feat(rtk): add X-9Router-Token-Saver header to bypass token savers per request

tests/unit/headroom-chat-core.test.js

@@ -250,4 +250,48 @@ describe("handleChatCore Headroom diagnostics", () => {
       expect.stringContaining("reported token delta, but outbound JSON shrank <5%; provider may bill near-original payload")
     );
   });
+
+  it("bypasses token savers when requested by the client", async () => {
+    const log = { debug: vi.fn(), info: vi.fn(), warn: vi.fn() };
+    const pxpipeTransform = vi.fn();
+    const messages = [{ role: "user", content: "Write polished prose." }];
+
+    global.fetch = vi.fn(async (url) => {
+      throw new Error(`unexpected fetch: ${url}`);
+    });
+
+    await handleChatCore({
+      body: { model: "gpt-4o", stream: false, messages },
+      modelInfo: { provider: "openai", model: "gpt-4o" },
+      credentials: { apiKey: "test-key", providerSpecificData: {} },
+      log,
+      connectionId: "test-conn",
+      headroomEnabled: true,
+      headroomUrl: "http://localhost:8787",
+      headroomCompressUserMessages: true,
+      rtkEnabled: true,
+      cavemanEnabled: true,
+      cavemanLevel: "full",
+      ponytailEnabled: true,
+      ponytailLevel: "full",
+      pxpipeEnabled: true,
+      pxpipeTransform,
+      clientRawRequest: {
+        endpoint: "/v1/chat/completions",
+        body: {},
+        headers: {
+          accept: "application/json",
+          "x-9router-token-saver": "off",
+        },
+      },
+    });
+
+    expect(global.fetch).not.toHaveBeenCalled();
+    expect(pxpipeTransform).not.toHaveBeenCalled();
+    expect(executeMock).toHaveBeenCalledWith(expect.objectContaining({
+      body: expect.objectContaining({
+        messages: [{ role: "user", content: "Write polished prose." }],
+      }),
+    }));
+  });
 });