fix: stop infinite 404 retry loop for emote asset bundles

[dalkia]

Pull Request Description

What does this PR change?

1. Fix infinite 404 retry loop for emote asset bundles

When emote asset bundles fail to load (e.g. 404 from StreamingAssets), FinalizeEmoteLoadingSystem was only logging a warning but leaving AssetResults[bodyShape] as null. This caused CreateAssetBundlePromiseIfRequired to create a new promise every frame, producing an infinite loop of 404 requests.

Now stores a failed StreamableLoadingResult on the failure branch in FinalizeAssetBundleLoading, matching what we already do for wearables in FinalizeWearableLoadingSystemBase.SetAsFailed. This ensures the null check in CreateAssetBundlePromiseIfRequired stops re-creating promises.

2. Fix world scenes failing to load asset bundles (manifest 404)

World scenes don't query the asset-bundle-registry (unlike catalyst scenes), so they fall back to fetching manifests directly from ab-cdn.decentraland.org. The manifest URL in LoadAssetBundleManifestSystem was incorrectly appending a platform suffix (e.g. _webgl) that the CDN doesn't use for manifests, causing the manifest request to 404. This cascaded into all individual asset bundle loads failing: the failed manifest marked assetBundleManifestRequestFailed = true, which blocked the WEB source in PrepareAssetBundleLoadingParametersSystemBase, leaving only the EMBEDDED source (which also 404s for assets not bundled in the build).

Removed the platform suffix from the manifest URL. This is a temporary fix — once multi-scene-worlds is merged, worlds will query the registry like catalyst scenes and this fallback path won't be needed.

3. Shader variant updates

Updates the scene shader to include missing variants following this PR, and adds missing TMP shader variants (OUTLINE_ON for TMP Mobile, SOFTMASK_SIMPLE UNDERLAY_ON for Soft Mask TMP) to the shader variant collection for WebGL builds.

Test Instructions

Test Steps

1. Open a world scene (e.g. franfranfran.dcl.eth) on WebGL
2. Verify the world loads successfully — avatars should render with wearables and emotes
3. Check the browser console: there should be no repeated 404 requests for the same asset bundle hashes

Additional Testing Notes

• The emote fix mirrors the wearable failure handling pattern (SetAsFailed in FinalizeWearableLoadingSystemBase)
• Emotes that fail will not play, but the system will not spin indefinitely
• Catalyst scenes (non-worlds) should be unaffected since they get manifest versions from the asset-bundle-registry

Quality Checklist

• Changes have been tested locally
• Documentation has been updated (if required)
• Performance impact has been considered
• For SDK features: Test scene is included

Code Review Reference

Please review our Code Review Standards before submitting.

[github-actions]

Windows and Mac build successful in Unity Cloud! You can find a link to the downloadable artifact below.

Name	Link
Commit	1b6ccc3
Logs	https://github.com/decentraland/unity-explorer/actions/runs/25075681267
Download Windows	https://github.com/decentraland/unity-explorer/suites/66601654034/artifacts/6694506887
Download Windows S3	https://explorer-artifacts.decentraland.org/@dcl/unity-explorer/branch/fix/emote-loading-infinite-404-loop/pr-21581-1b6ccc3/Decentraland_windows64.zip
Download Mac	https://github.com/decentraland/unity-explorer/suites/66601654034/artifacts/6694394435
Download Mac S3	https://explorer-artifacts.decentraland.org/@dcl/unity-explorer/branch/fix/emote-loading-infinite-404-loop/pr-21581-1b6ccc3/Decentraland_macos.zip
Built on	2026-04-28T20:55:09Z