Upload board: dismiss all, real previews for indexed records

- 'dismiss all' clears every indexed record at once
- Indexed cards show the actual file preview: completed records now get a
  signed library media URL (raw for images, thumbnail for videos) so
  <img>/<video> tags can load it, including items hidden from guests
- Media raw/thumbnail endpoints accept the signature for anonymous
  requests and fall back to the normal guest-filtered path otherwise
- Guest blacklist keeps a persistent Redis mirror: an expired TTL or an
  unreachable e621 keeps the last successful list instead of falling
  back to the small local list

backend/apps/library/guest_filter.py

@@ -20,6 +20,7 @@ from django.core.cache import cache
 logger = logging.getLogger(__name__)
 
 CACHE_KEY = "j621.guest_blacklist"
+MIRROR_KEY = "j621.guest_blacklist.mirror"
 
 
 def parse_blacklist_patterns(lines):
@@ -37,10 +38,18 @@ def parse_blacklist_patterns(lines):
 
 
 def cached_guest_blacklist():
-    """Raw mirrored blacklist lines. Never hits the network."""
+    """Raw mirrored blacklist lines. Never hits the network.
+
+    Prefers the TTL'd entry, falls back to the persistent mirror (last
+    successful e621 fetch) and only then to the local fallback list, so an
+    expired TTL never degrades filtering.
+    """
     stored = cache.get(CACHE_KEY)
     if stored is not None:
         return list(stored)
+    mirror = cache.get(MIRROR_KEY)
+    if mirror is not None:
+        return list(mirror)
     return list(settings.GUEST_BLACKLIST_FALLBACK)
 
 
@@ -101,7 +110,11 @@ def refresh_guest_blacklist():
     lines = fetch_e621_default_blacklist()
     used_fallback = lines is None
     if used_fallback:
-        lines = list(settings.GUEST_BLACKLIST_FALLBACK)
+        # Keep the last successful mirror (or the local list) rather than
+        # degrading guest filtering when e621 is unreachable.
+        lines = cache.get(MIRROR_KEY) or list(settings.GUEST_BLACKLIST_FALLBACK)
+    else:
+        cache.set(MIRROR_KEY, lines, timeout=None)
     cache.set(CACHE_KEY, lines, settings.GUEST_BLACKLIST_TTL)
 
     patterns = parse_blacklist_patterns(lines)

backend/apps/library/serializers.py

@@ -1,10 +1,11 @@
 import os
+from pathlib import Path
 
 from django.core import signing
 from rest_framework import serializers
 
 from .models import MediaItem, MediaLocation, TempUpload
-from .services import UPLOAD_FILE_SALT, VIDEO_EXTENSIONS
+from .services import MEDIA_FILE_SALT, UPLOAD_FILE_SALT, VIDEO_EXTENSIONS
 
 
 class MediaLocationSerializer(serializers.ModelSerializer):
@@ -99,6 +100,7 @@ class TempUploadSerializer(serializers.ModelSerializer):
     temp_id = serializers.UUIDField(source="id", read_only=True)
     library_j_id = serializers.SerializerMethodField()
     file_url = serializers.SerializerMethodField()
+    preview_url = serializers.SerializerMethodField()
 
     class Meta:
         model = TempUpload
@@ -117,11 +119,19 @@ class TempUploadSerializer(serializers.ModelSerializer):
             "iqdb_data",
             "library_j_id",
             "file_url",
+            "preview_url",
             "created_at",
             "updated_at",
         ]
         read_only_fields = fields
 
+    def _request_user(self):
+        request = self.context.get("request")
+        user = getattr(request, "user", None)
+        if user is None or not getattr(user, "is_authenticated", False):
+            return None
+        return user
+
     def get_library_j_id(self, obj):
         return f"J-{obj.library_item_id}" if obj.library_item_id else None
 
@@ -129,12 +139,33 @@ class TempUploadSerializer(serializers.ModelSerializer):
         """Signed URL so <img>/<video> tags can fetch the staged file."""
         if not obj.file:
             return None
-        request = self.context.get("request")
-        user = getattr(request, "user", None)
-        if user is None or not getattr(user, "is_authenticated", False):
+        user = self._request_user()
+        if user is None:
             return None
         signature = signing.dumps(
             {"temp": str(obj.id), "user": user.id},
             salt=UPLOAD_FILE_SALT,
         )
         return f"/api/uploads/{obj.id}/file/?sig={signature}"
+
+    def get_preview_url(self, obj):
+        """A URL an <img>/<video> tag can load: staged file or library item."""
+        user = self._request_user()
+        if user is None:
+            return None
+        if obj.file:
+            return self.get_file_url(obj)
+        item = obj.library_item
+        if item is None:
+            return None
+        location = item.locations.first()
+        is_video = (
+            location is not None
+            and Path(location.rel_path).suffix.lower() in VIDEO_EXTENSIONS
+        )
+        action = "thumbnail" if is_video else "raw"
+        signature = signing.dumps(
+            {"item": item.id, "user": user.id, "action": action},
+            salt=MEDIA_FILE_SALT,
+        )
+        return f"/api/files/J-{item.id}/{action}/?sig={signature}"

backend/apps/library/services.py

@@ -25,6 +25,7 @@ ALLOWED_EXTENSIONS = {
 }
 VIDEO_EXTENSIONS = {".mp4", ".webm"}
 UPLOAD_FILE_SALT = "j621.upload-file"
+MEDIA_FILE_SALT = "j621.media-file"
 CHUNK_SIZE = 1024 * 1024
 RANGE_RE = re.compile(r"bytes=(\d*)-(\d*)$")
 

backend/apps/library/views.py

@@ -3,6 +3,7 @@ from pathlib import Path
 from urllib.parse import urlparse
 
 from django.conf import settings
+from django.core import signing
 from django.db.models import Min
 from django.http import Http404
 from django.shortcuts import get_object_or_404
@@ -67,9 +68,32 @@ class MediaItemViewSet(
         self.check_object_permissions(self.request, obj)
         return obj
 
+    def _signed_media_item(self, request, action_name):
+        """Signed media URLs let <img>/<video> tags bypass guest filtering."""
+        if request.user.is_authenticated:
+            return None
+        signature = request.query_params.get("sig")
+        if not signature:
+            return None
+        try:
+            payload = signing.loads(
+                signature, salt=services.MEDIA_FILE_SALT, max_age=86400
+            )
+        except signing.BadSignature:
+            return None
+        if payload.get("action") != action_name:
+            return None
+        return MediaItem.objects.filter(pk=payload.get("item")).first()
+
+    def _media_object(self, request, action_name):
+        item = self._signed_media_item(request, action_name)
+        if item is not None:
+            return item
+        return self.get_object()
+
     @action(detail=True, methods=["get"])
     def raw(self, request, pk=None):
-        item = self.get_object()
+        item = self._media_object(request, "raw")
         location = item.locations.first()
         if location is None:
             return Response(
@@ -82,7 +106,7 @@ class MediaItemViewSet(
 
     @action(detail=True, methods=["get"])
     def thumbnail(self, request, pk=None):
-        item = self.get_object()
+        item = self._media_object(request, "thumbnail")
         location = item.locations.first()
         if location is None:
             return Response(