FIX: eat all leading spaces llms provide when they stream them (#1280)

* FIX: eat all leading spaces llms provide when they stream them

* improve so we don't stop replying...

lib/ai_bot/chat_streamer.rb

@@ -39,6 +39,9 @@ module DiscourseAi
 
       def <<(partial)
         return if partial.to_s.empty?
+        # we throw away leading spaces prior to message creation for now
+        # by design
+        return if partial.to_s.blank? && !@reply
 
         if @client_id
           ChatSDK::Channel.stop_reply(

spec/lib/modules/ai_bot/playground_spec.rb

@@ -354,7 +354,7 @@ RSpec.describe DiscourseAi::AiBot::Playground do
           )
 
         prompts = nil
-        DiscourseAi::Completions::Llm.with_prepared_responses(["world"]) do |_, _, _prompts|
+        DiscourseAi::Completions::Llm.with_prepared_responses([[" ", "world"]]) do |_, _, _prompts|
           message =
             ChatSDK::Message.create(
               channel_id: channel.id,
@@ -386,6 +386,9 @@ RSpec.describe DiscourseAi::AiBot::Playground do
         TEXT
 
         expect(content.strip).to eq(expected)
+
+        reply = Chat::Message.order(:id).last
+        expect(reply.message).to eq("world")
       end
 
       it "should reply to a mention if properly enabled" do