Apply the revision of a composition key whose digest the want names, from the revisions the bucket keeps (issue 1945)

cmd/mesh-host/nodeagent.go

@@ -294,9 +294,20 @@ func nodeAgent(ctx context.Context, opts options, signer ed25519.PublicKey, sess
 			Haves:    sessionHaves{session},
 			Kept:     keptByModule(opts, signer),
 			Recorded: recordedIn(opts.state, say),
-			Trusted:  trustedKeys(opts, signer),
-			Backup:   backupNode(session),
-			Say:      say,
+			Revisions: func(ctx context.Context, key string) ([]agent.Update, error) {
+				got, err := session.KVHistory(ctx, composedBucket, key)
+				if err != nil {
+					return nil, err
+				}
+				out := make([]agent.Update, 0, len(got))
+				for _, u := range got {
+					out = append(out, agent.Update{Key: u.Key, Value: u.Value, Revision: u.Revision, Deleted: u.Deleted})
+				}
+				return out, nil
+			},
+			Trusted: trustedKeys(opts, signer),
+			Backup:  backupNode(session),
+			Say:     say,
 			Apply: func(ctx context.Context, c delivery.Composed, others []delivery.Composed) agent.Result {
 				actx, done := applyContext(session.WithLink(ctx))
 				res := applyComposition(actx, opts, c, others, sched, say)