File chunks travel over a per-transfer "f:<xid>" WebRTC DataChannel —
direct DTLS-encrypted P2P, the anchor never sees file data. Once the
initial handshake is done the anchor can disappear and transfers continue.
Key design choices:
- Receiver sends "ok" on the file DC before sender streams, eliminating
a race where tiny files could be fully sent/closed before the receiver's
OnMessage handler is registered (open-race §6 analogue for data DCs).
- Auto-accept: receiver accepts every incoming offer immediately.
- Download dir: per-network at <data-dir>/downloads-<netid>/.
- Backpressure: bufferedAmountLowThreshold to avoid overwhelming the DC.
- SHA-256 verified on receive; mismatches emit EvtError and discard temp file.
- IPC: send_file {peer_id, path} → offers the named file from share dir.
- EvtFileComplete {transfer_id, path} emitted on success.
IPC command: {"type":"send_file","peer_id":"<hex>","path":"<filename>"}
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Five interop issues fixed against PROTOCOL.md:
- Join signature now covers nonce_raw || net_ascii (64-char UTF-8 hex
string) as specified in §5.1, not net_raw_bytes. Both anchor server
and client updated to match.
- Chat wire fields renamed to spec names: text/ts (Unix ms int64)
replacing body/sent_at (ISO timestamp). Flat layout on PeerMessage
matches §8 exactly; store and TUI updated accordingly.
- Direct messages now use the spec "pm" type (flat {type,mid,text,ts})
instead of chat+to. Receiver reconstructs a ChatMessage with
dm:<short-id> room for IPC/storage. §8 compliant.
- File transfer message types changed to spec hyphenated names:
file-offer, file-accept, file-cancel, file-done with spec field
names (name/size not filename/size_bytes). §9 compliant.
- DataChannel open-race (§14 gotcha #3) fixed with sync.Once: doOpen
fires on OnOpen callback or immediately if the channel is already
open when WireDataChannel is called (answerer race).
Also fixes two bugs found during testing:
- mid was missing from outgoing wire messages, causing all received
messages to arrive with mid="" and collide on the UNIQUE DB
constraint. mid is now included on all sent chat/pm messages; a
random mid is generated for any received message that omits it.
- Test scripts hardened: kill -9 + active lsof polling replaces blind
sleep for port cleanup; join_network sent before peer_field queries
(local_peer is now network-scoped and nil until joined).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
