keyboard shortcut to cycle servers

mac/Sources/Byre/Startup.swift

@@ -88,6 +88,13 @@ final class Servers {
         saveRecords()
     }
 
+    func step(from origin: String?, by step: Int) -> String? {
+        guard let i = origin.flatMap({ origins.firstIndex(of: $0) }) else {
+            return origins.first
+        }
+        return origins[(i + step + origins.count) % origins.count]
+    }
+
     func openAll() {
         if origins.isEmpty {
             openWindow?(nil)
@@ -315,6 +322,7 @@ struct FatalView: View {
 }
 
 struct ServerFocus {
+    let origin: String?
     let store: Store?
     let overlays: Overlays
     let forget: (() -> Void)?
@@ -340,7 +348,7 @@ struct ServerWindow: View {
         if connection != nil {
             forgetting = forget
         }
-        return ServerFocus(store: connection?.store, overlays: overlays, forget: forgetting)
+        return ServerFocus(origin: connection?.origin.absoluteString, store: connection?.store, overlays: overlays, forget: forgetting)
     }
 
     private var frameColor: Color {
@@ -387,6 +395,9 @@ struct ServerWindow: View {
     var body: some View {
         framed
             .navigationTitle(connection?.origin.host() ?? "byre")
+            .background {
+                WindowReader(found: joinTabs)
+            }
             .focusedSceneValue(\.serverWindow, focus)
             .onChange(of: origin, initial: true) { old, new in
                 moved(old, new)
@@ -431,6 +442,16 @@ struct ServerWindow: View {
         Notifier.shared.deliver()
     }
 
+    private func joinTabs(_ window: NSWindow) {
+        window.tabbingMode = .preferred
+        DispatchQueue.main.async {
+            let host = NSApp.windows.first { $0 !== window && $0.isVisible && $0.tabbingIdentifier == window.tabbingIdentifier }
+            if let host, !(host.tabbedWindows ?? []).contains(window) {
+                host.addTabbedWindow(window, ordered: .above)
+            }
+        }
+    }
+
     private func adopt(_ candidates: [String]) {
         guard origin == nil, form.serverText.isEmpty, !form.connecting, let next = candidates.first(where: { !Servers.shared.shown.contains($0) }) else {
             return