Asset Catalogs: support reloading without losing local changes

Keep track of unsaved asset catalog changes, in a more granular way than
just one boolean per asset library. Individual catalogs can now be
marked with a flag `has_unsaved_changes`. This is taken into account
when reloading data from the catalog definition file (CDF):

- New catalog in CDF: gets loaded
- Already-known catalog in CDF:
    - local unsaved changes: on-disk catalog is ignored
    - otherwise: on-disk catalog replaces in-memory one
- Already-known catalog that does not exist in CDF:
    - local unsaved changes: catalog is kept around
    - otherwise: catalog is deleted.

Because this saving-is-also-loading behaviour, the "has unsaved changes"
flags are all stored in the undo buffer; undoing after saving will not
change the CDF, but at least it'll undo the loading from disk, and it'll
re-mark any changes as "not saved".

Reviewed By: Severin

Differential Revision: https://developer.blender.org/D12967

7 files changed, 309 insertions, 66 deletions

diff --git a/source/blender/blenkernel/BKE_asset_catalog.hh b/source/blender/blenkernel/BKE_asset_catalog.hh
index cbb15780a68..902c0e414d6 100644
--- a/source/blender/blenkernel/BKE_asset_catalog.hh
+++ b/source/blender/blenkernel/BKE_asset_catalog.hh
@@ -64,11 +64,13 @@ class AssetCatalogService {
   explicit AssetCatalogService(const CatalogFilePath &asset_library_root);
 
   /**
-   * Set global tag indicating that some catalog modifications are unsaved that could get lost
-   * on exit. This tag is not set by internal catalog code, the catalog service user is responsible
-   * for it. It is cleared by #write_to_disk().
-   */
-  void tag_has_unsaved_changes();
+   * Set tag indicating that some catalog modifications are unsaved, which could
+   * get lost on exit. This tag is not set by internal catalog code, the catalog
+   * service user is responsible for it. It is cleared by #write_to_disk().
+   *
+   * This "dirty" state is tracked per catalog, so that it's possible to gracefully load changes
+   * from disk. Any catalog with unsaved changes will not be overwritten by on-disk changes. */
+  void tag_has_unsaved_changes(AssetCatalog *edited_catalog);
   bool has_unsaved_changes() const;
 
   /** Load asset catalog definitions from the files found in the asset library. */
@@ -103,7 +105,7 @@ class AssetCatalogService {
    * - Already-known on-disk catalogs are ignored (so will be overwritten with our in-memory
    *   data). This includes in-memory marked-as-deleted catalogs.
    */
-  void merge_from_disk_before_writing();
+  void reload_catalogs();
 
   /** Return catalog with the given ID. Return nullptr if not found. */
   AssetCatalog *find_catalog(CatalogID catalog_id) const;
@@ -140,12 +142,6 @@ class AssetCatalogService {
   void prune_catalogs_by_id(CatalogID catalog_id);
 
   /**
-   * Delete a catalog, without deleting any of its children and without rebuilding the catalog
-   * tree. This is a lower-level function than #prune_catalogs_by_path.
-   */
-  void delete_catalog_by_id(CatalogID catalog_id);
-
-  /**
    * Update the catalog path, also updating the catalog path of all sub-catalogs.
    */
   void update_catalog_path(CatalogID catalog_id, const AssetCatalogPath &new_catalog_path);
@@ -178,7 +174,6 @@ class AssetCatalogService {
 
   Vector<std::unique_ptr<AssetCatalogCollection>> undo_snapshots_;
   Vector<std::unique_ptr<AssetCatalogCollection>> redo_snapshots_;
-  bool has_unsaved_changes_ = false;
 
   void load_directory_recursive(const CatalogFilePath &directory_path);
   void load_single_file(const CatalogFilePath &catalog_definition_file_path);
@@ -186,6 +181,31 @@ class AssetCatalogService {
   /** Implementation of #write_to_disk() that doesn't clear the "has unsaved changes" tag. */
   bool write_to_disk_ex(const CatalogFilePath &blend_file_path);
   void untag_has_unsaved_changes();
+  bool is_catalog_known_with_unsaved_changes(CatalogID catalog_id) const;
+
+  /**
+   * Delete catalogs, only keeping them when they are either listed in
+   * \a catalogs_to_keep or have unsaved changes.
+   *
+   * \note Deleted catalogs are hard-deleted, i.e. they just vanish instead of
+   * remembering them as "deleted".
+   */
+  void purge_catalogs_not_listed(const Set<CatalogID> &catalogs_to_keep);
+
+  /**
+   * Delete a catalog, without deleting any of its children and without rebuilding the catalog
+   * tree. The deletion in "Soft", in the sense that the catalog pointer is moved from `catalogs_`
+   * to `deleted_catalogs_`; the AssetCatalog instance itself is kept in memory. As a result, it
+   * will be removed from a CDF when saved to disk.
+   *
+   * This is a lower-level function than #prune_catalogs_by_path.
+   */
+  void delete_catalog_by_id_soft(CatalogID catalog_id);
+
+  /**
+   * Hard delete a catalog. This simply removes the catalog from existence. The deletion will not
+   * be remembered, and reloading the CDF will bring it back. */
+  void delete_catalog_by_id_hard(CatalogID catalog_id);
 
   std::unique_ptr<AssetCatalogDefinitionFile> parse_catalog_file(
       const CatalogFilePath &catalog_definition_file_path);
@@ -216,6 +236,7 @@ class AssetCatalogService {
   /* For access by subclasses, as those will not be marked as friend by #AssetCatalogCollection. */
   AssetCatalogDefinitionFile *get_catalog_definition_file();
   OwningAssetCatalogMap &get_catalogs();
+  OwningAssetCatalogMap &get_deleted_catalogs();
 };
 
