Fix #5362: Suggest ai-generated as a translated tag from pixiv response

app/logical/source/extractor/pixiv.rb

@@ -104,10 +104,17 @@ module Source
       end
 
       def tags
-        api_illust.dig(:tags, :tags).to_a.map do |item|
+        tags = api_illust.dig(:tags, :tags).to_a.map do |item|
           tag = item[:tag]
           [tag, "https://www.pixiv.net/search.php?s_mode=s_tag_full&#{{word: tag}.to_param}"]
         end
+
+        if api_illust["aiType"] == 2
+          # XXX There's no way to search for posts with the AI flag on Pixiv. The "AI" tag is the closest equivalent.
+          tags += [["AI", "https://www.pixiv.net/tags/AI/artworks"]]
+        end
+
+        tags
       end
 
       def normalize_tag(tag)

test/unit/sources/pixiv_test.rb

@@ -185,6 +185,17 @@ module Sources
         )
       end
 
+      context "An AI-generated post should get the AI tag" do
+        strategy_should_work(
+          "https://www.pixiv.net/en/artworks/103291492",
+          image_urls: ["https://i.pximg.net/img-original/img/2022/12/03/05/06/51/103291492_p0.png"],
+          artist_commentary_title: "Rem's present",
+          artist_name: "Anzatiridonia",
+          profile_url: "https://www.pixiv.net/users/33589885",
+          tags: %w[AI Re:ゼロから始める異世界生活 レム リゼロ レム(リゼロ) AIイラスト AnythingV3 Present sweater],
+        )
+      end
+
       context "fetching the commentary" do
         should "work when the description is blank" do
           get_source("https://www.pixiv.net/member_illust.php?mode=medium&illust_id=65981746")