diff --git a/src/agents/pi-embedded-runner/proxy-stream-wrappers.test.ts b/src/agents/pi-embedded-runner/proxy-stream-wrappers.test.ts
index 48dcb2b9041..7b3757d0cf8 100644
--- a/src/agents/pi-embedded-runner/proxy-stream-wrappers.test.ts
+++ b/src/agents/pi-embedded-runner/proxy-stream-wrappers.test.ts
@@ -7,6 +7,30 @@ import {
   createOpenRouterWrapper,
 } from "./proxy-stream-wrappers.js";
 
+function runSystemCacheWrapper(model: Partial<Model<"openai-completions">>) {
+  const payload = {
+    messages: [{ role: "system", content: "system prompt" }],
+  };
+  const baseStreamFn: StreamFn = (resolvedModel, _context, options) => {
+    options?.onPayload?.(payload, resolvedModel);
+    return createAssistantMessageEventStream();
+  };
+
+  const wrapped = createOpenRouterSystemCacheWrapper(baseStreamFn);
+  void wrapped(
+    {
+      api: "openai-completions",
+      provider: "openrouter",
+      id: "anthropic/claude-sonnet-4.6",
+      ...model,
+    } as Model<"openai-completions">,
+    { messages: [] },
+    {},
+  );
+
+  return payload;
+}
+
 describe("proxy stream wrappers", () => {
   it("adds OpenRouter attribution headers to stream options", () => {
     const calls: Array<{ headers?: Record<string, string> }> = [];
@@ -40,24 +64,7 @@ describe("proxy stream wrappers", () => {
   });
 
   it("injects cache_control markers for declared OpenRouter Anthropic models on the default route", () => {
-    const payload = {
-      messages: [{ role: "system", content: "system prompt" }],
-    };
-    const baseStreamFn: StreamFn = (model, _context, options) => {
-      options?.onPayload?.(payload, model);
-      return createAssistantMessageEventStream();
-    };
-
-    const wrapped = createOpenRouterSystemCacheWrapper(baseStreamFn);
-    void wrapped(
-      {
-        api: "openai-completions",
-        provider: "openrouter",
-        id: "anthropic/claude-sonnet-4.6",
-      } as Model<"openai-completions">,
-      { messages: [] },
-      {},
-    );
+    const payload = runSystemCacheWrapper({});
 
     expect(payload.messages[0]?.content).toEqual([
       { type: "text", text: "system prompt", cache_control: { type: "ephemeral" } },
@@ -65,49 +72,18 @@ describe("proxy stream wrappers", () => {
   });
 
   it("does not inject cache_control markers for declared OpenRouter providers on custom proxy URLs", () => {
-    const payload = {
-      messages: [{ role: "system", content: "system prompt" }],
-    };
-    const baseStreamFn: StreamFn = (model, _context, options) => {
-      options?.onPayload?.(payload, model);
-      return createAssistantMessageEventStream();
-    };
-
-    const wrapped = createOpenRouterSystemCacheWrapper(baseStreamFn);
-    void wrapped(
-      {
-        api: "openai-completions",
-        provider: "openrouter",
-        id: "anthropic/claude-sonnet-4.6",
-        baseUrl: "https://proxy.example.com/v1",
-      } as Model<"openai-completions">,
-      { messages: [] },
-      {},
-    );
+    const payload = runSystemCacheWrapper({
+      baseUrl: "https://proxy.example.com/v1",
+    });
 
     expect(payload.messages[0]?.content).toBe("system prompt");
   });
 
   it("injects cache_control markers for native OpenRouter hosts behind custom provider ids", () => {
-    const payload = {
-      messages: [{ role: "system", content: "system prompt" }],
-    };
-    const baseStreamFn: StreamFn = (model, _context, options) => {
-      options?.onPayload?.(payload, model);
-      return createAssistantMessageEventStream();
-    };
-
-    const wrapped = createOpenRouterSystemCacheWrapper(baseStreamFn);
-    void wrapped(
-      {
-        api: "openai-completions",
-        provider: "custom-openrouter",
-        id: "anthropic/claude-sonnet-4.6",
-        baseUrl: "https://openrouter.ai/api/v1",
-      } as Model<"openai-completions">,
-      { messages: [] },
-      {},
-    );
+    const payload = runSystemCacheWrapper({
+      provider: "custom-openrouter",
+      baseUrl: "https://openrouter.ai/api/v1",
+    });
 
     expect(payload.messages[0]?.content).toEqual([
       { type: "text", text: "system prompt", cache_control: { type: "ephemeral" } },