feat(protocol): freeze M4 native session RC6 contract

tools/run_native_conformance.py

@@ -4,12 +4,17 @@ from __future__ import annotations
 import pathlib
 import subprocess
 import tempfile
+import os
 
 ROOT = pathlib.Path(__file__).resolve().parents[1]
 
 
 def run(command: list[str]) -> None:
-    result = subprocess.run(command, cwd=ROOT, text=True, capture_output=True)
+    environment = os.environ.copy()
+    cache_root = pathlib.Path(tempfile.gettempdir()) / "versevdi-protocol-module-cache"
+    environment.setdefault("CLANG_MODULE_CACHE_PATH", str(cache_root / "clang"))
+    environment.setdefault("SWIFT_MODULECACHE_PATH", str(cache_root / "swift"))
+    result = subprocess.run(command, cwd=ROOT, env=environment, text=True, capture_output=True)
     if result.returncode != 0:
         raise SystemExit(result.stdout + result.stderr)
     print(result.stdout.strip())