skip uncompressed blends

compress_blend_files.bat

@@ -45,6 +45,18 @@ echo blend_files = sys.argv[sys.argv.index^("--"^) + 1:] if "--" in sys.argv els
 echo.
 echo print^("Found " + str^(len^(blend_files^)^) + " .blend files to compress"^)
 echo.
+echo def is_compressed_file^(path^):
+echo     try:
+echo         with open^(path, 'rb'^) as f:
+echo             header = f.read^(4^)
+echo             if header[:2] == b'\x1f\x8b':  # gzip
+echo                 return True
+echo             if header == b'\x28\xb5\x2f\xfd':  # zstd
+echo                 return True
+echo         return False
+echo     except Exception:
+echo         return False
+echo.
 echo for blend_file in blend_files:
 echo     if blend_file.lower^(^).endswith^(".blend"^):
 echo         try:
@@ -55,6 +67,10 @@ echo             # Check if output file already exists
 echo             if os.path.exists^(output_file^):
 echo                 print^("SKIP_EXISTING:" + blend_file^)
 echo                 continue
+echo             # Skip if source is already compressed
+echo             if is_compressed_file^(blend_file^):
+echo                 print^("SKIP_ALREADY_COMPRESSED:" + blend_file^)
+echo                 continue
 echo             print^("PROCESSING:" + blend_file^)
 echo             # Load the blend file
 echo             bpy.ops.wm.open_mainfile^(filepath=blend_file^)
@@ -133,6 +149,10 @@ for /f "tokens=1,2,3 delims=:" %%a in (blender_output.txt) do (
         set /a skipped+=1
         echo [!skipped!] SKIPPED ^(not .blend^): %%b
         echo.
+    ) else if "%%a"=="SKIP_ALREADY_COMPRESSED" (
+        set /a skipped+=1
+        echo [!skipped!] SKIPPED ^(already compressed^): %%b
+        echo.
     )
 )