Gassi: Tabs Treffen + Stamm-Gassis wie in der PWA

In der PWA ist die Seite 'Gassi-Treffen' mit drei Tabs:
- Treffen (walks.py — sich verabreden)
- Challenge (Monatsfoto)
- Stamm-Gassis (gassi_zeiten.py — regelmäßige Runden)

Mein bisheriger Mehr-Eintrag hieß 'Stamm-Gassi-Zeiten' und zeigte nur die
Stamm-Gassi-Funktion isoliert — das stimmte nicht mit der PWA überein.

Neu:
- GassiView mit Segmented Picker (Treffen / Stamm-Gassis)
- GassiTreffenList: GET /api/walks?lat&lon&radius=20000, Liste mit Datum,
  Uhrzeit, Ort, Teilnehmer-Zahl
- GassiTreffenDetail: Karte mit Pin, Stats, Beitreten/Verlassen
  (POST/DELETE /api/walks/{id}/join), Owner-Check
- AddWalkSheet: Titel, Datum, Uhrzeit, Treffpunkt-Name, Max-Teilnehmer,
  Beschreibung — POST /api/walks
- StammGassisList = bisherige GassiZeitenView umbenannt + Nav-Title raus
  (wird vom GassiView vergeben)

Im Mehr-Tab heißt der Link jetzt 'Gassi-Treffen' (pawprint-Icon) statt
'Stamm-Gassi-Zeiten' (alarm-Icon).

DTOs: WalkMeeting, WalkCreateBody, WalkJoinBody.

BanYaroGo/API/DTOs.swift

@@ -135,6 +135,39 @@ struct GassiZeit: Decodable, Identifiable {
     let dogRasse: String?
 }
 
+// MARK: - Walks (Gassi-Treffen)
+
+struct WalkMeeting: Decodable, Identifiable {
+    let id: Int
+    let userId: Int
+    let titel: String
+    let datum: String              // YYYY-MM-DD
+    let uhrzeit: String            // HH:MM
+    let lat: Double
+    let lon: Double
+    let ortName: String?
+    let maxTeilnehmer: Int
+    let beschreibung: String?
+    let status: String?
+    let veranstalterName: String?
+    let teilnehmerCount: Int?
+}
+
+struct WalkCreateBody: Encodable {
+    let titel: String
+    let datum: String
+    let uhrzeit: String
+    let lat: Double
+    let lon: Double
+    let ortName: String?
+    let maxTeilnehmer: Int
+    let beschreibung: String?
+}
+
+struct WalkJoinBody: Encodable {
+    let dogIds: [Int]
+}
+
 struct GassiZeitCreateBody: Encodable {
     let dogId: Int?
     let wochentage: [String]

