[#97] Add Unity scenes to LeadingEdge reference builds

[SkowronskiAndrew]

Summary

Fixes #97.

Adds two small Unity scenes to the LeadingEdge test project so the reference builds cover scene content. Scenes are a special case in every build pipeline, and the initial test project had none in its output. Both scenes show the shared GreenStatic.png texture through a SpriteRenderer (with distinct GameObject names so their content differs), and a new SceneList ScriptableObject references them by name through a serialized dictionary of LoadableSceneId, which is what pulls them into the Content Directory build.

The regenerated Content Directory output now demonstrates the scene conventions worth documenting: each scene becomes exactly one Content File (with the scene's GUID as its stable .cfid identity), the assets a scene references land in their own Content Files, and LoadableSceneId references are recorded in the manifest (LoadableSceneDependencies) rather than the external-reference table.

Changes

LeadingEdge project

• GenerateAssets.cs generates the two scenes (imports the texture as a Sprite) and the SceneList.asset, which is added to ContentDirectoryRoot.asset's direct references.
• BuildAssetBundles.cs adds a scenes bundle containing both scenes (AssetBundles require scenes and assets in separate bundles).
• Project AGENTS.md describes the new scene scenario; the tracked editor version moved to 6000.6.0b5.

Reference data (TestCommon/Data/LeadingEdgeBuilds)

• AssetBundle build regenerated: new scenes bundle; existing bundles are unchanged.
• Content Directory build and its build report (including ContentLayout.json, now listing LoadableSceneIds) regenerated. New Content Files for the scenes, the Sprite/Texture2D split of GreenStatic.png, unity_builtin_extra, and the SceneList asset.

Tests

• New SceneBundleContentTests: verifies the scenes bundle contains one SerializedFile per scene (plus sharedAssets), that scene files hold the expected objects via the serialized-file command, and that the shared texture is included exactly once.
• Analyze_FullAssetBundleSet_ResolvesCrossBundleReferences now excludes references into Unity's built-in resource files (unity_builtin_extra, unity default resources), which the scene bundle introduces and which always dangle.

Documentation

• contentdirectory-format.md gains a Scenes section: how scenes enter a build through LoadableSceneId, the one-Content-File-per-scene rule (contrasted with Player builds' sharedassets split), sequential object IDs in scene files, and worked ContentLayout.json examples from the reference build. Schema details stay on the contentlayout.md page.
• The "References between Content Files" walkthrough is updated to the regenerated build's indexes and hashes (the resolution steps are unchanged).

Testing

dotnet test — full suite green (730 passed, 10 skipped). New scene coverage as described above; manually verified the scenes bundle and the scene/SceneList Content Files with archive list/extract, serialized-file objectlist, and dump, and cross-checked the documented examples against the regenerated ContentLayout.json.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds small Unity scenes and a SceneList ScriptableObject to the LeadingEdge fixture, updates build scripts to bundle scenes correctly, and introduces tests/docs to validate scene content in produced build outputs.

Changes:

• Generate two scenes sharing a texture and add a SceneList asset that references them via LoadableSceneId.
• Update AssetBundle build script to output a dedicated scenes bundle and refresh checked-in reference build artifacts.
• Add NUnit coverage to sanity-check scene bundle contents and adjust dangling-ref expectations for built-in resources.

