fix(core): recover v2 context overflow (#31005)

packages/llm/test/provider/openai-responses.test.ts

@@ -1351,7 +1351,13 @@ describe("OpenAI Responses route", () => {
         ),
       )
 
-      expect(response.events).toEqual([{ type: "provider-error", message: "context_length_exceeded: prompt too long" }])
+      expect(response.events).toEqual([
+        {
+          type: "provider-error",
+          message: "context_length_exceeded: prompt too long",
+          classification: "context-overflow",
+        },
+      ])
     }),
   )