BanYaroGo/Views/AddWalkSheet.swift

@@ -0,0 +1,107 @@
+import SwiftUI
+import CoreLocation
+
+struct AddWalkSheet: View {
+    let coord: CLLocationCoordinate2D?
+    let onSaved: () async -> Void
+
+    @Environment(\.dismiss) private var dismiss
+
+    @State private var titel = ""
+    @State private var date = Calendar.current.date(byAdding: .day, value: 1, to: .now) ?? .now
+    @State private var time = Calendar.current.date(bySettingHour: 17, minute: 0, second: 0, of: .now) ?? .now
+    @State private var ortName = ""
+    @State private var maxTeilnehmer = 10
+    @State private var beschreibung = ""
+
+    @State private var isSaving = false
+    @State private var errorMessage: String?
+
+    var body: some View {
+        NavigationStack {
+            Form {
+                Section("Titel") {
+                    TextField("z. B. Gassi-Runde am Schlosspark", text: $titel)
+                }
+                Section("Datum & Uhrzeit") {
+                    DatePicker("Datum", selection: $date, in: Date.now..., displayedComponents: .date)
+                        .environment(\.locale, Locale(identifier: "de_DE"))
+                    DatePicker("Uhrzeit", selection: $time, displayedComponents: .hourAndMinute)
+                        .environment(\.locale, Locale(identifier: "de_DE"))
+                }
+                Section("Treffpunkt") {
+                    TextField("Name (z. B. Hauptplatz)", text: $ortName)
+                    if let coord {
+                        Text(String(format: "%.5f, %.5f", coord.latitude, coord.longitude))
+                            .font(.caption.monospacedDigit())
+                            .foregroundStyle(.secondary)
+                    } else {
+                        Text("Standort wird noch geholt — bitte einen Moment warten.")
+                            .font(.caption)
+                            .foregroundStyle(.secondary)
+                    }
+                }
+                Section("Max. Teilnehmer") {
+                    Stepper("\(maxTeilnehmer)", value: $maxTeilnehmer, in: 2...100)
+                }
+                Section("Beschreibung (optional)") {
+                    TextField("Was ist geplant? Wie lange?", text: $beschreibung, axis: .vertical)
+                        .lineLimit(2...6)
+                }
+                if let errorMessage {
+                    Section {
+                        Text(errorMessage).font(.footnote).foregroundStyle(.red)
+                    }
+                }
+            }
+            .navigationTitle("Neues Treffen")
+            .navigationBarTitleDisplayMode(.inline)
+            .toolbar {
+                ToolbarItem(placement: .cancellationAction) {
+                    Button("Abbrechen") { dismiss() }
+                        .disabled(isSaving)
+                }
+                ToolbarItem(placement: .confirmationAction) {
+                    if isSaving { ProgressView() }
+                    else {
+                        Button("Sichern") { Task { await save() } }
+                            .disabled(!canSave)
+                    }
+                }
+            }
+        }
+    }
+
+    private var canSave: Bool {
+        coord != nil && !titel.trimmingCharacters(in: .whitespaces).isEmpty
+    }
+
+    private func save() async {
+        guard let coord else { return }
+        isSaving = true
+        errorMessage = nil
+        defer { isSaving = false }
+
+        let dateFmt = DateFormatter(); dateFmt.dateFormat = "yyyy-MM-dd"
+        let timeFmt = DateFormatter(); timeFmt.dateFormat = "HH:mm"
+
+        let body = WalkCreateBody(
+            titel: titel.trimmingCharacters(in: .whitespaces),
+            datum: dateFmt.string(from: date),
+            uhrzeit: timeFmt.string(from: time),
+            lat: coord.latitude,
+            lon: coord.longitude,
+            ortName: ortName.trimmingCharacters(in: .whitespaces).isEmpty ? nil : ortName,
+            maxTeilnehmer: maxTeilnehmer,
+            beschreibung: beschreibung.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty ? nil : beschreibung
+        )
+
+        do {
+            let _: WalkMeeting = try await APIClient.shared.post("/api/walks", body: body)
+            await onSaved()
+            dismiss()
+        } catch {
+            errorMessage = error.localizedDescription
+        }
+    }
+}

