FIX: context repairs for @mentioned bot (#608)

When the bot is @mentioned, we need to be a lot more careful
about constructing context otherwise bot gets ultra confused.

This changes multiple things:

1. We were omitting all thread first messages (fixed)
2. Include thread title (if available) in context
3. Construct context in a clearer way separating user request from data

lib/ai_bot/playground.rb

@@ -220,6 +220,13 @@ module DiscourseAi
 
       def chat_context(message, channel, persona_user)
         has_vision = bot.persona.class.vision_enabled
+        include_thread_titles = !channel.direct_message_channel? && !message.thread_id
+
+        current_id = message.id
+        if !channel.direct_message_channel?
+          # we are interacting via mentions ... strip mention
+          instruction_message = message.message.gsub(/@#{bot.bot_user.username}/i, "").strip
+        end
 
         messages = nil
 
@@ -233,7 +240,11 @@ module DiscourseAi
         elsif !channel.direct_message_channel? && !message.thread_id
           messages =
             Chat::Message
-              .where(chat_channel_id: channel.id, thread_id: nil)
+              .joins("left join chat_threads on chat_threads.id = chat_messages.thread_id")
+              .where(chat_channel_id: channel.id)
+              .where(
+                "chat_messages.thread_id IS NULL OR chat_threads.original_message_id = chat_messages.id",
+              )
               .order(id: :desc)
               .limit(max_messages)
               .to_a
@@ -250,21 +261,30 @@ module DiscourseAi
         builder = DiscourseAi::Completions::PromptMessagesBuilder.new
 
         messages.each do |m|
+          # restore stripped message
+          m.message = instruction_message if m.id == current_id && instruction_message
+
           if available_bot_user_ids.include?(m.user_id)
             builder.push(type: :model, content: m.message)
           else
             upload_ids = nil
             upload_ids = m.uploads.map(&:id) if has_vision && m.uploads.present?
+            mapped_message = m.message
+
+            thread_title = nil
+            thread_title = m.thread&.title if include_thread_titles && m.thread_id
+            mapped_message = "(#{thread_title})\n#{m.message}" if thread_title
+
             builder.push(
               type: :user,
-              content: m.message,
+              content: mapped_message,
               name: m.user.username,
               upload_ids: upload_ids,
             )
           end
         end
 
-        builder.to_a(limit: max_messages)
+        builder.to_a(limit: max_messages, style: channel.direct_message_channel? ? :default : :chat)
       end
 
       def reply_to_chat_message(message, channel)
@@ -283,6 +303,9 @@ module DiscourseAi
         reply = nil
         guardian = Guardian.new(persona_user)
 
+        force_thread = message.thread_id.nil? && channel.direct_message_channel?
+        in_reply_to_id = channel.direct_message_channel? ? message.id : nil
+
         new_prompts =
           bot.reply(context) do |partial, cancel, placeholder|
             if !reply
@@ -294,8 +317,8 @@ module DiscourseAi
                   thread_id: message.thread_id,
                   channel_id: channel.id,
                   guardian: guardian,
-                  in_reply_to_id: message.id,
+                  in_reply_to_id: in_reply_to_id,
-                  force_thread: message.thread_id.nil? && channel.direct_message_channel?,
+                  force_thread: force_thread,
                   enforce_membership: !channel.direct_message_channel?,
                 )
               ChatSDK::Message.start_stream(message_id: reply.id, guardian: guardian)

lib/completions/prompt_messages_builder.rb

@@ -3,11 +3,14 @@
 module DiscourseAi
   module Completions
     class PromptMessagesBuilder
+      MAX_CHAT_UPLOADS = 5
+
       def initialize
         @raw_messages = []
       end
 
-      def to_a(limit: nil)
+      def to_a(limit: nil, style: nil)
+        return chat_array(limit: limit) if style == :chat
         result = []
 
         # this will create a "valid" messages array
@@ -68,6 +71,51 @@ module DiscourseAi
 
         @raw_messages << message
       end
+
+      private
+
+      def chat_array(limit:)
+        buffer = +""
+
+        if @raw_messages.length > 1
+          buffer << (<<~TEXT).strip
+            You are replying inside a Discourse chat. Here is a summary of the conversation so far:
+            {{{
+          TEXT
+
+          upload_ids = []
+
+          @raw_messages[0..-2].each do |message|
+            buffer << "\n"
+
+            upload_ids.concat(message[:upload_ids]) if message[:upload_ids].present?
+
+            if message[:type] == :user
+              buffer << "#{message[:name] || "User"}: "
+            else
+              buffer << "Bot: "
+            end
+
+            buffer << message[:content]
+          end
+
+          buffer << "\n}}}"
+          buffer << "\n\n"
+          buffer << "Your instructions:"
+          buffer << "\n"
+        end
+
+        last_message = @raw_messages[-1]
+        buffer << "#{last_message[:name] || "User"} said #{last_message[:content]} "
+
+        message = { type: :user, content: buffer }
+        upload_ids.concat(last_message[:upload_ids]) if last_message[:upload_ids].present?
+
+        message[:upload_ids] = upload_ids[-MAX_CHAT_UPLOADS..-1] ||
+          upload_ids if upload_ids.present?
+
+        [message]
+      end
     end
   end
 end

spec/lib/modules/ai_bot/playground_spec.rb

@@ -147,6 +147,77 @@ RSpec.describe DiscourseAi::AiBot::Playground do
         persona.update!(allow_chat: true, mentionable: true, default_llm: "anthropic:claude-3-opus")
       end
 
+      it "should behave in a sane way when threading is enabled" do
+        channel.update!(threading_enabled: true)
+
+        message =
+          ChatSDK::Message.create(
+            channel_id: channel.id,
+            raw: "thread 1 message 1",
+            guardian: guardian,
+          )
+
+        message =
+          ChatSDK::Message.create(
+            channel_id: channel.id,
+            raw: "thread 1 message 2",
+            in_reply_to_id: message.id,
+            guardian: guardian,
+          )
+
+        thread = message.thread
+        thread.update!(title: "a magic thread")
+
+        message =
+          ChatSDK::Message.create(
+            channel_id: channel.id,
+            raw: "thread 2 message 1",
+            guardian: guardian,
+          )
+
+        message =
+          ChatSDK::Message.create(
+            channel_id: channel.id,
+            raw: "thread 2 message 2",
+            in_reply_to_id: message.id,
+            guardian: guardian,
+          )
+
+        prompts = nil
+        DiscourseAi::Completions::Llm.with_prepared_responses(["world"]) do |_, _, _prompts|
+          message =
+            ChatSDK::Message.create(
+              channel_id: channel.id,
+              raw: "Hello @#{persona.user.username}",
+              guardian: guardian,
+            )
+
+          prompts = _prompts
+        end
+
+        # don't start a thread cause it will get confusing
+        message.reload
+        expect(message.thread_id).to be_nil
+
+        prompt = prompts[0]
+
+        content = prompt.messages[1][:content]
+        # this is fragile by design, mainly so the example can be ultra clear
+        expected = (<<~TEXT).strip
+          You are replying inside a Discourse chat. Here is a summary of the conversation so far:
+          {{{
+          #{user.username}: (a magic thread)
+          thread 1 message 1
+          #{user.username}: thread 2 message 1
+          }}}
+
+          Your instructions:
+          #{user.username} said Hello
+        TEXT
+
+        expect(content.strip).to eq(expected)
+      end
+
       it "should reply to a mention if properly enabled" do
         prompts = nil