Hold a found directory, a found service's unit, a container that would mount found data, and a step run in a held container on an adopted node (hq ADR 0103)

internal/declaration/declaration.go

@@ -956,10 +956,12 @@ type Declaration struct {
 // is adopted; it is told, in every declaration, so a host restarted from the declaration it kept
 // is in the same mode it was in before.
 //
-// Untaken names, per module assigned here and not yet taken, the ids of its file and container
-// resources — the only shapes a predecessor can already have on the machine. The host cannot
-// split a resource id into its module, because module names may contain dots, so the controller
-// says which ids belong to which module rather than leaving the host to guess.
+// Untaken names, per module assigned here and not yet taken, the ids of its resources. Any kind
+// may be listed: a file, a directory, a service's unit or a container can already be on the
+// machine, and an action run inside a held container reaches what was found (novox/hq ADR 0103);
+// the host decides per kind what can be held. The host cannot split a resource id into its
+// module, because module names may contain dots, so the controller says which ids belong to which
+// module rather than leaving the host to guess.
 type Adoption struct {
 	Taken   []string            `json:"taken"`
 	Untaken map[string][]string `json:"untaken,omitempty"`
@@ -1026,15 +1028,9 @@ func checkAdoption(a *Adoption, resources []Resource, allowActions bool) []strin
 				continue
 			}
 			owner[id] = module
-			kind, declared := kinds[id]
-			switch {
-			case !declared:
+			if _, declared := kinds[id]; !declared {
 				problems = append(problems, fmt.Sprintf(
 					"adoption: %q of the untaken module %q is not in this declaration", id, module))
-			case kind != TypeFile && kind != TypeContainer:
-				problems = append(problems, fmt.Sprintf(
-					"adoption: %q of the untaken module %q is a %s, and only a file or a "+
-						"container can be found on a machine", id, module, kind))
 			}
 		}
 	}