diff --git a/apps/desktop/src-tauri/build.rs b/apps/desktop/src-tauri/build.rs
index c0380b8..5902e68 100644
--- a/apps/desktop/src-tauri/build.rs
+++ b/apps/desktop/src-tauri/build.rs
@@ -29,7 +29,7 @@ fn main() {
         );
     }
     if std::env::var("PROFILE").as_deref() == Ok("release")
-        && matches!(target.as_str(), "windows" | "linux")
+        && matches!(target.as_str(), "windows" | "linux" | "macos")
     {
         let root = std::path::Path::new(env!("CARGO_MANIFEST_DIR")).join("../../..");
         let status = std::process::Command::new(if cfg!(windows) { "python" } else { "python3" })
diff --git a/docs/EXTRACTION-ISOLATION.md b/docs/EXTRACTION-ISOLATION.md
index dba3dd0..aab13a7 100644
--- a/docs/EXTRACTION-ISOLATION.md
+++ b/docs/EXTRACTION-ISOLATION.md
@@ -215,3 +215,16 @@ Windows throughput, cold filesystem caches or steady-state search latency.
 No persistent parser/cache optimization is justified by this small observation.
 Raw ignored report: `.searchi/qa/document-throughput-013.json`, SHA-256
 `b86df0bf2ca0953317033b35b4642e6e0fadb93e50c499a7a28b1ae82512acd1`.
+
+## macOS staging preparation
+
+The helper staging tool now detects Darwin as macOS, recognizes native thin
+64-bit little-endian Mach-O executables for Intel/Apple Silicon, and preserves
+executable mode. Desktop release verification now covers macOS too. Header
+layout and constants follow Apple's [loader header](https://github.com/apple-oss-distributions/xnu/blob/main/EXTERNAL_HEADERS/mach-o/loader.h)
+and [CPU definitions](https://github.com/apple-oss-distributions/xnu/blob/main/osfmk/mach/machine.h).
+Six staging tests passed normally and under optimized Python, including mocked
+Darwin defaults and synthetic header rejection. The actual staged Windows
+helper still verifies. This is preparation only: native macOS build, loader
+closure, resource-limit behavior, signing and application execution remain open.
+Universal/fat extraction-helper binaries are not supported by this staging tool.
diff --git a/tools/stage_extraction_worker.py b/tools/stage_extraction_worker.py
index e817d0f..6a014dc 100644
--- a/tools/stage_extraction_worker.py
+++ b/tools/stage_extraction_worker.py
@@ -53,10 +53,17 @@ def identity(path):
             machine = struct.unpack_from('<H', signature, 4)[0] if signature[:4] == b'PE\0\0' else 0
             arch = {0x8664: 'x86_64', 0xAA64: 'aarch64'}.get(machine)
             platform = 'windows'
-        elif header[:6] == b'\x7fELF\x02\x01':
+        elif len(header) == 64 and header[:6] == b'\x7fELF\x02\x01':
             machine = struct.unpack_from('<H', header, 18)[0]
             arch = {62: 'x86_64', 183: 'aarch64'}.get(machine)
             platform = 'linux'
+        elif len(header) >= 32 and header[:4] == b'\xcf\xfa\xed\xfe':
+            # Apple's mach_header_64: thin little-endian native executable.
+            cpu, _, filetype, commands, command_bytes = struct.unpack_from('<IIIII', header, 4)
+            if filetype != 2 or not 0 < commands <= 8192 or not commands * 8 <= command_bytes <= path.stat().st_size - 32:
+                raise ValueError('Invalid extraction Mach-O executable header')
+            arch = {0x01000007: 'x86_64', 0x0100000c: 'aarch64'}.get(cpu)
+            platform = 'macos'
         else:
             raise ValueError('Unsupported extraction executable format')
         if arch is None:
@@ -106,7 +113,7 @@ def stage(binary, provenance, destination, root=ROOT):
         try:
             if target == name and hashlib.sha256(data).hexdigest() != record['sha256']:
                 raise ValueError('Extraction binary changed while staging')
-            if target == name and platform == 'linux':
+            if target == name and platform != 'windows':
                 temporary.chmod(0o755)
             os.replace(temporary, destination / target)
         finally:
@@ -119,7 +126,7 @@ def main():
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument('--destination', type=Path, default=ROOT / 'apps/desktop/src-tauri/resources')
     parser.add_argument('--verify-only', action='store_true')
-    parser.add_argument('--platform', choices=['windows', 'linux'], default='windows' if os.name == 'nt' else 'linux')
+    parser.add_argument('--platform', choices=['windows', 'linux', 'macos'], default='windows' if os.name == 'nt' else ('macos' if host_platform.system() == 'Darwin' else 'linux'))
     parser.add_argument('--architecture', choices=['x86_64', 'aarch64'], default='aarch64' if host_platform.machine().lower() in {'aarch64', 'arm64'} else 'x86_64')
     args = parser.parse_args()
     if args.verify_only:
diff --git a/tools/test_stage_extraction_worker.py b/tools/test_stage_extraction_worker.py
index 137aecb..50c9d3b 100644
--- a/tools/test_stage_extraction_worker.py
+++ b/tools/test_stage_extraction_worker.py
@@ -56,6 +56,26 @@ class ExtractionStageTests(unittest.TestCase):
                 worker.stage(binary, before, resources, root)
             self.assertEqual((resources / 'searchi-extract-worker.exe').read_bytes(), binary.read_bytes())
 
+    def test_macos_thin_headers_and_staging(self):
+        import struct
+        for cpu, arch in [(0x01000007, 'x86_64'), (0x0100000c, 'aarch64')]:
+            with self.subTest(architecture=arch), tempfile.TemporaryDirectory() as directory:
+                root, binary, resources = self.fixture(directory)
+                data = struct.pack('<8I', 0xfeedfacf, cpu, 0, 2, 1, 8, 0, 0) + struct.pack('<2I', 0, 8)
+                binary.write_bytes(data)
+                worker.stage(binary, worker.fingerprint(root), resources, root)
+                records = worker.verify(resources, root, 'macos', arch)
+                self.assertIn('searchi-extract-worker', records)
+                for invalid in [data[:31], data[:12] + struct.pack('<I', 6) + data[16:], data[:4] + struct.pack('<I', 7) + data[8:], data[:20] + struct.pack('<I', 9999) + data[24:]]:
+                    binary.write_bytes(invalid)
+                    with self.assertRaises(ValueError):
+                        worker.identity(binary)
+
+    def test_darwin_default_uses_macos_and_arm64(self):
+        with patch.object(worker.os, 'name', 'posix'), patch.object(worker.host_platform, 'system', return_value='Darwin'), patch.object(worker.host_platform, 'machine', return_value='arm64'), patch.object(worker, 'verify') as verify, patch('sys.argv', ['stage_extraction_worker.py', '--verify-only']):
+            worker.main()
+            self.assertEqual(verify.call_args.args[2:], ('macos', 'aarch64'))
+
     def test_failed_build_never_stages_existing_binary(self):
         with patch.object(worker.subprocess, 'run', side_effect=RuntimeError('cargo failed')), patch.object(worker, 'stage') as stage, patch('sys.argv', ['stage_extraction_worker.py']):
             with self.assertRaises(RuntimeError):