Add cross-device grocery list sync via Nextcloud Cookbook API

Store a _groceryState JSON field on each recipe to track which
ingredients have been added, completed, or removed. Uses per-item
last-writer-wins conflict resolution with ISO 8601 timestamps.
Debounced push (2s) avoids excessive API calls; pull reconciles
on recipe open and app launch. Includes a settings toggle to
enable/disable sync.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Nextcloud Cookbook iOS Client.xcodeproj/project.pbxproj

@@ -72,6 +72,8 @@
 		D1A0CE012D0A000100000001 /* GroceryListMode.swift in Sources */ = {isa = PBXBuildFile; fileRef = D1A0CE002D0A000100000001 /* GroceryListMode.swift */; };
 		D1A0CE032D0A000200000002 /* RemindersGroceryStore.swift in Sources */ = {isa = PBXBuildFile; fileRef = D1A0CE022D0A000200000002 /* RemindersGroceryStore.swift */; };
 		D1A0CE052D0A000300000003 /* GroceryListManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = D1A0CE042D0A000300000003 /* GroceryListManager.swift */; };
+		E1B0CF072D0B000400000004 /* GroceryStateModels.swift in Sources */ = {isa = PBXBuildFile; fileRef = E1B0CF062D0B000400000004 /* GroceryStateModels.swift */; };
+		E1B0CF092D0B000500000005 /* GroceryStateSyncManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = E1B0CF082D0B000500000005 /* GroceryStateSyncManager.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -161,6 +163,8 @@
 		D1A0CE002D0A000100000001 /* GroceryListMode.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GroceryListMode.swift; sourceTree = "<group>"; };
 		D1A0CE022D0A000200000002 /* RemindersGroceryStore.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RemindersGroceryStore.swift; sourceTree = "<group>"; };
 		D1A0CE042D0A000300000003 /* GroceryListManager.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GroceryListManager.swift; sourceTree = "<group>"; };
+		E1B0CF062D0B000400000004 /* GroceryStateModels.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GroceryStateModels.swift; sourceTree = "<group>"; };
+		E1B0CF082D0B000500000005 /* GroceryStateSyncManager.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = GroceryStateSyncManager.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -301,6 +305,8 @@
 				D1A0CE002D0A000100000001 /* GroceryListMode.swift */,
 				D1A0CE022D0A000200000002 /* RemindersGroceryStore.swift */,
 				D1A0CE042D0A000300000003 /* GroceryListManager.swift */,
+				E1B0CF062D0B000400000004 /* GroceryStateModels.swift */,
+				E1B0CF082D0B000500000005 /* GroceryStateSyncManager.swift */,
 			);
 			path = Data;
 			sourceTree = "<group>";
@@ -638,6 +644,8 @@
 				D1A0CE012D0A000100000001 /* GroceryListMode.swift in Sources */,
 				D1A0CE032D0A000200000002 /* RemindersGroceryStore.swift in Sources */,
 				D1A0CE052D0A000300000003 /* GroceryListManager.swift in Sources */,
+				E1B0CF072D0B000400000004 /* GroceryStateModels.swift in Sources */,
+				E1B0CF092D0B000500000005 /* GroceryStateSyncManager.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

Nextcloud Cookbook iOS Client/Data/GroceryListManager.swift

@@ -14,6 +14,11 @@ class GroceryListManager: ObservableObject {
 
     let localStore = GroceryList()
     let remindersStore = RemindersGroceryStore()
+    var syncManager: GroceryStateSyncManager?
+
+    /// Recipe IDs modified by our own CRUD — skip these in the onDataChanged callback
+    /// to avoid duplicate syncs.
+    private var recentlyModifiedByUs: Set<String> = []
 
