }
+
+        let point = gesture.location(in: arView)
+        guard let tankEntity else { return }
+        if let hit = arView.entity(at: point), Self.entity(hit, isPartOf: tankEntity) {
+            isTankSelected.toggle()
+        } else {
+            isTankSelected = false
+        }
+    }
+
+    private func removeTank() {
+        if let tankAnchor { arView?.scene.removeAnchor(tankAnchor) }
+        tankAnchor = nil
+        tankEntity = nil
+        safetyZoneEntity = nil
+        isTankSelected = false
+    }
+
+    /// Scene-Mesh-Occlusion (LiDAR) nur für oberirdische Tanks – sonst würde das
+    /// rekonstruierte Boden-Mesh den halbtransparenten, vergrabenen Teil verdecken.
+    private func updateSceneOcclusion() {
+        guard let arView else { return }
+        let wantsOcclusion = useLiDAR && persistence.tank.placement != .belowGround
+        arView.environment.sceneUnderstanding.options = wantsOcclusion ? [.occlusion] : []
+    }
+
+    private func updateDepthFadeGroundY() {
+        guard persistence.tank.placement == .belowGround, let tankEntity else { return }
+        let groundY = tankEntity.position(relativeTo: nil).y
+        TankDepthFadeMaterial.updateGroundY(groundY, on: tankEntity)
+    }
+
+    // MARK: - Persistenz & Status
+
+    private func persistWorldMap() {
+        arView?.session.getCurrentWorldMap { map, _ in
+            // Completion läuft nicht auf dem Main-Thread – hier off-main archivieren.
+            guard let map, let data = WorldMapArchiver.archive(map) else { return }
+            Task { @MainActor [weak self] in self?.persistence.saveWorldMap(data) }
+        }
+    }
+
+    private func persistTankTransform() {
+        guard let tankEntity else { return }
+        updateDepthFadeGroundY()
+        persistence.saveTankTransform(tankEntity.transformMatrix(relativeTo: nil).floatArray)
+    }
+
+    private func startMappingPoll() {
+        mappingPollTask?.cancel()
+        mappingPollTask = Task { @MainActor in
+            while !Task.isCancelled {
+                if let status = self.arView?.session.currentFrame?.worldMappingStatus {
+                    self.worldMappingStatus = status
+                }
+                try? await Task.sleep(for: .seconds(1))
+            }
+        }
+    }
+
+    // MARK: - Helfer
+
+    private static func text(for status: ARStatus) -> String {
+        switch status {
+        case .relocalizing: "Position wird wiederhergestellt …"
+        case .excessiveMotion: "Zu schnelle Bewegung – bitte langsamer."
+        case .insufficientFeatures: "Zu wenige Merkmale – geh bitte umher und sorge für mehr Licht."
+        case .unavailable: "AR ist auf diesem Gerät nicht verfügbar."
+        }
+    }
+
+    /// Prüft, ob eine getroffene Entity der Tank-Container oder eines seiner Kinder ist.
+    private static func entity(_ entity: Entity, isPartOf root: Entity) -> Bool {
+        var current: Entity? = entity
+        while let node = current {
+            if node === root { return true }
+            current = node.parent
+        }
+        return false
+    }
+}

GasTankAR/Views/TankAR/ARStatusOverlay.swift

@@ -0,0 +1,234 @@
+//
+//  ARStatusOverlay.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import SwiftUI
+import ARKit
+
+/// Dezente, nicht-distraktive Overlays über der AR-View: ein schmaler Status-Banner
+/// oben sowie Aktions-Karten unten für die Entscheidungs-States der State-Machine.
+struct ARStatusOverlay: View {
+    let controller: ARSessionController
+    let onCancel: () -> Void
+
+    var body: some View {
+        ZStack {
+            // Fadenkreuz exakt im Bildschirmzentrum – dort trifft der Raycast.
+            if controller.state == .selectLocation {
+                crosshair
+            }
+
+            VStack {
+                if let message = controller.statusMessage {
+                    statusBanner(message)
+                        .transition(.move(edge: .top).combined(with: .opacity))
+                }
+
+                Spacer()
+
+                bottomContent
+                    .transition(.move(edge: .bottom).combined(with: .opacity))
+            }
+            .padding()
+        }
+        .animation(.easeInOut(duration: 0.25), value: controller.statusMessage)
+        .animation(.easeInOut(duration: 0.25), value: controller.state)
+        .animation(.easeInOut(duration: 0.25), value: controller.isTankSelected)
+    }
+
+    // MARK: - Fadenkreuz & Auslöser (Kamera-Style)
+
+    private var crosshair: some View {
+        ZStack {
+            Circle()
+                .stroke(.white.opacity(0.9), lineWidth: 2)
+                .frame(width: 44, height: 44)
+            Circle()
+                .fill(.white)
+                .frame(width: 5, height: 5)
+        }
+        .shadow(radius: 2)
+        .allowsHitTesting(false)
+    }
+
+    private var shutterButton: some View {
+        VStack(spacing: 10) {
+            Text("Tank platzieren")
+                .font(.subheadline.weight(.medium))
+                .padding(.horizontal, 12)
+                .padding(.vertical, 6)
+                .background(.ultraThinMaterial, in: .capsule)
+
+            Button {
+                controller.capture()
+            } label: {
+                ZStack {
+                    Circle()
+                        .stroke(.white, lineWidth: 4)
+                        .frame(width: 74, height: 74)
+                    Circle()
+                        .fill(.white)
+                        .frame(width: 60, height: 60)
+                }
+                .shadow(radius: 4)
+                .contentShape(.circle)
+            }
+            .buttonStyle(.plain)
+            .accessibilityLabel("Tank platzieren")
+        }
+    }
+
+    // MARK: - Status-Banner
+
+    private func statusBanner(_ message: String) -> some View {
+        HStack(spacing: 8) {
+            Image(systemName: "exclamationmark.triangle.fill")
+                .foregroundStyle(.yellow)
+            Text(message)
+                .font(.footnote)
+                .fixedSize(horizontal: false, vertical: true)
+        }
+        .padding(.horizontal, 14)
+        .padding(.vertical, 10)
+        .background(.ultraThinMaterial, in: .capsule)
+        .frame(maxWidth: .infinity)
+    }
+
+    // MARK: - Untere Aktions-Inhalte je State
+
+    @ViewBuilder
+    private var bottomContent: some View {
+        switch controller.state {
+        case .selectLocation:
+            shutterButton
+
+        case .showOptions:
+            actionCard(
+                title: "Zu wenige Merkmale erkannt",
+                message: "Die Umgebung bietet ARKit zu wenig Struktur."
+            ) {
+                Button("Weiter umhergehen") { controller.keepMoving() }
+                    .buttonStyle(.borderedProminent)
+                Button("Marker platzieren") { controller.placeAnchorMarker() }
+                    .buttonStyle(.bordered)
+                Button("Abbrechen", role: .cancel, action: onCancel)
+                    .buttonStyle(.bordered)
+            }
+
+        case .anchorDetection:
+            hintCard(
+                icon: "viewfinder",
+                text: "Richte die Kamera auf den Marker, um ihn zu erkennen.",
+                showsProgress: true,
+                onCancel: onCancel
+            )
+
+        case .askToCancel:
+            actionCard(
+                title: "Marker nicht erkannt",
+                message: "Der Marker konnte nicht zuverlässig erkannt werden."
+            ) {
+                Button("Erneut versuchen") { controller.tryAgainAnchor() }
+                    .buttonStyle(.borderedProminent)
+                Button("Abbrechen", role: .cancel, action: onCancel)
+                    .buttonStyle(.bordered)
+            }
+
+        case .relocating:
+            hintCard(
+                icon: "arrow.triangle.2.circlepath",
+                text: "Position wird wiederhergestellt …",
+                showsProgress: true
+            )
+
+        case .relocationFailed:
+            actionCard(
+                title: "Position nicht gefunden",
+                message: "Die gespeicherte Position konnte nicht wiederhergestellt werden. Neu starten und den Tank neu platzieren?"
+            ) {
+                Button("Neu starten & platzieren", systemImage: "arrow.counterclockwise") {
+                    controller.restart()
+                }
+                .buttonStyle(.borderedProminent)
+                Button("Weiter versuchen") {
+                    controller.retryRelocation()
+                }
+                .buttonStyle(.bordered)
+                Button("Abbrechen", role: .cancel, action: onCancel)
+                    .buttonStyle(.bordered)
+            }
+
+        case .immersive:
+            if controller.isTankSelected {
+                TankManipulationPanel(controller: controller)
+            } else if controller.measurementPhase == .idle && controller.pipeRoutingPhase == .idle {
+                Text("Tank antippen zum Neu-Platzieren · Ziehen / 2 Finger / Pinch zum Anpassen")
+                    .font(.caption)
+                    .multilineTextAlignment(.center)
+                    .padding(.horizontal, 12)
+                    .padding(.vertical, 6)
+                    .background(.ultraThinMaterial, in: .capsule)
+            }
+
+        default:
+            // initializingWorld / initializingNotPossible / userMovesAround übernimmt das
+            // Coaching-Overlay; immersive/worldNotInitialized brauchen keine Aktion.
+            EmptyView()
+        }
+    }
+
+    // MARK: - Bausteine
+
+    private func hintCard(
+        icon: String,
+        text: String,
+        showsProgress: Bool = false,
+        onCancel: (() -> Void)? = nil
+    ) -> some View {
+        HStack(spacing: 12) {
+            if showsProgress {
+                ProgressView()
+            } else {
+                Image(systemName: icon)
+                    .font(.title3)
+                    .foregroundStyle(.tint)
+            }
+            Text(text)
+                .font(.subheadline)
+            Spacer(minLength: 0)
+            if let onCancel {
+                Button("Abbrechen", role: .cancel, action: onCancel)
+                    .buttonStyle(.bordered)
+                    .controlSize(.small)
+            }
+        }
+        .padding()
+        .background(.ultraThinMaterial, in: .rect(cornerRadius: 16))
+    }
+
+    private func actionCard<Buttons: View>(
+        title: String,
+        message: String,
+        @ViewBuilder buttons: () -> Buttons
+    ) -> some View {
+        VStack(alignment: .leading, spacing: 12) {
+            VStack(alignment: .leading, spacing: 4) {
+                Text(title)
+                    .font(.headline)
+                Text(message)
+                    .font(.subheadline)
+                    .foregroundStyle(.secondary)
+            }
+
+            VStack(spacing: 8) {
+                buttons()
+            }
+            .frame(maxWidth: .infinity)
+        }
+        .padding()
+        .background(.ultraThinMaterial, in: .rect(cornerRadius: 16))
+    }
+}