 /**
@@ -246,6 +267,9 @@ class AssetCatalogCollection {
    * The aim is to support an arbitrary number of such files per asset library in the future. */
   std::unique_ptr<AssetCatalogDefinitionFile> catalog_definition_file_;
 
+  /** Whether any of the catalogs have unsaved changes. */
+  bool has_unsaved_changes_ = false;
+
   static OwningAssetCatalogMap copy_catalog_map(const OwningAssetCatalogMap &orig);
 };
 
@@ -269,6 +293,7 @@ class AssetCatalogTreeItem {
   CatalogID get_catalog_id() const;
   StringRefNull get_simple_name() const;
   StringRefNull get_name() const;
+  bool has_unsaved_changes() const;
   /** Return the full catalog path, defined as the name of this catalog prefixed by the full
    * catalog path of its parent and a separator. */
   AssetCatalogPath catalog_path() const;
@@ -287,6 +312,8 @@ class AssetCatalogTreeItem {
   CatalogID catalog_id_;
   /** Copy of #AssetCatalog::simple_name. */
   std::string simple_name_;
+  /** Copy of #AssetCatalog::flags.has_unsaved_changes. */
+  bool has_unsaved_changes_ = false;
 
   /** Pointer back to the parent item. Used to reconstruct the hierarchy from an item (e.g. to
    * build a path). */
@@ -353,9 +380,14 @@ class AssetCatalogDefinitionFile {
   bool write_to_disk(const CatalogFilePath &dest_file_path) const;
 
   bool contains(CatalogID catalog_id) const;
-  /* Add a new catalog. Undefined behavior if a catalog with the same ID was already added. */
+  /** Add a catalog, overwriting the one with the same catalog ID. */
+  void add_overwrite(AssetCatalog *catalog);
+  /** Add a new catalog. Undefined behavior if a catalog with the same ID was already added. */
   void add_new(AssetCatalog *catalog);
 
+  /** Remove the catalog from the collection of catalogs stored in this file. */
+  void forget(CatalogID catalog_id);
+
   using AssetCatalogParsedFn = FunctionRef<bool(std::unique_ptr<AssetCatalog>)>;
   void parse_catalog_file(const CatalogFilePath &catalog_definition_file_path,
                           AssetCatalogParsedFn callback);
@@ -405,6 +437,14 @@ class AssetCatalog {
      * load-and-merged with a file that also has these catalogs, the first one in that file is
      * always sorted first, regardless of the sort order of its UUID. */
     bool is_first_loaded = false;
+
+    /* Merging on-disk changes into memory will not overwrite this catalog.
+     * For example, when a catalog was renamed (i.e. changed path) in this Blender session,
+     * reloading the catalog definition file should not overwrite that change.
+     *
+     * Note that this flag is ignored when is_deleted=true; deleted catalogs that are still in
+     * memory are considered "unsaved" by definition. */
+    bool has_unsaved_changes = false;
   } flags;
 
   /**
diff --git a/source/blender/blenkernel/BKE_asset_library.hh b/source/blender/blenkernel/BKE_asset_library.hh
index 64c8afecaef..15f7991e75e 100644
--- a/source/blender/blenkernel/BKE_asset_library.hh
+++ b/source/blender/blenkernel/BKE_asset_library.hh
@@ -49,6 +49,9 @@ struct AssetLibrary {
 
   void load(StringRefNull library_root_directory);
 
+  /** Load catalogs that have changed on disk. */
+  void refresh();
+
   /**
    * Update `catalog_simple_name` by looking up the asset's catalog by its ID.
    *
diff --git a/source/blender/blenkernel/intern/asset_catalog.cc b/source/blender/blenkernel/intern/asset_catalog.cc
index 9dd5ccdf3cf..a1647426c41 100644
--- a/source/blender/blenkernel/intern/asset_catalog.cc
+++ b/source/blender/blenkernel/intern/asset_catalog.cc
@@ -67,23 +67,45 @@ AssetCatalogService::AssetCatalogService(const CatalogFilePath &asset_library_ro
 {
 }
 
