fix(agent): validate assistant model requests

tests/unit/llm-models.test.ts

@@ -29,7 +29,13 @@ describe("normalizeLlmModelsPayload", () => {
 
   it("ignores invalid or empty model rows", () => {
     const models = normalizeLlmModelsPayload({
-      data: [{ id: "" }, { id: "   " }, { id: "bad model" }, { object: "model" }],
+      data: [
+        { id: "" },
+        { id: "   " },
+        { id: "bad model" },
+        { id: " llama3.2 " },
+        { object: "model" },
+      ],
     });
 
     assert.deepEqual(models, []);
@@ -111,6 +117,39 @@ describe("resolveAssistantModel", () => {
   });
 
   it("rejects invalid requested models", () => {
+    const resolved = resolveAssistantModel({
+      requestedModel: "bad model",
+      savedModel: null,
+      fallbackModel: "llama3.2",
+      models: [
+        { id: "llama3.2", label: "llama3.2" },
+        { id: "bad model", label: "bad model" },
+      ],
+    });
+
+    assert.deepEqual(resolved, {
+      ok: false,
+      model: "llama3.2",
+      error: "Invalid assistant model",
+    });
+  });
+
+  it("rejects empty requested models", () => {
+    const resolved = resolveAssistantModel({
+      requestedModel: "",
+      savedModel: null,
+      fallbackModel: "llama3.2",
+      models: [{ id: "llama3.2", label: "llama3.2" }],
+    });
+
+    assert.deepEqual(resolved, {
+      ok: false,
+      model: "llama3.2",
+      error: "Invalid assistant model",
+    });
+  });
+
+  it("rejects unavailable requested models", () => {
     const resolved = resolveAssistantModel({
       requestedModel: "missing",
       savedModel: null,