feat(recommendation): extend Score with ContextualMatchScore + ContextWeight

internal/recommendation/score_test.go

@@ -148,3 +148,37 @@ func TestSkipRatio_Half(t *testing.T) {
 		t.Errorf("skipRatio(4,2) = %v, want 0.5", got)
 	}
 }
+
+func TestScore_ContextualMatch_PerfectMatchAtWeight2(t *testing.T) {
+	w := defaultWeights()
+	w.ContextWeight = 2.0
+	in := ScoringInputs{ContextualMatchScore: 1.0}
+	got := Score(in, w, time.Now(), fixedRNG(0.5))
+	// base 1.0 + recency 1.0 (never played) + contextual 2.0 = 4.0
+	want := 4.0
+	if math.Abs(got-want) > 1e-9 {
+		t.Errorf("score = %v, want %v", got, want)
+	}
+}
+
+func TestScore_ContextualMatch_HalfMatchAtWeight2(t *testing.T) {
+	w := defaultWeights()
+	w.ContextWeight = 2.0
+	in := ScoringInputs{ContextualMatchScore: 0.5}
+	got := Score(in, w, time.Now(), fixedRNG(0.5))
+	// base 1.0 + recency 1.0 + contextual 1.0 = 3.0
+	want := 3.0
+	if math.Abs(got-want) > 1e-9 {
+		t.Errorf("score = %v, want %v", got, want)
+	}
+}
+
+func TestScore_ContextualMatch_ZeroNoEffect(t *testing.T) {
+	wWithCtx := defaultWeights()
+	wWithCtx.ContextWeight = 2.0
+	withCtx := Score(ScoringInputs{ContextualMatchScore: 0}, wWithCtx, time.Now(), fixedRNG(0.5))
+	withoutCtx := Score(ScoringInputs{}, defaultWeights(), time.Now(), fixedRNG(0.5))
+	if math.Abs(withCtx-withoutCtx) > 1e-9 {
+		t.Errorf("score-with-zero-ctx = %v, score-without = %v; should be equal", withCtx, withoutCtx)
+	}
+}