diff --git a/packages/core/src/client/headers.ts b/packages/core/src/client/headers.ts
index 9d84d39..5f8d30e 100644
--- a/packages/core/src/client/headers.ts
+++ b/packages/core/src/client/headers.ts
@@ -1,15 +1,19 @@
 /**
  * Shared HTTP request headers for all outgoing requests.
  *
- * Centralises the `x-dashscope-source-config` header so Bailian/DashScope API
- * transports use the same product identity. Generic npm, OSS, and result-file
- * transfers deliberately do not send this gateway-consumed metadata.
+ * Centralises the `x-dashscope-source-config` and `x-dashscope-openapisource`
+ * headers so Bailian/DashScope API transports use the same product identity.
+ * Generic npm, OSS, and result-file transfers deliberately do not send this
+ * gateway-consumed metadata.
  */
 
 import type { Identity } from "../config/schema.ts";
 
 export const CHANNEL = "bailian-cli";
 
+/** Static source identifier advertised to the DashScope/Bailian OpenAPI gateway. */
+export const OPEN_API_SOURCE = "BailianCLI";
+
 export type TrackingIdentity = Pick<Identity, "binName" | "version">;
 
 export function sourceConfig(identity: TrackingIdentity): string {
@@ -27,5 +31,6 @@ export function sourceConfig(identity: TrackingIdentity): string {
 export function trackingHeaders(identity: TrackingIdentity): Record<string, string> {
   return {
     "x-dashscope-source-config": sourceConfig(identity),
+    "x-dashscope-openapisource": OPEN_API_SOURCE,
   };
 }
diff --git a/packages/core/src/client/index.ts b/packages/core/src/client/index.ts
index 76b8615..6ad05dc 100644
--- a/packages/core/src/client/index.ts
+++ b/packages/core/src/client/index.ts
@@ -36,7 +36,13 @@ export {
   type ImageInputStyle,
   type ImageSizeProfile,
 } from "./image-routes.ts";
-export { CHANNEL, sourceConfig, trackingHeaders, type TrackingIdentity } from "./headers.ts";
+export {
+  CHANNEL,
+  OPEN_API_SOURCE,
+  sourceConfig,
+  trackingHeaders,
+  type TrackingIdentity,
+} from "./headers.ts";
 export type { HttpDeps, RequestOpts } from "./http.ts";
 export { request, requestJson } from "./http.ts";
 export { createInstrumentedFetch, type FetchImplementation } from "./instrumented-fetch.ts";
diff --git a/packages/core/tests/instrumented-fetch.test.ts b/packages/core/tests/instrumented-fetch.test.ts
index ccecf99..51eb180 100644
--- a/packages/core/tests/instrumented-fetch.test.ts
+++ b/packages/core/tests/instrumented-fetch.test.ts
@@ -57,6 +57,7 @@ test("adds UA and tracking header on Alibaba Cloud hosts", async () => {
       tags: { t1: "public", t2: "bl", t3: "1.2.3" },
     }),
   );
+  expect(headers.get("x-dashscope-openapisource")).toBe("BailianCLI");
   expect(headers.get("authorization")).toBe("Bearer k");
 });
 
@@ -66,6 +67,7 @@ test("adds UA but no tracking header on third-party hosts", async () => {
   });
   expect(headers.get("user-agent")).toBe("bailian-cli/1.2.3");
   expect(headers.get("x-dashscope-source-config")).toBeNull();
+  expect(headers.get("x-dashscope-openapisource")).toBeNull();
 });
 
 test("does not override a caller-provided User-Agent", async () => {
@@ -86,6 +88,7 @@ test("passes non-URL-parseable inputs through without tracking headers", async (
   const { url, headers } = await capture("/relative/path");
   expect(url).toBe("/relative/path");
   expect(headers.get("x-dashscope-source-config")).toBeNull();
+  expect(headers.get("x-dashscope-openapisource")).toBeNull();
 });
 
 test("uses kscli identity and version in source config", () => {