Review + A bunch of tests for good measure

app/models/tag.rb

@@ -503,12 +503,13 @@ def eligible_for_fandom_autocomplete?
   end
 
   def was_eligible_for_fandom_autocomplete?
-    (self.is_a?(Character) || self.is_a?(Relationship))
+    self.is_a?(Character) || self.is_a?(Relationship) && canonical_before_last_save
   end
 
   def remove_stale_from_autocomplete
     super
-    if self.is_a?(Character) || self.is_a?(Relationship)
+
+    if was_eligible_for_fandom_autocomplete?
       parents.each do |parent|
         REDIS_AUTOCOMPLETE.zrem(self.transliterate("autocomplete_fandom_#{parent.name.downcase}_#{type.downcase}"), autocomplete_value_before_last_save) if parent.is_a?(Fandom)
       end

spec/models/tag_wrangling_spec.rb

@@ -607,6 +607,40 @@
       character.destroy
       expect_autocomplete_to_return(fandom, [])
     end
+
+    it "adds to autocomplete when a character becomes canonical" do
+      fandom = create(:canonical_fandom)
+      character = create(:character)
+
+      fandom.add_association(character)
+      expect_autocomplete_to_return(fandom, [])
+
+      character.reload.update! canonical: true
+      expect_autocomplete_to_return(fandom, [character])
+    end
+
+    it "removes from autocomplete when a character loses its canonicity" do
+      fandom = create(:canonical_fandom)
+      character = create(:canonical_character)
+
+      fandom.add_association(character)
+      expect_autocomplete_to_return(fandom, [character])
+
+      character.reload.update! canonical: false
+      expect_autocomplete_to_return(fandom, [])
+    end
+
+    it "updates autocomplete when a character name changes" do
+      fandom = create(:canonical_fandom)
+      character = create(:canonical_character)
+
+      fandom.add_association(character)
+      expect_autocomplete_to_return(fandom, [character])
+
+      User.current_user = create(:admin)
+      character.reload.update! name: "Toto"
+      expect_autocomplete_to_return(fandom, [character])
+    end
   end
 
   def expect_autocomplete_to_return(fandom, characters)