ML-146: honour API retry headers

test/music_library/retry_delay_test.exs

@@ -0,0 +1,77 @@
+defmodule MusicLibrary.RetryDelayTest do
+  use ExUnit.Case, async: true
+
+  alias MusicLibrary.RetryDelay
+
+  describe "retry_after_seconds/1" do
+    test "parses integer seconds" do
+      response = response(%{"retry-after" => ["42"]})
+
+      assert RetryDelay.retry_after_seconds(response) == 42
+    end
+
+    test "clamps parsed values to safe bounds" do
+      assert RetryDelay.retry_after_seconds(response(%{"retry-after" => ["1"]})) == 5
+      assert RetryDelay.retry_after_seconds(response(%{"retry-after" => ["999"]})) == 300
+    end
+
+    test "returns nil for missing or malformed values" do
+      assert RetryDelay.retry_after_seconds(response(%{})) == nil
+      assert RetryDelay.retry_after_seconds(response(%{"retry-after" => ["tomorrow"]})) == nil
+      assert RetryDelay.retry_after_seconds(response(%{"retry-after" => ["-1"]})) == nil
+    end
+
+    test "clamps zero to the safe minimum" do
+      assert RetryDelay.retry_after_seconds(response(%{"retry-after" => ["0"]})) == 5
+    end
+  end
+
+  describe "reset_seconds/2" do
+    test "uses the largest valid comma-separated reset window" do
+      response = response(%{"x-ratelimit-reset" => ["12, 60"]})
+
+      assert RetryDelay.reset_seconds(response, "x-ratelimit-reset") == 60
+    end
+
+    test "ignores malformed windows and clamps the selected value" do
+      response = response(%{"x-ratelimit-reset" => ["bad, 2, 600"]})
+
+      assert RetryDelay.reset_seconds(response, "x-ratelimit-reset") == 300
+    end
+  end
+
+  describe "openai_reset_seconds/1" do
+    test "uses the largest reset across retry-after, request, and token windows" do
+      response =
+        response(%{
+          "retry-after" => ["10"],
+          "x-ratelimit-reset-requests" => ["20s"],
+          "x-ratelimit-reset-tokens" => ["1m30s"]
+        })
+
+      assert RetryDelay.openai_reset_seconds(response) == 90
+    end
+
+    test "clamps sub-second OpenAI durations to the safe minimum" do
+      response = response(%{"x-ratelimit-reset-requests" => ["120ms"]})
+
+      assert RetryDelay.openai_reset_seconds(response) == 5
+    end
+
+    test "parses minute durations and clamps long values" do
+      response = response(%{"x-ratelimit-reset-tokens" => ["10m"]})
+
+      assert RetryDelay.openai_reset_seconds(response) == 300
+    end
+
+    test "returns nil when OpenAI reset headers are absent or malformed" do
+      assert RetryDelay.openai_reset_seconds(response(%{})) == nil
+
+      assert RetryDelay.openai_reset_seconds(
+               response(%{"x-ratelimit-reset-requests" => ["soon"]})
+             ) == nil
+    end
+  end
+
+  defp response(headers), do: Req.Response.new(status: 429, headers: headers)
+end

test/music_library/worker/error_handler_test.exs

@@ -22,6 +22,19 @@ defmodule MusicLibrary.Worker.ErrorHandlerTest do
       assert ErrorHandler.to_oban_result({:error, err}) == {:snooze, 60}
     end
 
+    test "parsed retry headers determine the snooze duration" do
+      response =
+        Req.Response.new(
+          status: 503,
+          headers: %{"retry-after" => ["42"]},
+          body: %{"error" => "rate"}
+        )
+
+      err = MusicBrainz.API.ErrorResponse.from_response(response)
+
+      assert ErrorHandler.to_oban_result({:error, err}) == {:snooze, 42}
+    end
+
     test "Discogs 429 → {:snooze, 60}" do
       err = Discogs.API.ErrorResponse.from_response(%{status: 429, body: %{"message" => "rate"}})
       assert ErrorHandler.to_oban_result({:error, err}) == {:snooze, 60}