GasTankAR/Views/TankAR/ARViewContainer.swift

@@ -0,0 +1,29 @@
+//
+//  ARViewContainer.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import SwiftUI
+import RealityKit
+
+/// Dünner UIKit-Adapter: hostet nur die `ARView` und übergibt sie an den Controller.
+/// Enthält bewusst keine Logik.
+struct ARViewContainer: UIViewRepresentable {
+    let controller: ARSessionController
+
+    func makeCoordinator() -> ARSessionController { controller }
+
+    func makeUIView(context: Context) -> ARView {
+        let view = ARView(frame: .zero)
+        context.coordinator.attach(to: view)
+        return view
+    }
+
+    func updateUIView(_ uiView: ARView, context: Context) {}
+
+    static func dismantleUIView(_ uiView: ARView, coordinator: ARSessionController) {
+        MainActor.assumeIsolated { coordinator.detach() }
+    }
+}

GasTankAR/Views/TankAR/DirtTextureFactory.swift

@@ -0,0 +1,57 @@
+//
+//  DirtTextureFactory.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import RealityKit
+import UIKit
+
+/// Erzeugt prozedural eine kachelbare Erd-/Dreck-Textur (ohne Bild-Asset) für die Grubenwand,
+/// damit sichtbar wird, dass sich der Tank unter der Erde befindet.
+@MainActor
+enum DirtTextureFactory {
+    /// Einmalig erzeugte, wiederverwendete Textur.
+    static let texture: TextureResource? = makeTexture()
+
+    private static func makeTexture() -> TextureResource? {
+        let size = CGSize(width: 256, height: 256)
+        let image = UIGraphicsImageRenderer(size: size).image { context in
+            let rect = CGRect(origin: .zero, size: size)
+
+            // Erd-Grundton.
+            UIColor(red: 0.42, green: 0.30, blue: 0.18, alpha: 1).setFill()
+            context.fill(rect)
+
+            // Größere Erdflecken / Steine für Struktur.
+            for _ in 0..<70 {
+                let diameter = CGFloat.random(in: 6...26)
+                let origin = CGPoint(x: .random(in: -10...size.width), y: .random(in: -10...size.height))
+                let brightness = CGFloat.random(in: -0.12...0.12)
+                UIColor(
+                    red: max(0, min(1, 0.42 + brightness)),
+                    green: max(0, min(1, 0.30 + brightness)),
+                    blue: max(0, min(1, 0.18 + brightness)),
+                    alpha: 1
+                ).setFill()
+                context.cgContext.fillEllipse(in: CGRect(x: origin.x, y: origin.y, width: diameter, height: diameter))
+            }
+
+            // Feine Körnung (helle + dunkle Sprenkel).
+            for _ in 0..<2000 {
+                let point = CGPoint(x: .random(in: 0..<size.width), y: .random(in: 0..<size.height))
+                let diameter = CGFloat.random(in: 0.5...2.5)
+                let isDark = Bool.random()
+                let color = isDark
+                    ? UIColor(white: 0, alpha: .random(in: 0.05...0.2))
+                    : UIColor(white: 1, alpha: .random(in: 0.03...0.12))
+                color.setFill()
+                context.cgContext.fillEllipse(in: CGRect(x: point.x, y: point.y, width: diameter, height: diameter))
+            }
+        }
+
+        guard let cgImage = image.cgImage else { return nil }
+        return try? TextureResource.generate(from: cgImage, options: .init(semantic: .color))
+    }
+}

GasTankAR/Views/TankAR/Matrix+Array.swift

@@ -0,0 +1,26 @@
+//
+//  Matrix+Array.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import simd
+
+extension simd_float4x4 {
+    /// Spaltenweise Darstellung als 16 Floats (für die Persistenz).
+    var floatArray: [Float] {
+        [columns.0, columns.1, columns.2, columns.3].flatMap { [$0.x, $0.y, $0.z, $0.w] }
+    }
+
+    /// Rekonstruiert eine Matrix aus 16 spaltenweisen Floats.
+    init?(floatArray array: [Float]) {
+        guard array.count == 16 else { return nil }
+        self.init(
+            SIMD4(array[0], array[1], array[2], array[3]),
+            SIMD4(array[4], array[5], array[6], array[7]),
+            SIMD4(array[8], array[9], array[10], array[11]),
+            SIMD4(array[12], array[13], array[14], array[15])
+        )
+    }
+}

GasTankAR/Views/TankAR/Measurement.swift

@@ -0,0 +1,37 @@
+//
+//  Measurement.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import Foundation
+import simd
+
+/// Eine benannte Strecke zwischen zwei im Raum gewählten Punkten (Welt-Koordinaten).
+struct Measurement: Identifiable {
+    let id = UUID()
+    var name: String
+    let start: SIMD3<Float>
+    let end: SIMD3<Float>
+
+    /// Länge der Strecke in Metern.
+    var distance: Float { simd_distance(start, end) }
+
+    /// Länge als lesbarer Text, z. B. „1,23 m".
+    var formattedDistance: String {
+        String(format: "%.2f m", distance)
+    }
+}
+
+/// Ablaufphasen beim Anlegen einer Strecke.
+enum MeasurementPhase: Equatable {
+    /// Kein Messvorgang aktiv.
+    case idle
+    /// Wartet auf den ersten Punkt.
+    case awaitingFirstPoint
+    /// Wartet auf den zweiten Punkt.
+    case awaitingSecondPoint
+    /// Beide Punkte gesetzt – wartet auf die Benennung.
+    case naming
+}

GasTankAR/Views/TankAR/MeasurementEntityFactory.swift

@@ -0,0 +1,98 @@
+//
+//  MeasurementEntityFactory.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import RealityKit
+import UIKit
+
+/// Baut die AR-Visualisierung einer Strecke: zwei Endpunkt-Kugeln, die verbindende Linie
+/// sowie ein Text-Label (Bezeichnung + Länge) am Mittelpunkt der Strecke.
+///
+/// Enthält außerdem wiederverwendbare Bausteine für die *Live*-Vorschau während des Messens
+/// (Cursor-Kugel, skalierbare Linie, aktualisierbares Label).
+@MainActor
+enum MeasurementEntityFactory {
+    /// Name des Label-Halters – wird zum Wiederfinden fürs Billboarding genutzt.
+    static let labelName = "MeasurementLabel"
+
+    private static let color = UIColor.systemYellow
+    private static let pointRadius: Float = 0.012
+    private static let lineThickness: Float = 0.006
+    private static let labelHeight: Float = 0.06
+    private static let labelYOffset: Float = 0.03
+
+    /// Kleine Kugel für einen (auch vorläufigen) Messpunkt.
+    static func makePoint(at position: SIMD3<Float>) -> ModelEntity {
+        let sphere = ModelEntity(
+            mesh: .generateSphere(radius: pointRadius),
+            materials: [UnlitMaterial(color: color)]
+        )
+        sphere.position = position
+        return sphere
+    }
+
+    /// Vollständige Strecken-Visualisierung (Punkte + Linie + Label).
+    static func makeMeasurement(_ measurement: Measurement) -> Entity {
+        let container = Entity()
+        container.name = "Measurement-\(measurement.id.uuidString)"
+        container.addChild(makePoint(at: measurement.start))
+        container.addChild(makePoint(at: measurement.end))
+
+        let line = makeLineBase()
+        configureLine(line, from: measurement.start, to: measurement.end)
+        container.addChild(line)
+
+        let label = makeLabelHolder()
+        label.position = labelPosition(from: measurement.start, to: measurement.end)
+        label.addChild(makeText("\(measurement.name)  (\(measurement.formattedDistance))"))
+        container.addChild(label)
+        return container
+    }
+
+    /// Basis-Linie der Länge 1 m (entlang +Z). Für die Live-Linie wird sie via ``configureLine`` skaliert/rotiert.
+    static func makeLineBase() -> ModelEntity {
+        ModelEntity(
+            mesh: .generateBox(size: SIMD3(lineThickness, lineThickness, 1)),
+            materials: [UnlitMaterial(color: color)]
+        )
+    }
+
+    /// Richtet eine per ``makeLineBase`` erzeugte Linie zwischen zwei Punkten aus (Länge über Z-Skalierung).
+    static func configureLine(_ line: Entity, from start: SIMD3<Float>, to end: SIMD3<Float>) {
+        let length = max(simd_distance(start, end), 0.0001)
+        line.transform = Transform(
+            scale: SIMD3(1, 1, length),
+            rotation: simd_quatf(from: SIMD3(0, 0, 1), to: normalize(end - start)),
+            translation: (start + end) / 2
+        )
+    }
+
+    /// Leerer Label-Halter (Billboard-Anker). Der Text wird als zentriertes Kind eingehängt.
+    static func makeLabelHolder() -> Entity {
+        let holder = Entity()
+        holder.name = labelName
+        return holder
+    }
+
+    /// Zentriertes Text-Entity für einen Label-Halter.
+    static func makeText(_ string: String) -> ModelEntity {
+        let mesh = MeshResource.generateText(
+            string,
+            extrusionDepth: 0.001,
+            font: .systemFont(ofSize: CGFloat(labelHeight), weight: .semibold)
+        )
+        var material = UnlitMaterial(color: .white)
+        material.faceCulling = .none
+        let text = ModelEntity(mesh: mesh, materials: [material])
+        text.position = -text.visualBounds(relativeTo: nil).center
+        return text
+    }
+
+    /// Position des Labels (Streckenmitte, leicht angehoben).
+    static func labelPosition(from start: SIMD3<Float>, to end: SIMD3<Float>) -> SIMD3<Float> {
+        (start + end) / 2 + SIMD3(0, labelYOffset, 0)
+    }
+}

GasTankAR/Views/TankAR/MeasurementListView.swift

@@ -0,0 +1,59 @@
+//
+//  MeasurementListView.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import SwiftUI
+
+/// Von unten einschwebendes Sheet mit den angelegten Strecken. Ist keine vorhanden,
+/// wird zum Hinzufügen aufgefordert.
+struct MeasurementListView: View {
+    let controller: ARSessionController
+    /// Startet einen neuen Messvorgang (schließt das Sheet und lässt den Nutzer zwei Punkte wählen).
+    let onAddStrecke: () -> Void
+
+    var body: some View {
+        NavigationStack {
+            Group {
+                if controller.measurements.isEmpty {
+                    ContentUnavailableView {
+                        Label("Keine Strecken", systemImage: "ruler")
+                    } description: {
+                        Text("Füge eine Strecke hinzu und wähle dafür zwei Punkte im Raum.")
+                    } actions: {
+                        Button("Strecke hinzufügen", systemImage: "plus", action: onAddStrecke)
+                            .buttonStyle(.borderedProminent)
+                    }
+                } else {
+                    List {
+                        ForEach(controller.measurements) { measurement in
+                            HStack {
+                                VStack(alignment: .leading, spacing: 2) {
+                                    Text(measurement.name)
+                                        .font(.headline)
+                                    Text(measurement.formattedDistance)
+                                        .font(.subheadline)
+                                        .foregroundStyle(.secondary)
+                                }
+                                Spacer()
+                                Image(systemName: "ruler")
+                                    .foregroundStyle(.secondary)
+                            }
+                        }
+                        .onDelete { controller.deleteMeasurements(at: $0) }
+                    }
+                }
+            }
+            .navigationTitle("Strecken")
+            .navigationBarTitleDisplayMode(.inline)
+            .toolbar {
+                ToolbarItem(placement: .topBarTrailing) {
+                    Button("Hinzufügen", systemImage: "plus", action: onAddStrecke)
+                }
+            }
+        }
+        .presentationDetents([.medium, .large])
+    }
+}

