StreamChunk.message is a raw Hash while PromptResponse.message is a typed object

[TheRealNeil]

Summary

chunk.message in streaming callbacks returns a raw Hash, while response.message after generation returns a typed Common::Messages::* object. This inconsistency means .content works on one but not the other.

Example

class MyAgent < ActiveAgent::Base
  on_stream :handle_chunk

  def handle_chunk(chunk)
    chunk.message[:content]  # ✅ Works — message is a Hash
    chunk.message.content    # ❌ NoMethodError — Hash doesn't have .content
  end
end

# But after generation:
response = MyAgent.ask(message: "Hi").generate_now
response.message.content    # ✅ Works — message is a Common::Messages::Assistant
response.message[:content]  # ❌ Doesn't work

Root Cause

• PromptResponse#messages are cast through Types::MessagesType, which converts them into Common::Messages::* objects with method accessors (.content, .role).
• StreamChunk#message wraps the raw Hash from the provider's message_stack, which is built by merging deltas during streaming in ChatProvider#process_stream_chunk. No type casting is applied.

Suggestion

Consider casting StreamChunk#message through the same type system so the API is consistent, or document the difference clearly. A uniform interface where both chunk.message.content and response.message.content work would be less surprising.