Native tmux control mode (tmux -CC) support

Sources/GhosttyTerminalView.swift

@@ -2860,6 +2860,44 @@ class GhosttyApp {
                     }
                 }
             }
+        case GHOSTTY_ACTION_TMUX_STATE:
+            guard let terminalSurface = surfaceView.terminalSurface else { return true }
+            let tmuxState = action.action.tmux_state
+            DispatchQueue.main.async {
+                switch tmuxState {
+                case GHOSTTY_TMUX_STATE_ENTERED:
+                    terminalSurface.tmuxActive = true
+                    #if DEBUG
+                    dlog("tmux.entered tab=\(surfaceView.tabId?.uuidString.prefix(5) ?? "nil") surface=\(terminalSurface.id.uuidString.prefix(5))")
+                    #endif
+                case GHOSTTY_TMUX_STATE_EXITED:
+                    terminalSurface.tmuxActive = false
+                    #if DEBUG
+                    dlog("tmux.exited tab=\(surfaceView.tabId?.uuidString.prefix(5) ?? "nil") surface=\(terminalSurface.id.uuidString.prefix(5))")
+                    #endif
+                case GHOSTTY_TMUX_STATE_WINDOWS_CHANGED:
+                    // The tmux window/pane layout changed. Output is written
+                    // directly to the surface terminal by the stream handler's
+                    // octal decoder, so no renderer pointer swap is needed.
+                    if let surface = terminalSurface.surface {
+                        let paneCount = ghostty_surface_tmux_pane_count(surface)
+                        let windowCount = ghostty_surface_tmux_window_count(surface)
+                        #if DEBUG
+                        dlog("tmux.windowsChanged windows=\(windowCount) panes=\(paneCount)")
+                        #endif
+                        _ = paneCount
+                        _ = windowCount
+                    }
+                default:
+                    break
+                }
+                NotificationCenter.default.post(
+                    name: .ghosttyTmuxStateChanged,
+                    object: terminalSurface,
+                    userInfo: ["state": tmuxState]
+                )
+            }
+            return true
         default:
             return false
         }
@@ -3130,6 +3168,8 @@ final class TerminalSurface: Identifiable, ObservableObject {
         }
     }
     @Published private(set) var keyboardCopyModeActive: Bool = false
+    /// Whether this surface is currently in tmux control mode (DCS 1000p).
+    @Published var tmuxActive: Bool = false
     private var searchNeedleCancellable: AnyCancellable?
     var currentKeyStateIndicatorText: String? { surfaceView.currentKeyStateIndicatorText }
 
@@ -7185,6 +7225,7 @@ extension Notification.Name {
     static let ghosttySearchFocus = Notification.Name("ghosttySearchFocus")
     static let ghosttyConfigDidReload = Notification.Name("ghosttyConfigDidReload")
     static let ghosttyDefaultBackgroundDidChange = Notification.Name("ghosttyDefaultBackgroundDidChange")
+    static let ghosttyTmuxStateChanged = Notification.Name("ghosttyTmuxStateChanged")
     static let browserSearchFocus = Notification.Name("browserSearchFocus")
 }
 

Sources/Panels/TerminalPanel.swift

@@ -24,6 +24,9 @@ final class TerminalPanel: Panel, ObservableObject {
 
     @Published private(set) var tmuxLayoutReport: TmuxPaneLayoutReport?
 
+    /// Whether the terminal is in tmux control mode (tmux -CC)
+    @Published private(set) var tmuxActive: Bool = false
+
     /// Search state for find functionality
     @Published var searchState: TerminalSurface.SearchState? {
         didSet {
@@ -84,6 +87,14 @@ final class TerminalPanel: Panel, ObservableObject {
                 }
             }
             .store(in: &cancellables)
+
+        // Subscribe to tmux control mode state changes
+        surface.$tmuxActive
+            .removeDuplicates()
+            .sink { [weak self] active in
+                self?.tmuxActive = active
+            }
+            .store(in: &cancellables)
     }
 
