posix portability: linux syscalls -> libc (std.c) in one shared path. All raw std.os.linux.* call sites converted with the errno-convention flip (libc returns -1 + thread-local errno, not -errno): open/close/read/write/rename in tty.zig, gui.zig, look.zig; harness too (snapshot.zig: getcwd/mkdir/chdir/fork+waitpid/getdents64->opendir-readdir, e2e_harness.zig: clock_gettime/write/close), so the parity suite itself is POSIX-portable. Per-OS branches kept only where platforms genuinely diverge: shellCwd in look.zig (linux /proc/<pid>/cwd readlink; darwin libproc proc_pidinfo PROC_PIDVNODEPATHINFO with a hand-declared extern; other POSIX degrades to null), bash path (/usr/bin/bash on linux, /bin/bash elsewhere), TIOCSWINSZ constant (absent from std.c.T on darwin). forkpty/execv/chdir externs were already libc and are portable (fork-safety preserved: absolute-path execv, no malloc between fork and exec, initial spawns before worker threads). build.zig: forward target/optimize to the ghostty dep for native/cross (web keeps its no-target fetch), disable ghostty simd for darwin cross-builds (apple_sdk needs xcrun; scalar fallback = web config), link libutil on the BSDs. Pinned ghostty needs two one-line zig-0.16 darwin fixes, applied in the zig-pkg cache and documented in build.zig. Verified: aarch64-macos + x86_64-macos + x86_64-freebsd cross-compiles green; linux native tty + gui + web green; snapshot suite 18/18 with goldens untouched. Out of scope: gui-on-macos needs Metal shaders (SDL GPU rejects our SPIR-V there).

1 files changed, 26 insertions, 1 deletions

diff --git a/build.zig b/build.zig
index 22dd7158..f9aa1070 100644
--- a/build.zig
+++ b/build.zig
@@ -59,6 +59,10 @@ pub fn build(b: *std.Build) void {
     // static archives the emcc link needs beyond the zig object (grammars, SDL)
     var wasm_libs: std.ArrayList(std.Build.LazyPath) = .empty;
 
+    // forkpty: in libc proper on glibc>=2.34 and darwin; the BSDs keep it in libutil
+    if (target.result.os.tag == .freebsd or target.result.os.tag == .netbsd or target.result.os.tag == .openbsd)
+        root_mod.linkSystemLibrary("util", .{});
+
     const opts = b.addOptions();
     opts.addOption(Platform, "platform", platform);
     opts.addOption(bool, "syntax_highlighting", tree_sitter_grammars != .disabled);
@@ -171,7 +175,26 @@ pub fn build(b: *std.Build) void {
     }).module("vaxis");
 
     var ghostty_vt_for_snap: ?*std.Build.Module = null;
-    if (b.lazyDependency("ghostty", .{ .simd = target.result.os.tag != .emscripten })) |dep| {
+    // ghostty's simd libs (simdutf/highway, C++) locate the Apple SDK via
+    // xcrun on darwin targets, so cross-compiling to macOS from elsewhere
+    // uses the scalar fallback (the same configuration the web shell ships).
+    // Native/cross builds hand ghostty the real target (it defaults to the
+    // host otherwise); the web path keeps its original no-target fetch, whose
+    // zig object never uses ghostty's artifacts.
+    // NOTE: darwin targets also need two one-line zig-0.16 fixes in the
+    // pinned ghostty (applied in the zig-pkg cache; re-apply after a fresh
+    // fetch, or bump the pin once upstream carries them):
+    //   src/os/mach.zig — std.heap.next_mmap_addr_hint is gone (make the hint
+    //     var module-local) and posix.mmap prot is now a packed struct
+    //     (.{ .READ = true, .WRITE = true });
+    //   src/terminal/kitty/graphics_image.zig:185 — shm_open's variadic mode
+    //     literal 0 must be @as(std.c.mode_t, 0).
+    const ghostty_simd = !target.result.os.tag.isDarwin() or b.graph.host.result.os.tag.isDarwin();
+    const ghostty_dep = if (is_emscripten)
+        b.lazyDependency("ghostty", .{ .simd = false })
+    else
+        b.lazyDependency("ghostty", .{ .target = target, .optimize = optimize, .simd = ghostty_simd });
+    if (ghostty_dep) |dep| {
         const ghostty_vt = dep.module("ghostty-vt");
         ghostty_vt_for_snap = ghostty_vt;
         ghostty_vt.addImport("uucode", uucode_mod);
@@ -309,6 +332,8 @@ pub fn build(b: *std.Build) void {
             }),
         });
         if (ghostty_vt_for_snap) |vt| snap.root_module.addImport("ghostty-vt", vt);
+        if (target.result.os.tag == .freebsd or target.result.os.tag == .netbsd or target.result.os.tag == .openbsd)
+            snap.root_module.linkSystemLibrary("util", .{});
         b.installArtifact(snap);
         const run_snap = b.addRunArtifact(snap);
         run_snap.addArtifactArg(exe);