apprt: propagate OSC10/11 (set term fore/background color) through to apprt

This is to allow the running apprt to set the UI theme to match the
terminal application coloring.

include/ghostty.h

@@ -512,6 +512,20 @@ typedef struct {
   ghostty_input_trigger_s trigger;
 } ghostty_action_key_sequence_s;
 
+// apprt.action.SetBackground
+typedef struct {
+  uint8_t r;
+  uint8_t g;
+  uint8_t b;
+} ghostty_action_set_background_s;
+
+// apprt.action.SetForeground
+typedef struct {
+  uint8_t r;
+  uint8_t g;
+  uint8_t b;
+} ghostty_action_set_foreground_s;
+
 // apprt.Action.Key
 typedef enum {
   GHOSTTY_ACTION_NEW_WINDOW,
@@ -545,6 +559,8 @@ typedef enum {
   GHOSTTY_ACTION_QUIT_TIMER,
   GHOSTTY_ACTION_SECURE_INPUT,
   GHOSTTY_ACTION_KEY_SEQUENCE,
+  GHOSTTY_ACTION_SET_BACKGROUND,
+  GHOSTTY_ACTION_SET_FOREGROUND,
 } ghostty_action_tag_e;
 
 typedef union {
@@ -567,6 +583,8 @@ typedef union {
   ghostty_action_quit_timer_e quit_timer;
   ghostty_action_secure_input_e secure_input;
   ghostty_action_key_sequence_s key_sequence;
+  ghostty_action_set_background_s set_background;
+  ghostty_action_set_foreground_s set_foreground;
 } ghostty_action_u;
 
 typedef struct {

src/Surface.zig

@@ -799,6 +799,22 @@ pub fn handleMessage(self: *Surface, msg: Message) !void {
             }, .unlocked);
         },
 
+        .set_background => |color| {
+            try self.rt_app.performAction(
+                .{ .surface = self },
+                .set_background,
+                .{ .r = color.r, .g = color.g, .b = color.b },
+            );
+        },
+
+        .set_foreground => |color| {
+            try self.rt_app.performAction(
+                .{ .surface = self },
+                .set_background,
+                .{ .r = color.r, .g = color.g, .b = color.b },
+            );
+        },
+
         .set_mouse_shape => |shape| {
             log.debug("changing mouse shape: {}", .{shape});
             try self.rt_app.performAction(

src/apprt/action.zig

@@ -186,6 +186,12 @@ pub const Action = union(Key) {
     /// key mode because other input may be ignored.
     key_sequence: KeySequence,
 
+    /// The terminal background color was changed.
+    set_background: SetBackground,
+
+    /// The terminal foreground color was changed.
+    set_foreground: SetForeground,
+
     /// Sync with: ghostty_action_tag_e
     pub const Key = enum(c_int) {
         new_window,
@@ -219,6 +225,8 @@ pub const Action = union(Key) {
         quit_timer,
         secure_input,
         key_sequence,
+        set_background,
+        set_foreground,
     };
 
     /// Sync with: ghostty_action_u
@@ -448,3 +456,15 @@ pub const KeySequence = union(enum) {
         };
     }
 };
+
+pub const SetBackground = extern struct {
+    r: u8,
+    g: u8,
+    b: u8,
+};
+
+pub const SetForeground = extern struct {
+    r: u8,
+    g: u8,
+    b: u8,
+};

src/apprt/glfw.zig

@@ -223,6 +223,8 @@ pub const App = struct {
             .mouse_over_link,
             .cell_size,
             .renderer_health,
+            .set_foreground,
+            .set_background,
             => log.info("unimplemented action={}", .{action}),
         }
     }

src/apprt/gtk/App.zig

@@ -485,6 +485,8 @@ pub fn performAction(
         .key_sequence,
         .render_inspector,
         .renderer_health,
+        .set_foreground,
+        .set_background,
         => log.warn("unimplemented action={}", .{action}),
     }
 }

src/apprt/surface.zig

@@ -70,6 +70,12 @@ pub const Message = union(enum) {
     /// unless the surface exits.
     password_input: bool,
 
+    /// The terminal background color was changed.
+    set_background: terminal.color.RGB,
+
+    /// The terminal foreground color was changed.
+    set_foreground: terminal.color.RGB,
+
     pub const ReportTitleStyle = enum {
         csi_21_t,
 

src/termio/stream_handler.zig

@@ -1215,12 +1215,14 @@ pub const StreamHandler = struct {
                 _ = self.renderer_mailbox.push(.{
                     .foreground_color = color,
                 }, .{ .forever = {} });
+                self.surfaceMessageWriter(.{ .set_background = color });
             },
             .background => {
                 self.background_color = color;
                 _ = self.renderer_mailbox.push(.{
                     .background_color = color,
                 }, .{ .forever = {} });
+                self.surfaceMessageWriter(.{ .set_background = color });
             },
             .cursor => {
                 self.cursor_color = color;