FEATURE: Tweak HyDE prompts for better grounding in forum subject and limit response size (#200)

* FEATURE: Tweak HyDE prompts for better grounding in forum subject and limit response size

* fix test

* lint

lib/modules/embeddings/hyde_generators/anthropic.rb

@@ -6,10 +6,11 @@ module DiscourseAi
       class Anthropic < DiscourseAi::Embeddings::HydeGenerators::Base
         def prompt(search_term)
           <<~TEXT
-              Given a search term given between <input> tags, generate a forum post about the search term.
-              Respond with the generated post between <ai> tags.
-
+              Given a search term given between <input> tags, generate a forum post about a given subject.
+              #{basic_prompt_instruction}
               <input>#{search_term}</input>
+
+              Respond with the generated post between <ai> tags.
             TEXT
         end
 
@@ -22,6 +23,7 @@ module DiscourseAi
             ::DiscourseAi::Inference::AnthropicCompletions.perform!(
               prompt(query),
               SiteSetting.ai_embeddings_semantic_search_hyde_model,
+              max_tokens: 400,
             ).dig(:completion)
 
           Nokogiri::HTML5.fragment(response).at("ai").text

lib/modules/embeddings/hyde_generators/base.rb

@@ -11,6 +11,17 @@ module DiscourseAi
             )
           end
         end
+
+        def basic_prompt_instruction
+          <<~TEXT
+            Act as a content writer for a forum.
+            The forum description is as follows:
+            #{SiteSetting.title}
+            #{SiteSetting.site_description}
+
+            Given the forum description write a forum post about the following subject:
+          TEXT
+        end
       end
     end
   end

lib/modules/embeddings/hyde_generators/llama2.rb

@@ -8,12 +8,13 @@ module DiscourseAi
           <<~TEXT
               [INST] <<SYS>>
               You are a helpful bot
-              You create forum posts about a given topic
+              You create forum posts about a given subject
               <</SYS>>
 
-              Topic: #{search_term}
+              #{basic_prompt_instruction}
+              #{search_term}
               [/INST]
-              Here is a forum post about the above topic:
+              Here is a forum post about the above subject:
             TEXT
         end
 

lib/modules/embeddings/hyde_generators/llama2_ftos.rb

@@ -8,13 +8,14 @@ module DiscourseAi
           <<~TEXT
               ### System:
               You are a helpful bot
-              You create forum posts about a given topic
+              You create forum posts about a given subject
               
               ### User:
-              Topic: #{search_term}
+              #{basic_prompt_instruction}
+              #{search_term}
     
               ### Assistant:
-              Here is a forum post about the above topic:
+              Here is a forum post about the above subject:
             TEXT
         end
 

lib/modules/embeddings/hyde_generators/openai.rb

@@ -8,9 +8,9 @@ module DiscourseAi
           [
             {
               role: "system",
-              content: "You are a helpful bot. You create forum posts about a given topic.",
+              content: "You are a helpful bot. You create forum posts about a given subject.",
             },
-            { role: "user", content: "Create a forum post about the topic: #{search_term}" },
+            { role: "user", content: "#{basic_prompt_instruction}\n#{search_term}" },
           ]
         end
 
@@ -22,6 +22,7 @@ module DiscourseAi
           ::DiscourseAi::Inference::OpenAiCompletions.perform!(
             prompt(query),
             SiteSetting.ai_embeddings_semantic_search_hyde_model,
+            max_tokens: 400,
           ).dig(:choices, 0, :message, :content)
         end
       end

spec/lib/modules/embeddings/semantic_search_spec.rb

@@ -17,7 +17,13 @@ RSpec.describe DiscourseAi::Embeddings::SemanticSearch do
       SiteSetting.ai_embeddings_discourse_service_api_endpoint = "http://test.com"
 
       prompt = DiscourseAi::Embeddings::HydeGenerators::OpenAi.new.prompt(query)
-      OpenAiCompletionsInferenceStubs.stub_response(prompt, hypothetical_post)
+      OpenAiCompletionsInferenceStubs.stub_response(
+        prompt,
+        hypothetical_post,
+        req_opts: {
+          max_tokens: 400,
+        },
+      )
 
       hyde_embedding = [0.049382, 0.9999]
       EmbeddingsGenerationStubs.discourse_service(