Score the recall fixture and write up what it shows

Real recall is 48% after the gate, and one must-be-silent query gets an
answer anyway. Review finding 2 (the score distributions overlap, so no
gate separates a real recall from a false one) and finding 4 (the memStore
branch at voice.go:776 is unreachable for notes). Adds an embedder cache
so the gate sweep does not re-embed the fixture nine times.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CGeSZxh1DCtRxmFVSYVGvJ

internal/memory/recalleval/recalleval.go

@@ -104,6 +104,34 @@ func InMemory() (memory.Store, func(), error) {
 	return memory.NewInMemoryStore(), func() {}, nil
 }
 
+// Cache wraps an embedder so repeated text is embedded once. The gate sweep
+// scores the same fixture at nine thresholds, and every case re-inserts the
+// filler notes — without this the ONNX run spends minutes re-embedding
+// identical strings. Latency numbers come from the uncached run.
+func Cache(inner router.Embedder) router.Embedder {
+	return &cachingEmbedder{inner: inner, seen: map[string][]float32{}}
+}
+
+type cachingEmbedder struct {
+	inner router.Embedder
+	seen  map[string][]float32
+}
+
+func (c *cachingEmbedder) Dim() int     { return c.inner.Dim() }
+func (c *cachingEmbedder) Close() error { return nil } // the caller owns inner
+
+func (c *cachingEmbedder) Embed(ctx context.Context, text string) ([]float32, error) {
+	if v, ok := c.seen[text]; ok {
+		return v, nil
+	}
+	v, err := c.inner.Embed(ctx, text)
+	if err != nil {
+		return nil, err
+	}
+	c.seen[text] = v
+	return v, nil
+}
+
 // Outcome — one scored case.
 type Outcome struct {
 	Case Case

internal/memory/recalleval/recalleval_test.go

@@ -268,7 +268,9 @@ func TestONNXRecall(t *testing.T) {
 		t.Fatalf("Score: %v", err)
 	}
 	t.Log("\n" + rep.String() + rep.Failures())
-	t.Log("\ngate sweep:\n" + sweep(t, emb, f))
+	// Cached for the sweep only: the headline run above must pay the real
+	// embedder cost so its latency numbers mean something.
+	t.Log("\ngate sweep:\n" + sweep(t, Cache(emb), f))
 }
 
 // sweep scores the fixture at a range of gates and renders one line each. Two