BanYaroGo/Views/GassiTreffenDetail.swift

@@ -0,0 +1,172 @@
+import SwiftUI
+import MapKit
+
+struct GassiTreffenDetail: View {
+    let meetingId: Int
+    let fallbackTitle: String
+    let onChange: () async -> Void
+
+    @Environment(AuthSession.self) private var auth
+    @Environment(\.dismiss) private var dismiss
+
+    @State private var meeting: WalkMeeting?
+    @State private var isLoading = false
+    @State private var errorMessage: String?
+    @State private var isMutating = false
+
+    @State private var dogs: [Dog] = []
+    @State private var hasJoined: Bool? = nil
+
+    var body: some View {
+        ScrollView {
+            VStack(alignment: .leading, spacing: 16) {
+                if let meeting {
+                    detailContent(meeting)
+                } else if isLoading {
+                    ProgressView().padding(.top, 60)
+                } else if let errorMessage {
+                    ContentUnavailableView(
+                        "Fehler",
+                        systemImage: "exclamationmark.triangle",
+                        description: Text(errorMessage)
+                    )
+                    .padding(.top, 60)
+                }
+            }
+            .padding()
+        }
+        .navigationTitle(meeting?.titel ?? fallbackTitle)
+        .navigationBarTitleDisplayMode(.inline)
+        .task { await load() }
+    }
+
+    @ViewBuilder
+    private func detailContent(_ m: WalkMeeting) -> some View {
+        Map(initialPosition: .region(MKCoordinateRegion(
+            center: CLLocationCoordinate2D(latitude: m.lat, longitude: m.lon),
+            span: MKCoordinateSpan(latitudeDelta: 0.02, longitudeDelta: 0.02)
+        ))) {
+            Annotation(m.titel, coordinate: CLLocationCoordinate2D(latitude: m.lat, longitude: m.lon)) {
+                Image(systemName: "pawprint.circle.fill")
+                    .font(.title)
+                    .foregroundStyle(.white, Color.accentColor)
+                    .background(.white, in: Circle())
+            }
+        }
+        .frame(height: 220)
+        .clipShape(RoundedRectangle(cornerRadius: 12))
+        .allowsHitTesting(false)
+
+        VStack(alignment: .leading, spacing: 6) {
+            HStack {
+                Image(systemName: "calendar")
+                Text(formatDate(m.datum))
+                Text(m.uhrzeit).monospacedDigit()
+            }
+            .font(.headline)
+
+            if let ort = m.ortName, !ort.isEmpty {
+                Label(ort, systemImage: "mappin.and.ellipse")
+                    .font(.subheadline)
+                    .foregroundStyle(.secondary)
+            }
+
+            HStack {
+                Label("\(m.teilnehmerCount ?? 0) / \(m.maxTeilnehmer) Teilnehmer", systemImage: "person.2.fill")
+                if let veranstalter = m.veranstalterName {
+                    Spacer()
+                    Text("von \(veranstalter)")
+                        .font(.caption)
+                        .foregroundStyle(.secondary)
+                }
+            }
+            .font(.subheadline)
+            .padding(.top, 4)
+        }
+
+        if let beschreibung = m.beschreibung, !beschreibung.isEmpty {
+            Text(beschreibung)
+                .font(.body)
+                .padding(.top, 4)
+        }
+
+        if !isOwn(m) {
+            joinButton(m)
+        }
+
+        if let errorMessage {
+            Text(errorMessage)
+                .font(.footnote)
+                .foregroundStyle(.red)
+        }
+    }
+
+    private func joinButton(_ m: WalkMeeting) -> some View {
+        Button {
+            Task { await toggleJoin() }
+        } label: {
+            HStack {
+                Image(systemName: (hasJoined == true) ? "person.crop.circle.badge.minus" : "person.crop.circle.badge.plus")
+                Text((hasJoined == true) ? "Verlassen" : "Beitreten").bold()
+            }
+            .frame(maxWidth: .infinity, minHeight: 50)
+        }
+        .background((hasJoined == true) ? Color.red : Color.accentColor, in: Capsule())
+        .foregroundStyle(.white)
+        .disabled(isMutating)
+    }
+
+    private func isOwn(_ m: WalkMeeting) -> Bool {
+        m.userId == auth.profile?.id
+    }
+
+    private func load() async {
+        isLoading = true
+        errorMessage = nil
+        defer { isLoading = false }
+        do {
+            meeting = try await APIClient.shared.get("/api/walks/\(meetingId)")
+            if dogs.isEmpty {
+                dogs = (try? await APIClient.shared.get("/api/dogs")) ?? []
+            }
+            // We don't have a clean "have I joined" endpoint, so we treat hasJoined
+            // as nil → button shows "Beitreten". After successful join we set true,
+            // after successful leave we set false.
+        } catch {
+            errorMessage = error.localizedDescription
+        }
+    }
+
+    private func toggleJoin() async {
+        isMutating = true
+        errorMessage = nil
+        defer { isMutating = false }
+        do {
+            if hasJoined == true {
+                try await APIClient.shared.delete("/api/walks/\(meetingId)/join")
+                hasJoined = false
+            } else {
+                let body = WalkJoinBody(dogIds: dogs.map { $0.id })
+                let _: WalkMeeting = try await APIClient.shared.post("/api/walks/\(meetingId)/join", body: body)
+                hasJoined = true
+            }
+            await onChange()
+            await load()
+        } catch {
+            errorMessage = error.localizedDescription
+        }
+    }
+
+    private func formatDate(_ s: String) -> String {
+        let parser = DateFormatter()
+        parser.locale = Locale(identifier: "en_US_POSIX")
+        parser.dateFormat = "yyyy-MM-dd"
+        if let d = parser.date(from: String(s.prefix(10))) {
+            let out = DateFormatter()
+            out.locale = Locale(identifier: "de_DE")
+            out.dateStyle = .full
+            return out.string(from: d)
+        }
+        return s
+    }
+}