-void AssetCatalogService::tag_has_unsaved_changes()
+void AssetCatalogService::tag_has_unsaved_changes(AssetCatalog *edited_catalog)
 {
-  has_unsaved_changes_ = true;
+  if (edited_catalog) {
+    edited_catalog->flags.has_unsaved_changes = true;
+  }
+  BLI_assert(catalog_collection_);
+  catalog_collection_->has_unsaved_changes_ = true;
 }
 
 void AssetCatalogService::untag_has_unsaved_changes()
 {
-  has_unsaved_changes_ = false;
+  BLI_assert(catalog_collection_);
+  catalog_collection_->has_unsaved_changes_ = false;
+
+  /* TODO(Sybren): refactor; this is more like "post-write cleanup" than "remove a tag" code. */
+
+  /* Forget about any deleted catalogs. */
+  if (catalog_collection_->catalog_definition_file_) {
+    for (CatalogID catalog_id : catalog_collection_->deleted_catalogs_.keys()) {
+      catalog_collection_->catalog_definition_file_->forget(catalog_id);
+    }
+  }
+  catalog_collection_->deleted_catalogs_.clear();
+
+  /* Mark all remaining catalogs as "without unsaved changes". */
+  for (auto &catalog_uptr : catalog_collection_->catalogs_.values()) {
+    catalog_uptr->flags.has_unsaved_changes = false;
+  }
 }
 
 bool AssetCatalogService::has_unsaved_changes() const
 {
-  return has_unsaved_changes_;
+  BLI_assert(catalog_collection_);
+  return catalog_collection_->has_unsaved_changes_;
 }
 
 bool AssetCatalogService::is_empty() const
 {
+  BLI_assert(catalog_collection_);
   return catalog_collection_->catalogs_.is_empty();
 }
 
@@ -91,6 +113,10 @@ OwningAssetCatalogMap &AssetCatalogService::get_catalogs()
 {
   return catalog_collection_->catalogs_;
 }
+OwningAssetCatalogMap &AssetCatalogService::get_deleted_catalogs()
+{
+  return catalog_collection_->deleted_catalogs_;
+}
 
 AssetCatalogDefinitionFile *AssetCatalogService::get_catalog_definition_file()
 {
@@ -155,7 +181,7 @@ AssetCatalogFilter AssetCatalogService::create_catalog_filter(
   return AssetCatalogFilter(std::move(matching_catalog_ids));
 }
 
-void AssetCatalogService::delete_catalog_by_id(const CatalogID catalog_id)
+void AssetCatalogService::delete_catalog_by_id_soft(const CatalogID catalog_id)
 {
   std::unique_ptr<AssetCatalog> *catalog_uptr_ptr = catalog_collection_->catalogs_.lookup_ptr(
       catalog_id);
@@ -176,6 +202,15 @@ void AssetCatalogService::delete_catalog_by_id(const CatalogID catalog_id)
   catalog_collection_->catalogs_.remove(catalog_id);
 }
 
+void AssetCatalogService::delete_catalog_by_id_hard(CatalogID catalog_id)
+{
+  catalog_collection_->catalogs_.remove(catalog_id);
+  catalog_collection_->deleted_catalogs_.remove(catalog_id);
+
+  /* TODO(Sybren): adjust this when supporting mulitple CDFs. */
+  catalog_collection_->catalog_definition_file_->forget(catalog_id);
+}
+
 void AssetCatalogService::prune_catalogs_by_path(const AssetCatalogPath &path)
 {
   /* Build a collection of catalog IDs to delete. */
@@ -189,7 +224,7 @@ void AssetCatalogService::prune_catalogs_by_path(const AssetCatalogPath &path)
 
   /* Delete the catalogs. */
   for (const CatalogID cat_id : catalogs_to_delete) {
-    this->delete_catalog_by_id(cat_id);
+    this->delete_catalog_by_id_soft(cat_id);
   }
 
   this->rebuild_tree();
@@ -231,6 +266,7 @@ void AssetCatalogService::update_catalog_path(const CatalogID catalog_id,
 AssetCatalog *AssetCatalogService::create_catalog(const AssetCatalogPath &catalog_path)
 {
   std::unique_ptr<AssetCatalog> catalog = AssetCatalog::from_path(catalog_path);
+  catalog->flags.has_unsaved_changes = true;
 
   /* So we can std::move(catalog) and still use the non-owning pointer: */
   AssetCatalog *const catalog_ptr = catalog.get();
@@ -349,7 +385,7 @@ std::unique_ptr<AssetCatalogDefinitionFile> AssetCatalogService::parse_catalog_f
   return cdf;
 }
 
-void AssetCatalogService::merge_from_disk_before_writing()
+void AssetCatalogService::reload_catalogs()
 {
   /* TODO(Sybren): expand to support multiple CDFs. */
   AssetCatalogDefinitionFile *const cdf = catalog_collection_->catalog_definition_file_.get();
@@ -357,26 +393,66 @@ void AssetCatalogService::merge_from_disk_before_writing()
     return;
   }
 
-  auto catalog_parsed_callback = [this](std::unique_ptr<AssetCatalog> catalog) {
-    const bUUID catalog_id = catalog->catalog_id;
+  /* Keeps track of the catalog IDs that are seen in the CDF, so that we also know what was deleted
+   * from the file on disk. */
+  Set<CatalogID> cats_in_file;
 