GasTankAR/Views/TankAR/PhotoEncoder.swift

@@ -0,0 +1,107 @@
+//
+//  PhotoEncoder.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import ImageIO
+import UniformTypeIdentifiers
+import CoreLocation
+import UIKit
+
+/// Kodiert einen Snapshot als JPEG und bettet dabei EXIF-Aufnahmezeit sowie – falls vorhanden –
+/// GPS-Metadaten direkt in die Bilddatei ein (ImageIO). So tragen auch exportierte Bilder ihren
+/// Aufnahmeort mit sich.
+enum PhotoEncoder {
+    /// Erzeugt JPEG-Daten mit eingebetteten Metadaten. Fällt bei Fehlern auf `UIImage.jpegData` zurück.
+    static func jpegData(
+        from image: UIImage,
+        coordinate: CLLocationCoordinate2D?,
+        date: Date,
+        compressionQuality: CGFloat = 0.9
+    ) -> Data? {
+        guard let cgImage = image.cgImage else {
+            return image.jpegData(compressionQuality: compressionQuality)
+        }
+
+        let output = NSMutableData()
+        guard let destination = CGImageDestinationCreateWithData(
+            output, UTType.jpeg.identifier as CFString, 1, nil
+        ) else {
+            return image.jpegData(compressionQuality: compressionQuality)
+        }
+
+        var properties: [CFString: Any] = [
+            kCGImageDestinationLossyCompressionQuality: compressionQuality,
+            kCGImagePropertyOrientation: CGImagePropertyOrientation(image.imageOrientation).rawValue,
+            kCGImagePropertyExifDictionary: [
+                kCGImagePropertyExifDateTimeOriginal: Self.exifDateFormatter.string(from: date),
+                kCGImagePropertyExifDateTimeDigitized: Self.exifDateFormatter.string(from: date),
+            ],
+        ]
+
+        if let coordinate {
+            properties[kCGImagePropertyGPSDictionary] = gpsProperties(for: coordinate, date: date)
+        }
+
+        CGImageDestinationAddImage(destination, cgImage, properties as CFDictionary)
+        guard CGImageDestinationFinalize(destination) else {
+            return image.jpegData(compressionQuality: compressionQuality)
+        }
+        return output as Data
+    }
+
+    private static func gpsProperties(for coordinate: CLLocationCoordinate2D, date: Date) -> [CFString: Any] {
+        [
+            kCGImagePropertyGPSLatitude: abs(coordinate.latitude),
+            kCGImagePropertyGPSLatitudeRef: coordinate.latitude >= 0 ? "N" : "S",
+            kCGImagePropertyGPSLongitude: abs(coordinate.longitude),
+            kCGImagePropertyGPSLongitudeRef: coordinate.longitude >= 0 ? "E" : "W",
+            kCGImagePropertyGPSDateStamp: Self.gpsDateFormatter.string(from: date),
+            kCGImagePropertyGPSTimeStamp: Self.gpsTimeFormatter.string(from: date),
+        ]
+    }
+
+    /// EXIF-Zeitstempel in lokaler Zeit („yyyy:MM:dd HH:mm:ss").
+    private static let exifDateFormatter: DateFormatter = {
+        let formatter = DateFormatter()
+        formatter.locale = Locale(identifier: "en_US_POSIX")
+        formatter.dateFormat = "yyyy:MM:dd HH:mm:ss"
+        return formatter
+    }()
+
+    /// GPS-Datum in UTC („yyyy:MM:dd").
+    private static let gpsDateFormatter: DateFormatter = {
+        let formatter = DateFormatter()
+        formatter.locale = Locale(identifier: "en_US_POSIX")
+        formatter.timeZone = TimeZone(identifier: "UTC")
+        formatter.dateFormat = "yyyy:MM:dd"
+        return formatter
+    }()
+
+    /// GPS-Uhrzeit in UTC („HH:mm:ss").
+    private static let gpsTimeFormatter: DateFormatter = {
+        let formatter = DateFormatter()
+        formatter.locale = Locale(identifier: "en_US_POSIX")
+        formatter.timeZone = TimeZone(identifier: "UTC")
+        formatter.dateFormat = "HH:mm:ss"
+        return formatter
+    }()
+}
+
+private extension CGImagePropertyOrientation {
+    init(_ orientation: UIImage.Orientation) {
+        switch orientation {
+        case .up: self = .up
+        case .down: self = .down
+        case .left: self = .left
+        case .right: self = .right
+        case .upMirrored: self = .upMirrored
+        case .downMirrored: self = .downMirrored
+        case .leftMirrored: self = .leftMirrored
+        case .rightMirrored: self = .rightMirrored
+        @unknown default: self = .up
+        }
+    }
+}

GasTankAR/Views/TankAR/PipeRoute.swift

@@ -0,0 +1,49 @@
+//
+//  PipeRoute.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import Foundation
+import simd
+
+/// Eine Rohrführung als geordnete Folge von Wegpunkten (Welt-Koordinaten), die zu einem
+/// zusammenhängenden Pfad verbunden werden – visualisiert die geplante Rohrverlegung.
+struct PipeRoute {
+    private(set) var waypoints: [SIMD3<Float>] = []
+
+    var count: Int { waypoints.count }
+
+    /// Gesamtlänge des Pfads über alle Segmente in Metern.
+    var totalLength: Float {
+        guard waypoints.count > 1 else { return 0 }
+        return zip(waypoints, waypoints.dropFirst())
+            .reduce(0) { $0 + simd_distance($1.0, $1.1) }
+    }
+
+    var formattedLength: String {
+        String(format: "%.2f m", totalLength)
+    }
+
+    mutating func add(_ waypoint: SIMD3<Float>) {
+        waypoints.append(waypoint)
+    }
+
+    @discardableResult
+    mutating func removeLast() -> SIMD3<Float>? {
+        waypoints.isEmpty ? nil : waypoints.removeLast()
+    }
+
+    mutating func clear() {
+        waypoints.removeAll()
+    }
+}
+
+/// Ablaufphasen beim Erstellen einer Rohrführung.
+enum PipeRoutingPhase: Equatable {
+    /// Kein Rohr-Routing aktiv.
+    case idle
+    /// Wegpunkte werden gesetzt.
+    case placing
+}

GasTankAR/Views/TankAR/PipeRouteEntityFactory.swift

@@ -0,0 +1,54 @@
+//
+//  PipeRouteEntityFactory.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import RealityKit
+import UIKit
+
+/// Baut die AR-Visualisierung einer Rohrführung: Wegpunkt-Kugeln und die verbindenden
+/// Segmente. Bewusst in einer markanten, naturfremden Farbe (Pink/Magenta) gehalten.
+@MainActor
+enum PipeRouteEntityFactory {
+    /// Markante, in der Natur kaum vorkommende Linien-/Punktfarbe.
+    private static let color = UIColor.systemPink
+    private static let waypointRadius: Float = 0.02
+    private static let segmentThickness: Float = 0.012
+
+    /// Kugel für einen Wegpunkt.
+    static func makeWaypoint(at position: SIMD3<Float>) -> ModelEntity {
+        let sphere = ModelEntity(
+            mesh: .generateSphere(radius: waypointRadius),
+            materials: [UnlitMaterial(color: color)]
+        )
+        sphere.position = position
+        return sphere
+    }
+
+    /// Verbindungssegment zwischen zwei Wegpunkten.
+    static func makeSegment(from start: SIMD3<Float>, to end: SIMD3<Float>) -> ModelEntity {
+        let segment = makeSegmentBase()
+        configureSegment(segment, from: start, to: end)
+        return segment
+    }
+
+    /// Basis-Segment der Länge 1 m (entlang +Z) – für die Live-Vorschau wiederverwendbar.
+    static func makeSegmentBase() -> ModelEntity {
+        ModelEntity(
+            mesh: .generateBox(size: SIMD3(segmentThickness, segmentThickness, 1)),
+            materials: [UnlitMaterial(color: color)]
+        )
+    }
+
+    /// Richtet ein Segment zwischen zwei Punkten aus (Länge über Z-Skalierung).
+    static func configureSegment(_ segment: Entity, from start: SIMD3<Float>, to end: SIMD3<Float>) {
+        let length = max(simd_distance(start, end), 0.0001)
+        segment.transform = Transform(
+            scale: SIMD3(1, 1, length),
+            rotation: simd_quatf(from: SIMD3(0, 0, 1), to: normalize(end - start)),
+            translation: (start + end) / 2
+        )
+    }
+}

GasTankAR/Views/TankAR/ReferenceImageProvider.swift

@@ -0,0 +1,56 @@
+//
+//  ReferenceImageProvider.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import ARKit
+import UIKit
+
+/// Liefert die Referenzbilder für die Anker-Erkennung. Bevorzugt die AR-Ressourcengruppe
+/// „ARMarkers"; fällt sonst auf einen programmatisch erzeugten Platzhalter-Marker zurück.
+enum ReferenceImageProvider {
+    static func load() -> Set<ARReferenceImage> {
+        if let group = ARReferenceImage.referenceImages(inGroupNamed: "ARMarkers", bundle: .main) {
+            return group
+        }
+        if let placeholder = makePlaceholder() {
+            return [placeholder]
+        }
+        return []
+    }
+
+    private static func makePlaceholder() -> ARReferenceImage? {
+        let size = CGSize(width: 512, height: 512)
+        let renderer = UIGraphicsImageRenderer(size: size)
+        let image = renderer.image { context in
+            let cg = context.cgContext
+            UIColor.white.setFill()
+            cg.fill(CGRect(origin: .zero, size: size))
+
+            let palette: [UIColor] = [.black, .systemBlue, .systemRed, .systemGreen, .systemOrange, .systemPurple]
+            let cells = 8
+            let cellSize = size.width / CGFloat(cells)
+            for row in 0..<cells {
+                for column in 0..<cells {
+                    let index = (row * cells + column) % palette.count
+                    palette[index].setFill()
+                    let rect = CGRect(
+                        x: CGFloat(column) * cellSize,
+                        y: CGFloat(row) * cellSize,
+                        width: cellSize,
+                        height: cellSize
+                    )
+                    if (row + column).isMultiple(of: 2) {
+                        cg.fillEllipse(in: rect.insetBy(dx: 4, dy: 4))
+                    } else {
+                        cg.fill(rect.insetBy(dx: 6, dy: 6))
+                    }
+                }
+            }
+        }
+        guard let cgImage = image.cgImage else { return nil }
+        return ARReferenceImage(cgImage, orientation: .up, physicalWidth: 0.15)
+    }
+}

