Read this node's placement from its node and module keys, or its placement.<node> before the holder converts it, so a write of the holder's is composed only once its node key lands (issue 774, research 072 row 37)

internal/link/watch.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"strings"
 	"time"
 
 	"github.com/nats-io/nats.go"
@@ -23,7 +24,9 @@ type KVUpdate struct {
 // never polls.
 type KVBus interface {
 	// KVWatch yields the keys of the bucket matching the pattern now, a Caught update, then every change, until ctx ends
-	// or the link does (the channel is then closed). A bucket the node's account may not read is an error.
+	// or the link does (the channel is then closed). A bucket the node's account may not read is an error. The pattern
+	// may be several, separated by spaces (WatchPatterns), watched as one: a node's placement in either form of its
+	// keys (research 072 row 37).
 	KVWatch(ctx context.Context, bucket, pattern string) (<-chan KVUpdate, error)
 }
 
@@ -41,7 +44,7 @@ func (b OverNATS) KVWatch(ctx context.Context, bucket, pattern string) (<-chan K
 	if err != nil {
 		return nil, fmt.Errorf("the bucket %s: %w", bucket, err)
 	}
-	w, err := kv.Watch(pattern, nats.Context(ctx))
+	w, err := kv.WatchFiltered(strings.Fields(pattern), nats.Context(ctx))
 	if err != nil {
 		return nil, fmt.Errorf("watching %s in %s: %w", pattern, bucket, err)
 	}
@@ -296,3 +299,6 @@ func (q *Session) KVWatchAwait(ctx context.Context, bucket, pattern string, wait
 	}()
 	return out, nil
 }
+
+// WatchPatterns is several key patterns as one pattern KVWatch takes.
+func WatchPatterns(patterns ...string) string { return strings.Join(patterns, " ") }