fix(agent): reject padded assistant model ids

tests/unit/agent-messages.test.ts

@@ -43,4 +43,13 @@ describe("clientChatInputSchema", () => {
 
     assert.equal(parsed.success, false);
   });
+
+  it("rejects whitespace-padded model IDs", () => {
+    const parsed = clientChatInputSchema.safeParse({
+      model: " qwen2.5-coder ",
+      messages: [{ role: "user", content: "hello" }],
+    });
+
+    assert.equal(parsed.success, false);
+  });
 });