-    /* The following two conditions could be or'ed together. Keeping them separated helps when
-     * adding debug prints, breakpoints, etc. */
-    if (catalog_collection_->catalogs_.contains(catalog_id)) {
-      /* This catalog was already seen, so just ignore it. */
-      return false;
-    }
-    if (catalog_collection_->deleted_catalogs_.contains(catalog_id)) {
-      /* This catalog was already seen and subsequently deleted, so just ignore it. */
+  auto catalog_parsed_callback = [this, &cats_in_file](std::unique_ptr<AssetCatalog> catalog) {
+    const CatalogID catalog_id = catalog->catalog_id;
+    cats_in_file.add(catalog_id);
+
+    const bool should_skip = is_catalog_known_with_unsaved_changes(catalog_id);
+    if (should_skip) {
+      /* Do not overwrite unsaved local changes. */
       return false;
     }
 
-    /* This is a new catalog, so let's keep it around. */
-    catalog_collection_->catalogs_.add_new(catalog_id, std::move(catalog));
+    /* This is either a new catalog, or we can just replace the in-memory one with the newly loaded
+     * one. */
+    catalog_collection_->catalogs_.add_overwrite(catalog_id, std::move(catalog));
     return true;
   };
 
   cdf->parse_catalog_file(cdf->file_path, catalog_parsed_callback);
+  this->purge_catalogs_not_listed(cats_in_file);
+  this->rebuild_tree();
+}
+
+void AssetCatalogService::purge_catalogs_not_listed(const Set<CatalogID> &catalogs_to_keep)
+{
+  Set<CatalogID> cats_to_remove;
+  for (CatalogID cat_id : this->catalog_collection_->catalogs_.keys()) {
+    if (catalogs_to_keep.contains(cat_id)) {
+      continue;
+    }
+    if (is_catalog_known_with_unsaved_changes(cat_id)) {
+      continue;
+    }
+    /* This catalog is not on disk, but also not modified, so get rid of it. */
+    cats_to_remove.add(cat_id);
+  }
+
+  for (CatalogID cat_id : cats_to_remove) {
+    delete_catalog_by_id_hard(cat_id);
+  }
+}
+
+bool AssetCatalogService::is_catalog_known_with_unsaved_changes(const CatalogID catalog_id) const
+{
+  if (catalog_collection_->deleted_catalogs_.contains(catalog_id)) {
+    /* Deleted catalogs are always considered modified, by definition. */
+    return true;
+  }
+
+  const std::unique_ptr<AssetCatalog> *catalog_uptr_ptr =
+      catalog_collection_->catalogs_.lookup_ptr(catalog_id);
+  if (!catalog_uptr_ptr) {
+    /* Catalog is unknown. */
+    return false;
+  }
+
+  const bool has_unsaved_changes = (*catalog_uptr_ptr)->flags.has_unsaved_changes;
+  return has_unsaved_changes;
 }
 
 bool AssetCatalogService::write_to_disk(const CatalogFilePath &blend_file_path)
@@ -386,6 +462,7 @@ bool AssetCatalogService::write_to_disk(const CatalogFilePath &blend_file_path)
   }
 
   untag_has_unsaved_changes();
+  rebuild_tree();
   return true;
 }
 
@@ -395,7 +472,7 @@ bool AssetCatalogService::write_to_disk_ex(const CatalogFilePath &blend_file_pat
 
   /* - Already loaded a CDF from disk? -> Always write to that file. */
   if (catalog_collection_->catalog_definition_file_) {
-    merge_from_disk_before_writing();
+    reload_catalogs();
     return catalog_collection_->catalog_definition_file_->write_to_disk();
   }
 
@@ -407,7 +484,7 @@ bool AssetCatalogService::write_to_disk_ex(const CatalogFilePath &blend_file_pat
 
   const CatalogFilePath cdf_path_to_write = find_suitable_cdf_path_for_writing(blend_file_path);
   catalog_collection_->catalog_definition_file_ = construct_cdf_in_memory(cdf_path_to_write);
-  merge_from_disk_before_writing();
+  reload_catalogs();
   return catalog_collection_->catalog_definition_file_->write_to_disk();
 }
 
@@ -507,7 +584,9 @@ void AssetCatalogService::create_missing_catalogs()
     }
 
     /* The parent doesn't exist, so create it and queue it up for checking its parent. */
-    create_catalog(parent_path);
+    AssetCatalog *parent_catalog = create_catalog(parent_path);
+    parent_catalog->flags.has_unsaved_changes = true;
+
     paths_to_check.insert(parent_path);
   }
 
@@ -555,6 +634,7 @@ std::unique_ptr<AssetCatalogCollection> AssetCatalogCollection::deep_copy() cons
 {
   auto copy = std::make_unique<AssetCatalogCollection>();
 
+  copy->has_unsaved_changes_ = this->has_unsaved_changes_;
   copy->catalogs_ = copy_catalog_map(this->catalogs_);
   copy->deleted_catalogs_ = copy_catalog_map(this->deleted_catalogs_);
 
@@ -602,6 +682,10 @@ StringRefNull AssetCatalogTreeItem::get_simple_name() const
 {
   return simple_name_;
 }
+bool AssetCatalogTreeItem::has_unsaved_changes() const
+{
+  return has_unsaved_changes_;
+}
 
