diff --git a/src/infra/tsdown-config.test.ts b/src/infra/tsdown-config.test.ts
index 7a653b54804c..25893d13e736 100644
--- a/src/infra/tsdown-config.test.ts
+++ b/src/infra/tsdown-config.test.ts
@@ -81,6 +81,13 @@ function readGatewayRunLoopSource(): string {
   return readFileSync(new URL("../cli/gateway-cli/run-loop.ts", import.meta.url), "utf8");
 }
 
+function readPiModelDiscoveryCacheSource(): string {
+  return readFileSync(
+    new URL("../agents/pi-embedded-runner/model-discovery-cache.ts", import.meta.url),
+    "utf8",
+  );
+}
+
 describe("tsdown config", () => {
   it("keeps core, plugin runtime, plugin-sdk, bundled root plugins, and bundled hooks in one dist graph", () => {
     const distGraph = requireUnifiedDistGraph();
@@ -150,9 +157,15 @@ describe("tsdown config", () => {
     );
   });
 
-  it("keeps synthetic auth refs behind one stable runtime dist entry", () => {
+  it("keeps PI model discovery synthetic auth refs behind one stable runtime dist entry", () => {
     const distGraph = requireUnifiedDistGraph();
+    const importSpecifiers = [
+      ...readPiModelDiscoveryCacheSource().matchAll(
+        /from ["']([^"']*synthetic-auth\.runtime\.js)["']/gu,
+      ),
+    ].map((match) => match[1]);
 
+    expect(importSpecifiers).toEqual(["../../plugins/synthetic-auth.runtime.js"]);
     expect(entrySources(distGraph)["plugins/synthetic-auth.runtime"]).toBe(
       "src/plugins/synthetic-auth.runtime.ts",
     );