build(macos): build the original Swift app against the Rust core

Ghostty's macOS app stays the original, unchanged Swift app (agreed
scope); it is wired to the Rust core instead of the Zig core.
scripts/macos-swift-app.sh (`just macos-swift-app <ghostty-src>`)
mirrors the Zig build's GhosttyXcodebuild.zig:
1. scripts/xcframework.sh builds the Rust libghostty (identical
   include/ghostty.h ABI) as <src>/macos/GhosttyKit.xcframework,
2. `just install <src>/zig-out` provides the resources the Xcode project
   bundles from ../zig-out/share (ghostty, terminfo, completions, man,
   locale, vim, nvim, bat),
3. xcodebuild -target Ghostty in a clean environment.
macOS + Xcode only; DRY_RUN=1 previews the steps (verified on Linux).

Test Plan:
- DRY_RUN=1 scripts/macos-swift-app.sh ../ghostty
- on macOS: just macos-swift-app ../ghostty && open the built app

README.md

@@ -19,6 +19,22 @@ Windows test suites also run under Wine (`just test-windows-wine`), macOS has
 not been run natively. The Swift macOS app is not part of the port; it is a
 client of the libghostty C API.
 
+### The macOS app (original Swift app on the Rust core)
+
+Ghostty's macOS app stays the original Swift app, unchanged. It is wired to
+the Rust core instead of the Zig core: the Rust `libghostty` exports the
+identical `include/ghostty.h` ABI. On a Mac with Xcode:
+
+```sh
+just macos-swift-app ../ghostty          # Release; or: just macos-swift-app ../ghostty Debug
+```
+
+This builds the Rust core as `GhosttyKit.xcframework` into
+`<ghostty>/macos/`, installs the resources into `<ghostty>/zig-out/share`
+(what the Xcode project bundles) and runs `xcodebuild`, mirroring
+`zig build -Demit-macos-app`. Not runnable on this Linux machine
+(`DRY_RUN=1` previews the steps).
+
 ## Building and running
 
 Requirements: Rust (edition 2024), GTK ≥ 4.14, libadwaita ≥ 1.5,

docs/rewrite/STATUS.md

@@ -109,11 +109,12 @@ Legend: ⬜ todo · 🟨 in progress · ✅ done (gate passed, committed) · ⚠
 ## Phase 9 — macOS Swift app → Rust (AppKit via objc2; compile-checked)
 | WP | Scope | Owner | State | Notes |
 |---|---|---|---|---|
-| MA1 | foundation: crate, app/AppDelegate, menu, Ghostty.App/Config wrappers, helpers, bundle script, design doc | sonnet | ✅ | compile-checked; MA2–MA5 on hold pending user decision |
-| MA2 | Ghostty/ incl. Surface View (Metal layer, input, IME, DnD, a11y) | – | ⬜ | after MA1 |
-| MA3 | Features/Terminal (windows, tabs, styles) + Splits | – | ⬜ | after MA1 |
-| MA4 | QuickTerminal, Command Palette, Settings, About, Clipboard, Global Keybinds, Secure Input, Services, App Icon | – | ⬜ | after MA1 |
-| MA5 | AppleScript, Update (Sparkle), App Intents (assess) | – | ⬜ | after MA1 |
+| MA1 | foundation: crate, app/AppDelegate, menu, Ghostty.App/Config wrappers, helpers, bundle script, design doc | sonnet | ↩️ | reverted (cfded0e): user decision — keep the original Swift app, wire it to the Rust core |
+| MSW | `just macos-swift-app`: original Swift app built against the Rust libghostty (xcframework + resources + xcodebuild) | opus | ✅ | macOS-only; dry-run verified here |
+| MA2 | Ghostty/ incl. Surface View (Metal layer, input, IME, DnD, a11y) | – | ✖ | after MA1 | cancelled
+| MA3 | Features/Terminal (windows, tabs, styles) + Splits | – | ✖ | after MA1 | cancelled
+| MA4 | QuickTerminal, Command Palette, Settings, About, Clipboard, Global Keybinds, Secure Input, Services, App Icon | – | ✖ | after MA1 | cancelled
+| MA5 | AppleScript, Update (Sparkle), App Intents (assess) | – | ✖ | after MA1 | cancelled
 