GasTankAR/Views/TankAR/SafetyZone.swift

@@ -0,0 +1,128 @@
+//
+//  SafetyZone.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 27.08.26.
+//
+
+import RealityKit
+import UIKit
+
+/// Ein Sicherheitsabstand rund um den Tank: ein Kreis mit gegebenem Radius und Farbe,
+/// dessen Mittelpunkt der Tank ist.
+///
+/// Modular gehalten: Ein weiterer Sicherheitsabstand wird schlicht durch Hinzufügen
+/// eines Eintrags zu ``SafetyZone/all`` ergänzt – die Darstellung folgt automatisch.
+struct SafetyZone: Identifiable {
+    let id = UUID()
+    /// Radius des Kreises in Metern (Abstand vom Tank-Mittelpunkt).
+    let radius: Float
+    /// Farbe des Rings.
+    let color: UIColor
+    /// Anzeigename, z. B. für Barrierefreiheit oder eine spätere Legende.
+    let label: String
+
+    /// Alle darzustellenden Sicherheitsabstände. Zum Ergänzen genügt ein weiterer Eintrag.
+    static let all: [SafetyZone] = [
+        SafetyZone(radius: 3, color: .systemRed, label: "3 m"),
+        SafetyZone(radius: 5, color: .systemOrange, label: "5 m"),
+    ]
+}
+
+/// Baut die flachen, auf dem Boden liegenden Ringe für die Sicherheitsabstände.
+@MainActor
+enum SafetyZoneFactory {
+    /// Halbe Linienbreite des Rings in Metern (Ring = Radius ± Halbbreite).
+    private static let lineHalfWidth: Float = 0.03
+    /// Anzahl der Segmente pro Ring (höher = runder).
+    private static let segments = 96
+    /// Deckkraft der Ringe.
+    private static let opacity: Float = 0.85
+    /// Texthöhe der Meter-Beschriftung in Metern.
+    private static let labelHeight: Float = 0.25
+    /// Winkelpositionen (im Bogenmaß), an denen die Beschriftung auf dem Ring liegt.
+    /// Mehrere Positionen sorgen dafür, dass die Meterangabe aus jeder Richtung lesbar ist.
+    private static let labelAngles: [Float] = [0, .pi / 2, .pi, 3 * .pi / 2]
+
+    /// Erzeugt eine Entity mit je einem Ring pro Sicherheitsabstand, zentriert im Ursprung
+    /// und flach in der XZ-Ebene (y = 0) liegend.
+    static func makeEntity(for zones: [SafetyZone] = SafetyZone.all) -> Entity {
+        let root = Entity()
+        root.name = "SafetyZones"
+        for zone in zones {
+            root.addChild(makeRing(for: zone))
+        }
+        return root
+    }
+
+    private static func makeRing(for zone: SafetyZone) -> Entity {
+        let container = Entity()
+        container.name = "SafetyZone-\(zone.label)"
+
+        let mesh = annulusMesh(radius: zone.radius, halfWidth: lineHalfWidth, segments: segments)
+
+        var material = UnlitMaterial(color: zone.color.withAlphaComponent(CGFloat(opacity)))
+        material.blending = .transparent(opacity: .init(floatLiteral: opacity))
+        // Beidseitig sichtbar – unabhängig von der Blickrichtung auf den Boden.
+        material.faceCulling = .none
+
+        container.addChild(ModelEntity(mesh: mesh, materials: [material]))
+
+        for angle in labelAngles {
+            container.addChild(makeLabel(for: zone, at: angle))
+        }
+        return container
+    }
+
+    /// Erzeugt eine flach auf dem Boden liegende Meter-Beschriftung, tangential zum Ring
+    /// ausgerichtet (Oberkante zeigt zur Mitte, damit sie von außen aufrecht lesbar ist).
+    private static func makeLabel(for zone: SafetyZone, at angle: Float) -> Entity {
+        let mesh = MeshResource.generateText(
+            zone.label,
+            extrusionDepth: 0.002,
+            font: .systemFont(ofSize: CGFloat(labelHeight), weight: .bold)
+        )
+
+        var material = UnlitMaterial(color: zone.color)
+        material.faceCulling = .none
+
+        let text = ModelEntity(mesh: mesh, materials: [material])
+        // Auf den eigenen Ursprung zentrieren.
+        let bounds = text.visualBounds(relativeTo: nil)
+        text.position = -bounds.center
+
+        let holder = Entity()
+        holder.addChild(text)
+        holder.position = SIMD3(sin(angle) * zone.radius, 0.01, cos(angle) * zone.radius)
+        holder.orientation = simd_quatf(angle: angle, axis: SIMD3(0, 1, 0))
+            * simd_quatf(angle: -.pi / 2, axis: SIMD3(1, 0, 0))
+        return holder
+    }
+
+    /// Erzeugt einen flachen Kreisring (Annulus) in der XZ-Ebene.
+    private static func annulusMesh(radius: Float, halfWidth: Float, segments: Int) -> MeshResource {
+        var positions: [SIMD3<Float>] = []
+        var indices: [UInt32] = []
+        let inner = max(0, radius - halfWidth)
+        let outer = radius + halfWidth
+
+        for i in 0...segments {
+            let angle = Float(i) / Float(segments) * 2 * .pi
+            let cosA = cos(angle)
+            let sinA = sin(angle)
+            positions.append(SIMD3(inner * cosA, 0, inner * sinA))
+            positions.append(SIMD3(outer * cosA, 0, outer * sinA))
+        }
+
+        for i in 0..<segments {
+            let base = UInt32(i * 2)
+            indices.append(contentsOf: [base, base + 1, base + 2])
+            indices.append(contentsOf: [base + 2, base + 1, base + 3])
+        }
+
+        var descriptor = MeshDescriptor(name: "safetyRing")
+        descriptor.positions = MeshBuffers.Positions(positions)
+        descriptor.primitives = .triangles(indices)
+        return (try? MeshResource.generate(from: [descriptor])) ?? .generatePlane(width: 0, depth: 0)
+    }
+}

GasTankAR/Views/TankAR/SessionConfigurationFactory.swift

@@ -0,0 +1,47 @@
+//
+//  SessionConfigurationFactory.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import ARKit
+
+/// Baut die `ARWorldTrackingConfiguration` für den AR-Modus.
+/// Kapselt die LiDAR-/People-Occlusion-/Image-Detection-Logik an einem Ort.
+struct SessionConfigurationFactory {
+    let useLiDAR: Bool
+    let referenceImages: Set<ARReferenceImage>
+
+    func make(withImages: Bool, initialWorldMap: ARWorldMap?) -> ARWorldTrackingConfiguration {
+        let config = ARWorldTrackingConfiguration()
+        config.planeDetection = [.horizontal]
+
+        if useLiDAR {
+            if ARWorldTrackingConfiguration.supportsSceneReconstruction(.mesh) {
+                config.sceneReconstruction = .mesh
+            }
+            if ARWorldTrackingConfiguration.supportsFrameSemantics(.sceneDepth) {
+                config.frameSemantics.insert(.sceneDepth)
+            }
+        } else {
+            config.sceneReconstruction = []
+            config.frameSemantics = []
+        }
+
+        // People Occlusion funktioniert auch ohne LiDAR (A12+): Personen zwischen Kamera
+        // und Tank verdecken das Objekt korrekt. (Beliebige Objekte wie Stühle brauchen LiDAR.)
+        if ARWorldTrackingConfiguration.supportsFrameSemantics(.personSegmentationWithDepth) {
+            config.frameSemantics.insert(.personSegmentationWithDepth)
+        }
+
+        if let initialWorldMap {
+            config.initialWorldMap = initialWorldMap
+        }
+        if withImages {
+            config.detectionImages = referenceImages
+            config.maximumNumberOfTrackedImages = 1
+        }
+        return config
+    }
+}

GasTankAR/Views/TankAR/TankDepthFadeMaterial.swift

@@ -0,0 +1,63 @@
+//
+//  TankDepthFadeMaterial.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import RealityKit
+import Metal
+
+/// Kapselt das Höhen-Fade-CustomMaterial für den unterirdischen Tank:
+/// verblasst die Opacity anhand der Welt-Höhe (Kopf opak, vergrabener Teil transparent).
+@MainActor
+enum TankDepthFadeMaterial {
+    /// Fade-Band (Meter) unterhalb der Bodenkante, über das die Transparenz einsetzt.
+    static let band: Float = 0.15
+    /// Minimale Opacity des vergrabenen Teils.
+    static let belowAlpha: Float = 0.3
+
+    private static let shader: CustomMaterial.SurfaceShader? = {
+        guard let library = MTLCreateSystemDefaultDevice()?.makeDefaultLibrary() else { return nil }
+        return CustomMaterial.SurfaceShader(named: "tankDepthFadeSurface", in: library)
+    }()
+
+    /// Ersetzt die Materialien der Entity (rekursiv) durch das Fade-CustomMaterial.
+    static func apply(to entity: Entity) {
+        guard let shader else { return }
+        forEachModelEntity(entity) { modelEntity in
+            guard var component = modelEntity.model else { return }
+            component.materials = component.materials.map { material in
+                guard var custom = try? CustomMaterial(from: material, surfaceShader: shader) else {
+                    return material
+                }
+                custom.blending = .transparent(opacity: 1.0)
+                custom.custom.value = SIMD4<Float>(0, band, belowAlpha, 0)
+                return custom
+            }
+            modelEntity.model = component
+        }
+    }
+
+    /// Aktualisiert die Boden-Höhe (Welt-Y) in bereits angewandten Fade-Materialien.
+    static func updateGroundY(_ groundY: Float, on entity: Entity) {
+        forEachModelEntity(entity) { modelEntity in
+            guard var component = modelEntity.model else { return }
+            component.materials = component.materials.map { material in
+                guard var custom = material as? CustomMaterial else { return material }
+                custom.custom.value = SIMD4<Float>(groundY, band, belowAlpha, 0)
+                return custom
+            }
+            modelEntity.model = component
+        }
+    }
+
+    private static func forEachModelEntity(_ entity: Entity, _ body: (ModelEntity) -> Void) {
+        if let modelEntity = entity as? ModelEntity {
+            body(modelEntity)
+        }
+        for child in entity.children {
+            forEachModelEntity(child, body)
+        }
+    }
+}

