Render Add Source buttons inline on macOS where toolbar items aren't shown

Pre-macOS 26 doesn't reliably surface a detail-pane NavigationStack's
toolbar confirmation items in the window title bar, leaving the
"Add Source" actions invisible. Gate the toolbar placement behind
macOS 26+ and fall back to an inline form/header button on older
macOS across the add-source views and the sources list.

Yattee/Views/Settings/AddSource/AddLocalFolderView.swift

@@ -31,6 +31,21 @@ struct AddLocalFolderView: View {
         !name.isEmpty && selectedFolderURL != nil
     }
 
+    /// macOS surfaces toolbar confirmation items from a pushed-in-sheet view
+    /// reliably only from macOS 26 onward. On older macOS we render the
+    /// "Add Source" action button inline in the form instead.
+    private var usesToolbarActionButton: Bool {
+        #if os(macOS)
+        if #available(macOS 26, *) {
+            return true
+        } else {
+            return false
+        }
+        #else
+        return false
+        #endif
+    }
+
     // MARK: - Body
 
     var body: some View {
@@ -99,10 +114,15 @@ struct AddLocalFolderView: View {
             if let result = testResult {
                 SourceTestResultSection(result: result)
             }
+
+            if !usesToolbarActionButton {
+                actionSection
+            }
         }
         .formStyle(.grouped)
         .navigationTitle(String(localized: "sources.addLocalFolder"))
         .toolbar {
+            if usesToolbarActionButton {
                 ToolbarItem(placement: .confirmationAction) {
                     Button(String(localized: "sources.addSource")) {
                         addSource()
@@ -112,6 +132,7 @@ struct AddLocalFolderView: View {
                 }
             }
         }
+    }
     #endif
 
     // MARK: - Sections

Yattee/Views/Settings/AddSource/AddRemoteServerView.swift

@@ -87,6 +87,22 @@ struct AddRemoteServerView: View {
         return false
     }
 
+    /// macOS surfaces toolbar confirmation items from a pushed-in-sheet view
+    /// reliably only from macOS 26 onward. On older macOS (and on iOS/tvOS) we
+    /// render the "Add Source" action button inline in the form instead, so it
+    /// is always visible.
+    private var usesToolbarActionButton: Bool {
+        #if os(macOS)
+        if #available(macOS 26, *) {
+            return true
+        } else {
+            return false
+        }
+        #else
+        return false
+        #endif
+    }
+
     private var canAdd: Bool {
         guard !urlString.isEmpty else { return false }
 
@@ -172,9 +188,9 @@ struct AddRemoteServerView: View {
 
             if isFieldsRevealed {
                 serverConfigurationFields
-                #if !os(macOS)
+                if !usesToolbarActionButton {
                     actionSection
-                #endif
+                }
             }
         }
         #if os(iOS)
@@ -183,8 +199,8 @@ struct AddRemoteServerView: View {
         #if os(macOS)
         .formStyle(.grouped)
         .toolbar {
+            if isFieldsRevealed, usesToolbarActionButton {
                 ToolbarItem(placement: .confirmationAction) {
-                if isFieldsRevealed {
                     Button {
                         addSource()
                     } label: {

Yattee/Views/Settings/AddSource/AddSMBView.swift

@@ -36,6 +36,21 @@ struct AddSMBView: View {
         !name.isEmpty && !server.isEmpty
     }
 
+    /// macOS surfaces toolbar confirmation items from a pushed-in-sheet view
+    /// reliably only from macOS 26 onward. On older macOS we render the
+    /// "Add Source" action button inline in the form instead.
+    private var usesToolbarActionButton: Bool {
+        #if os(macOS)
+        if #available(macOS 26, *) {
+            return true
+        } else {
+            return false
+        }
+        #else
+        return false
+        #endif
+    }
+
     // MARK: - Body
 
     var body: some View {
@@ -133,10 +148,15 @@ struct AddSMBView: View {
             if let result = testResult {
                 SourceTestResultSection(result: result)
             }
+
+            if !usesToolbarActionButton {
+                actionSection
+            }
         }
         .formStyle(.grouped)
         .navigationTitle(String(localized: "sources.addSMB"))
         .toolbar {
+            if usesToolbarActionButton {
                 ToolbarItem(placement: .confirmationAction) {
                     Button {
                         addSource()
@@ -154,6 +174,7 @@ struct AddSMBView: View {
                     .keyboardShortcut(.defaultAction)
                 }
             }
+        }
         .onAppear {
             if let prefillServer {
                 server = prefillServer

