diff --git a/src/agents/pi-embedded-runner-extraparams-moonshot.test.ts b/src/agents/pi-embedded-runner-extraparams-moonshot.test.ts
index 94802ad04a7..23cdd18c79d 100644
--- a/src/agents/pi-embedded-runner-extraparams-moonshot.test.ts
+++ b/src/agents/pi-embedded-runner-extraparams-moonshot.test.ts
@@ -1,8 +1,6 @@
-import type { StreamFn } from "@mariozechner/pi-agent-core";
-import type { Context, Model } from "@mariozechner/pi-ai";
 import { afterEach, beforeEach, describe, expect, it } from "vitest";
+import { runExtraParamsPayloadCase } from "./pi-embedded-runner-extraparams.test-support.js";
 import { __testing as extraParamsTesting } from "./pi-embedded-runner/extra-params.js";
-import { applyExtraParamsToAgent } from "./pi-embedded-runner/extra-params.js";
 import {
   createMoonshotThinkingWrapper,
   resolveMoonshotThinkingType,
@@ -40,45 +38,8 @@ afterEach(() => {
 });
 
 describe("applyExtraParamsToAgent Moonshot and Ollama Kimi", () => {
-  function runPayloadCase(params: {
-    provider: "moonshot" | "ollama";
-    modelId: string;
-    thinkingLevel?: "off" | "low" | "medium" | "high";
-    payload?: Record<string, unknown>;
-    cfg?: Record<string, unknown>;
-  }) {
-    const payloads: Record<string, unknown>[] = [];
-    const baseStreamFn: StreamFn = (model, _context, options) => {
-      const payload = { ...params.payload };
-      options?.onPayload?.(payload, model);
-      payloads.push(payload);
-      return {} as ReturnType<StreamFn>;
-    };
-    const agent = { streamFn: baseStreamFn };
-
-    applyExtraParamsToAgent(
-      agent,
-      params.cfg as Parameters<typeof applyExtraParamsToAgent>[1],
-      params.provider,
-      params.modelId,
-      undefined,
-      params.thinkingLevel,
-    );
-
-    const model = {
-      api: "openai-completions",
-      provider: params.provider,
-      id: params.modelId,
-    } as Model<"openai-completions">;
-    const context: Context = { messages: [] };
-    void agent.streamFn?.(model, context, {});
-
-    expect(payloads).toHaveLength(1);
-    return payloads[0] ?? {};
-  }
-
   it("maps thinkingLevel=off to Moonshot thinking.type=disabled", () => {
-    const payload = runPayloadCase({
+    const payload = runExtraParamsPayloadCase({
       provider: "moonshot",
       modelId: "kimi-k2.5",
       thinkingLevel: "off",
@@ -88,7 +49,7 @@ describe("applyExtraParamsToAgent Moonshot and Ollama Kimi", () => {
   });
 
   it("maps non-off thinking levels to Moonshot thinking.type=enabled and normalizes tool_choice", () => {
-    const payload = runPayloadCase({
+    const payload = runExtraParamsPayloadCase({
       provider: "moonshot",
       modelId: "kimi-k2.5",
       thinkingLevel: "low",
@@ -100,7 +61,7 @@ describe("applyExtraParamsToAgent Moonshot and Ollama Kimi", () => {
   });
 
   it("disables thinking instead of broadening pinned Moonshot tool_choice", () => {
-    const payload = runPayloadCase({
+    const payload = runExtraParamsPayloadCase({
       provider: "moonshot",
       modelId: "kimi-k2.5",
       thinkingLevel: "low",
@@ -112,7 +73,7 @@ describe("applyExtraParamsToAgent Moonshot and Ollama Kimi", () => {
   });
 
   it("respects explicit Moonshot thinking param from model config", () => {
-    const payload = runPayloadCase({
+    const payload = runExtraParamsPayloadCase({
       provider: "moonshot",
       modelId: "kimi-k2.5",
       thinkingLevel: "high",
@@ -135,7 +96,7 @@ describe("applyExtraParamsToAgent Moonshot and Ollama Kimi", () => {
   });
 
   it("applies Moonshot payload compatibility to Ollama Kimi cloud models", () => {
-    const payload = runPayloadCase({
+    const payload = runExtraParamsPayloadCase({
       provider: "ollama",
       modelId: "kimi-k2.5:cloud",
       thinkingLevel: "low",
@@ -147,7 +108,7 @@ describe("applyExtraParamsToAgent Moonshot and Ollama Kimi", () => {
   });
 
   it("maps thinkingLevel=off for Ollama Kimi cloud models through Moonshot compatibility", () => {
-    const payload = runPayloadCase({
+    const payload = runExtraParamsPayloadCase({
       provider: "ollama",
       modelId: "kimi-k2.5:cloud",
       thinkingLevel: "off",
@@ -157,7 +118,7 @@ describe("applyExtraParamsToAgent Moonshot and Ollama Kimi", () => {
   });
 
   it("disables thinking instead of broadening pinned Ollama Kimi cloud tool_choice", () => {
-    const payload = runPayloadCase({
+    const payload = runExtraParamsPayloadCase({
       provider: "ollama",
       modelId: "kimi-k2.5:cloud",
       thinkingLevel: "low",
diff --git a/src/agents/pi-embedded-runner-extraparams-openrouter.test.ts b/src/agents/pi-embedded-runner-extraparams-openrouter.test.ts
index e343d04d8e3..77b2e3f1dfc 100644
--- a/src/agents/pi-embedded-runner-extraparams-openrouter.test.ts
+++ b/src/agents/pi-embedded-runner-extraparams-openrouter.test.ts
@@ -1,8 +1,6 @@
-import type { StreamFn } from "@mariozechner/pi-agent-core";
-import type { Context, Model } from "@mariozechner/pi-ai";
 import { afterEach, beforeEach, describe, expect, it } from "vitest";
+import { runExtraParamsPayloadCase } from "./pi-embedded-runner-extraparams.test-support.js";
 import { __testing as extraParamsTesting } from "./pi-embedded-runner/extra-params.js";
-import { applyExtraParamsToAgent } from "./pi-embedded-runner/extra-params.js";
 import {
   createOpenRouterSystemCacheWrapper,
   createOpenRouterWrapper,
@@ -49,43 +47,9 @@ afterEach(() => {
 });
 
