perf: bound public activity aggregation

apps/api/app/media_catalog.py

@@ -12,6 +12,7 @@ TACKLE_MEDIA_ROLES = {"tackle_card", "tackle_detail", "rig_diagram", "tackle_scr
 KNOWN_MEDIA_ROLES = WATERBODY_MEDIA_ROLES | TACKLE_MEDIA_ROLES
 MEDIA_ROLES_BY_ENTITY = {"waterbody": WATERBODY_MEDIA_ROLES, "tackle": TACKLE_MEDIA_ROLES}
 _manifest_cache: tuple[Path, int, int, dict] | None = None
+_asset_index_cache: tuple[int, dict[str, tuple[str, str | None]]] | None = None
 
 
 def _read_manifest() -> dict:
@@ -107,21 +108,23 @@ def published_file(digest: str) -> tuple[Path, str] | None:
     if len(digest) != 64 or any(char not in "0123456789abcdef" for char in digest):
         return None
     manifest = _read_manifest()
-    item = next((row for row in manifest.get("assets", []) if row.get("status") == "approved" and row.get("sha256") == digest), None)
-    media_type = None
-    local_path = None
-    if item:
-        media_type = item.get("content_type")
-        local_path = item.get("local_path")
-    else:
+    global _asset_index_cache
+    cache_key = id(manifest)
+    if _asset_index_cache is None or _asset_index_cache[0] != cache_key:
+        index: dict[str, tuple[str, str | None]] = {}
         for row in manifest.get("assets", []):
             if row.get("status") != "approved":
                 continue
-            variant = next((candidate for candidate in row.get("derivatives", []) if candidate.get("sha256") == digest), None)
-            if variant:
-                media_type = variant.get("content_type")
-                local_path = variant.get("local_path")
-                break
+            if row.get("sha256") and row.get("local_path"):
+                index[str(row["sha256"])] = (str(row["local_path"]), row.get("content_type"))
+            for variant in row.get("derivatives", []):
+                if variant.get("sha256") and variant.get("local_path"):
+                    index.setdefault(str(variant["sha256"]), (str(variant["local_path"]), variant.get("content_type")))
+        _asset_index_cache = (cache_key, index)
+    asset = _asset_index_cache[1].get(digest)
+    if asset is None:
+        return None
+    local_path, media_type = asset
     if not local_path:
         return None
     target = (MEDIA_ROOT / local_path).resolve()