diff --git a/spec/lib/captain/summary_service_spec.rb b/spec/lib/captain/summary_service_spec.rb
new file mode 100644
index 000000000..56ef0b8e2
--- /dev/null
+++ b/spec/lib/captain/summary_service_spec.rb
@@ -0,0 +1,59 @@
+require 'rails_helper'
+
+RSpec.describe Captain::SummaryService do
+  let(:account) { create(:account) }
+  let(:inbox) { create(:inbox, account: account) }
+  let(:conversation) { create(:conversation, account: account, inbox: inbox) }
+  let(:event) do
+    {
+      'name' => 'summarize',
+      'data' => {
+        'conversation_display_id' => conversation.display_id
+      }
+    }
+  end
+  let(:service) { described_class.new(account: account, event: event) }
+  let(:mock_chat) { instance_double(RubyLLM::Chat) }
+  let(:mock_context) { instance_double(RubyLLM::Context, chat: mock_chat) }
+  let(:mock_response) { instance_double(RubyLLM::Message, content: 'Summary of conversation', input_tokens: 100, output_tokens: 50) }
+
+  before do
+    create(:installation_config, name: 'CAPTAIN_OPEN_AI_API_KEY', value: 'test-key')
+    allow(Llm::Config).to receive(:with_api_key).and_yield(mock_context)
+    allow(mock_chat).to receive(:with_instructions)
+    allow(mock_chat).to receive(:ask).and_return(mock_response)
+  end
+
+  describe '#summarize_message' do
+    it 'passes correct model to API' do
+      expect(service).to receive(:make_api_call).with(
+        hash_including(model: Captain::BaseEditorService::GPT_MODEL)
+      ).and_call_original
+
+      service.summarize_message
+    end
+
+    it 'passes system prompt and conversation text as messages' do
+      allow(service).to receive(:prompt_from_file).with('summary').and_return('Summarize this')
+
+      expect(service).to receive(:make_api_call) do |args|
+        expect(args[:messages].length).to eq(2)
+        expect(args[:messages][0][:role]).to eq('system')
+        expect(args[:messages][0][:content]).to eq('Summarize this')
+        expect(args[:messages][1][:role]).to eq('user')
+        expect(args[:messages][1][:content]).to be_a(String)
+        { message: 'Summary' }
+      end
+
+      service.summarize_message
+    end
+
+    it 'returns formatted response' do
+      result = service.summarize_message
+
+      expect(result[:message]).to eq('Summary of conversation')
+      expect(result[:usage]['prompt_tokens']).to eq(100)
+      expect(result[:usage]['completion_tokens']).to eq(50)
+    end
+  end
+end