     private var mode: GroceryListMode {
         GroceryListMode(rawValue: UserSettings.shared.groceryListMode) ?? .inApp
@@ -23,11 +28,29 @@ class GroceryListManager: ObservableObject {
         remindersStore.onDataChanged = { [weak self] in
             guard let self else { return }
             if self.mode == .appleReminders {
+                let previousDict = self.groceryDict
                 self.groceryDict = self.remindersStore.groceryDict
+
+                // Only sync recipes that changed externally (e.g. checked off in Reminders app),
+                // not ones we just modified ourselves.
+                for recipeId in self.remindersStore.groceryDict.keys {
+                    guard !self.recentlyModifiedByUs.contains(recipeId) else { continue }
+                    // Detect if item count changed (external add/remove/complete)
+                    let oldCount = previousDict[recipeId]?.items.count ?? 0
+                    let newCount = self.remindersStore.groceryDict[recipeId]?.items.count ?? 0
+                    if oldCount != newCount {
+                        self.syncManager?.scheduleSync(forRecipeId: recipeId)
+                    }
+                }
+                self.recentlyModifiedByUs.removeAll()
             }
         }
     }
 
+    func configureSyncManager(appState: AppState) {
+        syncManager = GroceryStateSyncManager(appState: appState, groceryManager: self)
+    }
+
     // MARK: - Grocery Operations
 
     func addItem(_ itemName: String, toRecipe recipeId: String, recipeName: String? = nil) {
@@ -36,9 +59,11 @@ class GroceryListManager: ObservableObject {
             localStore.addItem(itemName, toRecipe: recipeId, recipeName: recipeName)
             groceryDict = localStore.groceryDict
         case .appleReminders:
+            recentlyModifiedByUs.insert(recipeId)
             remindersStore.addItem(itemName, toRecipe: recipeId, recipeName: recipeName)
             groceryDict = remindersStore.groceryDict
         }
+        syncManager?.scheduleSync(forRecipeId: recipeId)
     }
 
     func addItems(_ items: [String], toRecipe recipeId: String, recipeName: String? = nil) {
@@ -47,9 +72,11 @@ class GroceryListManager: ObservableObject {
             localStore.addItems(items, toRecipe: recipeId, recipeName: recipeName)
             groceryDict = localStore.groceryDict
         case .appleReminders:
+            recentlyModifiedByUs.insert(recipeId)
             remindersStore.addItems(items, toRecipe: recipeId, recipeName: recipeName)
             groceryDict = remindersStore.groceryDict
         }
+        syncManager?.scheduleSync(forRecipeId: recipeId)
     }
 
     func deleteItem(_ itemName: String, fromRecipe recipeId: String) {
@@ -58,9 +85,10 @@ class GroceryListManager: ObservableObject {
             localStore.deleteItem(itemName, fromRecipe: recipeId)
             groceryDict = localStore.groceryDict
         case .appleReminders:
+            recentlyModifiedByUs.insert(recipeId)
             remindersStore.deleteItem(itemName, fromRecipe: recipeId)
-            // Cache update happens async in RemindersGroceryStore via onDataChanged
         }
+        syncManager?.scheduleSync(forRecipeId: recipeId)
     }
 
     func deleteGroceryRecipe(_ recipeId: String) {
@@ -69,18 +97,25 @@ class GroceryListManager: ObservableObject {
             localStore.deleteGroceryRecipe(recipeId)
             groceryDict = localStore.groceryDict
         case .appleReminders:
+            recentlyModifiedByUs.insert(recipeId)
             remindersStore.deleteGroceryRecipe(recipeId)
         }
+        syncManager?.scheduleSync(forRecipeId: recipeId)
     }
 
     func deleteAll() {
+        let recipeIds = Array(groceryDict.keys)
         switch mode {
         case .inApp:
             localStore.deleteAll()
             groceryDict = localStore.groceryDict
         case .appleReminders:
+            recentlyModifiedByUs.formUnion(recipeIds)
             remindersStore.deleteAll()
         }
+        for recipeId in recipeIds {
+            syncManager?.scheduleSync(forRecipeId: recipeId)
+        }
     }
 