 AssetCatalogPath AssetCatalogTreeItem::catalog_path() const
 {
@@ -668,9 +752,11 @@ void AssetCatalogTree::insert_item(const AssetCatalog &catalog)
 
     /* If full path of this catalog already exists as parent path of a previously read catalog,
      * we can ensure this tree item's UUID is set here. */
-    if (is_last_component &&
-        (BLI_uuid_is_nil(item.catalog_id_) || catalog.flags.is_first_loaded)) {
-      item.catalog_id_ = catalog.catalog_id;
+    if (is_last_component) {
+      if (BLI_uuid_is_nil(item.catalog_id_) || catalog.flags.is_first_loaded) {
+        item.catalog_id_ = catalog.catalog_id;
+      }
+      item.has_unsaved_changes_ = catalog.flags.has_unsaved_changes;
     }
 
     /* Walk further into the path (no matter if a new item was created or not). */
@@ -705,6 +791,16 @@ void AssetCatalogDefinitionFile::add_new(AssetCatalog *catalog)
   catalogs_.add_new(catalog->catalog_id, catalog);
 }
 
+void AssetCatalogDefinitionFile::add_overwrite(AssetCatalog *catalog)
+{
+  catalogs_.add_overwrite(catalog->catalog_id, catalog);
+}
+
+void AssetCatalogDefinitionFile::forget(CatalogID catalog_id)
+{
+  catalogs_.remove(catalog_id);
+}
+
 void AssetCatalogDefinitionFile::parse_catalog_file(
     const CatalogFilePath &catalog_definition_file_path,
     AssetCatalogParsedFn catalog_loaded_callback)
@@ -742,16 +838,8 @@ void AssetCatalogDefinitionFile::parse_catalog_file(
       continue;
     }
 
-    if (this->contains(non_owning_ptr->catalog_id)) {
-      std::cerr << catalog_definition_file_path << ": multiple definitions of catalog "
-                << non_owning_ptr->catalog_id << " in the same file, using first occurrence."
-                << std::endl;
-      /* Don't store 'catalog'; unique_ptr will free its memory. */
-      continue;
-    }
-
     /* The AssetDefinitionFile should include this catalog when writing it back to disk. */
-    this->add_new(non_owning_ptr);
+    this->add_overwrite(non_owning_ptr);
   }
 }
 
diff --git a/source/blender/blenkernel/intern/asset_catalog_test.cc b/source/blender/blenkernel/intern/asset_catalog_test.cc
index a6e372e4ae6..a2835d7b3b2 100644
--- a/source/blender/blenkernel/intern/asset_catalog_test.cc
+++ b/source/blender/blenkernel/intern/asset_catalog_test.cc
@@ -35,6 +35,7 @@ const bUUID UUID_ID_WITHOUT_PATH("e34dd2c5-5d2e-4668-9794-1db5de2a4f71");
 const bUUID UUID_POSES_ELLIE("df60e1f6-2259-475b-93d9-69a1b4a8db78");
 const bUUID UUID_POSES_ELLIE_WHITESPACE("b06132f6-5687-4751-a6dd-392740eb3c46");
 const bUUID UUID_POSES_ELLIE_TRAILING_SLASH("3376b94b-a28d-4d05-86c1-bf30b937130d");
+const bUUID UUID_POSES_ELLIE_BACKSLASHES("a51e17ae-34fc-47d5-ba0f-64c2c9b771f7");
 const bUUID UUID_POSES_RUZENA("79a4f887-ab60-4bd4-94da-d572e27d6aed");
 const bUUID UUID_POSES_RUZENA_HAND("81811c31-1a88-4bd7-bb34-c6fc2607a12e");
 const bUUID UUID_POSES_RUZENA_FACE("82162c1f-06cc-4d91-a9bf-4f72c104e348");
@@ -59,11 +60,21 @@ class TestableAssetCatalogService : public AssetCatalogService {
     return AssetCatalogService::get_catalog_definition_file();
   }
 
+  OwningAssetCatalogMap &get_deleted_catalogs()
+  {
+    return AssetCatalogService::get_deleted_catalogs();
+  }
+
   void create_missing_catalogs()
   {
     AssetCatalogService::create_missing_catalogs();
   }
 
+  void delete_catalog_by_id_soft(CatalogID catalog_id)
+  {
+    AssetCatalogService::delete_catalog_by_id_soft(catalog_id);
+  }
+
   int64_t count_catalogs_with_path(const CatalogFilePath &path)
   {
     int64_t count = 0;
@@ -305,8 +316,7 @@ TEST_F(AssetCatalogTest, load_catalog_path_backslashes)
   AssetCatalogService service(asset_library_root_);
   service.load_from_disk(asset_library_root_ + "/" + "blender_assets.cats.txt");
 
-  const bUUID ELLIE_BACKSLASHES_UUID("a51e17ae-34fc-47d5-ba0f-64c2c9b771f7");
-  const AssetCatalog *found_by_id = service.find_catalog(ELLIE_BACKSLASHES_UUID);
+  const AssetCatalog *found_by_id = service.find_catalog(UUID_POSES_ELLIE_BACKSLASHES);
   ASSERT_NE(nullptr, found_by_id);
   EXPECT_EQ(AssetCatalogPath("character/Ellie/backslashes"), found_by_id->path)
       << "Backslashes should be normalised when loading from disk.";
@@ -799,11 +809,11 @@ TEST_F(AssetCatalogTest, delete_catalog_leaf)
 
