Builder drops scene dependencies referenced by `SkinnedMeshRenderer.sharedMaterials` and `AnimationController.graph` — assets missing from bundle, scene fails to load at runtime

[johngorat]

Version

• cocos-cli 0.0.1-alpha.28 (repo checkout; scene authoring and build driven via the MCP server: scene-* commands, builder-build)
• engine 4.0.0-alpha.20
• Node 25.9.0, macOS arm64

Summary

The builder's scene dependency walker collects some component-referenced assets but not others. For a scene containing a skinned character, consistently across rebuilds (with temp/builder cleared each time):

Bundled correctly (same source .glb, same build — these serve as the positive control):

• SkinnedMeshRenderer.mesh (glTF sub-asset)
• SkinnedMeshRenderer.skeleton (glTF sub-asset)
• SkeletalAnimation.clips / defaultClip (glTF sub-asset; useBakedAnimation: false)

Dropped (absent from every bundle's config.json uuids[], no file under import/):

• SkinnedMeshRenderer.sharedMaterials — reproduced with BOTH a glTF sub-asset material (<uuid>@xxxxx) AND a plain .mtl file asset (referenced by nothing else)
• cc.animation.AnimationController.graph — an .animgraph file asset

In all dropped cases the reference is serialized into the built scene JSON, so at runtime the engine requests the asset, gets a 404, and the scene load aborts on the missing dependency. Example failures from our run (full-form uuids, as they appear in this build's uuids[] — the bundled sub-assets of the same glb are listed there in full form too, so the absence is not a compressed-uuid search artifact):

404  assets/main/import/e0/e0bbe7b1-8180-4cea-b34c-59607307f0e1.json   (.animgraph)
404  assets/main/import/1f/1fabb4fd-5158-427a-83a7-374ba99514e0.json   (.mtl)

All dropped assets are healthy in the asset DB: imported: true, invalid: false, library JSON present, full records returned by asset-info queries.

Possibly related: on an earlier alpha (0.0.1-alpha.19) we observed cc.SkeletalAnimation clips not being bundled when useBakedAnimation: true (not filed at the time, and not re-confirmed on alpha.28) — it looks like the same dependency-collection layer, different component property.

Note: cc.MeshRenderer materials in another (non-skinned) scene of this project bundle fine, so the gap appears specific to certain component types/properties rather than to materials in general.

Steps to reproduce (as performed in our project; happy to build a minimal repro project on request)

1. Import a skinned .glb (any source; ours was UE-exported). Create a new 3D scene; instantiate the glb's generated .prefab sub-asset (scene-create-node-by-asset on the slash-URL), unpack-prefab it.
2. Set SkinnedMeshRenderer.sharedMaterials[0] to a .mtl asset referenced by no other scene. Add cc.animation.AnimationController on the host node and set graph to an .animgraph asset (ours contained a 2-state graph referencing one clip; we did not test whether an empty default graph also reproduces). Save the scene.
3. Build web-desktop with the unmodified default build config (builder-query-default-build-config) with the repro scene included; clear temp/builder first.
4. Check build/web-desktop/assets/*/config.json: the material and animgraph uuids are absent from every bundle's uuids[]; no corresponding files under import/. The glb's mesh/skeleton/clip sub-asset uuids from the same scene ARE present (positive control).
5. Serve the build and load the scene: repeated 404s for those uuids (see above); the scene never finishes loading.

Expected

Every asset referenced by a scene component property is included in the bundle — or at minimum the build fails/warns about the dropped dependency, instead of producing a scene that cannot load.

Actual

Material and animation-graph references silently vanish from the bundle while remaining in the serialized scene → guaranteed runtime 404 + scene load failure.

Workaround

Move the affected assets under assets/resources/ — everything there is force-bundled. Verified end-to-end for the .animgraph and the .mtl: after the move the 404s disappear and the scene loads and animates.

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This report was drafted with AI assistance and manually verified against our project before posting.