diff --git a/cmd/sanderling/main_test.go b/cmd/sanderling/main_test.go
index fa9ebc0..7367551 100644
--- a/cmd/sanderling/main_test.go
+++ b/cmd/sanderling/main_test.go
@@ -93,6 +93,41 @@ func TestParseTestArgs_AVDIsOptional(t *testing.T) {
 	}
 }
 
+func TestParseTestArgs_GeneratorDefaultsToSeeded(t *testing.T) {
+	options, err := parseTestArgs([]string{"--spec", "s.ts", "--bundle-id", "com.example"}, io.Discard)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if options.generator != "seeded" {
+		t.Fatalf("generator default: got %q, want seeded", options.generator)
+	}
+}
+
+func TestParseTestArgs_AcceptsLLMGenerator(t *testing.T) {
+	options, err := parseTestArgs([]string{
+		"--spec", "s.ts",
+		"--bundle-id", "com.example",
+		"--generator", "llm",
+	}, io.Discard)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if options.generator != "llm" {
+		t.Fatalf("generator: got %q, want llm", options.generator)
+	}
+}
+
+func TestParseTestArgs_RejectsUnknownGenerator(t *testing.T) {
+	_, err := parseTestArgs([]string{
+		"--spec", "s.ts",
+		"--bundle-id", "com.example",
+		"--generator", "oracle",
+	}, io.Discard)
+	if err == nil || !strings.Contains(err.Error(), "unsupported generator") {
+		t.Fatalf("expected unsupported-generator error, got %v", err)
+	}
+}
+
 func TestParseTestArgs_RejectsUnknownPlatform(t *testing.T) {
 	_, err := parseTestArgs([]string{
 		"--spec", "s.ts",
diff --git a/internal/runner/llm_source_test.go b/internal/runner/llm_source_test.go
index 044cc73..b0e936d 100644
--- a/internal/runner/llm_source_test.go
+++ b/internal/runner/llm_source_test.go
@@ -230,6 +230,39 @@ func candidateIndex(candidates []verifier.ActionCandidate, kind verifier.ActionK
 	return -1
 }
 
+func TestPickSourcesSelectsLLMWhenRequested(t *testing.T) {
+	fake := newFakeOpenRouter(t)
+	_, verifierInstance := newLLMSource(t, fake)
+	action, _, err := pickSources(Options{
+		Verifier:  verifierInstance,
+		Generator: "llm",
+		Logger:    slog.New(slog.NewTextHandler(io.Discard, nil)),
+	})
+	if err != nil {
+		t.Fatalf("pickSources: %v", err)
+	}
+	if _, ok := action.(*llmSource); !ok {
+		t.Errorf("action source = %T, want *llmSource for --generator llm", action)
+	}
+}
+
+func TestPickSourcesSeededByDefault(t *testing.T) {
+	fake := newFakeOpenRouter(t)
+	_, verifierInstance := newLLMSource(t, fake)
+	action, _, err := pickSources(Options{
+		Verifier:  verifierInstance,
+		Generator: "seeded",
+		Logger:    slog.New(slog.NewTextHandler(io.Discard, nil)),
+	})
+	if err != nil {
+		t.Fatalf("pickSources: %v", err)
+	}
+	// Even with a generator = llm() config present, the seeded flag wins.
+	if _, ok := action.(gojaSource); !ok {
+		t.Errorf("action source = %T, want gojaSource for --generator seeded", action)
+	}
+}
+
 func TestLLMSourceDrivesExecutedActions(t *testing.T) {
 	fake := newFakeOpenRouter(t)
 	source, verifierInstance := newLLMSource(t, fake)