From 5c2a01de3372cba8404a7c5012673aec92cce091 Mon Sep 17 00:00:00 2001
From: Fawzi Mohamed <fawzi@gmx.ch>
Date: Sat, 23 May 2026 08:27:26 +0200
Subject: [PATCH] Improve alt handing in the kitty protocol on macOS

Set mods with kitty protocol the same way they are set with
fn legacy (key_encode.zig:445) as it makes macos_option_as_alt
right/left setting more usable (does not consider alt pressed if it
is option).
This also makes applications like flow that rely on the alt flag work
correctly. There an argument that the text modifier should be ignored
if the text attribute is present, but having alt set consistently
seems good practice in any case.
See also https://github.com/ghostty-org/ghostty/discussions/9511
---
 src/input/key_encode.zig | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/src/input/key_encode.zig b/src/input/key_encode.zig
index 6ab5a4cc8..976369141 100644
--- a/src/input/key_encode.zig
+++ b/src/input/key_encode.zig
@@ -232,15 +232,31 @@ fn kitty(
     // If this is just a modifier we require "report all" to send the sequence.
     if (entry.modifier and !opts.kitty_flags.report_all) return;
 
+    // The mods we encode for this are just the input mods (shift, ctrl,
+    // super, alt unless it is actually option).
+    const mods = mods: {
+            var mods_input: KittyMods = .fromInput(
+                event.action,
+                event.key,
+                all_mods,
+            );
+            if (comptime builtin.target.os.tag.isDarwin()) alt: {
+                switch (opts.macos_option_as_alt) {
+                    .false => {},
+                    .true => break :alt,
+                    .left => if (event.mods.sides.alt == .left) break :alt,
+                    .right => if (event.mods.sides.alt == .right) break :alt,
+                }
+                mods_input.alt = false;
+            }
+            break :mods mods_input;
+        };
+
     const seq: KittySequence = seq: {
         var seq: KittySequence = .{
             .key = entry.code,
             .final = entry.final,
-            .mods = .fromInput(
-                event.action,
-                event.key,
-                all_mods,
-            ),
+            .mods = mods,
         };
 
         if (opts.kitty_flags.report_events) {