BanYaroGo/Views/GassiTreffenList.swift

@@ -0,0 +1,129 @@
+import SwiftUI
+
+struct GassiTreffenList: View {
+    @State private var location = OneShotLocation()
+    @State private var meetings: [WalkMeeting] = []
+    @State private var isLoading = false
+    @State private var errorMessage: String?
+    @State private var showAdd = false
+
+    var body: some View {
+        content
+            .toolbar {
+                ToolbarItem(placement: .topBarTrailing) {
+                    Button {
+                        showAdd = true
+                    } label: {
+                        Label("Planen", systemImage: "plus")
+                    }
+                }
+            }
+            .sheet(isPresented: $showAdd) {
+                AddWalkSheet(coord: location.coordinate) { await load() }
+            }
+            .task {
+                location.request()
+                await load()
+            }
+            .onChange(of: location.coordinate?.latitude) { _, _ in
+                Task { await load() }
+            }
+            .refreshable { await load() }
+    }
+
+    @ViewBuilder
+    private var content: some View {
+        if isLoading && meetings.isEmpty {
+            ProgressView()
+        } else if let errorMessage, meetings.isEmpty {
+            ContentUnavailableView(
+                "Konnte nicht laden",
+                systemImage: "wifi.slash",
+                description: Text(errorMessage)
+            )
+        } else if meetings.isEmpty {
+            ContentUnavailableView(
+                "Noch keine Treffen",
+                systemImage: "person.2",
+                description: Text("In 20 km Umkreis sind aktuell keine Gassi-Treffen geplant. Tippe oben rechts auf +, um eins zu planen.")
+            )
+        } else {
+            List(meetings) { meeting in
+                NavigationLink {
+                    GassiTreffenDetail(meetingId: meeting.id, fallbackTitle: meeting.titel) {
+                        await load()
+                    }
+                } label: {
+                    TreffenRow(meeting: meeting)
+                }
+            }
+        }
+    }
+
+    private func load() async {
+        isLoading = true
+        errorMessage = nil
+        defer { isLoading = false }
+        do {
+            var path = "/api/walks?radius=20000"
+            if let coord = location.coordinate {
+                path = "/api/walks?lat=\(coord.latitude)&lon=\(coord.longitude)&radius=20000"
+            }
+            meetings = try await APIClient.shared.get(path)
+        } catch {
+            errorMessage = error.localizedDescription
+        }
+    }
+}
+
+private struct TreffenRow: View {
+    let meeting: WalkMeeting
+
+    var body: some View {
+        HStack(spacing: 12) {
+            Image(systemName: "pawprint.circle.fill")
+                .font(.title)
+                .foregroundStyle(.white, Color.accentColor)
+                .frame(width: 40)
+            VStack(alignment: .leading, spacing: 4) {
+                Text(meeting.titel).font(.headline)
+                HStack(spacing: 6) {
+                    Image(systemName: "calendar")
+                    Text(formatDate(meeting.datum))
+                    Text(meeting.uhrzeit)
+                }
+                .font(.caption.monospacedDigit())
+                .foregroundStyle(.secondary)
+                if let ort = meeting.ortName, !ort.isEmpty {
+                    HStack(spacing: 4) {
+                        Image(systemName: "mappin.and.ellipse")
+                        Text(ort)
+                    }
+                    .font(.caption)
+                    .foregroundStyle(.secondary)
+                    .lineLimit(1)
+                }
+            }
+            Spacer()
+            VStack(alignment: .trailing, spacing: 2) {
+                Text("\(meeting.teilnehmerCount ?? 0)/\(meeting.maxTeilnehmer)")
+                    .font(.caption.bold().monospacedDigit())
+                Text("Teilnehmer").font(.caption2).foregroundStyle(.secondary)
+            }
+        }
+        .padding(.vertical, 4)
+    }
+
+    private func formatDate(_ s: String) -> String {
+        let parser = DateFormatter()
+        parser.locale = Locale(identifier: "en_US_POSIX")
+        parser.dateFormat = "yyyy-MM-dd"
+        if let d = parser.date(from: String(s.prefix(10))) {
+            let out = DateFormatter()
+            out.locale = Locale(identifier: "de_DE")
+            out.dateFormat = "EEE d. MMM"
+            return out.string(from: d)
+        }
+        return s
+    }
+}