GasTankAR/Views/TankAR/TankEntityFactory.swift

@@ -0,0 +1,93 @@
+//
+//  TankEntityFactory.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import RealityKit
+import UIKit
+
+/// Baut die darzustellende Tank-Entity (aus `GasTank.usdz`): lädt/cached das Modell,
+/// richtet es je nach Aufstellungsart aus, erzeugt die Kollisionsform und – bei
+/// unterirdischer Aufstellung – den Höhen-Transparenz-Effekt.
+@MainActor
+final class TankEntityFactory {
+    /// Name des USDZ-Assets im Bundle.
+    private static let modelName = "GasTank"
+    /// Anteil der Modellhöhe, der bei unterirdischer Aufstellung oben herausragt („Kopf").
+    private static let belowGroundExposedFraction: Float = 0.25
+    /// Zusätzlicher Abstand zwischen Tank-Umkreis und Grubenwand (in Metern) – großzügig,
+    /// damit die Grube nicht gequetscht wirkt.
+    private static let pitMargin: Float = 0.4
+    /// Zusätzliche Tiefe der Grubensohle unter der Tankunterkante (in Metern).
+    private static let pitFloorClearance: Float = 0.1
+
+    /// Vorab geladenes Modell; wird pro Platzierung geklont.
+    private var loadedModel: Entity?
+
+    /// Lädt das USDZ asynchron vor (blockiert den Main-Actor nicht).
+    func preload() {
+        guard loadedModel == nil else { return }
+        Task { @MainActor in
+            self.loadedModel = try? await Entity(named: Self.modelName)
+        }
+    }
+
+    /// Erzeugt den manipulierbaren Container (mit Kollision fürs Gesten-Hit-Testing).
+    func makeContainer(for tank: Tank) -> ModelEntity {
+        let model = loadModelClone()
+        let bounds = model.visualBounds(relativeTo: nil)
+        let container = ModelEntity()
+
+        switch tank.placement {
+        case .aboveGround:
+            model.position.y -= bounds.min.y   // Unterkante auf die Fläche
+
+        case .belowGround:
+            // Modell absenken, sodass nur der obere Teil („Kopf") herausragt …
+            let exposed = bounds.extents.y * Self.belowGroundExposedFraction
+            let buried = bounds.extents.y - exposed
+            model.position.y -= (bounds.max.y - exposed)
+            // … und den Boden „aufreißen": eine runde Grube ausheben, in welcher der Tank steht.
+            // Radius = Umkreis der Grundfläche (halbe Diagonale) + großzügiger Rand.
+            let footprintRadius = 0.5 * (bounds.extents.x * bounds.extents.x + bounds.extents.z * bounds.extents.z).squareRoot()
+            container.addChild(TankPitFactory.makePit(
+                radius: footprintRadius + Self.pitMargin,
+                depth: buried + Self.pitFloorClearance,
+                center: bounds.center
+            ))
+        }
+
+        container.addChild(model)
+
+        let colliderBounds = model.visualBounds(relativeTo: container)
+        container.collision = CollisionComponent(shapes: [
+            ShapeResource
+                .generateBox(size: colliderBounds.extents)
+                .offsetBy(translation: colliderBounds.center)
+        ])
+
+        // Auswahl-Markierung (Eck-Winkel) – zunächst versteckt, wird bei Auswahl eingeblendet.
+        let highlight = TankHighlightFactory.makeHighlight(for: colliderBounds)
+        highlight.isEnabled = false
+        container.addChild(highlight)
+
+        return container
+    }
+
+    /// Liefert einen Klon des vorab geladenen Modells. Fällt auf synchrones Laden
+    /// bzw. – wenn das USDZ fehlt – auf einen einfachen Cube zurück.
+    private func loadModelClone() -> Entity {
+        if loadedModel == nil {
+            loadedModel = try? Entity.load(named: Self.modelName)
+        }
+        if let loadedModel {
+            return loadedModel.clone(recursive: true)
+        }
+        return ModelEntity(
+            mesh: .generateBox(size: 0.3),
+            materials: [SimpleMaterial(color: .white, isMetallic: false)]
+        )
+    }
+}

GasTankAR/Views/TankAR/TankHighlightFactory.swift

@@ -0,0 +1,69 @@
+//
+//  TankHighlightFactory.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import RealityKit
+import UIKit
+
+/// Baut die Auswahl-Markierung um den Tank: ein (ansonsten unsichtbarer) Quader, dessen
+/// acht Ecken mit kräftig gefärbten Winkeln hervorgehoben werden – deutlich sichtbar,
+/// ohne den Tank selbst zu verdecken.
+@MainActor
+enum TankHighlightFactory {
+    /// Name der Markierungs-Entity (zum Ein-/Ausblenden bei Auswahl).
+    static let name = "TankSelectionHighlight"
+
+    private static let color = UIColor.systemTeal
+
+    /// Erzeugt die Eck-Winkel passend zur Bounding-Box (im Koordinatensystem des Containers).
+    static func makeHighlight(for bounds: BoundingBox) -> Entity {
+        let root = Entity()
+        root.name = name
+
+        let extents = bounds.extents
+        let smallestEdge = min(extents.x, min(extents.y, extents.z))
+        let armLength = max(0.05, smallestEdge * 0.3)
+        let thickness = max(0.008, smallestEdge * 0.05)
+
+        var material = UnlitMaterial(color: color)
+        material.faceCulling = .none
+
+        for x in [bounds.min.x, bounds.max.x] {
+            for y in [bounds.min.y, bounds.max.y] {
+                for z in [bounds.min.z, bounds.max.z] {
+                    let corner = SIMD3(x, y, z)
+                    // Vorzeichen: Winkel zeigt von der Ecke nach innen (zur Boxmitte).
+                    let signX: Float = (x == bounds.min.x) ? 1 : -1
+                    let signY: Float = (y == bounds.min.y) ? 1 : -1
+                    let signZ: Float = (z == bounds.min.z) ? 1 : -1
+
+                    root.addChild(beam(
+                        size: SIMD3(armLength, thickness, thickness),
+                        center: corner + SIMD3(signX * armLength / 2, 0, 0),
+                        material: material
+                    ))
+                    root.addChild(beam(
+                        size: SIMD3(thickness, armLength, thickness),
+                        center: corner + SIMD3(0, signY * armLength / 2, 0),
+                        material: material
+                    ))
+                    root.addChild(beam(
+                        size: SIMD3(thickness, thickness, armLength),
+                        center: corner + SIMD3(0, 0, signZ * armLength / 2),
+                        material: material
+                    ))
+                }
+            }
+        }
+        return root
+    }
+
+    private static func beam(size: SIMD3<Float>, center: SIMD3<Float>, material: UnlitMaterial) -> ModelEntity {
+        let beam = ModelEntity(mesh: .generateBox(size: size), materials: [material])
+        beam.position = center
+        return beam
+    }
+}

GasTankAR/Views/TankAR/TankManipulationPanel.swift

@@ -0,0 +1,144 @@
+//
+//  TankManipulationPanel.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import SwiftUI
+
+/// Steuer-Panel für den ausgewählten Tank: Höhe (↑↓), Verschieben auf dem Boden
+/// (vor/zurück/links/rechts) und Drehen (⟲⟳). Erscheint von unten; Pinch bleibt möglich.
+/// Buttons unterstützen Gedrückt-halten für kontinuierliche Anpassung.
+struct TankManipulationPanel: View {
+    let controller: ARSessionController
+
+    var body: some View {
+        VStack(spacing: 14) {
+            HStack {
+                Text("Tank anpassen")
+                    .font(.headline)
+                Spacer()
+                Button {
+                    controller.deselectTank()
+                } label: {
+                    Image(systemName: "xmark.circle.fill")
+                        .font(.title2)
+                        .foregroundStyle(.secondary)
+                }
+                .buttonStyle(.plain)
+                .accessibilityLabel("Schließen")
+            }
+
+            HStack(alignment: .center, spacing: 24) {
+                heightGroup
+                moveGroup
+                rotateGroup
+            }
+
+            Button("Neu platzieren", systemImage: "arrow.up.and.down.and.arrow.left.and.right") {
+                controller.reposition()
+            }
+            .buttonStyle(.bordered)
+        }
+        .padding()
+        .background(.ultraThinMaterial, in: .rect(cornerRadius: 16))
+    }
+
+    // MARK: - Gruppen
+
+    private var heightGroup: some View {
+        controlGroup(title: "Höhe") {
+            VStack(spacing: 8) {
+                holdButton("chevron.up", label: "Höher") { controller.adjustTankHeight(up: true) }
+                holdButton("chevron.down", label: "Tiefer") { controller.adjustTankHeight(up: false) }
+            }
+        }
+    }
+
+    private var moveGroup: some View {
+        controlGroup(title: "Verschieben") {
+            VStack(spacing: 8) {
+                holdButton("arrow.up", label: "Vorwärts") { controller.moveTank(forward: true) }
+                HStack(spacing: 8) {
+                    holdButton("arrow.left", label: "Nach links") { controller.moveTank(left: true) }
+                    holdButton("arrow.right", label: "Nach rechts") { controller.moveTank(left: false) }
+                }
+                holdButton("arrow.down", label: "Rückwärts") { controller.moveTank(forward: false) }
+            }
+        }
+    }
+
+    private var rotateGroup: some View {
+        controlGroup(title: "Drehen") {
+            HStack(spacing: 8) {
+                holdButton("rotate.left", label: "Gegen den Uhrzeigersinn") { controller.rotateTank(clockwise: false) }
+                holdButton("rotate.right", label: "Im Uhrzeigersinn") { controller.rotateTank(clockwise: true) }
+            }
+        }
+    }
+
+    private func controlGroup<Content: View>(title: String, @ViewBuilder content: () -> Content) -> some View {
+        VStack(spacing: 8) {
+            content()
+            Text(title)
+                .font(.caption)
+                .foregroundStyle(.secondary)
+        }
+    }
+
+    private func holdButton(_ systemImage: String, label: String, action: @escaping () -> Void) -> some View {
+        HoldRepeatButton(
+            systemImage: systemImage,
+            accessibilityLabel: label,
+            action: action,
+            onRelease: { controller.commitTankEdit() }
+        )
+    }
+}
+
+/// Runder Button, der bei Gedrückt-halten die Aktion wiederholt (Tastenwiederholung).
+/// Einzel-Tap = ein Schritt; Halten = fortlaufend. Beim Loslassen wird `onRelease` aufgerufen.
+private struct HoldRepeatButton: View {
+    let systemImage: String
+    let accessibilityLabel: String
+    let action: () -> Void
+    let onRelease: () -> Void
+
+    @State private var repeatTask: Task<Void, Never>?
+
+    private static let initialDelay: Duration = .milliseconds(350)
+    private static let repeatInterval: Duration = .milliseconds(60)
+
+    var body: some View {
+        Image(systemName: systemImage)
+            .font(.title3)
+            .frame(width: 48, height: 48)
+            .background(.ultraThinMaterial, in: .circle)
+            .contentShape(.circle)
+            .gesture(
+                DragGesture(minimumDistance: 0)
+                    .onChanged { _ in if repeatTask == nil { start() } }
+                    .onEnded { _ in stop() }
+            )
+            .accessibilityLabel(accessibilityLabel)
+            .accessibilityAddTraits(.isButton)
+    }
+
+    private func start() {
+        action()   // sofortiger erster Schritt (Einzel-Tap)
+        repeatTask = Task { @MainActor in
+            try? await Task.sleep(for: Self.initialDelay)
+            while !Task.isCancelled {
+                action()
+                try? await Task.sleep(for: Self.repeatInterval)
+            }
+        }
+    }
+
+    private func stop() {
+        repeatTask?.cancel()
+        repeatTask = nil
+        onRelease()
+    }
+}

