diff --git a/extensions/openrouter/index.test.ts b/extensions/openrouter/index.test.ts
index 8f13f27d8a6..ff633d3f9d5 100644
--- a/extensions/openrouter/index.test.ts
+++ b/extensions/openrouter/index.test.ts
@@ -3,6 +3,45 @@ import { registerSingleProviderPlugin } from "../../test/helpers/plugins/plugin-
 import openrouterPlugin from "./index.js";
 
 describe("openrouter provider hooks", () => {
+  it("owns passthrough-gemini replay policy for Gemini-backed models", async () => {
+    const provider = await registerSingleProviderPlugin(openrouterPlugin);
+
+    expect(
+      provider.buildReplayPolicy?.({
+        provider: "openrouter",
+        modelApi: "openai-completions",
+        modelId: "gemini-2.5-pro",
+      } as never),
+    ).toMatchObject({
+      applyAssistantFirstOrderingFix: false,
+      validateGeminiTurns: false,
+      validateAnthropicTurns: false,
+      sanitizeThoughtSignatures: {
+        allowBase64Only: true,
+        includeCamelCase: true,
+      },
+    });
+
+    expect(
+      provider.buildReplayPolicy?.({
+        provider: "openrouter",
+        modelApi: "openai-completions",
+        modelId: "openai/gpt-5.4",
+      } as never),
+    ).toMatchObject({
+      applyAssistantFirstOrderingFix: false,
+      validateGeminiTurns: false,
+      validateAnthropicTurns: false,
+    });
+    expect(
+      provider.buildReplayPolicy?.({
+        provider: "openrouter",
+        modelApi: "openai-completions",
+        modelId: "openai/gpt-5.4",
+      } as never),
+    ).not.toHaveProperty("sanitizeThoughtSignatures");
+  });
+
   it("owns native reasoning output mode", async () => {
     const provider = await registerSingleProviderPlugin(openrouterPlugin);