#306

backend/app/controllers/tags_controller.rb

@@ -379,12 +379,20 @@ class TagsController < ApplicationController
   end
 
   def visible_root_tag_ids graph
-    graph[:tags_by_id].filter_map do |tag_id, _attrs|
+    root_ids = Set.new
+
+    graph[:tags_by_id].each do |tag_id, attrs|
       next unless visible_root_tag?(tag_id, graph)
       next unless visible_subtree?(tag_id, graph)
 
-      tag_id
+      if attrs[:deprecated]
+        collect_visible_child_tag_ids(tag_id, graph, root_ids, Set.new)
+      else
+        root_ids << tag_id
+      end
     end
+
+    root_ids.to_a
   end
 
   def visible_root_tag? tag_id, graph

backend/app/services/material_sync_importer.rb

@@ -44,6 +44,12 @@ class MaterialSyncImporter
           :update
         end
     uploaded_blob = uploaded_blob!
+    if @import_block
+      return Result.new(material: nil,
+                        action: :suppressed,
+                        suppressed: true,
+                        suppression: @import_block)
+    end
 
     Material.transaction do
       if material.persisted?
@@ -129,11 +135,19 @@ class MaterialSyncImporter
     return nil unless tempfile
 
     tempfile.rewind
+    file_sha256 = @attributes[:file_sha256] || Digest::SHA256.file(tempfile.path).hexdigest
+    @attributes[:file_sha256] = file_sha256
+
+    @import_block = MaterialImportBlockMatcher.match_for_sha256(file_sha256)
+    if @import_block
+      tempfile.rewind
+      return nil
+    end
+
     blob = ActiveStorage::Blob.create_and_upload!(
         io: tempfile,
         filename: @attributes[:filename],
         content_type: @attributes[:content_type])
-    file_sha256 = @attributes[:file_sha256] || Digest::SHA256.file(tempfile.path).hexdigest
     blob.metadata['sha256'] = file_sha256 if file_sha256.present?
     blob.save! if blob.changed?
     tempfile.rewind