     func toggleItemChecked(_ groceryItem: GroceryRecipeItem) {

Nextcloud Cookbook iOS Client/Data/GroceryStateModels.swift

@@ -0,0 +1,58 @@
+//
+//  GroceryStateModels.swift
+//  Nextcloud Cookbook iOS Client
+//
+
+import Foundation
+
+/// Tracks grocery list state for a recipe, stored as `_groceryState` in the recipe JSON on the server.
+struct GroceryState: Codable {
+    var version: Int = 1
+    var lastModified: String
+    var items: [String: GroceryItemState]
+
+    init(lastModified: String = GroceryStateDate.now(), items: [String: GroceryItemState] = [:]) {
+        self.version = 1
+        self.lastModified = lastModified
+        self.items = items
+    }
+}
+
+struct GroceryItemState: Codable {
+    enum Status: String, Codable {
+        case added
+        case completed
+        case removed
+    }
+
+    var status: Status
+    var addedAt: String
+    var modifiedAt: String
+
+    init(status: Status, addedAt: String = GroceryStateDate.now(), modifiedAt: String = GroceryStateDate.now()) {
+        self.status = status
+        self.addedAt = addedAt
+        self.modifiedAt = modifiedAt
+    }
+}
+
+/// ISO 8601 date helpers. Dates are stored as strings to avoid coupling to a parent encoder's date strategy.
+enum GroceryStateDate {
+    private static let formatter: ISO8601DateFormatter = {
+        let f = ISO8601DateFormatter()
+        f.formatOptions = [.withInternetDateTime]
+        return f
+    }()
+
+    static func now() -> String {
+        formatter.string(from: Date())
+    }
+
+    static func date(from string: String) -> Date? {
+        formatter.date(from: string)
+    }
+
+    static func string(from date: Date) -> String {
+        formatter.string(from: date)
+    }
+}

