Preserve exact smoke-test selections

internal/usecase/smoke_selection_test.go

@@ -262,6 +262,27 @@ func TestResolveSmokeTestTargetSelectionAndSettingsErrors(t *testing.T) {
 			},
 			wantErr: ErrProfileLoad,
 		},
+		{
+			name: "invalid prompt selection does not fall back",
+			request: domain.SmokeTestRequest{
+				Kind: domain.SmokeTestTextInference, PromptID: "missing.prompt", BackendID: "epsilon",
+			},
+			wantErr: ErrPromptLoad,
+		},
+		{
+			name: "blank explicit profile does not fall back",
+			request: domain.SmokeTestRequest{
+				Kind: domain.SmokeTestTextInference, ProfileID: " ", BackendID: "epsilon",
+			},
+			wantErr: ErrInvalidRequest,
+		},
+		{
+			name: "version cannot be supplied without prompt",
+			request: domain.SmokeTestRequest{
+				Kind: domain.SmokeTestTextInference, PromptVersion: " ", BackendID: "epsilon",
+			},
+			wantErr: ErrInvalidRequest,
+		},
 		{
 			name:    "dangling backend default fails only when selected",
 			request: domain.SmokeTestRequest{Kind: domain.SmokeTestTextInference, BackendID: "delta"},