fix(proxy): meet type-discipline gates in guard middleware and tests

Final declarations throughout, scope rebuilt instead of mutated in the
test injector, mutable-ok/noqa reasons supplied.

litellm/proxy/middleware/guard_middleware.py

@@ -30,7 +30,7 @@ Design constraints honored here:
 from __future__ import annotations
 
 import os
-from typing import TYPE_CHECKING
+from typing import Final, TYPE_CHECKING
 
 from starlette.types import ASGIApp, Receive, Scope, Send
 
@@ -39,10 +39,10 @@ from litellm._logging import verbose_proxy_logger
 if TYPE_CHECKING:
     from guard import SecurityConfig
 
-GUARD_ENABLED_ENV = "LITELLM_GUARD_ENABLED"
-GUARD_EXCLUDED_PATHS_ENV = "LITELLM_GUARD_EXCLUDED_PATHS"
-DEFAULT_EXCLUDED_PATHS = "/health,/health/liveliness,/health/readiness,/metrics"
-DEFAULT_TRUSTED_PROXIES = "10.0.0.0/8,172.16.0.0/12,192.168.0.0/16"
+GUARD_ENABLED_ENV: Final = "LITELLM_GUARD_ENABLED"
+GUARD_EXCLUDED_PATHS_ENV: Final = "LITELLM_GUARD_EXCLUDED_PATHS"
+DEFAULT_EXCLUDED_PATHS: Final = "/health,/health/liveliness,/health/readiness,/metrics"
+DEFAULT_TRUSTED_PROXIES: Final = "10.0.0.0/8,172.16.0.0/12,192.168.0.0/16"
 
 
 def _env_str(name: str, default: str = "") -> str:
@@ -50,7 +50,7 @@ def _env_str(name: str, default: str = "") -> str:
 
 
 def _env_int(name: str, default: int) -> int:
-    raw = os.getenv(name)
+    raw: Final = os.getenv(name)
     if raw is None or raw == "":
         return default
     return int(raw)
@@ -76,7 +76,7 @@ def _build_guard_config() -> SecurityConfig:
     """Build the SecurityConfig from the LITELLM_GUARD_* environment variables."""
     from guard import SecurityConfig
 
-    kwargs: dict[str, object] = {  # mutable-ok: assembled conditionally, then passed once to SecurityConfig
+    kwargs: Final[dict[str, object]] = {  # mutable-ok: assembled conditionally, then passed once to SecurityConfig
         "enable_rate_limiting": True,
         "rate_limit": _env_int("LITELLM_GUARD_RATE_LIMIT", 100),
         "rate_limit_window": _env_int("LITELLM_GUARD_RATE_LIMIT_WINDOW", 60),

tests/unit/proxy/middleware/test_guard_middleware.py

@@ -10,6 +10,7 @@ pyproject by this change), so behavior tests skip when it is absent.
 import asyncio
 import itertools
 import os
+from typing import Final
 
 import pytest
 from starlette.testclient import TestClient
@@ -19,18 +20,18 @@ from litellm.proxy.middleware.guard_middleware import (
     guard_enabled,
 )
 
-_IP = itertools.count(1)
+_IP: Final = itertools.count(1)
 
 try:
     import guard  # noqa: F401  # availability probe for skip logic
 
-    _GUARD_AVAILABLE = True
+    _GUARD_AVAILABLE: Final = True
 except ImportError:
-    _GUARD_AVAILABLE = False
+    _GUARD_AVAILABLE: Final = False
 
 
 def _unique_ip() -> str:
-    n = next(_IP)
+    n: Final = next(_IP)
     return f"198.51.{n // 250}.{(n % 250) + 1}"
 
 
@@ -57,7 +58,7 @@ def _build_app():
     async def ping(request):
         return JSONResponse({"ok": True})
 
-    app = Starlette(routes=[Route("/ping", ping, methods=["GET"])])
+    app: Final = Starlette(routes=[Route("/ping", ping, methods=["GET"])])
     app.add_middleware(GuardMiddleware)
     return app
 
