feat(core): add embedded v2 session runtime and tool foundation (#30632)

packages/llm/test/schema.test.ts

@@ -43,6 +43,17 @@ describe("llm schema", () => {
     expect(decoded.model.route.id).toBe("openai-responses")
   })
 
+  test("decodes chronological system messages", () => {
+    const decoded = decodeLLMRequest({
+      model,
+      system: [],
+      messages: [{ role: "system", content: [{ type: "text", text: "Operator update." }] }],
+      tools: [],
+    })
+
+    expect(decoded.messages[0]).toMatchObject({ role: "system", content: [{ type: "text", text: "Operator update." }] })
+  })
+
   test("rejects invalid event type", () => {
     expect(() => decodeLLMEvent({ type: "bogus" })).toThrow()
   })