GasTankAR/Views/TankAR/TankPitFactory.swift

@@ -0,0 +1,211 @@
+//
+//  TankPitFactory.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import RealityKit
+import UIKit
+
+/// Baut die „ausgehobene Grube" für einen unterirdischen Tank als **Zylinder**: Der Boden wird
+/// mit einer kreisrunden Occlusion-Maske „aufgerissen" und darunter ein runder Schacht
+/// ausgehoben (sichtbarer Wandmantel + Sohle), in dem der Tank steht.
+///
+/// Aufbau der zurückgegebenen Entity (lokaler Ursprung = Bodenkante, y = 0):
+/// - Wandmantel + Sohle reichen von y = 0 bis y = -`depth`.
+/// - Eine kreisrunde Occlusion-Maske in der Bodenebene verdeckt alles Vergrabene außerhalb
+///   der Öffnung, sodass der Eindruck eines echten Lochs im Boden entsteht.
+@MainActor
+enum TankPitFactory {
+    /// Anzahl der Segmente pro Kreis (höher = runder).
+    private static let segments = 48
+    /// Radius der kreisförmigen Boden-Occlusion-Maske (muss die Öffnung deutlich überragen).
+    private static let maskOuterRadius: Float = 20
+    /// Die Maske liegt minimal unter der Bodenkante, damit sie nicht mit bodennahen
+    /// Overlays (z. B. den Sicherheitsabstands-Ringen bei y = 0) um die Tiefe konkurriert.
+    private static let maskYOffset: Float = -0.005
+    /// Breite der hervorgehobenen Rand-Ringe.
+    private static let rimBand: Float = 0.03
+
+    /// Farbe des Wandmantels (heller, damit sich die Grube klar vom Boden abhebt).
+    private static let wallColor = UIColor(red: 0.62, green: 0.47, blue: 0.31, alpha: 1)
+    /// Farbe der Grubensohle (dunkler als die Wände – erzeugt Tiefeneindruck).
+    private static let floorColor = UIColor(red: 0.24, green: 0.18, blue: 0.12, alpha: 1)
+    /// Farbe der hervorgehobenen Rand-Ringe.
+    private static let rimColor = UIColor.systemYellow
+
+    /// Erzeugt die zylindrische Grube.
+    /// - Parameters:
+    ///   - radius: Radius der Grube (x/z) in Metern.
+    ///   - depth: Tiefe der Grube (y) in Metern.
+    ///   - center: horizontaler Mittelpunkt relativ zum Container (y wird ignoriert).
+    static func makePit(radius: Float, depth: Float, center: SIMD3<Float>) -> Entity {
+        let pit = Entity()
+        pit.name = "TankPit"
+        pit.position = SIMD3(center.x, 0, center.z)
+
+        // Sichtbarer Wandmantel mit Erd-/Dreck-Textur …
+        pit.addChild(wallModel(radius: radius, depth: depth))
+        // … runde Sohle (dunkler) …
+        pit.addChild(model(mesh: floorMesh(radius: radius, depth: depth), color: floorColor))
+        // … hervorgehobene Rand-Ringe oben und unten …
+        pit.addChild(model(mesh: ringMesh(radius: radius, y: 0), color: rimColor))
+        pit.addChild(model(mesh: ringMesh(radius: radius, y: -depth), color: rimColor))
+
+        // … und die kreisrunde Occlusion-Maske mit Loch über der Öffnung.
+        let mask = ModelEntity(
+            mesh: maskMesh(holeRadius: radius, outerRadius: maskOuterRadius),
+            materials: [OcclusionMaterial()]
+        )
+        mask.position.y = maskYOffset
+        pit.addChild(mask)
+
+        return pit
+    }
+
+    // MARK: - Bausteine
+
+    private static func model(mesh: MeshResource, color: UIColor) -> ModelEntity {
+        var material = UnlitMaterial(color: color)
+        material.faceCulling = .none   // beidseitig sichtbar (Blick von außen und in die Grube)
+        return ModelEntity(mesh: mesh, materials: [material])
+    }
+
+    /// Wandmantel mit gekachelter Erd-Textur (Fallback: einfarbig).
+    private static func wallModel(radius: Float, depth: Float) -> ModelEntity {
+        var material = UnlitMaterial(color: wallColor)
+        if let texture = DirtTextureFactory.texture {
+            material.color = .init(tint: .white, texture: .init(texture))
+        }
+        material.faceCulling = .none
+        return ModelEntity(mesh: wallMesh(radius: radius, depth: depth), materials: [material])
+    }
+
+    /// Kreispunkte in der XZ-Ebene auf gegebener Höhe.
+    private static func circle(radius: Float, y: Float) -> [SIMD3<Float>] {
+        (0..<segments).map { index in
+            let angle = Float(index) / Float(segments) * 2 * .pi
+            return SIMD3(radius * cos(angle), y, radius * sin(angle))
+        }
+    }
+
+    /// Wandmantel (senkrecht, y = 0 … -depth) inkl. UV-Koordinaten für die gekachelte Textur.
+    private static func wallMesh(radius: Float, depth: Float) -> MeshResource {
+        let top = circle(radius: radius, y: 0)
+        let bottom = circle(radius: radius, y: -depth)
+
+        // Kachelgröße ~0,5 m: horizontal über den Umfang, vertikal über die Tiefe.
+        let tileSize: Float = 0.5
+        let uRepeat = (2 * .pi * radius) / tileSize
+        let vMax = depth / tileSize
+
+        var builder = TriangleMeshBuilder()
+        for i in 0..<segments {
+            let next = (i + 1) % segments
+            let u0 = Float(i) / Float(segments) * uRepeat
+            let u1 = Float(i + 1) / Float(segments) * uRepeat
+            builder.addQuad(
+                top[i], top[next], bottom[next], bottom[i],
+                uv: (SIMD2(u0, 0), SIMD2(u1, 0), SIMD2(u1, vMax), SIMD2(u0, vMax)),
+                doubleSided: true
+            )
+        }
+        return builder.makeMesh(name: "tankPitWall")
+    }
+
+    /// Runde Sohle bei y = -depth (Dreiecksfächer um den Mittelpunkt).
+    private static func floorMesh(radius: Float, depth: Float) -> MeshResource {
+        let rim = circle(radius: radius, y: -depth)
+        let center = SIMD3<Float>(0, -depth, 0)
+
+        var builder = TriangleMeshBuilder()
+        for i in 0..<segments {
+            let next = (i + 1) % segments
+            builder.addTriangle(center, rim[i], rim[next], doubleSided: true)
+        }
+        return builder.makeMesh(name: "tankPitFloor")
+    }
+
+    /// Flacher, hervorgehobener Ring (Rand) auf gegebener Höhe.
+    private static func ringMesh(radius: Float, y: Float) -> MeshResource {
+        let inner = circle(radius: max(0, radius - rimBand), y: y)
+        let outer = circle(radius: radius + rimBand, y: y)
+
+        var builder = TriangleMeshBuilder()
+        for i in 0..<segments {
+            let next = (i + 1) % segments
+            builder.addQuad(inner[i], inner[next], outer[next], outer[i], doubleSided: true)
+        }
+        return builder.makeMesh(name: "tankPitRim")
+    }
+
+    /// Waagerechte Fläche in der Bodenebene mit kreisrundem Loch (Ring zwischen Loch und Außenrand).
+    private static func maskMesh(holeRadius: Float, outerRadius: Float) -> MeshResource {
+        let inner = circle(radius: holeRadius, y: 0)
+        let outer = circle(radius: outerRadius, y: 0)
+
+        var builder = TriangleMeshBuilder()
+        for i in 0..<segments {
+            let next = (i + 1) % segments
+            builder.addQuad(inner[i], inner[next], outer[next], outer[i], doubleSided: true)
+        }
+        return builder.makeMesh(name: "tankPitMask")
+    }
+}
+
+/// Kleiner Helfer, der Dreiecke/Vierecke zu einem Mesh sammelt.
+private struct TriangleMeshBuilder {
+    private var positions: [SIMD3<Float>] = []
+    private var indices: [UInt32] = []
+    private var uvs: [SIMD2<Float>] = []
+
+    /// Viereck mit UV-Koordinaten (für texturierte Flächen).
+    mutating func addQuad(
+        _ a: SIMD3<Float>, _ b: SIMD3<Float>, _ c: SIMD3<Float>, _ d: SIMD3<Float>,
+        uv: (SIMD2<Float>, SIMD2<Float>, SIMD2<Float>, SIMD2<Float>),
+        doubleSided: Bool = false
+    ) {
+        let base = UInt32(positions.count)
+        positions.append(contentsOf: [a, b, c, d])
+        uvs.append(contentsOf: [uv.0, uv.1, uv.2, uv.3])
+        indices.append(contentsOf: [base, base + 1, base + 2, base, base + 2, base + 3])
+        if doubleSided {
+            indices.append(contentsOf: [base, base + 2, base + 1, base, base + 3, base + 2])
+        }
+    }
+
+    mutating func addTriangle(
+        _ a: SIMD3<Float>, _ b: SIMD3<Float>, _ c: SIMD3<Float>,
+        doubleSided: Bool = false
+    ) {
+        let base = UInt32(positions.count)
+        positions.append(contentsOf: [a, b, c])
+        indices.append(contentsOf: [base, base + 1, base + 2])
+        if doubleSided {
+            indices.append(contentsOf: [base, base + 2, base + 1])
+        }
+    }
+
+    mutating func addQuad(
+        _ a: SIMD3<Float>, _ b: SIMD3<Float>, _ c: SIMD3<Float>, _ d: SIMD3<Float>,
+        doubleSided: Bool = false
+    ) {
+        let base = UInt32(positions.count)
+        positions.append(contentsOf: [a, b, c, d])
+        indices.append(contentsOf: [base, base + 1, base + 2, base, base + 2, base + 3])
+        if doubleSided {
+            indices.append(contentsOf: [base, base + 2, base + 1, base, base + 3, base + 2])
+        }
+    }
+
+    func makeMesh(name: String) -> MeshResource {
+        var descriptor = MeshDescriptor(name: name)
+        descriptor.positions = MeshBuffers.Positions(positions)
+        descriptor.primitives = .triangles(indices)
+        if uvs.count == positions.count {
+            descriptor.textureCoordinates = MeshBuffers.TextureCoordinates(uvs)
+        }
+        return (try? MeshResource.generate(from: [descriptor])) ?? .generateBox(size: 0.01)
+    }
+}