@@ -67,13 +68,14 @@ class _ClientIPInjector:
     the test IP, so mutate the scope before it reaches the app."""
 
     def __init__(self, asgi_app, client_ip):
-        self._asgi_app = asgi_app
-        self._client_ip = client_ip
+        self._asgi_app: Final = asgi_app
+        self._client_ip: Final = client_ip
 
     async def __call__(self, scope, receive, send):
-        if scope["type"] == "http":
-            scope["client"] = (self._client_ip, 50000)
-        await self._asgi_app(scope, receive, send)
+        # TestClient hardcodes scope["client"]; the middleware stack must see
+        # the TEST-NET address, so build a new scope rather than mutate.
+        screened: Final = {**scope, "client": (self._client_ip, 50000)} if scope["type"] == "http" else scope
+        await self._asgi_app(screened, receive, send)
 
 
 def _client(client_ip):
@@ -82,7 +84,7 @@ def _client(client_ip):
 
 def test_disabled_by_default(monkeypatch):
     monkeypatch.delenv("LITELLM_GUARD_ENABLED", raising=False)
-    client = _client(_unique_ip())
+    client: Final = _client(_unique_ip())
     assert client.get("/ping").status_code == 200
 
 
@@ -90,7 +92,7 @@ def test_fail_loud_without_package(monkeypatch):
     if _GUARD_AVAILABLE:
         pytest.skip("fastapi-guard is installed")
     monkeypatch.setenv("LITELLM_GUARD_ENABLED", "true")
-    client = _client(_unique_ip())
+    client: Final = _client(_unique_ip())
     # Flag on, package missing: request still passes (logged loudly), but
     # the guard attribute proves the wiring attempted the import.
     assert client.get("/ping").status_code == 200
@@ -98,7 +100,7 @@ def test_fail_loud_without_package(monkeypatch):
 
 @pytest.mark.skipif(not _GUARD_AVAILABLE, reason="fastapi-guard not installed")
 def test_blocked_ip_is_rejected(monkeypatch):
-    blocked = _unique_ip()
+    blocked: Final = _unique_ip()
     monkeypatch.setenv("LITELLM_GUARD_ENABLED", "true")
     monkeypatch.setenv("LITELLM_GUARD_BLOCKED_IPS", blocked)
     with _client(blocked) as client:
@@ -107,18 +109,18 @@ def test_blocked_ip_is_rejected(monkeypatch):
 
 @pytest.mark.skipif(not _GUARD_AVAILABLE, reason="fastapi-guard not installed")
 def test_rate_limit_returns_429(monkeypatch):
-    client_ip = _unique_ip()
+    client_ip: Final = _unique_ip()
     monkeypatch.setenv("LITELLM_GUARD_ENABLED", "true")
     monkeypatch.setenv("LITELLM_GUARD_RATE_LIMIT", "2")
     monkeypatch.setenv("LITELLM_GUARD_RATE_LIMIT_WINDOW", "60")
     with _client(client_ip) as client:
-        codes = [client.get("/ping").status_code for _ in range(3)]
+        codes: Final = [client.get("/ping").status_code for _ in range(3)]
     assert codes == [200, 200, 429]
 
 
 @pytest.mark.skipif(not _GUARD_AVAILABLE, reason="fastapi-guard not installed")
 def test_passive_mode_never_blocks(monkeypatch):
-    blocked = _unique_ip()
+    blocked: Final = _unique_ip()
     monkeypatch.setenv("LITELLM_GUARD_ENABLED", "true")
     monkeypatch.setenv("LITELLM_GUARD_PASSIVE_MODE", "true")
     monkeypatch.setenv("LITELLM_GUARD_BLOCKED_IPS", blocked)
@@ -131,5 +133,5 @@ def test_redis_stays_off_without_config(monkeypatch):
     monkeypatch.setenv("LITELLM_GUARD_ENABLED", "true")
     from litellm.proxy.middleware.guard_middleware import _build_guard_config
 
-    config = _build_guard_config()
+    config: Final = _build_guard_config()
     assert config.enable_redis is False