An empty declaration is sent, so a node drops what it last held (hq 127)

push skipped any node whose declaration composed to zero resources. A
node that HELD something before — the broker opening a placement gave
an adopted node, say — then kept it forever: the empty declaration that
would drop it was never sent, and the node's own heartbeat re-applied
the stale resource with no way for the mesh to say it is gone. Now the
empty declaration is sent; the host drops what the mesh owned and keeps
what it found. A node that never held anything applies it as a no-op.
Surfaced on ace: the foundation-opening fix (#74) removed its only
resource, and the correction could not reach it until this.

cmd/mesh-controller/push.go

@@ -502,8 +502,14 @@ func composeEach(names []string,
 			continue
 		}
 		if len(declared.Resources) == 0 {
-			fmt.Printf("%s is assigned nothing — skipped\n", name)
-			continue
+			// Sent, not skipped (novox/hq issue 127). A node whose declaration composes to
+			// nothing may have HELD something before — the broker opening a placement gave it,
+			// say — and skipping the empty declaration leaves that last resource in force
+			// forever, re-applied by the node's own heartbeat, with no way for the mesh to say
+			// it is gone. An empty declaration is the correction: the host drops what the mesh
+			// owned and keeps what it found (the adoption envelope still rides along). A node
+			// that never held anything applies it as the no-op it is.
+			fmt.Printf("%s owns nothing now — sent so it drops what it last held\n", name)
 		}
 		sending = append(sending, readyNode{name, declared})
 	}