 TEST_F(AssetCatalogTest, delete_catalog_parent_by_id)
 {
-  AssetCatalogService service(asset_library_root_);
+  TestableAssetCatalogService service(asset_library_root_);
   service.load_from_disk(asset_library_root_ + "/" + "blender_assets.cats.txt");
 
   /* Delete a parent catalog. */
-  service.delete_catalog_by_id(UUID_POSES_RUZENA);
+  service.delete_catalog_by_id_soft(UUID_POSES_RUZENA);
 
   /* The catalog should have been deleted, but its children should still be there. */
   EXPECT_EQ(nullptr, service.find_catalog(UUID_POSES_RUZENA));
@@ -857,7 +867,7 @@ TEST_F(AssetCatalogTest, delete_catalog_write_to_disk)
   service.load_from_disk(asset_library_root_ + "/" +
                          AssetCatalogService::DEFAULT_CATALOG_FILENAME);
 
-  service.delete_catalog_by_id(UUID_POSES_ELLIE);
+  service.delete_catalog_by_id_soft(UUID_POSES_ELLIE);
 
   const CatalogFilePath save_to_path = use_temp_path();
   AssetCatalogDefinitionFile *cdf = service.get_catalog_definition_file();
@@ -938,7 +948,9 @@ TEST_F(AssetCatalogTest, merge_catalog_files)
    * CDF after we loaded it. */
   ASSERT_EQ(0, BLI_copy(modified_cdf_file.c_str(), temp_cdf_file.c_str()));
 
-  /* Overwrite the modified file. This should merge the on-disk file with our catalogs. */
+  /* Overwrite the modified file. This should merge the on-disk file with our catalogs.
+   * No catalog was marked as "has unsaved changes", so effectively this should not
+   * save anything, and reload what's on disk. */
   service.write_to_disk(cdf_dir + "phony.blend");
 
   AssetCatalogService loaded_service(cdf_dir);
@@ -946,16 +958,90 @@ TEST_F(AssetCatalogTest, merge_catalog_files)
 
   /* Test that the expected catalogs are there. */
   EXPECT_NE(nullptr, loaded_service.find_catalog(UUID_POSES_ELLIE));
-  EXPECT_NE(nullptr, loaded_service.find_catalog(UUID_POSES_ELLIE_WHITESPACE));
-  EXPECT_NE(nullptr, loaded_service.find_catalog(UUID_POSES_ELLIE_TRAILING_SLASH));
-  EXPECT_NE(nullptr, loaded_service.find_catalog(UUID_POSES_RUZENA));
-  EXPECT_NE(nullptr, loaded_service.find_catalog(UUID_POSES_RUZENA_HAND));
   EXPECT_NE(nullptr, loaded_service.find_catalog(UUID_POSES_RUZENA_FACE));
   EXPECT_NE(nullptr, loaded_service.find_catalog(UUID_AGENT_47)); /* New in the modified file. */
 
