b146cf1d0e
send_document() accepted reply_to but never passed it down, so attachments always threaded from the cached per-address context (or not at all) even when the caller named the message to reply to. The plain-text path (_send_email) already honored it; the attachment path now does too. The metadata half of #10131 (send_image rejecting metadata=) was already fixed on main by the adapter parity pass. Diagnosis from #10131 and the explicit-reply_to-wins shape from PR #10321 (which targeted the pre-plugin path). Fixes #10131 Co-authored-by: LeonSGP43 <cine.dreamer.one@gmail.com>