Feature request: Support sending threaded/inline replies via `imsg send`

[blortski]

Problem

imsg send currently has no way to send a message as an inline reply to a specific previous message. When building conversational AI agents over iMessage, the agent can receive reply context (thanks to thread_originator_guid in v0.5.0), but cannot reply back in-thread.

Proposed Change

Add a --reply-to <guid> flag to imsg send that sets thread_originator_guid on the outgoing message, causing Messages.app to display it as an inline reply.

Technical Notes

• thread_originator_guid and thread_originator_part are writable fields on the message table in chat.db
• AppleScript's send command doesn't support threading, so this would likely require IMCore/MessageKit private frameworks
• I understand this may be non-trivial — just filing for visibility and to gauge interest

Use Case

AI assistants communicating via iMessage. The assistant receives a reply to message X, processes it, and wants to respond in the same thread so the conversation stays visually linked in the Messages UI.

[jamesla]

+1 this would be great