feat(assets): replace is_procedural/is_gpu_procedural bools with AssetType enum, add MP3 type

- Add AssetType enum {STATIC, PROC, PROC_GPU, MP3} to AssetRecord
- Add GetAssetType() API to asset_manager.h/cc
- asset_packer: parse 'MP3' compression keyword in assets.txt
- tracker: remove magic-byte is_mp3_asset(); use GetAssetType() instead
- assets.txt: NEVER_MP3 now uses 'MP3' compression type
- doc/ASSET_SYSTEM.md: rewritten to document new types and API

handoff(Gemini): AssetType enum landed; MP3 detection is now explicit via asset metadata.

1 files changed, 17 insertions, 15 deletions

diff --git a/tools/asset_packer.cc b/tools/asset_packer.cc
index 7e186b6..0d48906 100644
--- a/tools/asset_packer.cc
+++ b/tools/asset_packer.cc
@@ -80,9 +80,8 @@ static bool ParseProceduralParams(const std::string& params_str,
 // Helper struct to hold all information about an asset during parsing
 struct AssetBuildInfo {
   std::string name;
-  std::string filename; // Original filename for static assets
-  bool is_procedural;
-  bool is_gpu_procedural;
+  std::string filename;  // Original filename for static assets
+  std::string asset_type; // "STATIC", "PROC", "PROC_GPU", "MP3"
   std::string proc_func_name;     // Function name string
   std::vector<float> proc_params; // Parameters for procedural function
 
@@ -439,21 +438,23 @@ int main(int argc, char* argv[]) {
       info.data_array_name = "ASSET_DATA_" + info.name;
       info.params_array_name = "ASSET_PROC_PARAMS_" + info.name;
       info.func_name_str_name = "ASSET_PROC_FUNC_STR_" + info.name;
-      info.is_procedural = false;
-      info.is_gpu_procedural = false;
+      info.asset_type = "STATIC";
 
       if (compression_type_str.rfind("PROC_GPU(", 0) == 0) {
-        info.is_procedural = true;
-        info.is_gpu_procedural = true;
+        info.asset_type = "PROC_GPU";
         if (!ParseProceduralFunction(compression_type_str, &info, true)) {
           return 1;
         }
       } else if (compression_type_str.rfind("PROC(", 0) == 0) {
-        info.is_procedural = true;
-        info.is_gpu_procedural = false;
+        info.asset_type = "PROC";
         if (!ParseProceduralFunction(compression_type_str, &info, false)) {
           return 1;
         }
+      } else if (compression_type_str == "MP3") {
+        info.asset_type = "MP3";
+      } else if (compression_type_str != "NONE") {
+        fprintf(stderr, "Warning: Unknown compression type '%s' for asset: %s\n",
+                compression_type_str.c_str(), info.name.c_str());
       }
 
       asset_build_infos.push_back(info);
@@ -479,7 +480,7 @@ int main(int argc, char* argv[]) {
   std::fclose(assets_h_file);
 
   for (const auto& info : asset_build_infos) {
-    if (!info.is_procedural) {
+    if (info.asset_type != "PROC" && info.asset_type != "PROC_GPU") {
       std::string base_dir =
           assets_txt_path.substr(0, assets_txt_path.find_last_of("/\\") + 1);
       std::filesystem::path base_path = std::filesystem::absolute(base_dir);
@@ -542,15 +543,16 @@ int main(int argc, char* argv[]) {
   fprintf(assets_data_cc_file, "  static const AssetRecord assets[] = {\n");
   for (const auto& info : asset_build_infos) {
     fprintf(assets_data_cc_file, "    { ");
-    if (info.is_procedural) {
-      fprintf(assets_data_cc_file, "nullptr, 0, true, %s, %s, %s, %zu",
-              info.is_gpu_procedural ? "true" : "false",
+    if (info.asset_type == "PROC" || info.asset_type == "PROC_GPU") {
+      fprintf(assets_data_cc_file, "nullptr, 0, AssetType::%s, %s, %s, %zu",
+              info.asset_type.c_str(),
               info.func_name_str_name.c_str(), info.params_array_name.c_str(),
               info.proc_params.size());
     } else {
       fprintf(assets_data_cc_file,
-              "%s, ASSET_SIZE_%s, false, false, nullptr, nullptr, 0",
-              info.data_array_name.c_str(), info.name.c_str());
+              "%s, ASSET_SIZE_%s, AssetType::%s, nullptr, nullptr, 0",
+              info.data_array_name.c_str(), info.name.c_str(),
+              info.asset_type.c_str());
     }
     fprintf(assets_data_cc_file, " },\n");
   }