test: cover explicit git -C terminal probe

tests/test_native_mcp_preference.py

@@ -1,6 +1,7 @@
 """Tests for native MCP preference gate and shell circuit breaker (#270)."""
 import sys
 import unittest
+import shutil
 from pathlib import Path
 
 sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
@@ -76,11 +77,33 @@ class TestTerminalDiagnostics(unittest.TestCase):
         self.assertEqual(res["error_type"], "missing cwd")
 
     def test_probe_terminal_spawn_honors_custom_command(self):
-        res = nmp.probe_terminal_spawn(command=[sys.executable, "-c", "raise SystemExit(3)"])
+        res = nmp.probe_terminal_spawn(
+            command=[sys.executable, "-c", "raise SystemExit(3)"]
+        )
         self.assertTrue(res["healthy"])
         self.assertEqual(res["command"][0], sys.executable)
         self.assertEqual(res["exit_code"], 3)
 
+    @unittest.skipUnless(shutil.which("git"), "git is required for git -C probe")
+    def test_probe_terminal_spawn_supports_explicit_git_c_worktree(self):
+        import subprocess
+        import tempfile
+
+        with tempfile.TemporaryDirectory() as tmp:
+            subprocess.run(
+                ["git", "init", tmp],
+                check=True,
+                capture_output=True,
+                text=True,
+            )
+            res = nmp.probe_terminal_spawn(
+                cwd="/",
+                command=["git", "-C", tmp, "status", "--short"],
+            )
+
+        self.assertTrue(res["healthy"])
+        self.assertEqual(res["command"][1], "-C")
+
     def test_probe_terminal_spawn_blocks_missing_custom_command(self):
         res = nmp.probe_terminal_spawn(command=["nonexistent_exec_for_test"])
         self.assertFalse(res["healthy"])