BanYaroGo/Views/GassiView.swift

@@ -0,0 +1,36 @@
+import SwiftUI
+
+struct GassiView: View {
+    @State private var tab: Tab = .treffen
+
+    private enum Tab: String, CaseIterable, Identifiable {
+        case treffen     = "Treffen"
+        case stammGassis = "Stamm-Gassis"
+        var id: String { rawValue }
+    }
+
+    var body: some View {
+        VStack(spacing: 0) {
+            Picker("Bereich", selection: $tab) {
+                ForEach(Tab.allCases) { t in
+                    Text(t.rawValue).tag(t)
+                }
+            }
+            .pickerStyle(.segmented)
+            .padding(.horizontal)
+            .padding(.top, 8)
+
+            Divider()
+                .padding(.top, 8)
+
+            switch tab {
+            case .treffen:
+                GassiTreffenList()
+            case .stammGassis:
+                StammGassisList()
+            }
+        }
+        .navigationTitle("Gassi-Treffen")
+        .navigationBarTitleDisplayMode(.inline)
+    }
+}

BanYaroGo/Views/GassiZeitenView.swift

@@ -1,7 +1,7 @@
 import SwiftUI
 import UserNotifications
 
-struct GassiZeitenView: View {
+struct StammGassisList: View {
     @State private var items: [GassiZeit] = []
     @State private var isLoading = false
     @State private var errorMessage: String?
@@ -15,8 +15,6 @@ struct GassiZeitenView: View {
 
     var body: some View {
         content
-            .navigationTitle("Stamm-Gassi-Zeiten")
-            .navigationBarTitleDisplayMode(.inline)
             .toolbar {
                 ToolbarItem(placement: .topBarTrailing) {
                     Button { showAdd = true } label: { Image(systemName: "plus") }

BanYaroGo/Views/SettingsView.swift

@@ -29,9 +29,9 @@ struct SettingsView: View {
 
                 Section("Hund & Alltag") {
                     NavigationLink {
-                        GassiZeitenView()
+                        GassiView()
                     } label: {
-                        Label("Stamm-Gassi-Zeiten", systemImage: "alarm.fill")
+                        Label("Gassi-Treffen", systemImage: "pawprint.fill")
                     }
                     NavigationLink {
                         GiftkoederView()