delivery, catalogue: the node-engine's compose-candidate verb, compositions carrying their plan or refusal, the kept import form and a build's imports on its key, so the engine alone composes and the indexer switches form without a rebuild (ADR 0593 §4, §6, §7)

Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL

go/catalogue/engine_seat.go

@@ -69,6 +69,14 @@ func EngineVerbs() []Verb {
 			"responders: retried with a growing wait; a refusal never). With module, that module's apply is also tried " +
 			"again. Changes only what a pass the engine makes on its own would change.",
 			Input: schema(map[string]string{"module": "a module placed on this machine whose apply is also tried again (optional)"}, nil)},
+		// A composition that does not exist yet (novox/hq ADR 0593 §7). Optional until every engine serves it: a node
+		// whose engine does not is a node that does not answer (§9).
+		{Name: "compose-candidate", Optional: true, Description: "Compose a check's candidate on this machine in shadow, " +
+			"with its own sealed values and the indexer's manifest verdicts, and say per module placed here whether it " +
+			"composes (with its digest and whether the candidate changes it), is refused by the candidate or is held " +
+			"without it, each with why, and the verdict of the machine's own composition (novox/hq ADR 0593 §7). Read-only: " +
+			"applies nothing and writes nothing. Answered by this machine's engine alone, within the asker's bound.",
+			Input: schema(map[string]string{"candidate": "the key of the indexer's candidate, <group>.<heads hash>"}, []string{"candidate"})},
 	}
 }