Bring wire protocol into full YAW/2 spec compliance

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>

internal/proto/proto.go

@@ -35,40 +35,64 @@ type MsgType string
 
 const (
 	MsgChat         MsgType = "chat"
+	MsgPm           MsgType = "pm"           // private message, §8
 	MsgPeerGossip   MsgType = "peer_gossip"
 	MsgFileListReq  MsgType = "file_list_req"
 	MsgFileListResp MsgType = "file_list_resp"
-	MsgFileOffer    MsgType = "file_offer"
-	MsgFileResp     MsgType = "file_response"
-	MsgFileDone     MsgType = "file_done"
+	MsgFileOffer    MsgType = "file-offer"   // §9, hyphenated per spec
+	MsgFileAccept   MsgType = "file-accept"
+	MsgFileCancel   MsgType = "file-cancel"
+	MsgFileDone     MsgType = "file-done"
 	MsgPing         MsgType = "ping"
 	MsgPong         MsgType = "pong"
 )
 
+// PmMessage is a private message sent directly over a single peer link (§8 "pm").
+// The sender/receiver are implicit from the DataChannel; no room or from fields on the wire.
+type PmMessage struct {
+	Text string `json:"text"`
+	Ts   int64  `json:"ts"` // Unix milliseconds
+}
+
 // PeerMessage is the top-level container sent over the "yaw" DataChannel.
+// The spec types (hello, chat, pm, file-offer …) are flat JSON objects; we
+// embed the fields directly using inline structs where needed, but for structured
+// types we include the payload pointer. Unknown fields are ignored (forward compat).
 // File chunks go over a separate binary DataChannel labeled "f:<xid>".
 type PeerMessage struct {
 	Type MsgType `json:"type"`
 
-	// Only one of these will be set, depending on Type.
-	Chat         *ChatMessage  `json:"chat,omitempty"`
+	// chat / pm fields (flat on the wire per spec §8)
+	Mid  string `json:"mid,omitempty"`  // optional dedup id; required when relay hops > 0
+	Room string `json:"room,omitempty"` // chat only
+	Text string `json:"text,omitempty"` // chat and pm
+	Ts   int64  `json:"ts,omitempty"`   // chat and pm (Unix ms)
+
+	// Non-spec extensions (unknown types are silently ignored by other impls)
 	Gossip       *PeerGossip   `json:"gossip,omitempty"`
 	FileListResp *FileListResp `json:"file_list_resp,omitempty"`
-	FileOffer    *FileOffer    `json:"file_offer,omitempty"`
-	FileResp     *FileResponse `json:"file_response,omitempty"`
-	FileDone     *FileDone     `json:"file_done,omitempty"`
-	Seq          *uint64       `json:"seq,omitempty"` // for ping/pong
+
+	// file transfer (§9) — fields are flat on the wire
+	Xid    string `json:"xid,omitempty"`
+	Name   string `json:"name,omitempty"`
+	Size   int64  `json:"size,omitempty"`
+	SHA256 string `json:"sha256,omitempty"`
+
+	// file-done / file-cancel / file-accept just need xid (already above)
+	Reason string `json:"reason,omitempty"` // file-cancel
+
+	Seq *uint64 `json:"seq,omitempty"` // ping/pong
 }
 
-// ChatMessage is a message to a room or a DM.
+// ChatMessage is a group chat message (wire type "chat", §8).
+// Also used internally for persisting PMs after they are received.
 type ChatMessage struct {
-	Mid    string    `json:"mid"`          // random 16-byte hex, for deduplication (YAW/2 §8)
-	ID     string    `json:"id"`           // internal uuid, kept for local use
-	From   PeerID    `json:"from"`
-	To     *PeerID   `json:"to,omitempty"` // nil = broadcast to room
-	Room   string    `json:"room"`
-	Body   string    `json:"body"`
-	SentAt time.Time `json:"sent_at"`
+	Mid  string `json:"mid,omitempty"` // optional dedup id (required when relay hops > 0)
+	From PeerID `json:"from,omitempty"` // set by receiver from DC context; not on wire for pm
+	To   *PeerID `json:"to,omitempty"`  // internal only — not transmitted; set for DMs
+	Room string `json:"room"`
+	Text string `json:"text"`
+	Ts   int64  `json:"ts"` // Unix milliseconds
 }
 
 // PeerGossip shares known peer addresses.
@@ -95,27 +119,13 @@ type FileListResp struct {
 	Files []FileEntry `json:"files"`
 }
 
-// FileOffer initiates a file transfer.
+// FileOffer is used internally when emitting EvtIncomingFile to the IPC layer.
+// On the wire, file-offer fields are flat inside PeerMessage (xid/name/size/sha256).
 type FileOffer struct {
-	Mid       string `json:"mid"`        // dedup id
-	Xid       string `json:"xid"`        // transfer id, used as DataChannel label "f:<xid>"
-	Filename  string `json:"filename"`
-	SizeBytes int64  `json:"size_bytes"`
-	SHA256    string `json:"sha256"`     // hex
-}
-
-// FileResponse accepts or declines a FileOffer.
-type FileResponse struct {
-	Mid      string `json:"mid"`
-	Xid      string `json:"xid"`
-	Accepted bool   `json:"accepted"`
-}
-
-// FileDone signals that all chunks have been sent. Receiver verifies SHA256.
-type FileDone struct {
-	Mid    string `json:"mid"`
 	Xid    string `json:"xid"`
-	SHA256 string `json:"sha256"` // hex
+	Name   string `json:"name"`
+	Size   int64  `json:"size"`
+	SHA256 string `json:"sha256"`
 }
 
 // ── DataChannel hello (YAW/2 §6) ─────────────────────────────────────────────