2 files changed, 46 insertions, 0 deletions

diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index e4822c4cb7f..9a5f6ac6bbc 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -108,11 +108,14 @@
 #include "BLI_mempool.h"
 #include "BLI_threads.h"
 
+#include "RNA_types.h"
+
 #include "BLT_translation.h"
 
 #include "BKE_action.h"
 #include "BKE_anim_data.h"
 #include "BKE_armature.h"
+#include "BKE_asset_engine.h"
 #include "BKE_brush.h"
 #include "BKE_collection.h"
 #include "BKE_colortools.h"
@@ -2876,6 +2879,12 @@ static void direct_link_id_common(
     BLI_listbase_clear((ListBase *)drawdata);
   }
 
+  if (id->uuid) {
+    BLO_read_data_address(reader, &id->uuid);
+    /* Make sure runtime fields are always zeroed out. */
+    BKE_asset_uuid_runtime_reset(id->uuid);
+  }
+
   /* Handle 'private IDs'. */
   direct_link_id_embedded_id(reader, current_library, id, id_old);
 }
@@ -9555,6 +9564,18 @@ static BHead *read_libblock(FileData *fd,
       }
     }
 
+    if (id->uuid) {
+      /* Read all data into fd->datamap. */
+      bhead = read_data_into_datamap(fd, bhead, __func__);
+
+      id->uuid = newdataadr(fd, id->uuid);
+      /* Make sure runtime fields are always zeroed out. */
+      BKE_asset_uuid_runtime_reset(id->uuid);
+
+      oldnewmap_clear(fd->datamap);
+      return bhead;
+    }
+
     direct_link_id(fd, main, id_tag, id, id_old);
     return blo_bhead_next(fd, bhead);
   }
@@ -12134,6 +12155,21 @@ static void read_library_linked_ids(FileData *basefd,
          * (known case: some directly linked shapekey from a missing lib...). */
         /* BLI_assert(*realid != NULL); */
 
+        if (*realid && id->uuid) {
+          /* it is important to keep the UUID we stored in that .blend file, not the (potentially
+           * different) one we get from the library, updating UUID should be handled by asset
+           * engine later - even though changing UUID is not recommended in any case. */
+          if ((*realid)->uuid != NULL) {
+            MEM_SAFE_FREE((*realid)->uuid);
+          }
+          /* We can give ownership of that pointer to new ID. */
+          (*realid)->uuid = id->uuid;
+          id->uuid = NULL;
+        }
+        else {
+          MEM_SAFE_FREE(id->uuid);
+        }
+
         /* Now that we have a real ID, replace all pointers to placeholders in
          * fd->libmap with pointers to the real data-blocks. We do this for all
          * libraries since multiple might be referencing this ID. */
@@ -12148,6 +12184,8 @@ static void read_library_linked_ids(FileData *basefd,
 
     /* Clear GHash and free link placeholder IDs of the current type. */
     BLI_ghash_clear(loaded_ids, NULL, NULL);
+    /* Note: this is currently just freeing ID struct itself, assuming there is no remaining
+     * allocated sub-data owned by this ID. */
     BLI_freelistN(&pending_free_ids);
   }
 
diff --git a/source/blender/blenloader/intern/writefile.c b/source/blender/blenloader/intern/writefile.c
index 4e0325e72fa..d8576b4c6de 100644
--- a/source/blender/blenloader/intern/writefile.c
+++ b/source/blender/blenloader/intern/writefile.c
@@ -738,6 +738,9 @@ static void write_iddata(BlendWriter *writer, ID *id)
   if (id->properties && !ELEM(GS(id->name), ID_WM)) {
     IDP_WriteProperty(id->properties, writer);
   }
+  if (id->uuid) {
+    BLO_write_struct(writer, AssetUUID, id->uuid);
+  }
 
   if (id->override_library) {
     BLO_write_struct(writer, IDOverrideLibrary, id->override_library);
@@ -3926,6 +3929,11 @@ static void write_libraries(WriteData *wd, Main *main)
               BLI_assert(0);
             }
             writestruct(wd, ID_LINK_PLACEHOLDER, ID, 1, id);
+            /* It is mandatory to write id's asset uuid reference for placeholders too, otherwise
+             * the whole asset info would be completely lost when reloading the linked data-block,
+             * especially in case it is not immediately found and needs to go through the whole
+             * 'asset engine update' process after main .blend read process is finished. */
+            write_iddata(&writer, id);
           }
         }
       }