-  /* When there are overlaps, the in-memory (i.e. last-saved) paths should win. */
+  /* Test that catalogs removed from modified CDF are gone. */
+  EXPECT_EQ(nullptr, loaded_service.find_catalog(UUID_POSES_ELLIE_WHITESPACE));
+  EXPECT_EQ(nullptr, loaded_service.find_catalog(UUID_POSES_ELLIE_TRAILING_SLASH));
+  EXPECT_EQ(nullptr, loaded_service.find_catalog(UUID_POSES_RUZENA));
+  EXPECT_EQ(nullptr, loaded_service.find_catalog(UUID_POSES_RUZENA_HAND));
+
+  /* On-disk changed catalogs should have overridden in-memory not-changed ones. */
   const AssetCatalog *ruzena_face = loaded_service.find_catalog(UUID_POSES_RUZENA_FACE);
-  EXPECT_EQ("character/Ružena/poselib/face", ruzena_face->path.str());
+  EXPECT_EQ("character/Ružena/poselib/gezicht", ruzena_face->path.str());
+}
+
+TEST_F(AssetCatalogTest, refresh_catalogs_with_modification)
+{
+  const CatalogFilePath cdf_dir = create_temp_path();
+  const CatalogFilePath original_cdf_file = asset_library_root_ + "/blender_assets.cats.txt";
+  const CatalogFilePath modified_cdf_file = asset_library_root_ + "/catalog_reload_test.cats.txt";
+  const CatalogFilePath temp_cdf_file = cdf_dir + "blender_assets.cats.txt";
+  ASSERT_EQ(0, BLI_copy(original_cdf_file.c_str(), temp_cdf_file.c_str()));
+
+  /* Load the unmodified, original CDF. */
+  TestableAssetCatalogService service(asset_library_root_);
+  service.load_from_disk(cdf_dir);
+
+  /* === Perfom changes that should be handled gracefully by the reloading code: */
+
+  /* 1. Delete a subtree of catalogs. */
+  service.prune_catalogs_by_id(UUID_POSES_RUZENA);
+  /* 2. Rename a catalog. */
+  service.tag_has_unsaved_changes(service.find_catalog(UUID_POSES_ELLIE_TRAILING_SLASH));
+  service.update_catalog_path(UUID_POSES_ELLIE_TRAILING_SLASH, "character/Ellie/test-value");
+
+  /* Copy a modified file, to mimic a situation where someone changed the
+   * CDF after we loaded it. */
+  ASSERT_EQ(0, BLI_copy(modified_cdf_file.c_str(), temp_cdf_file.c_str()));
+
+  AssetCatalog *const ellie_whitespace_before_reload = service.find_catalog(
+      UUID_POSES_ELLIE_WHITESPACE);
+
+  /* This should merge the on-disk file with our catalogs. */
+  service.reload_catalogs();
+
+  /* === Test that the expected catalogs are there. */
+  EXPECT_NE(nullptr, service.find_catalog(UUID_POSES_ELLIE));
+  EXPECT_NE(nullptr, service.find_catalog(UUID_POSES_ELLIE_WHITESPACE));
+  EXPECT_NE(nullptr, service.find_catalog(UUID_POSES_ELLIE_TRAILING_SLASH));
+
+  /* === Test changes made to the CDF: */
+
+  /* Removed from the file. */
+  EXPECT_EQ(nullptr, service.find_catalog(UUID_POSES_ELLIE_BACKSLASHES));
+  /* Added to the file. */
+  EXPECT_NE(nullptr, service.find_catalog(UUID_AGENT_47));
+  /* Path modified in file. */
+  AssetCatalog *ellie_whitespace_after_reload = service.find_catalog(UUID_POSES_ELLIE_WHITESPACE);
+  EXPECT_EQ(AssetCatalogPath("whitespace from file"), ellie_whitespace_after_reload->path);
+  EXPECT_NE(ellie_whitespace_after_reload, ellie_whitespace_before_reload);
+  /* Simple name modified in file. */
+  EXPECT_EQ(std::string("Hah simple name after all"),
+            service.find_catalog(UUID_WITHOUT_SIMPLENAME)->simple_name);
+
+  /* === Test persistence of in-memory changes: */
+
+  /* This part of the tree we deleted, but still existed in the CDF. They should remain deleted
+   * after reloading: */
+  EXPECT_EQ(nullptr, service.find_catalog(UUID_POSES_RUZENA));
+  EXPECT_EQ(nullptr, service.find_catalog(UUID_POSES_RUZENA_HAND));
+  EXPECT_EQ(nullptr, service.find_catalog(UUID_POSES_RUZENA_FACE));
+
+  /* This catalog had its path changed in the test and in the CDF. The change from the test (i.e.
+   * the in-memory, yet-unsaved change) should persist. */
+  EXPECT_EQ(AssetCatalogPath("character/Ellie/test-value"),
+            service.find_catalog(UUID_POSES_ELLIE_TRAILING_SLASH)->path);
+
+  /* Overwrite the modified file. This should merge the on-disk file with our catalogs, and clear
+   * the "has_unsaved_changes" flags. */
+  service.write_to_disk(cdf_dir + "phony.blend");
+
+  EXPECT_FALSE(service.find_catalog(UUID_POSES_ELLIE_TRAILING_SLASH)->flags.has_unsaved_changes)
+      << "The catalogs whose path we changed should now be saved";
+  EXPECT_TRUE(service.get_deleted_catalogs().is_empty())
+      << "Deleted catalogs should not be remembered after saving.";
 }
 
 TEST_F(AssetCatalogTest, backups)
@@ -966,9 +1052,9 @@ TEST_F(AssetCatalogTest, backups)
   ASSERT_EQ(0, BLI_copy(original_cdf_file.c_str(), writable_cdf_file.c_str()));
 
   /* Read a CDF, modify, and write it. */
-  AssetCatalogService service(cdf_dir);
+  TestableAssetCatalogService service(cdf_dir);
   service.load_from_disk();
-  service.delete_catalog_by_id(UUID_POSES_ELLIE);
+  service.delete_catalog_by_id_soft(UUID_POSES_ELLIE);
   service.write_to_disk(cdf_dir + "phony.blend");
 
   const CatalogFilePath backup_path = writable_cdf_file + "~";
@@ -1100,6 +1186,13 @@ TEST_F(AssetCatalogTest, create_missing_catalogs_after_loading)
   ASSERT_NE(nullptr, cat_ellie) << "Missing parents should be created immediately after loading.";
   ASSERT_NE(nullptr, cat_ruzena) << "Missing parents should be created immediately after loading.";
 
