recalleval: fold a doubled doc comment, name the top-k literal (V-581)

bestRecall carried two stacked doc comments (both starting "bestRecall
mirrors...") from a prior edit that appended rather than replaced;
folded into one. Also named the literal 3 passed to Search as
daemonTopK, mirroring memoryRecallWidth in actions_query.go, so the
Recall3 doc and the call site cannot drift from each other again.

internal/memory/recalleval/recalleval.go

@@ -38,6 +38,11 @@ var fixtureJSON []byte
 // other version rather than misreading a fixture and reporting a number.
 const SchemaVersion = 1
 
+// daemonTopK — how many candidates the read path asks for, mirroring
+// memoryRecallWidth in cmd/mavend/actions_query.go. Kept in step so recall@3
+// measures the same top-3 the daemon actually reads, not an arbitrary width.
+const daemonTopK = 3
+
 // StoredNote — one thing the user said once, as it lands in the semantic store.
 // Kind is "note" or "fact"; both share the vector index (see
 // cmd/mavend/recall.go), so a fact can legitimately win a recall.
@@ -267,8 +272,9 @@ type TagStat struct{ Passed, Total int }
 // Recall1 — fraction of answerable cases whose wanted note ranked first.
 func (r Report) Recall1() float64 { return ratio(r.Rank1, r.Answerable) }
 
-// Recall3 — same, in the top three. The daemon asks for 3 (voice.go), so this
-// is the ceiling a better gate or a reranker could reach.
+// Recall3 — same, in the top three. The daemon asks for daemonTopK candidates
+// (mirroring memoryRecallWidth in voice.go's caller), so this is the ceiling a
+// better gate or a reranker could reach.
 func (r Report) Recall3() float64 { return ratio(r.Rank3, r.Answerable) }
 
 // Answered — fraction of answerable cases the daemon would actually answer
@@ -399,7 +405,7 @@ func scoreCase(ctx context.Context, emb router.Embedder, newStore NewStore, minS
 		o.Reasons = []string{fmt.Sprintf("embed query: %v", err)}
 		return o, nil
 	}
-	hits, err := st.Search(ctx, qvec, 3)
+	hits, err := st.Search(ctx, qvec, daemonTopK)
 	o.Latency = time.Since(start)
 	if err != nil {
 		o.Err = err
@@ -455,14 +461,13 @@ func rankNote(inTop3 bool) string {
 }
 
 // bestRecall mirrors cmd/mavend/recall.go — the gate the daemon actually
-// applies to a memory hit. Duplicated rather than imported because package main
-// is not importable; recalleval_test.go asserts the two agree in behaviour.
-// The daemon returns the whole hit (a note and a fact are said differently);
-// the harness only scores what came back, so it keeps returning the text.
-// bestRecall mirrors the daemon's gate in cmd/mavend/recall.go, including the
-// topic veto added for #470: a score that clears the gate still has to be
-// about what he asked. Keep the two in step — a fixture that measures a
-// weaker gate than the daemon runs flatters it.
+// applies to a memory hit, including the topic veto added for #470: a score
+// that clears the gate still has to be about what he asked. Duplicated rather
+// than imported because package main is not importable; recalleval_test.go
+// asserts the two agree in behaviour, so a weaker gate here than the daemon
+// runs cannot flatter the score. The daemon returns the whole hit (a note and
+// a fact are said differently); the harness only scores what came back, so it
+// keeps returning the text.
 func bestRecall(query string, results []memory.Result, minScore, minMargin float64) string {
 	if !memory.Confident(results, minScore, minMargin) {
 		return ""