C2/C3: restore rotation keybinds (REPLY/LS-cycle) + focus contract routing on the focused chat surface

HellionChat/Ui/Windows/ChannelPopoutWindow.cs

@@ -13,7 +13,7 @@ namespace HellionChat.Ui.Windows;
 // via ctor — see plan §B.2. The ###id carries the slot index so all N
 // instances are unique for WindowSystem.AddWindow and ImGui state is stable
 // per slot (not per bound tab).
-internal sealed class ChannelPopoutWindow : Window
+internal sealed class ChannelPopoutWindow : Window, IFocusableChatWindow
 {
     private readonly int _slotIndex;
     private readonly MessageList _messages;
@@ -75,6 +75,18 @@ internal sealed class ChannelPopoutWindow : Window
         IsOpen = false;
     }
 
+    // IFocusableChatWindow — this pop-out's own InputBar carries the focus state
+    // the keybind tail checks when deciding whether to route at this surface (C3).
+    public bool HasFocusedInput => _input.IsFocused;
+
+    // Arm-and-hold the one-frame Activate flag; the pop-out's Draw applies the
+    // ImGui focus next frame. Framework-thread safe (field write only).
+    public void RequestInputFocus()
+    {
+        BringToFront();
+        _input.Activate = true;
+    }
+
     public override void PreDraw()
     {
         // Gate the native title bar on the user toggle (1.5.6 parity). DrawHeader

HellionChat/Ui/Windows/IFocusableChatWindow.cs

@@ -0,0 +1,14 @@
+namespace HellionChat.Ui.Windows;
+
+// Focus contract shared by the main window and each pop-out so the keybind tail
+// can route channel-set / REPLY / prefill to whichever surface currently owns the
+// input focus, without the KeybindManager reaching into either window's privates.
+// HasFocusedInput reads the bound InputBar's per-frame focus state; RequestInputFocus
+// only arms the one-frame Activate flag (ImGui focus is frame-bound — never call
+// SetKeyboardFocusHere from the framework thread).
+internal interface IFocusableChatWindow
+{
+    bool HasFocusedInput { get; }
+
+    void RequestInputFocus();
+}

HellionChat/Ui/Windows/MainWindow.cs

@@ -16,7 +16,7 @@ namespace HellionChat.Ui.Windows;
 // Components are fully qualified through the Ui.Components prefix so the
 // old Ui.StatusBar type (still alive until the cleanup block removes it)
 // cannot shadow the new layer through parent-namespace resolution.
-internal sealed class MainWindow : Window
+internal sealed class MainWindow : Window, IFocusableChatWindow
 {
     private const float DefaultWidth = 620f;
     private const float DefaultHeight = 340f;
@@ -205,6 +205,18 @@ internal sealed class MainWindow : Window
         _input.Activate = true;
     }
 
+    // IFocusableChatWindow — the keybind tail resolves which surface owns the
+    // input focus before routing a channel-set/REPLY/prefill at it (C3).
+    public bool HasFocusedInput => _input.IsFocused;
+
+    // Arm-and-hold: field writes only, safe from the framework thread; the draw
+    // path applies the actual ImGui focus next frame (same path as ActivateChat).
+    public void RequestInputFocus()
+    {
+        BringToFront();
+        _input.Activate = true;
+    }
+
     // new-shadow on Window.Toggle so the open path also writes Config. A user-hide
     // counts as "not visible", so /hellion is a reliable one-press recovery even when
     // the Enter keybind can't fire (DirectChat / a focused game text field).