Make sync work

src/syndicate/actors.nim

@@ -325,7 +325,6 @@ proc message*[T](turn: var Turn; r: Cap; v: T) =
 
 proc sync(turn: var Turn; e: Entity; peer: Cap) =
   e.sync(turn, peer)
-  # or turn.message(peer, true) ?
 
 proc sync*(turn: var Turn; r, peer: Cap) =
   enqueue(turn, r.relay) do (turn: var Turn):
@@ -595,8 +594,15 @@ proc newCap*(relay: Facet; e: Entity): Cap =
 proc newCap*(turn; e: Entity): Cap =
   Cap(relay: turn.facet, target: e)
 
-proc sync*(turn, refer: Cap, cb: proc(t: Turn) {.gcsafe.}) =
-  raiseAssert "not implemented"
+type SyncContinuation {.final.} = ref object of Entity
+  action: TurnAction
+
+method message(entity: SyncContinuation; turn: var Turn; v: AssertionRef) =
+  entity.action(turn)
+
+proc sync*(turn: var Turn; refer: Cap; act: TurnAction) =
+  let e = SyncContinuation(action: act)
+  sync(turn, refer, newCap(turn, SyncContinuation(action: act)))
 
 proc running*(actor): bool =
   result = not actor.exited

src/syndicate/protocols/protocol.nim

@@ -20,7 +20,7 @@ type
 
   Extension* = Value
   Sync* {.preservesRecord: "sync".} = object
-    `peer`* {.preservesLiteral: "#!#t".}: tuple[]
+    `peer`* {.preservesEmbedded.}: Value
 
   TurnEvent* {.preservesTuple.} = object
     `oid`*: Oid

src/syndicate/relays.nim

@@ -25,6 +25,7 @@ type
   Assertion = Value
   WireRef = sturdy.WireRef
   Turn = syndicate.Turn
+  Handle = actors.Handle
 
 type
   PacketWriter = proc (pkt: sink Packet): Future[void] {.gcsafe.}
@@ -146,10 +147,11 @@ method sync(re: RelayEntity; turn: var Turn; peer: Cap) {.gcsafe.} =
   var
     peerEntity = newSyncPeerEntity(re.relay, peer)
     exported: seq[WireSymbol]
-  discard rewriteCapOut(re.relay, turn.newCap(peerEntity), exported)
-      # TODO: discard?
+    wr = rewriteCapOut(re.relay, turn.newCap(peerEntity), exported)
   peerEntity.e = exported[0]
-  re.send(turn, Event(orKind: EventKind.Sync))
+  var ev = Event(orKind: EventKind.Sync)
+  ev.sync.peer = wr.toPreserves.embed
+  re.send(turn, ev)
 
 proc newRelayEntity(label: string; r: Relay; o: Oid): RelayEntity =
   RelayEntity(label: label, relay: r, oid: o)
@@ -170,10 +172,12 @@ proc rewriteCapIn(relay; facet; n: WireRef, imported: var seq[WireSymbol]): Cap
   case n.orKind
   of WireRefKind.mine:
     var e = relay.imported.grab(n.mine.oid)
-    if e.isNil: e = newWireSymbol(
-        relay.imported,
-        n.mine.oid,
-        newCap(facet, newRelayEntity("rewriteCapIn", relay, n.mine.oid)))
+    if e.isNil:
+      e = newWireSymbol(
+          relay.imported,
+          n.mine.oid,
+          newCap(facet, newRelayEntity("rewriteCapIn", relay, n.mine.oid)),
+        )
     imported.add e
     result = e.cap
   of WireRefKind.yours: