Review parts are asked one at a time: the node judges one at a time, a second ask only spent its bound waiting (issue 1966, quick fix)

Claude-Session: https://claude.ai/code/session_01JG73KK8HD1gufnqyFxMFdW

modules/mesh-knowledge/cmd/mesh-knowledge/review_parts.go

@@ -25,8 +25,9 @@ const HeadPart = "head"
 // MostFrameBytes is the most the frame of a section part holds.
 const MostFrameBytes = 16 << 10
 
-// MostParallelParts is how many judgements of one version run at once.
-const MostParallelParts = 2
+// MostParallelParts is how many judgements of one version run at once. The node runs one judgement at a time (ADR 0278
+// §25), so a second ask would only spend its own bound waiting for the first (issue 1966).
+const MostParallelParts = 1
 
 // PartReview is the latest verdict of one part: the digest of what it was judged with, so a part whose text and frame are
 // unchanged keeps it.

modules/mesh-knowledge/cmd/mesh-knowledge/review_parts_test.go

@@ -20,7 +20,7 @@ func TestAVersionIsReviewedInPartsAndARevisionJudgesOnlyWhatChanged(t *testing.T
 	var asked []string
 	var failOn string
 	inner := w.k.Judge
-	// The first two judgements wait for each other, so the test sees them run at once and not one after the other.
+	// The first judgement is counted at once; the test sees that no second one runs beside it.
 	var arrived atomic.Int32
 	meet := make(chan struct{})
 	w.k.Judge = func(q string, s map[string]any, model string) (json.RawMessage, string, error) {
@@ -63,8 +63,8 @@ func TestAVersionIsReviewedInPartsAndARevisionJudgesOnlyWhatChanged(t *testing.T
 	if e.Current.Status != StatusProposed || e.Current.Judging == nil || e.Current.Judging.State != JudgingFailed || len(e.Current.Parts) != 4 {
 		t.Fatalf("%v: %s, %+v, %d parts", said, e.Current.Status, e.Current.Judging, len(e.Current.Parts))
 	}
-	if most.Load() > MostParallelParts || most.Load() < 2 {
-		t.Fatalf("%d judgements at once; at most %d, and the parts run side by side", most.Load(), MostParallelParts)
+	if most.Load() != 1 || MostParallelParts != 1 {
+		t.Fatalf("%d judgements at once; exactly 1 (the node judges one at a time), const %d", most.Load(), MostParallelParts)
 	}
 	if got := len(w.said.of(EventPartReviewed)); got != 4 || len(w.said.of(EventReviewed)) != 1 {
 		t.Fatalf("part-reviewed %d, reviewed %d", got, len(w.said.of(EventReviewed)))