diff --git a/extensions/qa-matrix/src/runners/contract/model-selection.test.ts b/extensions/qa-matrix/src/runners/contract/model-selection.test.ts
index 5a49128416b..ede92b96d9c 100644
--- a/extensions/qa-matrix/src/runners/contract/model-selection.test.ts
+++ b/extensions/qa-matrix/src/runners/contract/model-selection.test.ts
@@ -45,6 +45,7 @@ describe("matrix qa model selection", () => {
       primaryModel: "custom-primary",
       alternateModel: "custom-alt",
     });
+    expect(loadQaLabRuntimeModule).not.toHaveBeenCalled();
     expect(defaultQaRuntimeModelForMode).not.toHaveBeenCalled();
   });
 });
diff --git a/extensions/qa-matrix/src/runners/contract/model-selection.ts b/extensions/qa-matrix/src/runners/contract/model-selection.ts
index 1f3d4652be8..338378d85f8 100644
--- a/extensions/qa-matrix/src/runners/contract/model-selection.ts
+++ b/extensions/qa-matrix/src/runners/contract/model-selection.ts
@@ -13,14 +13,21 @@ export function resolveMatrixQaModels(params: {
   alternateModel?: string;
 }): ResolvedMatrixQaModels {
   const providerMode = normalizeQaProviderMode(params.providerMode ?? "live-frontier");
+  const primaryModel = params.primaryModel?.trim();
+  const alternateModel = params.alternateModel?.trim();
+  if (primaryModel && alternateModel) {
+    return {
+      providerMode,
+      primaryModel,
+      alternateModel,
+    };
+  }
+
   const qaLabRuntime = loadQaLabRuntimeModule();
   return {
     providerMode,
-    primaryModel:
-      params.primaryModel?.trim() ||
-      qaLabRuntime.defaultQaRuntimeModelForMode(providerMode),
+    primaryModel: primaryModel || qaLabRuntime.defaultQaRuntimeModelForMode(providerMode),
     alternateModel:
-      params.alternateModel?.trim() ||
-      qaLabRuntime.defaultQaRuntimeModelForMode(providerMode, { alternate: true }),
+      alternateModel || qaLabRuntime.defaultQaRuntimeModelForMode(providerMode, { alternate: true }),
   };
 }