Nextcloud Cookbook iOS Client/Data/GroceryStateSyncManager.swift

@@ -0,0 +1,168 @@
+//
+//  GroceryStateSyncManager.swift
+//  Nextcloud Cookbook iOS Client
+//
+
+import Foundation
+import OSLog
+
+@MainActor
+class GroceryStateSyncManager {
+    private weak var appState: AppState?
+    private weak var groceryManager: GroceryListManager?
+
+    private var debounceTimers: [String: Task<Void, Never>] = [:]
+    private let debounceInterval: TimeInterval = 2.0
+
+    init(appState: AppState, groceryManager: GroceryListManager) {
+        self.appState = appState
+        self.groceryManager = groceryManager
+    }
+
+    // MARK: - Push Flow
+
+    /// Debounced sync trigger. Waits `debounceInterval` seconds then pushes state for the recipe.
+    func scheduleSync(forRecipeId recipeId: String) {
+        guard UserSettings.shared.grocerySyncEnabled else { return }
+
+        debounceTimers[recipeId]?.cancel()
+        debounceTimers[recipeId] = Task { [weak self] in
+            try? await Task.sleep(nanoseconds: UInt64(2_000_000_000))
+            guard !Task.isCancelled else { return }
+            await self?.pushGroceryState(forRecipeId: recipeId)
+        }
+    }
+
+    /// Builds local grocery state, fetches server recipe, merges, and PUTs back.
+    func pushGroceryState(forRecipeId recipeId: String) async {
+        guard let appState, let groceryManager else { return }
+        guard let recipeIdInt = Int(recipeId) else { return }
+
+        // Build local state from current grocery data
+        let localState = buildLocalState(forRecipeId: recipeId, groceryManager: groceryManager)
+
+        // Fetch latest recipe from server
+        guard let serverRecipe = await appState.getRecipe(id: recipeIdInt, fetchMode: .onlyServer) else {
+            Logger.data.error("Grocery sync: failed to fetch recipe \(recipeId) from server")
+            return
+        }
+
+        // Merge local state with server state
+        let serverState = serverRecipe.groceryState
+        let merged = mergeStates(local: localState, server: serverState)
+
+        // Upload merged state
+        var updatedRecipe = serverRecipe
+        updatedRecipe.groceryState = merged
+        let (_, alert) = await appState.uploadRecipe(recipeDetail: updatedRecipe, createNew: false)
+        if let alert {
+            Logger.data.error("Grocery sync: failed to push state for recipe \(recipeId): \(String(describing: alert))")
+        }
+    }
+
+    // MARK: - Pull Flow
+
+    /// Reconciles server grocery state with local grocery data. Called when a recipe is loaded.
+    func reconcileFromServer(serverState: GroceryState?, recipeId: String, recipeName: String) {
+        guard let groceryManager else { return }
+        guard let serverState, !serverState.items.isEmpty else { return }
+
+        let localItems = Set(
+            groceryManager.groceryDict[recipeId]?.items.map(\.name) ?? []
+        )
+
+        for (itemName, itemState) in serverState.items {
+            switch itemState.status {
+            case .added:
+                if !localItems.contains(itemName) {
+                    groceryManager.addItem(itemName, toRecipe: recipeId, recipeName: recipeName)
+                }
+            case .removed:
+                if localItems.contains(itemName) {
+                    groceryManager.deleteItem(itemName, fromRecipe: recipeId)
+                }
+            case .completed:
+                // Don't re-add completed items; leave local state as-is
+                break
+            }
+        }
+    }
+
+    // MARK: - Initial Sync
+
+    /// Pushes any local-only items and reconciles server items on app launch.
+    func performInitialSync() async {
+        guard let appState, let groceryManager else { return }
+
+        let recipeIds = Array(groceryManager.groceryDict.keys)
+        for recipeId in recipeIds {
+            guard let recipeIdInt = Int(recipeId) else { continue }
+
+            // Push local state to server
+            await pushGroceryState(forRecipeId: recipeId)
+
+            // Fetch back and reconcile
+            if let serverRecipe = await appState.getRecipe(id: recipeIdInt, fetchMode: .onlyServer) {
+                let recipeName = groceryManager.groceryDict[recipeId]?.name ?? serverRecipe.name
+                reconcileFromServer(
+                    serverState: serverRecipe.groceryState,
+                    recipeId: recipeId,
+                    recipeName: recipeName
+                )
+            }
+        }
+    }
+
+    // MARK: - Merge Logic
+
+    /// Merges local and server states using per-item last-writer-wins on `modifiedAt`.
+    private func mergeStates(local: GroceryState, server: GroceryState?) -> GroceryState {
+        guard let server else { return local }
+
+        var merged = local.items
+        for (itemName, serverItem) in server.items {
+            if let localItem = merged[itemName] {
+                // Both have the item — keep the one with the later modifiedAt
+                let localDate = GroceryStateDate.date(from: localItem.modifiedAt) ?? .distantPast
+                let serverDate = GroceryStateDate.date(from: serverItem.modifiedAt) ?? .distantPast
+                if serverDate > localDate {
+                    merged[itemName] = serverItem
+                }
+            } else {
+                // Only server has this item — keep it
+                merged[itemName] = serverItem
+            }
+        }
+
+        // Garbage collection: remove items that are removed/completed and older than 30 days
+        let thirtyDaysAgo = Date().addingTimeInterval(-30 * 24 * 60 * 60)
+        merged = merged.filter { _, item in
+            if item.status == .added { return true }
+            guard let modDate = GroceryStateDate.date(from: item.modifiedAt) else { return true }
+            return modDate > thirtyDaysAgo
+        }
+
+        return GroceryState(
+            lastModified: GroceryStateDate.now(),
+            items: merged
+        )
+    }
+
+    // MARK: - Build Local State
+
+    /// Builds a `GroceryState` from the current local grocery data for a recipe.
+    private func buildLocalState(forRecipeId recipeId: String, groceryManager: GroceryListManager) -> GroceryState {
+        guard let groceryRecipe = groceryManager.groceryDict[recipeId] else {
+            return GroceryState()
+        }
+
+        var items: [String: GroceryItemState] = [:]
+        let now = GroceryStateDate.now()
+        for item in groceryRecipe.items {
+            let status: GroceryItemState.Status = item.isChecked ? .completed : .added
+            items[item.name] = GroceryItemState(status: status, addedAt: now, modifiedAt: now)
+        }
+
+        return GroceryState(lastModified: now, items: items)
+    }
+}

Nextcloud Cookbook iOS Client/Data/ObservableRecipeDetail.swift

@@ -26,6 +26,7 @@ class ObservableRecipeDetail: ObservableObject {
     @Published var recipeIngredient: [String]
     @Published var recipeInstructions: [String]
     @Published var nutrition: [String:String]
+    var groceryState: GroceryState?
 
