feat(desktop): add new session sheet and settings view

NewSessionSheet for creating tmux sessions with agent type selection.
SettingsView placeholder for future configuration options.

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

Author: grokify

apps/desktop/Sources/Nexus/Views/NewSessionSheet.swift

@@ -0,0 +1,131 @@
+import SwiftUI
+
+/// Sheet for creating a new tmux session
+struct NewSessionSheet: View {
+    @Environment(\.dismiss) private var dismiss
+
+    @State private var sessionName: String = ""
+    @State private var selectedAgentType: AgentType?
+    @State private var customCommand: String = ""
+    @State private var useCustomCommand: Bool = false
+    @State private var isCreating: Bool = false
+    @State private var errorMessage: String?
+
+    let sessionManager: SessionManager
+    let onSessionCreated: (NexusSession) -> Void
+
+    var body: some View {
+        VStack(spacing: 0) {
+            // Header
+            HStack {
+                Text("New Session")
+                    .font(.headline)
+                Spacer()
+                Button("Cancel") {
+                    dismiss()
+                }
+                .keyboardShortcut(.cancelAction)
+            }
+            .padding()
+
+            Divider()
+
+            // Form
+            Form {
+                // Session name
+                TextField("Session Name", text: $sessionName)
+                    .textFieldStyle(.roundedBorder)
+
+                // Agent type (optional)
+                Picker("Agent Type", selection: $selectedAgentType) {
+                    Text("None").tag(nil as AgentType?)
+                    ForEach(AgentType.allCases, id: \.self) { type in
+                        Text(type.displayName).tag(type as AgentType?)
+                    }
+                }
+
+                // Custom command toggle
+                Toggle("Use custom command", isOn: $useCustomCommand)
+
+                if useCustomCommand {
+                    TextField("Command", text: $customCommand)
+                        .textFieldStyle(.roundedBorder)
+                        .help("Command to run in the session (default: your shell)")
+                }
+
+                // Error message
+                if let error = errorMessage {
+                    Text(error)
+                        .foregroundColor(.red)
+                        .font(.caption)
+                }
+            }
+            .padding()
+
+            Divider()
+
+            // Footer
+            HStack {
+                Spacer()
+                Button("Create") {
+                    createSession()
+                }
+                .buttonStyle(.borderedProminent)
+                .keyboardShortcut(.defaultAction)
+                .disabled(sessionName.isEmpty || isCreating)
+            }
+            .padding()
+        }
+        .frame(width: 400)
+        .onAppear {
+            // Generate a default name
+            sessionName = generateDefaultName()
+        }
+    }
+
+    private func generateDefaultName() -> String {
+        let existingNames = Set(sessionManager.sessions.map { $0.name })
+        var index = 1
+        var name = "session-\(index)"
+
+        while existingNames.contains(name) {
+            index += 1
+            name = "session-\(index)"
+        }
+
+        return name
+    }
+
+    private func createSession() {
+        guard !sessionName.isEmpty else { return }
+
+        isCreating = true
+        errorMessage = nil
+
+        let command = useCustomCommand && !customCommand.isEmpty ? customCommand : nil
+
+        Task {
+            do {
+                var session = try await sessionManager.createSession(name: sessionName, command: command)
+                session.agentType = selectedAgentType
+
+                await MainActor.run {
+                    onSessionCreated(session)
+                    dismiss()
+                }
+            } catch {
+                await MainActor.run {
+                    errorMessage = error.localizedDescription
+                    isCreating = false
+                }
+            }
+        }
+    }
+}
+
+#Preview {
+    NewSessionSheet(
+        sessionManager: SessionManager(),
+        onSessionCreated: { _ in }
+    )
+}

apps/desktop/Sources/Nexus/Views/SettingsView.swift

@@ -0,0 +1,100 @@
+import SwiftUI
+
+/// Settings/Preferences window
+struct SettingsView: View {
+    var body: some View {
+        TabView {
+            GeneralSettingsView()
+                .tabItem {
+                    Label("General", systemImage: "gear")
+                }
+
+            AppearanceSettingsView()
+                .tabItem {
+                    Label("Appearance", systemImage: "paintbrush")
+                }
+
+            SessionSettingsView()
+                .tabItem {
+                    Label("Sessions", systemImage: "terminal")
+                }
+        }
+        .frame(width: 450, height: 300)
+    }
+}
+
+struct GeneralSettingsView: View {
+    @AppStorage("autoAttachOnLaunch") private var autoAttachOnLaunch = true
+    @AppStorage("showDetachedSessions") private var showDetachedSessions = true
+    @AppStorage("restoreWindowsOnLaunch") private var restoreWindowsOnLaunch = true
+
+    var body: some View {
+        Form {
+            Toggle("Auto-attach to last session on launch", isOn: $autoAttachOnLaunch)
+            Toggle("Show detached sessions in status bar", isOn: $showDetachedSessions)
+            Toggle("Restore windows on launch", isOn: $restoreWindowsOnLaunch)
+        }
+        .padding()
+    }
+}
+
+struct AppearanceSettingsView: View {
+    @AppStorage("terminalFontSize") private var fontSize: Double = 13
+    @AppStorage("cursorBlink") private var cursorBlink = true
+
+    var body: some View {
+        Form {
+            HStack {
+                Text("Font Size:")
+                Slider(value: $fontSize, in: 9...24, step: 1) {
+                    Text("Font Size")
+                }
+                Text("\(Int(fontSize))pt")
+                    .monospacedDigit()
+                    .frame(width: 40)
+            }
+
+            Toggle("Cursor blink", isOn: $cursorBlink)
+
+            // Placeholder for theme selection
+            Text("Theme settings coming in a future update")
+                .foregroundColor(.secondary)
+                .font(.caption)
+        }
+        .padding()
+    }
+}
+
+struct SessionSettingsView: View {
+    @AppStorage("idleThresholdSeconds") private var idleThreshold: Double = 30
+    @AppStorage("stuckThresholdSeconds") private var stuckThreshold: Double = 120
+    @AppStorage("defaultShell") private var defaultShell = "/bin/zsh"
+
+    var body: some View {
+        Form {
+            HStack {
+                Text("Idle after:")
+                Slider(value: $idleThreshold, in: 10...120, step: 10)
+                Text("\(Int(idleThreshold))s")
+                    .monospacedDigit()
+                    .frame(width: 40)
+            }
+
+            HStack {
+                Text("Stuck after:")
+                Slider(value: $stuckThreshold, in: 60...600, step: 30)
+                Text("\(Int(stuckThreshold))s")
+                    .monospacedDigit()
+                    .frame(width: 40)
+            }
+
+            TextField("Default Shell:", text: $defaultShell)
+                .textFieldStyle(.roundedBorder)
+        }
+        .padding()
+    }
+}
+
+#Preview {
+    SettingsView()
+}