Regenerate embeddings only when the test representation changes

lib/music_library/records/similarity.ex

@@ -316,6 +316,21 @@ defmodule MusicLibrary.Records.Similarity do
     )
   end
 
+  @spec generate_embedding(Record.t()) :: :noop | {:ok, RecordEmbedding.t()} | {:error, term()}
+  def generate_embedding(%Record{} = record) do
+    new_text = text_representation(record)
+
+    case get_embedding_text(record.id) do
+      {:ok, ^new_text} ->
+        :noop
+
+      _ ->
+        with {:ok, embedding} <- OpenAI.embeddings(new_text) do
+          store_embedding(record.id, embedding, new_text)
+        end
+    end
+  end
+
   @spec generate_embedding_async(Record.t()) :: {:ok, Oban.Job.t()} | {:error, Ecto.Changeset.t()}
   def generate_embedding_async(record) do
     meta = %{title: record.title, artists: Enum.map(record.artists, & &1.name)}

lib/music_library/worker/generate_record_embedding.ex

@@ -8,25 +8,10 @@ defmodule MusicLibrary.Worker.GenerateRecordEmbedding do
   def perform(%Oban.Job{args: %{"record_id" => record_id}}) do
     record = Records.get_record!(record_id)
 
-    with {:ok, embedding} <- generate_embedding(record),
-         {:ok, _} <- store_embedding(record, embedding) do
-      Records.notify_update(record)
+    case Similarity.generate_embedding(record) do
+      :noop -> :ok
+      {:ok, _} -> Records.notify_update(record)
+      {:error, _} = error -> error
     end
   end
-
-  defp generate_embedding(record) do
-    text = Similarity.text_representation(record)
-
-    case OpenAI.embeddings(text) do
-      {:ok, embedding} ->
-        {:ok, {embedding, text}}
-
-      error ->
-        error
-    end
-  end
-
-  defp store_embedding(record, {embedding, text_representation}) do
-    Similarity.store_embedding(record.id, embedding, text_representation)
-  end
 end

test/music_library/records/similarity_test.exs

@@ -238,6 +238,65 @@ defmodule MusicLibrary.Records.SimilarityTest do
     end
   end
 
+  describe "generate_embedding/1" do
+    test "generates and stores embedding for a record without existing embedding" do
+      record = record(%{genres: ["rock", "alternative"]})
+      embedding = Enum.map(1..1536, fn _ -> 0.5 end)
+
+      Req.Test.stub(OpenAI.API, fn conn ->
+        assert conn.request_path == "/v1/embeddings"
+
+        Req.Test.json(conn, %{
+          "data" => [%{"embedding" => embedding}]
+        })
+      end)
+
+      assert {:ok, _record_embedding} = Similarity.generate_embedding(record)
+      assert {:ok, _stored} = Similarity.get_embedding(record.id)
+    end
+
+    test "returns :noop when text representation is unchanged" do
+      record = record(%{genres: ["rock", "alternative"]})
+      text = Similarity.text_representation(record)
+      embedding = Enum.map(1..1536, fn _ -> 0.5 end)
+
+      {:ok, _} = Similarity.store_embedding(record.id, embedding, text)
+
+      assert :noop = Similarity.generate_embedding(record)
+    end
+
+    test "regenerates embedding when text representation changes" do
+      record = record(%{genres: ["rock"]})
+      old_text = "Old text representation"
+      old_embedding = Enum.map(1..1536, fn _ -> 0.5 end)
+      new_embedding = Enum.map(1..1536, fn _ -> 0.9 end)
+
+      {:ok, _} = Similarity.store_embedding(record.id, old_embedding, old_text)
+
+      Req.Test.stub(OpenAI.API, fn conn ->
+        Req.Test.json(conn, %{
+          "data" => [%{"embedding" => new_embedding}]
+        })
+      end)
+
+      assert {:ok, _record_embedding} = Similarity.generate_embedding(record)
+
+      assert {:ok, stored_text} = Similarity.get_embedding_text(record.id)
+      refute stored_text == old_text
+    end
+
+    @tag :capture_log
+    test "returns error when OpenAI API fails" do
+      record = record(%{genres: ["rock"]})
+
+      Req.Test.stub(OpenAI.API, fn conn ->
+        Plug.Conn.send_resp(conn, 500, JSON.encode!(%{"error" => "internal server error"}))
+      end)
+
+      assert {:error, _reason} = Similarity.generate_embedding(record)
+    end
+  end
+
   describe "find_similar/2" do
     setup do
       # Create test records with embeddings