 describe("applyExtraParamsToAgent OpenRouter reasoning", () => {
-  function runPayloadCase(params: {
-    modelId: string;
-    thinkingLevel?: "off" | "low" | "medium" | "high";
-    payload?: Record<string, unknown>;
-  }) {
-    const payloads: Record<string, unknown>[] = [];
-    const baseStreamFn: StreamFn = (model, _context, options) => {
-      const payload = { ...params.payload };
-      options?.onPayload?.(payload, model);
-      payloads.push(payload);
-      return {} as ReturnType<StreamFn>;
-    };
-    const agent = { streamFn: baseStreamFn };
-
-    applyExtraParamsToAgent(
-      agent,
-      undefined,
-      "openrouter",
-      params.modelId,
-      undefined,
-      params.thinkingLevel,
-    );
-
-    const model = {
-      api: "openai-completions",
-      provider: "openrouter",
-      id: params.modelId,
-    } as Model<"openai-completions">;
-    const context: Context = { messages: [] };
-    void agent.streamFn?.(model, context, {});
-
-    expect(payloads).toHaveLength(1);
-    return payloads[0] ?? {};
-  }
-
   it("does not inject reasoning when thinkingLevel is off (default) for OpenRouter", () => {
-    const payload = runPayloadCase({
+    const payload = runExtraParamsPayloadCase({
+      provider: "openrouter",
       modelId: "deepseek/deepseek-r1",
       thinkingLevel: "off",
       payload: { model: "deepseek/deepseek-r1" },
@@ -96,7 +60,8 @@ describe("applyExtraParamsToAgent OpenRouter reasoning", () => {
   });
 
   it("injects reasoning.effort when thinkingLevel is non-off for OpenRouter", () => {
-    const payload = runPayloadCase({
+    const payload = runExtraParamsPayloadCase({
+      provider: "openrouter",
       modelId: "openrouter/auto",
       thinkingLevel: "low",
     });
@@ -105,7 +70,8 @@ describe("applyExtraParamsToAgent OpenRouter reasoning", () => {
   });
 
   it("removes legacy reasoning_effort and keeps reasoning unset when thinkingLevel is off", () => {
-    const payload = runPayloadCase({
+    const payload = runExtraParamsPayloadCase({
+      provider: "openrouter",
       modelId: "openrouter/auto",
       thinkingLevel: "off",
       payload: { reasoning_effort: "high" },
@@ -116,7 +82,8 @@ describe("applyExtraParamsToAgent OpenRouter reasoning", () => {
   });
 
   it("does not inject effort when payload already has reasoning.max_tokens", () => {
-    const payload = runPayloadCase({
+    const payload = runExtraParamsPayloadCase({
+      provider: "openrouter",
       modelId: "openrouter/auto",
       thinkingLevel: "low",
       payload: { reasoning: { max_tokens: 256 } },
@@ -126,7 +93,8 @@ describe("applyExtraParamsToAgent OpenRouter reasoning", () => {
   });
 
   it("does not inject reasoning.effort for x-ai/grok models on OpenRouter (#32039)", () => {
-    const payload = runPayloadCase({
+    const payload = runExtraParamsPayloadCase({
+      provider: "openrouter",
       modelId: "x-ai/grok-4.1-fast",
       thinkingLevel: "medium",
       payload: { reasoning_effort: "medium" },
diff --git a/src/agents/pi-embedded-runner-extraparams.test-support.ts b/src/agents/pi-embedded-runner-extraparams.test-support.ts
new file mode 100644
index 00000000000..69ee942b67f
--- /dev/null
+++ b/src/agents/pi-embedded-runner-extraparams.test-support.ts
@@ -0,0 +1,39 @@
+import type { StreamFn } from "@mariozechner/pi-agent-core";
+import type { Context, Model } from "@mariozechner/pi-ai";
+import { applyExtraParamsToAgent } from "./pi-embedded-runner/extra-params.js";
+
+export function runExtraParamsPayloadCase(params: {
+  provider: string;
+  modelId: string;
+  thinkingLevel?: "off" | "low" | "medium" | "high";
+  payload?: Record<string, unknown>;
+  cfg?: Record<string, unknown>;
+}) {
+  const payloads: Record<string, unknown>[] = [];
+  const baseStreamFn: StreamFn = (model, _context, options) => {
+    const payload = { ...params.payload };
+    options?.onPayload?.(payload, model);
+    payloads.push(payload);
+    return {} as ReturnType<StreamFn>;
+  };
+  const agent = { streamFn: baseStreamFn };
+
+  applyExtraParamsToAgent(
+    agent,
+    params.cfg as Parameters<typeof applyExtraParamsToAgent>[1],
+    params.provider,
+    params.modelId,
+    undefined,
+    params.thinkingLevel,
+  );
+
+  const model = {
+    api: "openai-completions",
+    provider: params.provider,
+    id: params.modelId,
+  } as Model<"openai-completions">;
+  const context: Context = { messages: [] };
+  void agent.streamFn?.(model, context, {});
+
+  return payloads[0] ?? {};
+}