Preserve reported token usage presence

llm_adapter_internal_test.go

@@ -47,6 +47,30 @@ func TestPublicLLMClientAdapterGivesClientOwnedNestedValues(t *testing.T) {
 	}
 }
 
+func TestPublicLLMClientAdapterCopiesUsagePresence(t *testing.T) {
+	presence := &TokenUsagePresence{PromptTokens: true}
+	client := &usagePresenceClient{response: &GenerateResponse{
+		Content:       "ok",
+		Usage:         TokenUsage{PromptTokens: 0, TotalTokens: 5},
+		UsagePresence: presence,
+	}}
+	adapter := publicLLMClientAdapter{client: client}
+	got, err := adapter.Generate(context.Background(), domain.GenerateRequest{})
+	if err != nil {
+		t.Fatal(err)
+	}
+	presence.PromptTokens = false
+	if got.UsagePresence == nil || !got.UsagePresence.PromptTokens || got.UsagePresence.TotalTokens || got.Usage.TotalTokens != 5 {
+		t.Fatalf("copied response = %+v", got)
+	}
+}
+
+type usagePresenceClient struct{ response *GenerateResponse }
+
+func (c *usagePresenceClient) Generate(context.Context, GenerateRequest) (*GenerateResponse, error) {
+	return c.response, nil
+}
+
 type retainingMutatingLLMClient struct {
 	retained GenerateRequest
 }