Fix Codex Desktop CLI resolution on Windows

scripts/install_mcp.py

@@ -209,8 +209,18 @@ def _codex_config_path(config_root: Path) -> Path:
     ) / "config.toml"
 
 
+def _codex_cli_path() -> Optional[str]:
+    """Resolve the usable Codex CLI, including the Desktop-provided path."""
+    desktop_cli = os.environ.get("CODEX_CLI_PATH")
+    if desktop_cli:
+        candidate = Path(desktop_cli).expanduser()
+        if candidate.is_file():
+            return str(candidate)
+    return shutil.which("codex")
+
+
 def _install_codex(config_root: Path) -> None:
-    codex = shutil.which("codex")
+    codex = _codex_cli_path()
     if codex is None:
         raise InstallError("Codex CLI is not on PATH.")
     _run_quiet([codex, "mcp", "remove", SERVER_NAME])

test/test_install_mcp_script.py

@@ -149,3 +149,28 @@ def test_codex_config_path_honors_codex_home(monkeypatch, tmp_path):
     monkeypatch.setenv("CODEX_HOME", str(custom_home))
 
     assert installer._codex_config_path(tmp_path) == custom_home / "config.toml"
+
+
+def test_codex_cli_path_prefers_desktop_environment(monkeypatch, tmp_path):
+    installer = _load_installer()
+    desktop_cli = tmp_path / "codex.exe"
+    desktop_cli.touch()
+    monkeypatch.setenv("CODEX_CLI_PATH", str(desktop_cli))
+    monkeypatch.setattr(
+        installer.shutil,
+        "which",
+        lambda command: "C:/Program Files/WindowsApps/codex.exe",
+    )
+
+    assert installer._codex_cli_path() == str(desktop_cli)
+
+
+def test_codex_cli_path_falls_back_to_path(monkeypatch, tmp_path):
+    installer = _load_installer()
+    monkeypatch.setenv(
+        "CODEX_CLI_PATH",
+        str(tmp_path / "missing-codex.exe"),
+    )
+    monkeypatch.setattr(installer.shutil, "which", lambda command: "codex")
+
+    assert installer._codex_cli_path() == "codex"