+  EXPECT_TRUE(cat_char->flags.has_unsaved_changes)
+      << "Missing parents should be marked as having changes.";
+  EXPECT_TRUE(cat_ellie->flags.has_unsaved_changes)
+      << "Missing parents should be marked as having changes.";
+  EXPECT_TRUE(cat_ruzena->flags.has_unsaved_changes)
+      << "Missing parents should be marked as having changes.";
+
   AssetCatalogDefinitionFile *cdf = loaded_service.get_catalog_definition_file();
   ASSERT_NE(nullptr, cdf);
   EXPECT_TRUE(cdf->contains(cat_char->catalog_id)) << "Missing parents should be saved to a CDF.";
diff --git a/source/blender/blenkernel/intern/asset_library.cc b/source/blender/blenkernel/intern/asset_library.cc
index 6c4660ae75d..aae8a289d32 100644
--- a/source/blender/blenkernel/intern/asset_library.cc
+++ b/source/blender/blenkernel/intern/asset_library.cc
@@ -128,6 +128,11 @@ void AssetLibrary::load(StringRefNull library_root_directory)
   this->catalog_service = std::move(catalog_service);
 }
 
+void AssetLibrary::refresh()
+{
+  this->catalog_service->reload_catalogs();
+}
+
 namespace {
 void asset_library_on_save_post(struct Main *main,
                                 struct PointerRNA **pointers,
diff --git a/source/blender/blenkernel/intern/asset_library_service.cc b/source/blender/blenkernel/intern/asset_library_service.cc
index aeded0bc128..7cf95ee4cc1 100644
--- a/source/blender/blenkernel/intern/asset_library_service.cc
+++ b/source/blender/blenkernel/intern/asset_library_service.cc
@@ -77,7 +77,9 @@ AssetLibrary *AssetLibraryService::get_asset_library_on_disk(StringRefNull top_l
   AssetLibraryPtr *lib_uptr_ptr = on_disk_libraries_.lookup_ptr(top_dir_trailing_slash);
   if (lib_uptr_ptr != nullptr) {
     CLOG_INFO(&LOG, 2, "get \"%s\" (cached)", top_dir_trailing_slash.c_str());
-    return lib_uptr_ptr->get();
+    AssetLibrary *lib = lib_uptr_ptr->get();
+    lib->refresh();
+    return lib;
   }
 
   AssetLibraryPtr lib_uptr = std::make_unique<AssetLibrary>();
diff --git a/source/blender/blenkernel/intern/asset_library_service_test.cc b/source/blender/blenkernel/intern/asset_library_service_test.cc
index ed132d7a8d8..80504bbdc05 100644
--- a/source/blender/blenkernel/intern/asset_library_service_test.cc
+++ b/source/blender/blenkernel/intern/asset_library_service_test.cc
@@ -30,6 +30,8 @@
 
 namespace blender::bke::tests {
 
+const bUUID UUID_POSES_ELLIE("df60e1f6-2259-475b-93d9-69a1b4a8db78");
+
 class AssetLibraryServiceTest : public testing::Test {
  public:
   CatalogFilePath asset_library_root_;
@@ -162,12 +164,18 @@ TEST_F(AssetLibraryServiceTest, has_any_unsaved_catalogs)
   const bUUID UUID_POSES_ELLIE("df60e1f6-2259-475b-93d9-69a1b4a8db78");
   cat_service->prune_catalogs_by_id(UUID_POSES_ELLIE);
   EXPECT_FALSE(service->has_any_unsaved_catalogs())
-      << "Deletion of catalogs via AssetCatalogService should not tag as 'unsaved changes'.";
+      << "Deletion of catalogs via AssetCatalogService should not automatically tag as 'unsaved "
+         "changes'.";
+
+  const bUUID UUID_POSES_RUZENA("79a4f887-ab60-4bd4-94da-d572e27d6aed");
+  AssetCatalog *cat = cat_service->find_catalog(UUID_POSES_RUZENA);
+  ASSERT_NE(nullptr, cat) << "Catalog " << UUID_POSES_RUZENA << " should be known";
 
-  cat_service->tag_has_unsaved_changes();
+  cat_service->tag_has_unsaved_changes(cat);
   EXPECT_TRUE(service->has_any_unsaved_catalogs())
       << "Tagging as having unsaved changes of a single catalog service should result in unsaved "
          "changes being reported.";
+  EXPECT_TRUE(cat->flags.has_unsaved_changes);
 }
 
 TEST_F(AssetLibraryServiceTest, has_any_unsaved_catalogs_after_write)
@@ -185,15 +193,19 @@ TEST_F(AssetLibraryServiceTest, has_any_unsaved_catalogs_after_write)
       << "Unchanged AssetLibrary should have no unsaved catalogs";
 
   AssetCatalogService *const cat_service = lib->catalog_service.get();
-  cat_service->tag_has_unsaved_changes();
+  AssetCatalog *cat = cat_service->find_catalog(UUID_POSES_ELLIE);
+
+  cat_service->tag_has_unsaved_changes(cat);
 
   EXPECT_TRUE(service->has_any_unsaved_catalogs())
       << "Tagging as having unsaved changes of a single catalog service should result in unsaved "
          "changes being reported.";
+  EXPECT_TRUE(cat->flags.has_unsaved_changes);
 
   cat_service->write_to_disk(writable_dir + "dummy_path.blend");
   EXPECT_FALSE(service->has_any_unsaved_catalogs())
       << "Written AssetCatalogService should have no unsaved catalogs";
+  EXPECT_FALSE(cat->flags.has_unsaved_changes);
 }
 
 }  // namespace blender::bke::tests