GasTankAR/Views/TankAR/TankShaders.metal

@@ -0,0 +1,56 @@
+//
+//  TankShaders.metal
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+#include <metal_stdlib>
+#include <RealityKit/RealityKit.h>
+
+using namespace metal;
+
+// Sampler für die durchgereichten Texturen des Originalmaterials.
+constexpr sampler textureSampler(address::clamp_to_edge, filter::bicubic);
+
+/// Surface-Shader für den unterirdischen Tank: reicht Basisfarbe/Roughness/Metallic
+/// des Originalmaterials durch und verblasst die Opacity anhand der Welt-Höhe.
+///
+/// custom_parameter():
+///   x = Boden-Höhe (Welt-Y)
+///   y = Fade-Band (Meter, über die die Transparenz einsetzt)
+///   z = minimale Opacity des vergrabenen Teils
+[[visible]]
+void tankDepthFadeSurface(realitykit::surface_parameters params)
+{
+    auto tex = params.textures();
+    auto constants = params.material_constants();
+
+    float2 uv = params.geometry().uv0();
+    // Modelle aus USDZ nutzen eine gespiegelte Y-UV.
+    uv.y = 1.0 - uv.y;
+
+    // Basisfarbe = Tint * Textur.
+    half3 tint = (half3)constants.base_color_tint();
+    half3 color = (half3)tex.base_color().sample(textureSampler, uv).rgb;
+    color *= tint;
+    params.surface().set_base_color(color);
+
+    // Roughness / Metallic durchreichen (wie PhysicallyBasedMaterial).
+    half roughness = tex.roughness().sample(textureSampler, uv).r * constants.roughness_scale();
+    params.surface().set_roughness(roughness);
+
+    half metallic = tex.metallic().sample(textureSampler, uv).r * constants.metallic_scale();
+    params.surface().set_metallic(metallic);
+
+    // Höhenbasierter Alpha-Fade.
+    float3 worldPosition = params.geometry().world_position();
+    float4 custom = params.uniforms().custom_parameter();
+    float groundY = custom.x;
+    float band = max(custom.y, 1e-3);
+    float belowAlpha = custom.z;
+
+    float t = clamp((groundY - worldPosition.y) / band, 0.0, 1.0);
+    float alpha = mix(1.0, belowAlpha, t);
+    params.surface().set_opacity(half(alpha));
+}

GasTankAR/Views/TankAR/WorldMapArchiver.swift

@@ -0,0 +1,20 @@
+//
+//  WorldMapArchiver.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import ARKit
+
+/// Kapselt das (De-)Serialisieren einer `ARWorldMap` via `NSKeyedArchiver`.
+/// Bewusst thread-neutral gehalten – das Archivieren sollte off-main erfolgen (teuer).
+enum WorldMapArchiver {
+    static func archive(_ worldMap: ARWorldMap) -> Data? {
+        try? NSKeyedArchiver.archivedData(withRootObject: worldMap, requiringSecureCoding: true)
+    }
+
+    static func unarchive(_ data: Data) -> ARWorldMap? {
+        try? NSKeyedUnarchiver.unarchivedObject(ofClass: ARWorldMap.self, from: data)
+    }
+}

GasTankAR/Views/TankEditor.swift

@@ -0,0 +1,102 @@
+//
+//  TankEditor.swift
+//  GasTankAR
+//
+//  Created by Dennis Nemec on 25.08.26.
+//
+
+import SwiftUI
+
+/// Wiederverwendbare Auswahl für die Tank-Eigenschaften (Größe, Farbe,
+/// Aufstellungsart und halbtransparente Darstellung).
+struct TankEditor: View {
+    @Binding var tank: Tank
+
+    var body: some View {
+        Picker("Größe", selection: $tank.size) {
+            ForEach(TankSize.allCases) { size in
+                Text(size.displayName).tag(size)
+            }
+        }
+
+        Picker("Farbe", selection: $tank.color) {
+            ForEach(TankColor.allCases) { color in
+                Text(color.displayName).tag(color)
+            }
+        }
+
+        VStack(alignment: .leading, spacing: 8) {
+            Text("Aufstellungsart")
+
+            HStack(spacing: 12) {
+                ForEach(TankPlacement.allCases) { placement in
+                    PlacementOption(
+                        placement: placement,
+                        isSelected: tank.placement == placement
+                    ) {
+                        tank.placement = placement
+                    }
+                }
+            }
+        }
+        .padding(.vertical, 4)
+
+        Toggle("Halbtransparent (nur Deckel)", isOn: $tank.showLidOnly)
+            .disabled(tank.placement != .belowGround)
+            .onChange(of: tank.placement) { _, newPlacement in
+                // Option nur für unterirdische Tanks sinnvoll – sonst zurücksetzen.
+                if newPlacement != .belowGround {
+                    tank.showLidOnly = false
+                }
+            }
+    }
+}
+
+/// Auswahlkachel für eine Aufstellungsart mit Icon und umrahmter Auswahl.
+private struct PlacementOption: View {
+    let placement: TankPlacement
+    let isSelected: Bool
+    let action: () -> Void
+
+    var body: some View {
+        Button(action: action) {
+            VStack(spacing: 8) {
+                Image(placement.imageName)
+                    .renderingMode(.template)
+                    .resizable()
+                    .scaledToFit()
+                    .foregroundStyle(Color.accentColor)
+                    .frame(height: 72)
+                    .scaleEffect(1.25)
+                    .padding(8)
+
+                Text(placement.displayName)
+                    .font(.caption)
+                    .foregroundStyle(isSelected ? .primary : .secondary)
+            }
+            .frame(maxWidth: .infinity)
+            .padding(8)
+            .background(
+                (isSelected ? Color.accentColor.opacity(0.12) : Color.clear),
+                in: .rect(cornerRadius: 12)
+            )
+            .overlay {
+                RoundedRectangle(cornerRadius: 12)
+                    .stroke(
+                        isSelected ? Color.accentColor : Color.secondary.opacity(0.4),
+                        lineWidth: isSelected ? 2 : 1
+                    )
+            }
+        }
+        .buttonStyle(.plain)
+    }
+}
+
+#Preview {
+    @Previewable @State var tank = Tank()
+    return Form {
+        Section("Tankauswahl") {
+            TankEditor(tank: $tank)
+        }
+    }
+}

GasTankARTests/ARFlowStateMachineTests.swift

@@ -0,0 +1,191 @@
+//
+//  ARFlowStateMachineTests.swift
+//  GasTankARTests
+//
+//  Created by Dennis Nemec on 26.08.26.
+//
+
+import Testing
+@testable import GasTankAR
+
+struct ARFlowStateMachineTests {
+
+    // MARK: - Start & Initialisierung
+
+    @Test func startsInWorldNotInitializedAndRunsConfiguration() {
+        var machine = ARFlowStateMachine(hasStoredTransform: false)
+        let commands = machine.reduce(.started)
+
+        #expect(machine.state == .worldNotInitialized)
+        #expect(commands.contains(.runConfiguration(useImages: false, useInitialMap: true, resetTracking: false)))
+    }
+
+    @Test func initializingTracking() {
+        var machine = ARFlowStateMachine(hasStoredTransform: false)
+        _ = machine.reduce(.started)
+        _ = machine.reduce(.trackingInitializing)
+        #expect(machine.state == .initializingWorld)
+    }
+
+    // MARK: - Scene erfolgreich initialisiert → Location wählen / wiederherstellen
+
+    @Test func normalTrackingWithoutStoredTransformGoesToSelectLocation() {
+        var machine = ARFlowStateMachine(hasStoredTransform: false)
+        _ = machine.reduce(.started)
+        _ = machine.reduce(.trackingNormal)
+        #expect(machine.state == .selectLocation)
+        #expect(machine.hasPlacedTank == false)
+    }
+
+    @Test func normalTrackingWithStoredTransformRestoresTank() {
+        var machine = ARFlowStateMachine(hasStoredTransform: true)
+        _ = machine.reduce(.started)
+        let commands = machine.reduce(.trackingNormal)
+        #expect(machine.state == .immersive)
+        #expect(machine.hasPlacedTank == true)
+        #expect(commands.contains(.placeTank(.storedTransform)))
+    }
+
+    // MARK: - Platzieren
+
+    @Test func captureFromSelectLocationPlacesTankAndPersists() {
+        var machine = ARFlowStateMachine(hasStoredTransform: false)
+        _ = machine.reduce(.started)
+        _ = machine.reduce(.trackingNormal)     // → selectLocation
+        let commands = machine.reduce(.captureConfirmed)
+
+        #expect(machine.state == .immersive)
+        #expect(machine.hasPlacedTank == true)
+        #expect(commands.contains(.placeTank(.screenCenter)))
+        #expect(commands.contains(.persistWorldMap))
+        #expect(commands.contains(.persistTankTransform))
+    }
+
+    @Test func captureIsIgnoredOutsideSelectLocation() {
+        var machine = ARFlowStateMachine(hasStoredTransform: false)
+        _ = machine.reduce(.started)            // worldNotInitialized
+        let commands = machine.reduce(.captureConfirmed)
+        #expect(commands.isEmpty)
+        #expect(machine.state == .worldNotInitialized)
+    }
+
+    // MARK: - Eskalation bei zu wenigen Merkmalen
+
+    @Test func insufficientFeaturesEscalatesToShowOptions() {
+        var machine = ARFlowStateMachine(hasStoredTransform: false)
+        _ = machine.reduce(.started)
+
+        let first = machine.reduce(.trackingInsufficientFeatures)
+        #expect(machine.state == .initializingNotPossible)
+        #expect(first.contains(.startMoveAroundTimer))
+
+        _ = machine.reduce(.moveAroundTimerFired)
+        #expect(machine.state == .userMovesAround)
+
+        _ = machine.reduce(.showOptionsTimerFired)
+        #expect(machine.state == .showOptions)
+    }
+
+    @Test func timersDoNothingInWrongState() {
+        var machine = ARFlowStateMachine(hasStoredTransform: false)
+        _ = machine.reduce(.started)
+        // Kein initializingNotPossible aktiv → moveAroundTimer ignoriert.
+        let commands = machine.reduce(.moveAroundTimerFired)
+        #expect(commands.isEmpty)
+        #expect(machine.state == .worldNotInitialized)
+    }
+
+    // MARK: - Anker-Erkennung (Marker)
+
+    @Test func placeAnchorMarkerStartsImageDetection() {
+        var machine = ARFlowStateMachine(hasStoredTransform: false)
+        _ = machine.reduce(.started)
+        _ = machine.reduce(.trackingNormal)     // selectLocation
+        let commands = machine.reduce(.placeAnchorMarkerTapped)
+
+        #expect(machine.state == .anchorDetection)
+        #expect(commands.contains(.runConfiguration(useImages: true, useInitialMap: false, resetTracking: false)))
+        #expect(commands.contains(.startAnchorDetectionTimer))
+    }
+
+    @Test func anchorDetectionTimeoutAsksToCancel() {
+        var machine = ARFlowStateMachine(hasStoredTransform: false)
+        _ = machine.reduce(.started)
+        _ = machine.reduce(.trackingNormal)
+        _ = machine.reduce(.placeAnchorMarkerTapped)
+        _ = machine.reduce(.anchorDetectionTimerFired)
+        #expect(machine.state == .askToCancel)
+    }
+
+    @Test func imageAnchorDetectedPlacesTank() {
+        var machine = ARFlowStateMachine(hasStoredTransform: false)
+        _ = machine.reduce(.started)
+        _ = machine.reduce(.trackingNormal)
+        _ = machine.reduce(.placeAnchorMarkerTapped)
+        let commands = machine.reduce(.imageAnchorDetected)
+
+        #expect(machine.state == .immersive)
+        #expect(machine.hasPlacedTank == true)
+        #expect(commands.contains(.placeTank(.imageAnchor)))
+    }
+
+    @Test func imageAnchorIgnoredWhenNotDetecting() {
+        var machine = ARFlowStateMachine(hasStoredTransform: false)
+        _ = machine.reduce(.started)
+        _ = machine.reduce(.trackingNormal)     // selectLocation
+        let commands = machine.reduce(.imageAnchorDetected)
+        #expect(commands.isEmpty)
+        #expect(machine.state == .selectLocation)
+    }
+
+    // MARK: - Relokalisierung
+
+    @Test func relocalizingStartsTimerAndTimeoutFails() {
+        var machine = ARFlowStateMachine(hasStoredTransform: true)
+        _ = machine.reduce(.started)
+        let relocating = machine.reduce(.trackingRelocalizing)
+        #expect(machine.state == .relocating)
+        #expect(relocating.contains(.startRelocationTimer))
+
+        _ = machine.reduce(.relocationTimerFired)
+        #expect(machine.state == .relocationFailed)
+    }
+
+    @Test func normalTrackingWhilePlacedGoesImmersive() {
+        var machine = ARFlowStateMachine(hasStoredTransform: false)
+        _ = machine.reduce(.started)
+        _ = machine.reduce(.trackingNormal)
+        _ = machine.reduce(.captureConfirmed)   // placed → immersive
+        _ = machine.reduce(.trackingRelocalizing)
+        #expect(machine.state == .relocating)
+        _ = machine.reduce(.trackingNormal)
+        #expect(machine.state == .immersive)
+    }
+
+    // MARK: - Neu platzieren / Neustart
+
+    @Test func repositionClearsTankAndReturnsToSelectLocation() {
+        var machine = ARFlowStateMachine(hasStoredTransform: true)
+        _ = machine.reduce(.started)
+        _ = machine.reduce(.trackingNormal)     // restored → immersive
+        let commands = machine.reduce(.repositionTapped)
+
+        #expect(machine.state == .selectLocation)
+        #expect(machine.hasPlacedTank == false)
+        #expect(machine.hasStoredTransform == false)
+        #expect(commands.contains(.removeTank))
+        #expect(commands.contains(.clearStoredTransform))
+    }
+
+    @Test func restartResetsTracking() {
+        var machine = ARFlowStateMachine(hasStoredTransform: true)
+        _ = machine.reduce(.started)
+        _ = machine.reduce(.trackingRelocalizing)
+        _ = machine.reduce(.relocationTimerFired)   // relocationFailed
+        let commands = machine.reduce(.restartTapped)
+
+        #expect(machine.state == .worldNotInitialized)
+        #expect(machine.hasStoredTransform == false)
+        #expect(commands.contains(.runConfiguration(useImages: false, useInitialMap: false, resetTracking: true)))
+    }
+}

