chore: gate ISS descriptor behind new-lods feature flag (#8917)

Adds a `new-lods` feature flag and short-circuits LoadISSDescriptorSystem
when it is disabled, so every scene falls back to the pre-ISS path.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: dalkia

Explorer/Assets/DCL/FeatureFlags/FeatureFlagsStrings.cs

@@ -78,6 +78,7 @@ public static class FeatureFlagsStrings
         public const string DOUBLE_CLICK_WALK = "alfa-double-click-walk";
         public const string AB_DEPS_DIGEST_CACHE_KEY = "alfa-ab-deps-digest-cache-key";
         public const string BYTE_WEIGHTED_LOADING_PROGRESS = "alfa-byte-weighted-loading-progress";
+        public const string NEW_LODS = "new-lods";
 
         public static class Endpoints
         {

Explorer/Assets/DCL/Infrastructure/ECS/ECS.asmdef

@@ -8,7 +8,8 @@
         "GUID:101b8b6ebaf64668909b49c4b7a1420d",
         "GUID:286980af24684da6acc1caa413039811",
         "GUID:275e22790c04e9b47a5085d7b0c4432a",
-        "GUID:3640f3c0b42946b0b8794a1ed8e06ca5"
+        "GUID:3640f3c0b42946b0b8794a1ed8e06ca5",
+        "GUID:e25ef972de004615a22937e739de2def"
     ],
     "includePlatforms": [],
     "excludePlatforms": [],

Explorer/Assets/DCL/Infrastructure/ECS/StreamableLoading/AssetBundles/InitialSceneState/LoadISSDescriptorSystem.cs

@@ -3,6 +3,7 @@
 using CommunicationData.URLHelpers;
 using Cysharp.Threading.Tasks;
 using DCL.Diagnostics;
+using DCL.FeatureFlags;
 using DCL.Ipfs;
 using DCL.Utility;
 using DCL.WebRequests;
@@ -50,6 +51,13 @@ internal LoadISSDescriptorSystem(World world, IWebRequestController webRequestCo
 
         protected override async UniTask<StreamableLoadingResult<ISSDescriptorMetadata>> FlowInternalAsync(GetISSDescriptorIntention intention, StreamableLoadingState state, IPartitionComponent partition, CancellationToken ct)
         {
+            // Feature-flag gate: when disabled, short-circuit with a failed result so the consumer
+            // in ResolveISSDescriptorSystem treats every scene as "no ISS" and falls back to the
+            // pre-ISS code path. Same shape as the SupportsISS check below — failed result is not
+            // persisted to disk by LoadSystemBase.
+            if (!FeatureFlagsConfiguration.Instance.IsEnabled(FeatureFlagsStrings.NEW_LODS))
+                return new StreamableLoadingResult<ISSDescriptorMetadata>(GetReportData(), new Exception("new-lods feature flag disabled"));
+
             // Skip network roundtrips entirely for AB versions that pre-date ISS support. Returning a
             // failed result (plain Exception, not StreamableLoadingException) keeps the disk cache clean
             // — LoadSystemBase only persists on success — and doesn't spam logs from the result ctor.