     /// Create a new terminal panel with a fresh surface

Sources/Workspace.swift

@@ -5539,6 +5539,9 @@ final class Workspace: Identifiable, ObservableObject {
     @Published private(set) var tmuxWorkspaceFlashPanelId: UUID?
     @Published private(set) var tmuxWorkspaceFlashReason: WorkspaceAttentionFlashReason?
     @Published private(set) var tmuxWorkspaceFlashToken: UInt64 = 0
+    /// Whether any terminal panel in this workspace is in tmux control mode.
+    @Published private(set) var tmuxControlModeActive: Bool = false
+    private var tmuxControlModeSubscription: AnyCancellable?
     private var manualUnreadMarkedAt: [UUID: Date] = [:]
     nonisolated private static let manualUnreadFocusGraceInterval: TimeInterval = 0.2
     nonisolated private static let manualUnreadClearDelayAfterFocusFlash: TimeInterval = 0.2
@@ -6043,6 +6046,16 @@ final class Workspace: Identifiable, ObservableObject {
             guard let self, let terminalPanel else { return }
             self.triggerWorkspacePaneFlash(panelId: terminalPanel.id, reason: reason)
         }
+
+        // Subscribe to tmux control mode state changes
+        let subscription = terminalPanel.$tmuxActive
+            .removeDuplicates()
+            .receive(on: DispatchQueue.main)
+            .sink { [weak self] active in
+                self?.tmuxControlModeActive = active
+            }
+        // Store the subscription (replacing any prior one)
+        tmuxControlModeSubscription = subscription
     }
 
     private func triggerWorkspacePaneFlash(panelId: UUID, reason: WorkspaceAttentionFlashReason) {

ghostty.h

@@ -621,6 +621,20 @@ typedef enum {
   GHOSTTY_READONLY_ON,
 } ghostty_action_readonly_e;
 
+// apprt.action.TmuxState
+typedef enum {
+  GHOSTTY_TMUX_STATE_ENTERED,
+  GHOSTTY_TMUX_STATE_EXITED,
+  GHOSTTY_TMUX_STATE_WINDOWS_CHANGED,
+} ghostty_action_tmux_state_e;
+
+// Tmux window info returned by ghostty_surface_tmux_window_info
+typedef struct {
+  uintptr_t id;
+  uintptr_t width;
+  uintptr_t height;
+} ghostty_tmux_window_s;
+
 // apprt.action.DesktopNotification.C
 typedef struct {
   const char* title;
@@ -910,6 +924,8 @@ typedef enum {
   GHOSTTY_ACTION_SEARCH_TOTAL,
   GHOSTTY_ACTION_SEARCH_SELECTED,
   GHOSTTY_ACTION_READONLY,
+  GHOSTTY_ACTION_COPY_TITLE_TO_CLIPBOARD,
+  GHOSTTY_ACTION_TMUX_STATE,
 } ghostty_action_tag_e;
 
 typedef union {
@@ -950,6 +966,7 @@ typedef union {
   ghostty_action_search_total_s search_total;
   ghostty_action_search_selected_s search_selected;
   ghostty_action_readonly_e readonly;
+  ghostty_action_tmux_state_e tmux_state;
 } ghostty_action_u;
 
 typedef struct {
@@ -1154,6 +1171,18 @@ void ghostty_inspector_metal_render(ghostty_inspector_t, void*, void*);
 bool ghostty_inspector_metal_shutdown(ghostty_inspector_t);
 #endif
 
+// Tmux control mode API
+bool ghostty_surface_tmux_active(ghostty_surface_t);
+uintptr_t ghostty_surface_tmux_window_count(ghostty_surface_t);
+uintptr_t ghostty_surface_tmux_window_info(ghostty_surface_t,
+                                           ghostty_tmux_window_s*,
+                                           uintptr_t);
+uintptr_t ghostty_surface_tmux_pane_count(ghostty_surface_t);
+uintptr_t ghostty_surface_tmux_pane_ids(ghostty_surface_t,
+                                       uintptr_t*,
+                                       uintptr_t);
+bool ghostty_surface_tmux_set_active_pane(ghostty_surface_t, uintptr_t);
+
 // APIs I'd like to get rid of eventually but are still needed for now.
 // Don't use these unless you know what you're doing.
 void ghostty_set_window_background_blur(ghostty_app_t, void*);

scripts/ghosttykit-checksums.txt

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