The composition verb says what holds each held module and the build it would be composed at (issue 1921, milestone 47/G H4)

The node's own composition named a held module's why only; it now also says whether its manifest's verdict or this
node-engine's decoder holds it, and at which build, as the input a check's composer reads says it. Said in the held
words, so the node-engine seat's answer keeps its shape.

Claude-Session: https://claude.ai/code/session_01NcbgfFSnn24M3GcqttoU7i

internal/compose/frombus/frombus.go

@@ -171,6 +171,10 @@ type Scope struct {
 	// on the node that its manifest's verdict or its decoder holds, into compose.Input.Holds, never into what the node composes: the
 	// check's composer, judging the change's manifest itself, composes it at that build (issue 1921).
 	takeInHeld bool
+	// Holds is told, after Compose read the input, what holds each module it holds by its manifest's verdict or its
+	// decoder (compose.Input.Holds), with the build it would compose it at, so the node says why it holds it (issue 1921,
+	// the composition verb). Nil: said nowhere.
+	Holds func(map[string]compose.Hold)
 }
 
 // InOwn is, of the modules p places on its node, those whose resources the node's own composition it runs
@@ -590,6 +594,16 @@ func Compose(ctx context.Context, r Reader, mesh Mesh, s Scope, fps map[string]s
 	if err != nil {
 		return nil, nil, held, err
 	}
+	if s.Holds != nil {
+		holds := map[string]compose.Hold{}
+		for name := range held {
+			if h, said := in.Holds[name]; said {
+				h.Build = fps[name]
+				holds[name] = h
+			}
+		}
+		s.Holds(holds)
+	}
 	// The pair credentials its composition reads, asked of the vault sealed to it (ADR 0550 §5).
 	asConsumer, asProvider, err := compose.CredentialsNeeded(in, s.Node)
 	if err != nil {