     // Additional functionality
     @Published var ingredientMultiplier: Double
@@ -48,6 +49,7 @@ class ObservableRecipeDetail: ObservableObject {
         recipeIngredient = []
         recipeInstructions = []
         nutrition = [:]
+        groceryState = nil
 
         ingredientMultiplier = 1
     }
@@ -68,6 +70,7 @@ class ObservableRecipeDetail: ObservableObject {
         recipeIngredient = recipeDetail.recipeIngredient
         recipeInstructions = recipeDetail.recipeInstructions
         nutrition = recipeDetail.nutrition
+        groceryState = recipeDetail.groceryState
 
         ingredientMultiplier = Double(recipeDetail.recipeYield == 0 ? 1 : recipeDetail.recipeYield)
     }
@@ -90,7 +93,8 @@ class ObservableRecipeDetail: ObservableObject {
             tool: self.tool,
             recipeIngredient: self.recipeIngredient,
             recipeInstructions: self.recipeInstructions,
-            nutrition: self.nutrition
+            nutrition: self.nutrition,
+            groceryState: self.groceryState
         )
     }
     

Nextcloud Cookbook iOS Client/Data/RecipeModels.swift

@@ -50,8 +50,9 @@ struct RecipeDetail: Codable {
     var recipeIngredient: [String]
     var recipeInstructions: [String]
     var nutrition: [String:String]
+    var groceryState: GroceryState?
 
-    init(name: String, keywords: String, dateCreated: String, dateModified: String, imageUrl: String, id: String, prepTime: String? = nil, cookTime: String? = nil, totalTime: String? = nil, description: String, url: String, recipeYield: Int, recipeCategory: String, tool: [String], recipeIngredient: [String], recipeInstructions: [String], nutrition: [String:String]) {
+    init(name: String, keywords: String, dateCreated: String, dateModified: String, imageUrl: String, id: String, prepTime: String? = nil, cookTime: String? = nil, totalTime: String? = nil, description: String, url: String, recipeYield: Int, recipeCategory: String, tool: [String], recipeIngredient: [String], recipeInstructions: [String], nutrition: [String:String], groceryState: GroceryState? = nil) {
         self.name = name
         self.keywords = keywords
         self.dateCreated = dateCreated
@@ -69,6 +70,7 @@ struct RecipeDetail: Codable {
         self.recipeIngredient = recipeIngredient
         self.recipeInstructions = recipeInstructions
         self.nutrition = nutrition
+        self.groceryState = groceryState
     }
 
     init() {
@@ -89,11 +91,13 @@ struct RecipeDetail: Codable {
         recipeIngredient = []
         recipeInstructions = []
         nutrition = [:]
+        groceryState = nil
     }
 
     // Custom decoder to handle value type ambiguity
     private enum CodingKeys: String, CodingKey {
         case name, keywords, dateCreated, dateModified, image, imageUrl, id, prepTime, cookTime, totalTime, description, url, recipeYield, recipeCategory, tool, recipeIngredient, recipeInstructions, nutrition
+        case groceryState = "_groceryState"
     }
 
     init(from decoder: Decoder) throws {
@@ -132,6 +136,8 @@ struct RecipeDetail: Codable {
         } else {
             nutrition = [:]
         }
+
+        groceryState = try? container.decode(GroceryState.self, forKey: .groceryState)
     }
 
     func encode(to encoder: Encoder) throws {
@@ -154,6 +160,7 @@ struct RecipeDetail: Codable {
         try container.encode(recipeIngredient, forKey: .recipeIngredient)
         try container.encode(recipeInstructions, forKey: .recipeInstructions)
         try container.encode(nutrition, forKey: .nutrition)
+        try container.encodeIfPresent(groceryState, forKey: .groceryState)
     }
 }
 

