Fetch a declaration's files given by digest from the bus's object bucket, verify them and report file-references (issue 1695, ADR 0486)

mesh-sdk is pinned to fix/1694-file-references 6c857e1c025f until it merges.

internal/link/queue.go

@@ -214,7 +214,7 @@ func (q *Queue) step(ctx context.Context) bool {
 			Superseded: declaredIn(latest.Body())}, setAside, old)
 	}
 
-	report := handleBody(ctx, q.Membership, latest.Body(), q.Apply)
+	report := handleBody(q.withFiles(ctx), q.Membership, latest.Body(), q.Apply)
 	switch {
 	case report.OlderThan != nil:
 		// **Refused, counted and said** (rule 2): one line here, the count on this and every later
@@ -260,7 +260,7 @@ func (q *Queue) reconcile(ctx context.Context, asked bool) {
 		}
 		return
 	}
-	report, ok := q.Reconcile(ctx)
+	report, ok := q.Reconcile(q.withFiles(ctx))
 	if !ok {
 		if asked {
 			q.Say("asked to say what this node last applied, and the reconcile could not say it")
@@ -457,6 +457,18 @@ func (q *Queue) attach(ctx context.Context, bus Bus) {
 	q.mu.Unlock()
 }
 
+// withFiles is ctx carrying the link now open, so an apply can fetch a declaration's files given by digest (novox/hq ADR
+// 0486, issue 1695). A queue with no link open carries none.
+func (q *Queue) withFiles(ctx context.Context) context.Context {
+	q.mu.Lock()
+	bus := q.bus
+	q.mu.Unlock()
+	if bus == nil {
+		return ctx
+	}
+	return WithFiles(ctx, bus)
+}
+
 // detach is the link closing: it waits for a delivery in hand to be applied and said — an apply that
 // stood aside for its successor is reported on this link before it is let go (issue 264) — and then
 // nothing more is said on it. A reconcile in hand is not waited for: a link that was dropped or roused