Yattee/Views/Settings/AddSource/AddWebDAVView.swift

@@ -37,6 +37,21 @@ struct AddWebDAVView: View {
         !name.isEmpty && !urlString.isEmpty && URL(string: urlString) != nil
     }
 
+    /// macOS surfaces toolbar confirmation items from a pushed-in-sheet view
+    /// reliably only from macOS 26 onward. On older macOS we render the
+    /// "Add Source" action button inline in the form instead.
+    private var usesToolbarActionButton: Bool {
+        #if os(macOS)
+        if #available(macOS 26, *) {
+            return true
+        } else {
+            return false
+        }
+        #else
+        return false
+        #endif
+    }
+
     // MARK: - Body
 
     var body: some View {
@@ -134,10 +149,15 @@ struct AddWebDAVView: View {
             if let result = testResult {
                 SourceTestResultSection(result: result)
             }
+
+            if !usesToolbarActionButton {
+                actionSection
+            }
         }
         .formStyle(.grouped)
         .navigationTitle(String(localized: "sources.addWebDAV"))
         .toolbar {
+            if usesToolbarActionButton {
                 ToolbarItem(placement: .confirmationAction) {
                     Button {
                         addSource()
@@ -155,6 +175,7 @@ struct AddWebDAVView: View {
                     .keyboardShortcut(.defaultAction)
                 }
             }
+        }
         .onAppear {
             if let url = prefillURL {
                 urlString = url.absoluteString

Yattee/Views/Settings/SourcesListView.swift

@@ -64,6 +64,16 @@ struct SourcesListView: View {
                         .focusSection()
                 }
             }
+            #elseif os(macOS)
+            VStack(spacing: 0) {
+                // macOS 15 does not surface a detail-pane NavigationStack's
+                // toolbar items to the window title bar, so the toolbar
+                // "Add Source" button is invisible there. Show an inline
+                // header button as a fallback on older macOS. On macOS 26+
+                // the toolbar button works, so this header is omitted.
+                macOSLegacyAddHeader
+                sourcesInner
+            }
             #else
             sourcesInner
             #endif
@@ -76,6 +86,7 @@ struct SourcesListView: View {
         #endif
         #if os(iOS) || os(macOS)
         .toolbar {
+            if showAddButtonInToolbar {
                 ToolbarItem(placement: .primaryAction) {
                     Button {
                         showingAddSheet = true
@@ -85,6 +96,7 @@ struct SourcesListView: View {
                     .accessibilityIdentifier("sources.addButton")
                 }
             }
+        }
         #endif
         #if os(tvOS)
         .navigationDestination(isPresented: $showingAddSheet) {
@@ -122,6 +134,47 @@ struct SourcesListView: View {
         #endif
     }
 
+    /// Whether the "Add Source" button should be placed in the window/navigation
+    /// toolbar. On macOS this only works reliably from macOS 26 onward (see
+    /// `macOSLegacyAddHeader`); iOS always uses the toolbar.
+    private var showAddButtonInToolbar: Bool {
+        #if os(iOS)
+        return true
+        #elseif os(macOS)
+        if #available(macOS 26, *) {
+            return true
+        } else {
+            return false
+        }
+        #else
+        return false
+        #endif
+    }
+
+    #if os(macOS)
+    // Inline fallback "Add Source" button for macOS versions where the
+    // detail-pane toolbar item is not shown (pre-macOS 26). Only needed when
+    // there are existing sources — the empty state already offers its own
+    // add button.
+    @ViewBuilder
+    private var macOSLegacyAddHeader: some View {
+        if !showAddButtonInToolbar, !isEmpty {
+            HStack {
+                Spacer()
+                Button {
+                    showingAddSheet = true
+                } label: {
+                    Label(String(localized: "sources.addSource"), systemImage: "plus")
+                }
+                .accessibilityIdentifier("sources.addButton")
+            }
+            .padding(.horizontal, 16)
+            .padding(.top, 12)
+            .padding(.bottom, 4)
+        }
+    }
+    #endif
+
     @ViewBuilder
     private var sourcesInner: some View {
         if isEmpty {