From c1d033e35ff690725637dc30f30e3f3df903110d Mon Sep 17 00:00:00 2001
From: Taylor Bell <taylorbell@gmail.com>
Date: Mon, 25 May 2026 00:40:42 -0600
Subject: [PATCH 1/2] ghostty: add ghostty_surface_set_selection_range C API
 (rebased on upstream/main)

Includes resolve of conflict: both selectCursorLine (upstream)
and setSelectionRange (Slice 0) are kept as independent cmux
additions to the fork.
---
 include/ghostty.h      |  6 ++++++
 src/Surface.zig        | 24 ++++++++++++++++++++++++
 src/apprt/embedded.zig | 21 +++++++++++++++++++++
 3 files changed, 51 insertions(+)

diff --git a/include/ghostty.h b/include/ghostty.h
index 3697f78d43f..9a1d0e2bf30 100644
--- a/include/ghostty.h
+++ b/include/ghostty.h
@@ -1180,6 +1180,12 @@ GHOSTTY_API void ghostty_surface_complete_clipboard_request(ghostty_surface_t,
 GHOSTTY_API bool ghostty_surface_has_selection(ghostty_surface_t);
 GHOSTTY_API bool ghostty_surface_select_cursor_cell(ghostty_surface_t);
 GHOSTTY_API bool ghostty_surface_select_cursor_line(ghostty_surface_t);
+GHOSTTY_API bool ghostty_surface_set_selection_range(ghostty_surface_t,
+                                                      uint32_t,
+                                                      uint32_t,
+                                                      uint32_t,
+                                                      uint32_t,
+                                                      bool);
 GHOSTTY_API bool ghostty_surface_clear_selection(ghostty_surface_t);
 GHOSTTY_API bool ghostty_surface_read_selection(ghostty_surface_t, ghostty_text_s*);
 GHOSTTY_API bool ghostty_surface_read_text(ghostty_surface_t,
diff --git a/src/Surface.zig b/src/Surface.zig
index a1fd96e7d9b..c373f204403 100644
--- a/src/Surface.zig
+++ b/src/Surface.zig
@@ -2118,6 +2118,30 @@ pub fn selectCursorLine(self: *Surface) !bool {
     return true;
 }
 
+/// Set a selection range from buffer (screen) coordinates (cmux-specific).
+pub fn setSelectionRange(
+    self: *Surface,
+    row_start: u32,
+    col_start: u32,
+    row_end: u32,
+    col_end: u32,
+    is_rectangular: bool,
+) !bool {
+    self.renderer_state.mutex.lock();
+    defer self.renderer_state.mutex.unlock();
+
+    const screen: *terminal.Screen = self.io.terminal.screens.active;
+    const col_start_cell = std.math.cast(terminal.size.CellCountInt, col_start) orelse return false;
+    const col_end_cell = std.math.cast(terminal.size.CellCountInt, col_end) orelse return false;
+    const start_pin = screen.pages.pin(.{ .screen = .{ .x = col_start_cell, .y = row_start } }) orelse return false;
+    const end_pin = screen.pages.pin(.{ .screen = .{ .x = col_end_cell, .y = row_end } }) orelse return false;
+
+    try self.setSelection(terminal.Selection.init(start_pin, end_pin, is_rectangular));
+    screen.dirty.selection = true;
+    try self.queueRender();
+    return true;
+}
+
 /// Clear the active selection (cmux-specific).
 pub fn clearSelection(self: *Surface) !bool {
     self.renderer_state.mutex.lock();
diff --git a/src/apprt/embedded.zig b/src/apprt/embedded.zig
index 340fedda58a..0f145487668 100644
--- a/src/apprt/embedded.zig
+++ b/src/apprt/embedded.zig
@@ -1684,6 +1684,27 @@ pub const CAPI = struct {
         };
     }
 
+    /// Set a selection range from buffer (screen) coordinates (cmux-specific).
+    export fn ghostty_surface_set_selection_range(
+        surface: *Surface,
+        row_start: u32,
+        col_start: u32,
+        row_end: u32,
+        col_end: u32,
+        is_rectangular: bool,
+    ) bool {
+        return surface.core_surface.setSelectionRange(
+            row_start,
+            col_start,
+            row_end,
+            col_end,
+            is_rectangular,
+        ) catch |err| {
+            log.warn("error setting selection range err={}", .{err});
+            return false;
+        };
+    }
+
     /// Same as ghostty_surface_read_text but reads from the user selection,
     /// if any.
     export fn ghostty_surface_read_selection(

From 0a650e9258af25c2dbbbddd81005d3e79ce074a2 Mon Sep 17 00:00:00 2001
From: Taylor Bell <taylorbell@gmail.com>
Date: Mon, 25 May 2026 09:08:28 -0600
Subject: [PATCH 2/2] ghostty: name set_selection_range parameters

---
 include/ghostty.h | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/ghostty.h b/include/ghostty.h
index 9a1d0e2bf30..1d249a3a855 100644
--- a/include/ghostty.h
+++ b/include/ghostty.h
@@ -1181,11 +1181,11 @@ GHOSTTY_API bool ghostty_surface_has_selection(ghostty_surface_t);
 GHOSTTY_API bool ghostty_surface_select_cursor_cell(ghostty_surface_t);
 GHOSTTY_API bool ghostty_surface_select_cursor_line(ghostty_surface_t);
 GHOSTTY_API bool ghostty_surface_set_selection_range(ghostty_surface_t,
-                                                      uint32_t,
-                                                      uint32_t,
-                                                      uint32_t,
-                                                      uint32_t,
-                                                      bool);
+                                                      uint32_t row_start,
+                                                      uint32_t col_start,
+                                                      uint32_t row_end,
+                                                      uint32_t col_end,
+                                                      bool is_rectangular);
 GHOSTTY_API bool ghostty_surface_clear_selection(ghostty_surface_t);
 GHOSTTY_API bool ghostty_surface_read_selection(ghostty_surface_t, ghostty_text_s*);
 GHOSTTY_API bool ghostty_surface_read_text(ghostty_surface_t,