asset changes

interfaces/Crafter.Build-Asset.cppm

@@ -36,4 +36,26 @@ namespace Crafter {
     // support requires a self-host rebuild via crafter-build itself,
     // which resolves the Crafter.Asset dep through project.cpp.
     export CRAFTER_API std::string CompressAsset(const fs::path& input, const fs::path& output);
+
+    // Split a single .obj + .mtl file by material group into per-material
+    // .cmesh files, per-unique-albedo .ctex files, and a scene.txt manifest
+    // under outDir. All albedo textures are resized to albedoSize × albedoSize
+    // before compression (required for a texture_2d_array where all layers
+    // must have identical dimensions).
+    //
+    // scene.txt format (read by the Sponza example at runtime):
+    //   <albedoCount>
+    //   <meshCount>
+    //   <albedoIdx_for_mesh_0>   (-1 = no albedo)
+    //   ...
+    //
+    // Idempotent: returns "" immediately if outDir/scene.txt already exists,
+    // so repeated builds skip the expensive split+resize step.
+    // Returns "" on success, an error string on failure.
+    export CRAFTER_API std::string BuildOBJBundle(
+        const fs::path& objPath,
+        const fs::path& mtlPath,
+        const fs::path& outDir,
+        std::uint16_t   albedoSize = 1024
+    );
 }

interfaces/Crafter.Build-External.cppm

@@ -97,4 +97,14 @@ export namespace Crafter {
     // recursively LoadProject's it. Returns a stable Configuration* owned
     // by the same internal cache as GitProject.
     CRAFTER_API Configuration* LocalProject(const LocalProjectSpec& spec);
+
+    // Clone (or update) the given git source into the shared external
+    // cache and return the path to the cloned working tree. Intended for
+    // example projects that need large asset bundles which shouldn't
+    // live in the parent repo — push the returned path (or specific
+    // files inside it) into `cfg.assets`. Reuses the same cache root as
+    // ExternalDependency / GitProject. Caching key = url + branch + commit;
+    // identical calls reuse the existing clone. Pin `source.commit` to a
+    // SHA for reproducible, offline-after-first-fetch builds.
+    CRAFTER_API fs::path GitFetch(const GitSource& source);
 }