 ## Log
 - 2026-10-11: Phase 0 complete; Phase 1 launched.
@@ -171,3 +172,4 @@ Legend: ⬜ todo · 🟨 in progress · ✅ done (gate passed, committed) · ⚠
 - 2026-10-12: Stop-hook: live D-Bus/portal behaviour still unexercised → LIVE launched (private buses; user session untouched).
 - 2026-10-12: LIVE committed (3605 tests). Remaining unverifiable here: native macOS, native Windows (Wine-tested), IME (no input-method daemon installed).
 - 2026-10-12: Stop-hook: Swift macOS app is part of Ghostty 1.3.1 → Phase 9 (port to Rust/AppKit) started with MA1.
+- 2026-10-12: User: Swift app was agreed out of scope; the /goal hook should not have overridden that. Phase 9 reverted; instead the original Swift app is wired to the Rust core (`just macos-swift-app`).

justfile

@@ -306,3 +306,8 @@ visual-parity *scenarios:
 live-dbus *scenarios:
     scripts/live-dbus/build-rust.sh
     RUST_BIN="${RUST_BIN:-target/vp/production/ghostty}" scripts/live-dbus-test.sh {{scenarios}}
+
+# Build Ghostty's original Swift macOS app against the Rust core (macOS only;
+# DRY_RUN=1 to preview). Example: just macos-swift-app ../ghostty
+macos-swift-app src config="Release":
+    scripts/macos-swift-app.sh {{ src }} {{ config }}

scripts/macos-swift-app.sh

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+# Build Ghostty's ORIGINAL Swift macOS app (unchanged) against the Rust core.
+#
+# Ghostty's Xcode project (<ghostty>/macos/Ghostty.xcodeproj) links
+# `macos/GhosttyKit.xcframework` and bundles resources from `../zig-out/share`
+# (see the Zig build's src/build/GhosttyXcodebuild.zig). The Rust libghostty
+# exports the identical include/ghostty.h ABI, so this script produces both
+# from the Rust workspace and then runs xcodebuild, exactly like
+# `zig build -Demit-macos-app`:
+#   1. scripts/xcframework.sh  -> <ghostty>/macos/GhosttyKit.xcframework
+#   2. `just install`          -> <ghostty>/zig-out/share/{ghostty,terminfo,...}
+#   3. xcodebuild -target Ghostty -configuration <CONFIG> (clean env, like Zig)
+#
+# Usage: scripts/macos-swift-app.sh <path-to-ghostty-source> [Release|Debug|ReleaseLocal]
+# Runs only on macOS (Xcode required). DRY_RUN=1 prints the commands instead.
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+src=${1:?usage: $0 <path-to-ghostty-source> [Release|Debug|ReleaseLocal]}
+config=${2:-Release}
+src=$(cd "$src" && pwd)
+[ -d "$src/macos/Ghostty.xcodeproj" ] || {
+    echo "error: $src/macos/Ghostty.xcodeproj not found" >&2
+    exit 1
+}
+
+run() {
+    if [ "${DRY_RUN:-}" = 1 ]; then
+        printf '+'
+        printf ' %q' "$@"
+        printf '\n'
+    else
+        "$@"
+    fi
+}
+
+if [ "${DRY_RUN:-}" != 1 ] && [ "$(uname -s)" != Darwin ]; then
+    echo "error: building the macOS app requires macOS with Xcode (use DRY_RUN=1 to preview)" >&2
+    exit 1
+fi
+
+# Debug configuration pairs with the dev profile (debug app id), like Zig.
+profile=production
+[ "$config" = Debug ] && profile=dev
+
+# 1. The Rust core as GhosttyKit.xcframework where the Xcode project expects it.
+run scripts/xcframework.sh universal "$profile" "$src/macos/GhosttyKit.xcframework"
+
+# 2. Resources the Xcode project copies from ../zig-out/share.
+run just install "$src/zig-out"
+
+# 3. xcodebuild with a clean environment (only PATH), as GhosttyXcodebuild.zig.
+run env -i PATH="$PATH" sh -c "cd '$src/macos' && xcodebuild -target Ghostty -configuration '$config'"
+
+echo "Ghostty.app: $src/macos/build/$config/Ghostty.app"