Reviewed changes

Copilot reviewed 28 out of 43 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
UnityProjects/LeadingEdge/Assets/Textures/GreenStatic.png.meta	Adds import settings for the shared sprite texture used by generated scenes.
UnityProjects/LeadingEdge/Assets/Textures.meta	Adds metadata for the new Textures folder.
UnityProjects/LeadingEdge/Assets/Scripts/SceneList.cs.meta	Adds meta for the new SceneList ScriptableObject script.
UnityProjects/LeadingEdge/Assets/Scripts/SceneList.cs	Introduces a ScriptableObject that maps scene names to LoadableSceneIds.
UnityProjects/LeadingEdge/Assets/ScriptableObjects/SceneList.asset.meta	Adds meta for the generated SceneList asset.
UnityProjects/LeadingEdge/Assets/ScriptableObjects/SceneList.asset	Adds a generated asset mapping Scene1/Scene2 to scene GUIDs.
UnityProjects/LeadingEdge/Assets/ScriptableObjects/ContentDirectoryRoot.asset	Adds SceneList as an additional root reference for content directory builds.
UnityProjects/LeadingEdge/Assets/Scenes/Scene2.unity.meta	Adds meta for the second generated scene.
UnityProjects/LeadingEdge/Assets/Scenes/Scene2.unity	Adds the second generated scene referencing the shared sprite.
UnityProjects/LeadingEdge/Assets/Scenes/Scene1.unity.meta	Adds meta for the first generated scene.
UnityProjects/LeadingEdge/Assets/Scenes/Scene1.unity	Adds the first generated scene referencing the shared sprite.
UnityProjects/LeadingEdge/Assets/Editor/GenerateAssets.cs	Extends asset generation to create scenes and a SceneList asset.
UnityProjects/LeadingEdge/Assets/Editor/BuildAssetBundles.cs	Adds a dedicated scene bundle build alongside existing per-asset bundles.
UnityProjects/LeadingEdge/AGENTS.md	Updates project description and documents newly added scenes.
UnityDataTool.Tests/SceneBundleContentTests.cs	Adds tests validating the scenes AssetBundle structure/content and texture deduplication.
UnityDataTool.Tests/AnalyzeDanglingRefsTests.cs	Updates expectations to allow built-in resource dangling references.
TestCommon/Data/LeadingEdgeBuilds/ContentDirectory/baff06b928d147276f2245dd3b19216a.json	Updates the checked-in content directory manifest to include scenes and new dependencies.
TestCommon/Data/LeadingEdgeBuilds/ContentDirectory/BuildManifestHash.txt	Updates the manifest hash pointer to the new content directory manifest.
TestCommon/Data/LeadingEdgeBuilds/ContentDirectory/15d5df98d98434e67e06716cfabfad1b.json	Removes the prior content directory manifest.
TestCommon/Data/LeadingEdgeBuilds/BuildReport-ContentDirectory/ScriptsOnlyCache.yaml	Updates build report cache to include SceneList / LoadableSceneId types.
TestCommon/Data/LeadingEdgeBuilds/BuildReport-ContentDirectory/ContentSizeSummary.txt	Updates build size summary reflecting inclusion of scenes/texture/built-ins.
TestCommon/Data/LeadingEdgeBuilds/BuildReport-ContentDirectory/ContentLayout.json	Updates ContentLayout.json with scene entries and new dependency structure.
TestCommon/Data/LeadingEdgeBuilds/BuildReport-ContentDirectory/BuildReportSummary.json	Updates build report summary fields for the new build output.
TestCommon/Data/LeadingEdgeBuilds/BuildReport-ContentDirectory/BuildLog.jsonl	Updates build log to reflect the new build steps/content.
TestCommon/Data/LeadingEdgeBuilds/BuildReport-ContentDirectory/BuildContentTEP.json	Updates TEP trace reflecting the new build content and durations.
TestCommon/Data/LeadingEdgeBuilds/AssetBundles/scenes.manifest	Adds manifest for the new scenes AssetBundle.
TestCommon/Data/LeadingEdgeBuilds/AssetBundles/AssetBundles.manifest	Updates root AssetBundles manifest to include scenes and new Unity version.
Documentation/contentdirectory-format.md	Documents how scenes appear in content directory builds and updates examples.

Comments suppressed due to low confidence (3)

UnityProjects/LeadingEdge/Assets/Editor/GenerateAssets.cs:1

• GenerateScenes() creates new scenes using NewSceneMode.Single, which closes currently open scenes. When run from the menu, this can prompt users to save/lose work and can disrupt editor state during automation. Consider creating scenes in Additive mode (and closing them after saving) or capturing/restoring the previously open scenes/active scene after generation.
  UnityProjects/LeadingEdge/Assets/Scripts/SceneList.cs:1
• This is a public mutable field on a ScriptableObject asset. That makes it easy for runtime code to accidentally modify the asset's serialized state (in-editor) or the in-memory data. A more robust API is to keep the backing field private [SerializeField] and expose a read-only view (e.g., via a getter returning IReadOnlyDictionary<string, LoadableSceneId>), so callers can query without mutating.
  UnityProjects/LeadingEdge/Assets/Scripts/SceneList.cs.meta:1
• This .meta file looks incomplete for a C# script asset (it typically includes a MonoImporter: section with default settings). Unity will likely regenerate it on import, creating noisy diffs and potential merge churn. Re-export/regenerate the meta from Unity so it matches the standard script meta format (while preserving the GUID).

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