Node agent: a node that never composed its own takes a failed placement read as not placed; one that did keeps waiting (issue 1126)

internal/selfcompose/selfcompose.go

@@ -993,8 +993,14 @@ func (r reader) Credentials(ctx context.Context, node string, asConsumer, asProv
 // marker. A read that fails chooses neither (review of the shadow, round 1: a timeout or a bus not ready at a restart
 // flipped a self-composing node to the controller's compositions for a whole run): it is tried again after wait(try),
 // each distinct failure said once, until ctx ends, which is then its error.
+//
+// switched says the node composed from its own placement key before (its have says it composes its own,
+// delivery.ComposesOwn, and that is kept on the bus, so it survives a restart). Only a node that never switched takes a
+// read that fails (a timeout, or a state its account may not read yet, as the seat's before its grant arrives) as "not
+// placed": it stays on the controller's compositions, says why once, and switches on a positive read of its key (the
+// watch endWhenPlaced keeps). A node that switched never goes back on a failed read, however long it lasts.
 func Placed(ctx context.Context, get func(ctx context.Context, bucket, key string) ([]byte, error), node string,
-	wait func(try int) time.Duration, say func(string)) (bool, error) {
+	wait func(try int) time.Duration, say func(string), switched bool) (bool, error) {
 	key, err := delivery.PlacementKey(node)
 	if err != nil {
 		return false, err
@@ -1011,6 +1017,10 @@ func Placed(ctx context.Context, get func(ctx context.Context, bucket, key strin
 		if ctx.Err() != nil {
 			return false, ctx.Err()
 		}
+		if !switched {
+			say(fmt.Sprintf("whether the catalogue places this node cannot be read (%s): it has never composed its own, so it applies the controller's compositions and switches when its key is read: %v", key, err))
+			return false, nil
+		}
 		if why := err.Error(); why != said {
 			say(fmt.Sprintf("whether the catalogue places this node cannot be read (%s): the node agent waits, choosing neither its own compositions nor the controller's: %v", key, err))
 			said = why