Transport.post(text, thread=...) returns the event ID, which can root a
thread; a threaded post carries m.thread with the reply fallback for
clients without threads. Inbound messages carry their event ID and thread
root: a message in a thread gives its root, a plain reply joins the
thread of the message it replies to when known, and the quoted lines of a
rich reply are no longer part of the text. The in-memory transport plays
threads for tests.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE
dongarandClaude Opus 5.5