Forward Option chords to the child on macOS

In raw tty mode Alt-n reached the child as a bare `n`: the ESC prefix was
dropped on the floor, and only on macOS. ghostty's encoder refuses the legacy
alt-esc prefix on a macOS build unless macos_option_as_alt says Option really
is Alt, and KeyEncodeOptions.fromTerminal cannot know that one — it says so in
a comment — so it defaults to false.

False is right for an app that lets macOS translate the chord and hands the
encoder the composed text. Every pardes shell decides the modifier itself and
hands the core the BASE key with the alt bit and no text at all, which
PardesView.keyDown and app.mjs both spell the same way, so by the time the
encoder runs there is nothing left to translate.

The unit suite has been catching this on macOS all along; it is only invisible
on Linux, where that branch does not compile in.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

1 files changed, 14 insertions, 1 deletions

diff --git a/src/panes.zig b/src/panes.zig
index 88e6a8ea..93abae30 100644
--- a/src/panes.zig
+++ b/src/panes.zig
@@ -6803,7 +6803,20 @@ pub const Terminal = struct {
                 .consumed_mods = .{ .shift = key.text.len > 0 and key.shift },
                 .utf8 = text,
                 .unshifted_codepoint = if (key.cp >= 'A' and key.cp <= 'Z') key.cp - 'A' + 'a' else if (key.cp < Key.up) key.cp else 0,
-            }, input.KeyEncodeOptions.fromTerminal(&state.vt)) catch return;
+            }, options: {
+                var opts = input.KeyEncodeOptions.fromTerminal(&state.vt);
+                // fromTerminal cannot know this one and says so, defaulting to
+                // "option is not alt" — right for an app that lets macOS do the
+                // unicode translation and hands the encoder the composed text.
+                // Every pardes shell resolves the modifier itself and hands the
+                // core the BASE key with the alt bit and no text at all (see
+                // PardesView.keyDown, and app.mjs doing the same with the same
+                // two bits), so by the time this runs alt already means alt.
+                // Left at the default, a macOS build drops the ESC prefix on
+                // the floor and forwards Alt-n to the child as a bare `n`.
+                opts.macos_option_as_alt = .true;
+                break :options opts;
+            }) catch return;
             if (writer.end > 0) p.emit(.{ .write = .{ .pane = @intCast(id), .bytes = .from(writer.buffered()) } });
             return;
         }