feat: add readonly surface mode

include/ghostty.h

@@ -797,6 +797,7 @@ typedef enum {
   GHOSTTY_ACTION_RESIZE_SPLIT,
   GHOSTTY_ACTION_EQUALIZE_SPLITS,
   GHOSTTY_ACTION_TOGGLE_SPLIT_ZOOM,
+  GHOSTTY_ACTION_TOGGLE_READONLY,
   GHOSTTY_ACTION_PRESENT_TERMINAL,
   GHOSTTY_ACTION_SIZE_LIMIT,
   GHOSTTY_ACTION_RESET_WINDOW_SIZE,

src/Surface.zig

@@ -145,6 +145,12 @@ focused: bool = true,
 /// Used to determine whether to continuously scroll.
 selection_scroll_active: bool = false,
 
+/// True if the surface is in read-only mode. When read-only, no input
+/// is sent to the PTY but terminal-level operations like selections,
+/// scrolling, and copy/paste keybinds still work. Warn before quit is
+/// always enabled in this state.
+readonly: bool = false,
+
 /// Used to send notifications that long running commands have finished.
 /// Requires that shell integration be active. Should represent a nanosecond
 /// precision timestamp. It does not necessarily need to correspond to the
@@ -871,6 +877,9 @@ pub fn deactivateInspector(self: *Surface) void {
 /// True if the surface requires confirmation to quit. This should be called
 /// by apprt to determine if the surface should confirm before quitting.
 pub fn needsConfirmQuit(self: *Surface) bool {
+    // If the surface is in read-only mode, always require confirmation
+    if (self.readonly) return true;
+
     // If the child has exited, then our process is certainly not alive.
     // We check this first to avoid the locking overhead below.
     if (self.child_exited) return false;
@@ -2559,6 +2568,12 @@ pub fn keyCallback(
         if (insp_ev) |*ev| ev else null,
     )) |v| return v;
 
+    // If the surface is in read-only mode, we consume the key event here
+    // without sending it to the PTY.
+    if (self.readonly) {
+        return .consumed;
+    }
+
     // If we allow KAM and KAM is enabled then we do nothing.
     if (self.config.vt_kam_allowed) {
         self.renderer_state.mutex.lock();
@@ -3267,7 +3282,9 @@ pub fn scrollCallback(
         // we convert to cursor keys. This only happens if we're:
         // (1) alt screen (2) no explicit mouse reporting and (3) alt
         // scroll mode enabled.
-        if (self.io.terminal.screens.active_key == .alternate and
+        // Additionally, we don't send cursor keys if the surface is in read-only mode.
+        if (!self.readonly and
+            self.io.terminal.screens.active_key == .alternate and
             self.io.terminal.flags.mouse_event == .none and
             self.io.terminal.modes.get(.mouse_alternate_scroll))
         {
@@ -3393,6 +3410,9 @@ fn mouseReport(
     assert(self.config.mouse_reporting);
     assert(self.io.terminal.flags.mouse_event != .none);
 
+    // If the surface is in read-only mode, do not send mouse reports to the PTY
+    if (self.readonly) return;
+
     // Depending on the event, we may do nothing at all.
     switch (self.io.terminal.flags.mouse_event) {
         .none => unreachable, // checked by assert above
@@ -5383,6 +5403,15 @@ pub fn performBindingAction(self: *Surface, action: input.Binding.Action) !bool
             {},
         ),
 
+        .toggle_readonly => {
+            self.readonly = !self.readonly;
+            return try self.rt_app.performAction(
+                .{ .surface = self },
+                .toggle_readonly,
+                {},
+            );
+        },
+
         .reset_window_size => return try self.rt_app.performAction(
             .{ .surface = self },
             .reset_window_size,

src/apprt/action.zig

@@ -139,6 +139,11 @@ pub const Action = union(Key) {
     /// to take up the entire window.
     toggle_split_zoom,
 
+    /// Toggle whether the surface is in read-only mode. When read-only,
+    /// no input is sent to the PTY but terminal-level operations like
+    /// selections, scrolling, and copy/paste keybinds still work.
+    toggle_readonly,
+
     /// Present the target terminal whether its a tab, split, or window.
     present_terminal,
 
@@ -335,6 +340,7 @@ pub const Action = union(Key) {
         resize_split,
         equalize_splits,
         toggle_split_zoom,
+        toggle_readonly,
         present_terminal,
         size_limit,
         reset_window_size,

src/apprt/gtk/class/application.zig

@@ -724,6 +724,10 @@ pub const Application = extern struct {
             .toggle_window_decorations => return Action.toggleWindowDecorations(target),
             .toggle_command_palette => return Action.toggleCommandPalette(target),
             .toggle_split_zoom => return Action.toggleSplitZoom(target),
+            .toggle_readonly => {
+                // The readonly state is managed in Surface.zig.
+                return true;
+            },
             .show_on_screen_keyboard => return Action.showOnScreenKeyboard(target),
             .command_finished => return Action.commandFinished(target, value),
 

src/input/Binding.zig

@@ -552,6 +552,16 @@ pub const Action = union(enum) {
     /// reflect this by displaying an icon indicating the zoomed state.
     toggle_split_zoom,
 
+    /// Toggle read-only mode for the current surface.
+    ///
+    /// When a surface is in read-only mode:
+    ///   - No input is sent to the PTY (mouse events, key encoding)
+    ///   - Input can still be used at the terminal level to make selections,
+    ///     copy/paste (keybinds), scroll, etc.
+    ///   - Warn before quit is always enabled in this state even if an active
+    ///     process is not running
+    toggle_readonly,
+
     /// Resize the current split in the specified direction and amount in
     /// pixels. The two arguments should be joined with a comma (`,`),
     /// like in `resize_split:up,10`.
@@ -1241,6 +1251,7 @@ pub const Action = union(enum) {
             .new_split,
             .goto_split,
             .toggle_split_zoom,
+            .toggle_readonly,
             .resize_split,
             .equalize_splits,
             .inspector,

src/input/command.zig

@@ -485,6 +485,12 @@ fn actionCommands(action: Action.Key) []const Command {
             .description = "Toggle the zoom state of the current split.",
         }},
 
+        .toggle_readonly => comptime &.{.{
+            .action = .toggle_readonly,
+            .title = "Toggle Read-Only Mode",
+            .description = "Toggle read-only mode for the current surface.",
+        }},
+
         .equalize_splits => comptime &.{.{
             .action = .equalize_splits,
             .title = "Equalize Splits",