Nextcloud Cookbook iOS Client/Data/UserSettings.swift

@@ -133,6 +133,12 @@ class UserSettings: ObservableObject {
         }
     }
 
+    @Published var grocerySyncEnabled: Bool {
+        didSet {
+            UserDefaults.standard.set(grocerySyncEnabled, forKey: "grocerySyncEnabled")
+        }
+    }
+    
     init() {
         self.username = UserDefaults.standard.object(forKey: "username") as? String ?? ""
         self.token = UserDefaults.standard.object(forKey: "token") as? String ?? ""
@@ -154,6 +160,7 @@ class UserSettings: ObservableObject {
         self.decimalNumberSeparator = UserDefaults.standard.object(forKey: "decimalNumberSeparator") as? String ?? "."
         self.groceryListMode = UserDefaults.standard.object(forKey: "groceryListMode") as? String ?? GroceryListMode.inApp.rawValue
         self.remindersListIdentifier = UserDefaults.standard.object(forKey: "remindersListIdentifier") as? String ?? ""
+        self.grocerySyncEnabled = UserDefaults.standard.object(forKey: "grocerySyncEnabled") as? Bool ?? true
         
         if authString == "" {
             if token != "" && username != "" {

Nextcloud Cookbook iOS Client/Localizable.xcstrings

@@ -2023,6 +2023,9 @@
           }
         }
       }
+    },
+    "Grocery list state is synced via your Nextcloud server by storing it alongside recipe data." : {
+
     },
     "Grocery list storage" : {
       "localizations" : {
@@ -4319,6 +4322,9 @@
           }
         }
       }
+    },
+    "Sync grocery list across devices" : {
+
     },
     "Thank you for downloading" : {
       "localizations" : {

Nextcloud Cookbook iOS Client/Views/MainView.swift

@@ -81,6 +81,10 @@ struct MainView: View {
                 }
             }
             await groceryList.load()
+            groceryList.configureSyncManager(appState: appState)
+            if UserSettings.shared.grocerySyncEnabled {
+                await groceryList.syncManager?.performInitialSync()
+            }
             recipeViewModel.presentLoadingIndicator = false
         }
     }

Nextcloud Cookbook iOS Client/Views/Recipes/RecipeView.swift

@@ -12,6 +12,7 @@ import SwiftUI
 
 struct RecipeView: View {
     @EnvironmentObject var appState: AppState
+    @EnvironmentObject var groceryList: GroceryListManager
     @Environment(\.dismiss) private var dismiss
     @StateObject var viewModel: ViewModel
     @GestureState private var dragOffset = CGSize.zero
@@ -75,6 +76,15 @@ struct RecipeView: View {
                     fetchMode: UserSettings.shared.storeImages ? .preferLocal : .onlyServer
                 )
 
+                // Reconcile server grocery state with local data
+                if UserSettings.shared.grocerySyncEnabled {
+                    groceryList.syncManager?.reconcileFromServer(
+                        serverState: viewModel.recipeDetail.groceryState,
+                        recipeId: String(viewModel.recipe.recipe_id),
+                        recipeName: viewModel.recipeDetail.name
+                    )
+                }
+
             } else {
                 // Prepare view for a new recipe
                 if let preloaded = viewModel.preloadedRecipeDetail {

Nextcloud Cookbook iOS Client/Views/SettingsView.swift

@@ -93,10 +93,16 @@ struct SettingsView: View {
                         }
                     }
                 }
+
+                Toggle(isOn: $userSettings.grocerySyncEnabled) {
+                    Text("Sync grocery list across devices")
+                }
             } header: {
                 Text("Grocery List")
             } footer: {
-                if userSettings.groceryListMode == GroceryListMode.appleReminders.rawValue {
+                if userSettings.grocerySyncEnabled {
+                    Text("Grocery list state is synced via your Nextcloud server by storing it alongside recipe data.")
+                } else if userSettings.groceryListMode == GroceryListMode.appleReminders.rawValue {
                     Text("Grocery items will be saved to Apple Reminders. The Grocery List tab will be hidden since you can manage items directly in the Reminders app.")
                 } else {
                     Text("Grocery items are stored locally on this device.")