GasTankARTests/DocuframeTests.swift

@@ -0,0 +1,218 @@
+//
+//  DocuframeTests.swift
+//  GasTankARTests
+//
+//  Created by Dennis Nemec on 28.08.26.
+//
+
+import Testing
+import Foundation
+import SwiftData
+@testable import GasTankAR
+
+// MARK: - Test-Doubles
+
+/// Konfigurierbarer Mock des ``DocuframeService`` (Actor → threadsicher & Sendable),
+/// der Aufrufe zählt und wahlweise einen Fehler wirft.
+private actor MockDocuframeService: DocuframeService {
+    enum Behavior: Sendable {
+        case success
+        case failure(DocuframeError)
+    }
+
+    let behavior: Behavior
+    private(set) var uploadCallCount = 0
+    private(set) var sendEmailCallCount = 0
+    private(set) var lastPhotoCount = 0
+    private(set) var lastLeadID: String?
+
+    init(behavior: Behavior = .success) {
+        self.behavior = behavior
+    }
+
+    func uploadPhotos(_ photos: [DocuframePhoto], projectLeadID: String) async throws {
+        uploadCallCount += 1
+        record(photos: photos, leadID: projectLeadID)
+        try applyBehavior()
+    }
+
+    func sendEmail(_ photos: [DocuframePhoto], projectLeadID: String) async throws {
+        sendEmailCallCount += 1
+        record(photos: photos, leadID: projectLeadID)
+        try applyBehavior()
+    }
+
+    private func record(photos: [DocuframePhoto], leadID: String) {
+        lastPhotoCount = photos.count
+        lastLeadID = leadID
+    }
+
+    private func applyBehavior() throws {
+        if case .failure(let error) = behavior { throw error }
+    }
+}
+
+/// Hält Container und Fotos für die Dauer eines Tests am Leben.
+@MainActor
+private struct TestEnvironment {
+    let container: ModelContainer
+    let photos: [ProjectPhoto]
+}
+
+@MainActor
+private func makeEnvironment(photoCount: Int) throws -> TestEnvironment {
+    let container = try ModelContainer(
+        for: Project.self,
+        configurations: ModelConfiguration(isStoredInMemoryOnly: true)
+    )
+    let context = container.mainContext
+    let project = Project(leadID: "LEAD-1", customerName: "Test", creationDate: Date(timeIntervalSince1970: 0))
+    context.insert(project)
+
+    var photos: [ProjectPhoto] = []
+    for index in 0..<photoCount {
+        let photo = ProjectPhoto(
+            creationDate: Date(timeIntervalSince1970: TimeInterval(index)),
+            imageData: Data([UInt8(index)]),
+            project: project
+        )
+        context.insert(photo)
+        photos.append(photo)
+    }
+    return TestEnvironment(container: container, photos: photos)
+}
+
+// MARK: - Fehler-Mapping
+
+struct DocuframeErrorTests {
+    @Test func mapsHTTPStatusCodesToErrors() {
+        #expect(DocuframeError.from(statusCode: 200) == nil)
+        #expect(DocuframeError.from(statusCode: 302) == nil)
+        #expect(DocuframeError.from(statusCode: 400) == .clientError(statusCode: 400))
+        #expect(DocuframeError.from(statusCode: 404) == .clientError(statusCode: 404))
+        #expect(DocuframeError.from(statusCode: 500) == .serverError(statusCode: 500))
+        #expect(DocuframeError.from(statusCode: 503) == .serverError(statusCode: 503))
+    }
+
+    @Test func httpResponseValidationThrowsForClientAndServerErrors() throws {
+        let url = URL(string: "https://docuframe.example.com")!
+
+        let success = try #require(HTTPURLResponse(url: url, statusCode: 204, httpVersion: nil, headerFields: nil))
+        #expect(throws: Never.self) { try success.validateDocuframeStatus() }
+
+        let clientError = try #require(HTTPURLResponse(url: url, statusCode: 400, httpVersion: nil, headerFields: nil))
+        #expect(throws: DocuframeError.clientError(statusCode: 400)) { try clientError.validateDocuframeStatus() }
+
+        let serverError = try #require(HTTPURLResponse(url: url, statusCode: 500, httpVersion: nil, headerFields: nil))
+        #expect(throws: DocuframeError.serverError(statusCode: 500)) { try serverError.validateDocuframeStatus() }
+    }
+}
+
+// MARK: - ViewModel
+
+@MainActor
+struct DocuframeViewModelTests {
+
+    // MARK: Auswahl
+
+    @Test func togglingSelectionTracksPhotos() throws {
+        let env = try makeEnvironment(photoCount: 2)
+        let viewModel = DocuframeViewModel(service: MockDocuframeService())
+
+        #expect(!viewModel.hasSelection)
+
+        viewModel.toggleSelection(env.photos[0])
+        #expect(viewModel.isSelected(env.photos[0]))
+        #expect(viewModel.selectionCount == 1)
+
+        viewModel.toggleSelection(env.photos[0])
+        #expect(!viewModel.isSelected(env.photos[0]))
+        #expect(!viewModel.hasSelection)
+    }
+
+    // MARK: Erfolg
+
+    @Test func uploadSuccessSetsSuccessResult() async throws {
+        let env = try makeEnvironment(photoCount: 2)
+        let mock = MockDocuframeService(behavior: .success)
+        let viewModel = DocuframeViewModel(service: mock)
+        env.photos.forEach(viewModel.toggleSelection)
+
+        await viewModel.upload(from: env.photos, leadID: "LEAD-1")
+
+        #expect(viewModel.isProcessing == false)
+        let result = try #require(viewModel.result)
+        #expect(!result.isError)
+        #expect(result.title == "Erledigt")
+        #expect(result.message == "2 Foto(s) in DOCUframe hochgeladen.")
+
+        let uploadCount = await mock.uploadCallCount
+        let photoCount = await mock.lastPhotoCount
+        let leadID = await mock.lastLeadID
+        #expect(uploadCount == 1)
+        #expect(photoCount == 2)
+        #expect(leadID == "LEAD-1")
+    }
+
+    @Test func sendEmailSuccessSetsSuccessResult() async throws {
+        let env = try makeEnvironment(photoCount: 1)
+        let mock = MockDocuframeService(behavior: .success)
+        let viewModel = DocuframeViewModel(service: mock)
+        viewModel.toggleSelection(env.photos[0])
+
+        await viewModel.sendEmail(from: env.photos, leadID: "LEAD-1")
+
+        let result = try #require(viewModel.result)
+        #expect(!result.isError)
+        #expect(result.message == "1 Foto(s) per E-Mail versendet.")
+        let sendCount = await mock.sendEmailCallCount
+        #expect(sendCount == 1)
+    }
+
+    // MARK: HTTP-Fehler
+
+    @Test func uploadServerErrorSetsFailureResult() async throws {
+        let env = try makeEnvironment(photoCount: 1)
+        let mock = MockDocuframeService(behavior: .failure(.serverError(statusCode: 500)))
+        let viewModel = DocuframeViewModel(service: mock)
+        viewModel.toggleSelection(env.photos[0])
+
+        await viewModel.upload(from: env.photos, leadID: "LEAD-1")
+
+        #expect(viewModel.isProcessing == false)
+        let result = try #require(viewModel.result)
+        #expect(result.isError)
+        #expect(result.title == "Fehler")
+        #expect(result.message == DocuframeError.serverError(statusCode: 500).localizedDescription)
+    }
+
+    @Test func sendEmailClientErrorSetsFailureResult() async throws {
+        let env = try makeEnvironment(photoCount: 1)
+        let mock = MockDocuframeService(behavior: .failure(.clientError(statusCode: 400)))
+        let viewModel = DocuframeViewModel(service: mock)
+        viewModel.toggleSelection(env.photos[0])
+
+        await viewModel.sendEmail(from: env.photos, leadID: "LEAD-1")
+
+        let result = try #require(viewModel.result)
+        #expect(result.isError)
+        #expect(result.message == DocuframeError.clientError(statusCode: 400).localizedDescription)
+    }
+
+    // MARK: Keine Auswahl
+
+    @Test func withoutSelectionReportsErrorAndSkipsService() async throws {
+        let env = try makeEnvironment(photoCount: 2)
+        let mock = MockDocuframeService()
+        let viewModel = DocuframeViewModel(service: mock)
+
+        await viewModel.upload(from: env.photos, leadID: "LEAD-1")
+
+        let result = try #require(viewModel.result)
+        #expect(result.isError)
+        #expect(result.message == DocuframeError.noPhotosSelected.localizedDescription)
+
+        let uploadCount = await mock.uploadCallCount
+        #expect(uploadCount == 0)
+    }
+}