Stop throttling signed media and ease the browser's e621 queue

Signed media URLs are fetched by <img>/<video> tags without an
Authorization header, so they were charged to the anonymous 120/min
bucket: past that, galleries and the fish-greeting download got 429 JSON
instead of image bytes. The raw/thumbnail/staged-file/similarity-file
actions are now exempt, and THROTTLE_ENABLED=false removes the general
anon+user limits for private/tailnet deployments (login/register/proxy
guards stay).

The SPA's e621 client also stops self-throttling so hard: 1s gap between
browsing calls (2.5s for the stricter IQDB endpoint) and a 15s cooldown
instead of 60s when e621 answers 429.

backend/apps/core/tests/test_security.py

@@ -429,6 +429,36 @@ class ThrottleTests(SecurityTestCase):
             {self.guest.get("/api/status/").status_code for _ in range(12)}, {200}
         )
 
+    def test_signed_media_urls_are_not_throttled(self):
+        """<img>/<video> tags fetch these without an Authorization header.
+
+        Regression: they were charged to the anonymous bucket, so galleries
+        and the fish-greeting download started returning 429 JSON instead of
+        the image bytes.
+        """
+        item = self.make_item("throttle-media", owner=self.users["sec-uploader"])
+        codes = {
+            self.guest.get(f"/api/files/J-{item.id}/raw/").status_code
+            for _ in range(150)
+        }
+        self.assertEqual(codes, {200})
+
+    def test_staged_upload_files_are_not_throttled(self):
+        temp = TempUpload.objects.create(
+            user=self.users["sec-uploader"],
+            file=SimpleUploadedFile("throttle-temp.bin", b"staged"),
+            original_filename="throttle-temp.bin",
+            md5=hashlib.md5(b"throttle-temp").hexdigest(),
+            size=6,
+        )
+        signature = signing.dumps(
+            {"temp": str(temp.id), "user": self.users["sec-uploader"].id},
+            salt=services.UPLOAD_FILE_SALT,
+        )
+        url = f"/api/uploads/{temp.id}/file/?sig={signature}"
+        codes = {self.guest.get(url).status_code for _ in range(150)}
+        self.assertEqual(codes, {200})
+
 
 class RemoteUrlTests(SecurityTestCase):
     def test_allowlist(self):

backend/apps/library/similarity.py

@@ -136,7 +136,12 @@ class SimilarityCheckViewSet(
             self.get_serializer(check).data, status=status.HTTP_201_CREATED
         )
 
-    @action(detail=True, methods=["get", "head"], permission_classes=[AllowAny])
+    @action(
+        detail=True,
+        methods=["get", "head"],
+        permission_classes=[AllowAny],
+        throttle_classes=[],
+    )
     def file(self, request, pk=None):
         """Serve the temp file; accepts a signed URL like staged uploads."""
         check = None

backend/apps/library/uploads.py

@@ -381,7 +381,12 @@ class TempUploadViewSet(
                 errors.append({"temp_id": value, "error": str(exc)})
         return Response({"discarded": discarded, "errors": errors})
 
-    @action(detail=True, methods=["get", "head"], permission_classes=[AllowAny])
+    @action(
+        detail=True,
+        methods=["get", "head"],
+        permission_classes=[AllowAny],
+        throttle_classes=[],
+    )
     def file(self, request, pk=None):
         """Serve the staged file; accepts a signed URL for media tags."""
         user = request.user if request.user.is_authenticated else None

backend/apps/library/views.py

@@ -148,7 +148,7 @@ class MediaItemViewSet(
             return item
         return self.get_object()
 
-    @action(detail=True, methods=["get"])
+    @action(detail=True, methods=["get"], throttle_classes=[])
     def raw(self, request, pk=None):
         item = self._media_object(request, "raw")
         location = item.locations.first()
@@ -161,7 +161,7 @@ class MediaItemViewSet(
             request, location.path, download=request.query_params.get("download") == "1"
         )
 
-    @action(detail=True, methods=["get"])
+    @action(detail=True, methods=["get"], throttle_classes=[])
     def thumbnail(self, request, pk=None):
         item = self._media_object(request, "thumbnail")
         location = item.locations.first()

backend/config/settings.py

@@ -255,6 +255,16 @@ CACHES = {
 
 # Django REST Framework
 
+# Private / tailnet-only deployments can drop the general anon+user limits
+# entirely (THROTTLE_ENABLED=false). The scoped guards below (login, register,
+# e621 proxy) and the media endpoints' own protections stay active either way.
+THROTTLE_ENABLED = os.getenv("THROTTLE_ENABLED", "true").strip().lower() not in {
+    "0",
+    "false",
+    "no",
+    "off",
+}
+
 REST_FRAMEWORK = {
     "DEFAULT_AUTHENTICATION_CLASSES": [
         "rest_framework.authentication.TokenAuthentication",
@@ -269,11 +279,18 @@ REST_FRAMEWORK = {
     ],
     "DEFAULT_PAGINATION_CLASS": "config.pagination.StandardPagination",
     "PAGE_SIZE": 48,
-    # Per-IP/per-user rate limits (counted in the shared Redis cache).
-    "DEFAULT_THROTTLE_CLASSES": [
-        "rest_framework.throttling.AnonRateThrottle",
-        "rest_framework.throttling.UserRateThrottle",
-    ],
+    # Per-IP/per-user rate limits (counted in the shared Redis cache). Signed
+    # media URLs are deliberately excluded at the view level: <img>/<video>
+    # tags fetch them without an Authorization header, so a library page would
+    # otherwise burn the anonymous bucket and start returning JSON 429s.
+    "DEFAULT_THROTTLE_CLASSES": (
+        [
+            "rest_framework.throttling.AnonRateThrottle",
+            "rest_framework.throttling.UserRateThrottle",
+        ]
+        if THROTTLE_ENABLED
+        else []
+    ),
     "DEFAULT_THROTTLE_RATES": {
         # Generous enough for the shell polling (status every 5s, stats every 2s).
         "anon": os.getenv("THROTTLE_ANON", "120/min"),