Add Engine.send_file(name, mime, data) and MessageHandler.on_file. Files stream
over each open RTC data channel as binary frames — M<json meta> · C<16-byte
id><16KB chunk>… · E<id> — and reassemble on the receiver in arrival order
(the channel is reliable+ordered). The data channel now distinguishes string
(clipboard) from binary (file) messages. Files are direct-only — never relayed,
matching prefer-direct.
Transport trait gains start(...files) + a default-noop send_file (only RTC
implements it). The agent saves received files to ~/Downloads; the apps stub
on_file (receive UI is a follow-up). All MessageHandler impls updated.
Proven by examples/file_demo.rs: A sends a 50KB blob (4 chunks), B reassembles
it to identical bytes over RTC.
Follow-ups: file transfer over LAN (same-network without RTC); attach/preview UI;
progress + size cap.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Patrick Ecord
d3dd785921
