chore: Update the prompts to include language of the account for FAQs (#12280)

There were customer reported issues with FAQs which were generated in a
different langauge than what they were expecting. The reason behind this
was that the language of the account was not considered in the prompt
provided. If the language of the content was say Spanish, and the
account locale was english. The output was not predicable. The output
depends on the model and the execution time.

This PR would update the prompt to behave consistently with the account
locale. Even though the content provided is in a different language, it
would generate FAQs in the account locale.

Changes:
- Updated the prompt to include a detailed expectation of the FAQs
quality along with the language
- Added specs for the services where the prompt generator is called.

Tested the prompt using Phoenix playground across GPT 5, GPT 4.1, GPT
4.0. The reasoning setting for GPT 5 needs to be low so that it doesn't
generate random questions like "What was this updated?"

spec/enterprise/jobs/captain/documents/response_builder_job_spec.rb

@@ -13,7 +13,7 @@ RSpec.describe Captain::Documents::ResponseBuilderJob, type: :job do
 
   before do
     allow(Captain::Llm::FaqGeneratorService).to receive(:new)
-      .with(document.content)
+      .with(document.content, document.account.locale_english_name)
       .and_return(faq_generator)
     allow(faq_generator).to receive(:generate).and_return(faqs)
   end
@@ -43,5 +43,26 @@ RSpec.describe Captain::Documents::ResponseBuilderJob, type: :job do
         expect(first_response.documentable).to eq(document)
       end
     end
+
+    context 'with different locales' do
+      let(:spanish_account) { create(:account, locale: 'pt') }
+      let(:spanish_assistant) { create(:captain_assistant, account: spanish_account) }
+      let(:spanish_document) { create(:captain_document, assistant: spanish_assistant, account: spanish_account) }
+      let(:spanish_faq_generator) { instance_double(Captain::Llm::FaqGeneratorService) }
+
+      before do
+        allow(Captain::Llm::FaqGeneratorService).to receive(:new)
+          .with(spanish_document.content, 'portuguese')
+          .and_return(spanish_faq_generator)
+        allow(spanish_faq_generator).to receive(:generate).and_return(faqs)
+      end
+
+      it 'passes the correct locale to FAQ generator' do
+        described_class.new.perform(spanish_document)
+
+        expect(Captain::Llm::FaqGeneratorService).to have_received(:new)
+          .with(spanish_document.content, 'portuguese')
+      end
+    end
   end
 end

spec/enterprise/services/captain/llm/faq_generator_service_spec.rb

@@ -0,0 +1,87 @@
+require 'rails_helper'
+
+RSpec.describe Captain::Llm::FaqGeneratorService do
+  let(:content) { 'Sample content for FAQ generation' }
+  let(:language) { 'english' }
+  let(:service) { described_class.new(content, language) }
+  let(:client) { instance_double(OpenAI::Client) }
+
+  before do
+    create(:installation_config, name: 'CAPTAIN_OPEN_AI_API_KEY', value: 'test-key')
+    allow(OpenAI::Client).to receive(:new).and_return(client)
+  end
+
+  describe '#generate' do
+    let(:sample_faqs) do
+      [
+        { 'question' => 'What is this service?', 'answer' => 'It generates FAQs.' },
+        { 'question' => 'How does it work?', 'answer' => 'Using AI technology.' }
+      ]
+    end
+
+    let(:openai_response) do
+      {
+        'choices' => [
+          {
+            'message' => {
+              'content' => { faqs: sample_faqs }.to_json
+            }
+          }
+        ]
+      }
+    end
+
+    context 'when successful' do
+      before do
+        allow(client).to receive(:chat).and_return(openai_response)
+        allow(Captain::Llm::SystemPromptsService).to receive(:faq_generator).and_return('system prompt')
+      end
+
+      it 'returns parsed FAQs' do
+        result = service.generate
+        expect(result).to eq(sample_faqs)
+      end
+
+      it 'calls OpenAI client with chat parameters' do
+        expect(client).to receive(:chat).with(parameters: hash_including(
+          model: 'gpt-4o-mini',
+          response_format: { type: 'json_object' },
+          messages: array_including(
+            hash_including(role: 'system'),
+            hash_including(role: 'user', content: content)
+          )
+        ))
+        service.generate
+      end
+
+      it 'calls SystemPromptsService with correct language' do
+        expect(Captain::Llm::SystemPromptsService).to receive(:faq_generator).with(language)
+        service.generate
+      end
+    end
+
+    context 'with different language' do
+      let(:language) { 'spanish' }
+
+      before do
+        allow(client).to receive(:chat).and_return(openai_response)
+      end
+
+      it 'passes the correct language to SystemPromptsService' do
+        expect(Captain::Llm::SystemPromptsService).to receive(:faq_generator).with('spanish')
+        service.generate
+      end
+    end
+
+    context 'when OpenAI API fails' do
+      before do
+        allow(client).to receive(:chat).and_raise(OpenAI::Error.new('API Error'))
+      end
+
+      it 'handles the error and returns empty array' do
+        expect(Rails.logger).to receive(:error).with('OpenAI API Error: API Error')
+        expect(service.generate).to eq([])
+      end
+    end
+  end
+end