diff --git a/.github/scripts/run_bazel_ci.py b/.github/scripts/run_bazel_ci.py
index e9a48ee3bf..f57f782e3f 100755
--- a/.github/scripts/run_bazel_ci.py
+++ b/.github/scripts/run_bazel_ci.py
@@ -65,7 +65,7 @@ class Options:
 @dataclass(frozen=True)
 class Invocation:
     command: list[str]
-    child_env: dict[str, str]
+    child_env: dict[str, str] | None
     ci_config: str
     post_config_args: list[str]
     remote_enabled: bool
@@ -205,9 +205,7 @@ def build_invocation(
         "--",
         *targets,
     )
-    child_env = dict(env)
-    if env.get("RUNNER_OS") == "Windows":
-        child_env["MSYS2_ARG_CONV_EXCL"] = "*"
+    child_env = None if env is os.environ else dict(env)
     return Invocation(command, child_env, config, post_args, remote_enabled)
 
 
diff --git a/.github/scripts/run_bazel_query_ci.py b/.github/scripts/run_bazel_query_ci.py
index 034080d5ea..aeda5d6ea3 100755
--- a/.github/scripts/run_bazel_query_ci.py
+++ b/.github/scripts/run_bazel_query_ci.py
@@ -40,9 +40,7 @@ def main(argv: Sequence[str] | None = None, env: Mapping[str, str] | None = None
         print(exc, file=sys.stderr)
         return 1
 
-    child_env = dict(env)
-    if env.get("RUNNER_OS") == "Windows":
-        child_env["MSYS2_ARG_CONV_EXCL"] = "*"
+    child_env = None if env is os.environ else dict(env)
     return subprocess.run(command, env=child_env, check=False).returncode
 
 
diff --git a/.github/scripts/test_run_bazel_ci.py b/.github/scripts/test_run_bazel_ci.py
index 3e4fea4f03..f23acc2d4a 100644
--- a/.github/scripts/test_run_bazel_ci.py
+++ b/.github/scripts/test_run_bazel_ci.py
@@ -87,7 +87,25 @@ class RunBazelCiTest(unittest.TestCase):
         self.assertIn("--host_platform=//:local_windows_msvc", invocation.command)
         self.assertIn("--jobs=8", invocation.command)
         self.assertIn(r"--test_env=PATH=C:\Windows", invocation.command)
-        self.assertEqual(invocation.child_env["MSYS2_ARG_CONV_EXCL"], "*")
+        self.assertEqual(
+            invocation.child_env,
+            {
+                "CODEX_BAZEL_BIN": "fake-bazel",
+                "CODEX_BAZEL_WINDOWS_PATH": r"C:\Windows",
+                "RUNNER_OS": "Windows",
+            },
+        )
+
+    def test_runtime_invocation_inherits_the_process_environment(self) -> None:
+        invocation = run_bazel_ci.build_invocation(
+            run_bazel_ci.Options(),
+            ["build"],
+            ["//codex-rs/cli:codex"],
+            os.environ,
+            pid=123,
+        )
+
+        self.assertIsNone(invocation.child_env)
 
     def test_remote_windows_cross_compile_uses_linux_build_environment(self) -> None:
         invocation = run_bazel_ci.build_invocation(