build(vt): carry vendored changes as Vendor/ghostty.patch

The submodule is pinned to an upstream commit; the cursor-semantic additions
to include/ghostty/vt/terminal.h and src/terminal/c/terminal.zig live in the
submodule working tree as uncommitted changes that a clean checkout (or CI)
never sees. Freeze them as a tracked patch and apply it after every submodule
update, before the VT build.

- Vendor/ghostty.patch: git diff of the two vendored edits (validated with
  git apply on a clean worktree of the pinned HEAD)
- docs/libghostty-vt.md: document the apply step and the .a/header sync
  requirement (ReleaseFast drops the enum bounds check → UB if mismatched)
- ci.yml + release.yml: git apply ../ghostty.patch before "Build Ghostty VT"

Author: freecodetiger

.github/workflows/ci.yml

@@ -56,6 +56,13 @@ jobs:
           echo "${GITHUB_WORKSPACE}/.tools/zig-${ZIG_ARCH}-macos-0.15.2" >> "$GITHUB_PATH"
           ".tools/zig-${ZIG_ARCH}-macos-0.15.2/zig" version
 
+      - name: Apply ProGhostty VT patch
+        working-directory: Vendor/ghostty
+        run: |
+          set -euxo pipefail
+          git apply ../ghostty.patch
+          test -f include/ghostty/vt/terminal.h
+
       - name: Build Ghostty VT
         working-directory: Vendor/ghostty
         run: |

.github/workflows/release.yml

@@ -44,6 +44,13 @@ jobs:
           echo "${GITHUB_WORKSPACE}/.tools/zig-${ZIG_ARCH}-macos-0.15.2" >> "$GITHUB_PATH"
           ".tools/zig-${ZIG_ARCH}-macos-0.15.2/zig" version
 
+      - name: Apply ProGhostty VT patch
+        working-directory: Vendor/ghostty
+        run: |
+          set -euxo pipefail
+          git apply ../ghostty.patch
+          test -f include/ghostty/vt/terminal.h
+
       - name: Build Ghostty VT
         working-directory: Vendor/ghostty
         run: |

Vendor/ghostty.patch

@@ -0,0 +1,50 @@
+diff --git a/include/ghostty/vt/terminal.h b/include/ghostty/vt/terminal.h
+index 0e6d048e1..e9d468254 100644
+--- a/include/ghostty/vt/terminal.h
++++ b/include/ghostty/vt/terminal.h
+@@ -868,6 +868,17 @@ typedef enum GHOSTTY_ENUM_TYPED {
+    * Output type: GhosttyKittyGraphics *
+    */
+   GHOSTTY_TERMINAL_DATA_KITTY_GRAPHICS = 30,
++
++  /**
++   * The semantic content of the active screen's cursor. After OSC 133;C the
++   * cursor semantic flips to .output even though previously-written input
++   * cells stay .input, so this distinguishes "cursor at a live input prompt"
++   * from "cursor on a stale / running command line" that per-cell markers
++   * cannot. Ghostty's prompt-click movement keys off this same state.
++   *
++   * Output type: GhosttyCellSemanticContent *
++   */
++  GHOSTTY_TERMINAL_DATA_CURSOR_SEMANTIC_CONTENT = 31,
+   GHOSTTY_TERMINAL_DATA_MAX_VALUE = GHOSTTY_ENUM_MAX_VALUE,
+ } GhosttyTerminalData;
+ 
+diff --git a/src/terminal/c/terminal.zig b/src/terminal/c/terminal.zig
+index d3293f3bc..231547e50 100644
+--- a/src/terminal/c/terminal.zig
++++ b/src/terminal/c/terminal.zig
+@@ -575,6 +575,7 @@ pub const TerminalData = enum(c_int) {
+     kitty_image_medium_temp_file = 28,
+     kitty_image_medium_shared_mem = 29,
+     kitty_graphics = 30,
++    cursor_semantic_content = 31,
+ 
+     /// Output type expected for querying the data of the given kind.
+     pub fn OutType(comptime self: TerminalData) type {
+@@ -603,6 +604,7 @@ pub const TerminalData = enum(c_int) {
+             .kitty_image_medium_shared_mem,
+             => bool,
+             .kitty_graphics => KittyGraphics,
++            .cursor_semantic_content => cell_c.SemanticContent,
+         };
+     }
+ };
+@@ -712,6 +714,7 @@ fn getTyped(
+             if (comptime !build_options.kitty_graphics) return .no_value;
+             out.* = &t.screens.active.kitty_images;
+         },
++        .cursor_semantic_content => out.* = @enumFromInt(@intFromEnum(t.screens.active.cursor.semantic_content)),
+     }
+ 
+     return .success;

docs/libghostty-vt.md

@@ -29,6 +29,30 @@ tar -xf .tools/zig-aarch64-macos-0.15.2.tar.xz -C .tools
 
 `.tools/` is intentionally ignored by git.
 
+## ProGhostty Patch
+
+`Vendor/ghostty.patch` carries ProGhostty's small additions to the vendored
+Ghostty source. The submodule is pinned to an upstream commit, so a clean
+checkout never contains these changes — the patch must be applied after every
+`git submodule update` and before building the VT library. CI applies it in both
+`ci.yml` and `release.yml`.
+
+```bash
+git submodule update --init --recursive
+cd Vendor/ghostty
+git apply ../ghostty.patch
+cd ../..
+```
+
+The patch adds `GHOSTTY_TERMINAL_DATA_CURSOR_SEMANTIC_CONTENT` (and its
+`getTyped` case) — the cursor semantic state ProGhostty's click-to-position
+uses to distinguish a live input prompt from a stale/running command line.
+
+> **Keep `.a` and header in sync.** The rebuilt `libghostty-vt.a` references the
+> new enum value. The C shim and the `.a` must come from the same build; a
+> rebuilt `.a` without the applied patch (or vice-versa) is undefined behavior,
+> since the enum value is read with no runtime bounds check under ReleaseFast.
+
 ## Build VT Library
 
 Run from `Vendor/ghostty`: