Say a deleted module's reason, read a context's reason at the merged branch, and keep the snapshot's bytes (hq ADR 0267, review)

cmd/mesh-controller/release_plan.go

@@ -1567,6 +1567,7 @@ func planWhatIf(ctx context.Context, inv *inventory.Inventory, repository string
 		return err
 	}
 	var from, packaging []inventory.Entry
+	deleted := map[string]bool{}
 	named := map[string]bool{}
 	for _, name := range modules {
 		named[name] = true
@@ -1576,6 +1577,9 @@ func planWhatIf(ctx context.Context, inv *inventory.Inventory, repository string
 		// request's check ask it (novox/hq ADR 0238).
 		r := reachOfMerge(m, entries, read, nil)
 		from, packaging = append(append([]inventory.Entry{}, r.Touched...), r.Deleted...), r.Packaging
+		for _, e := range r.Deleted {
+			deleted[e.Manifest.Module] = true
+		}
 	} else {
 		for _, e := range entries {
 			switch {
@@ -1609,6 +1613,9 @@ func planWhatIf(ctx context.Context, inv *inventory.Inventory, repository string
 	if len(named) == 0 {
 		for _, e := range from {
 			why[e.Manifest.Module] = whyMoved(e, read[e.Manifest.Module], m)
+			if deleted[e.Manifest.Module] {
+				why[e.Manifest.Module] = "its manifest is removed: deleted at its source, forgotten where nothing holds it, not built"
+			}
 		}
 	}
 	rolls := map[string]string{}