diff --git a/src/agents/pi-embedded-runner/extra-params.kilocode.test.ts b/src/agents/pi-embedded-runner/extra-params.kilocode.test.ts
index 97efccad7ce..b9143d20a46 100644
--- a/src/agents/pi-embedded-runner/extra-params.kilocode.test.ts
+++ b/src/agents/pi-embedded-runner/extra-params.kilocode.test.ts
@@ -1,15 +1,8 @@
-import type { StreamFn } from "@mariozechner/pi-agent-core";
-import type { Context, Model } from "@mariozechner/pi-ai";
-import { createAssistantMessageEventStream } from "@mariozechner/pi-ai";
+import type { Model } from "@mariozechner/pi-ai";
 import { afterEach, describe, expect, it } from "vitest";
 import type { OpenClawConfig } from "../../config/config.js";
 import { captureEnv } from "../../test-utils/env.js";
-import { applyExtraParamsToAgent } from "./extra-params.js";
-
-type CapturedCall = {
-  headers?: Record<string, string>;
-  payload?: Record<string, unknown>;
-};
+import { runExtraParamsCase } from "./extra-params.test-support.js";
 
 const TEST_CFG = {
   plugins: {
@@ -26,30 +19,19 @@ function applyAndCapture(params: {
   modelId: string;
   callerHeaders?: Record<string, string>;
   cfg?: OpenClawConfig;
-}): CapturedCall {
-  const captured: CapturedCall = {};
-
-  const baseStreamFn: StreamFn = (model, _context, options) => {
-    captured.headers = options?.headers;
-    options?.onPayload?.({}, model);
-    return createAssistantMessageEventStream();
-  };
-  const agent = { streamFn: baseStreamFn };
-
-  applyExtraParamsToAgent(agent, params.cfg ?? TEST_CFG, params.provider, params.modelId);
-
-  const model = {
-    api: "openai-completions",
-    provider: params.provider,
-    id: params.modelId,
-  } as Model<"openai-completions">;
-  const context: Context = { messages: [] };
-
-  void agent.streamFn?.(model, context, {
-    headers: params.callerHeaders,
+}) {
+  return runExtraParamsCase({
+    applyModelId: params.modelId,
+    applyProvider: params.provider,
+    callerHeaders: params.callerHeaders,
+    cfg: params.cfg ?? TEST_CFG,
+    model: {
+      api: "openai-completions",
+      provider: params.provider,
+      id: params.modelId,
+    } as Model<"openai-completions">,
+    payload: {},
   });
-
-  return captured;
 }
 
 function applyAndCaptureReasoning(params: {
@@ -58,35 +40,18 @@ function applyAndCaptureReasoning(params: {
   initialPayload?: Record<string, unknown>;
   thinkingLevel?: "minimal" | "low" | "medium" | "high";
 }) {
-  let capturedPayload: Record<string, unknown> | undefined;
-
-  const baseStreamFn: StreamFn = (model, _context, options) => {
-    const payload: Record<string, unknown> = { ...params.initialPayload };
-    options?.onPayload?.(payload, model);
-    capturedPayload = payload;
-    return createAssistantMessageEventStream();
-  };
-  const agent = { streamFn: baseStreamFn };
-
-  applyExtraParamsToAgent(
-    agent,
-    params.cfg ?? TEST_CFG,
-    "kilocode",
-    params.modelId,
-    undefined,
-    params.thinkingLevel ?? "high",
-  );
-
-  const model = {
-    api: "openai-completions",
-    provider: "kilocode",
-    id: params.modelId,
-  } as Model<"openai-completions">;
-  const context: Context = { messages: [] };
-
-  void agent.streamFn?.(model, context, {});
-
-  return capturedPayload;
+  return runExtraParamsCase({
+    applyModelId: params.modelId,
+    applyProvider: "kilocode",
+    cfg: params.cfg ?? TEST_CFG,
+    model: {
+      api: "openai-completions",
+      provider: "kilocode",
+      id: params.modelId,
+    } as Model<"openai-completions">,
+    payload: { ...params.initialPayload },
+    thinkingLevel: params.thinkingLevel ?? "high",
+  }).payload;
 }
 
 describe("extra-params: Kilocode wrapper", () => {
@@ -191,26 +156,18 @@ describe("extra-params: Kilocode kilo/auto reasoning", () => {
   });
 
   it("does not inject reasoning.effort for x-ai models", () => {
-    let capturedPayload: Record<string, unknown> | undefined;
-
-    const baseStreamFn: StreamFn = (model, _context, options) => {
-      const payload: Record<string, unknown> = { reasoning_effort: "high" };
-      options?.onPayload?.(payload, model);
-      capturedPayload = payload;
-      return createAssistantMessageEventStream();
-    };
-    const agent = { streamFn: baseStreamFn };
-
-    applyExtraParamsToAgent(agent, TEST_CFG, "kilocode", "x-ai/grok-3", undefined, "high");
-
-    const model = {
-      api: "openai-completions",
-      provider: "kilocode",
-      id: "x-ai/grok-3",
-    } as Model<"openai-completions">;
-    const context: Context = { messages: [] };
-
-    void agent.streamFn?.(model, context, {});
+    const capturedPayload = runExtraParamsCase({
+      applyModelId: "x-ai/grok-3",
+      applyProvider: "kilocode",
+      cfg: TEST_CFG,
+      model: {
+        api: "openai-completions",
+        provider: "kilocode",
+        id: "x-ai/grok-3",
+      } as Model<"openai-completions">,
+      payload: { reasoning_effort: "high" },
+      thinkingLevel: "high",
+    }).payload;
 
     // x-ai models reject reasoning.effort — should be skipped
     expect(capturedPayload?.reasoning).toBeUndefined();
diff --git a/src/agents/pi-embedded-runner/extra-params.openai.test.ts b/src/agents/pi-embedded-runner/extra-params.openai.test.ts
index 92e26c95ee0..f7f033f5827 100644
--- a/src/agents/pi-embedded-runner/extra-params.openai.test.ts
+++ b/src/agents/pi-embedded-runner/extra-params.openai.test.ts
@@ -1,41 +1,26 @@
-import type { StreamFn } from "@mariozechner/pi-agent-core";
-import type { Context, Model } from "@mariozechner/pi-ai";
-import { createAssistantMessageEventStream } from "@mariozechner/pi-ai";
+import type { Model } from "@mariozechner/pi-ai";
 import { afterEach, describe, expect, it } from "vitest";
 import { captureEnv } from "../../test-utils/env.js";
-import { applyExtraParamsToAgent } from "./extra-params.js";
-
-type CapturedCall = {
-  headers?: Record<string, string>;
-};
+import { runExtraParamsCase } from "./extra-params.test-support.js";
 
 function applyAndCapture(params: {
   provider: string;
   modelId: string;
   baseUrl?: string;
   callerHeaders?: Record<string, string>;
-}): CapturedCall {
-  const captured: CapturedCall = {};
-  const baseStreamFn: StreamFn = (model, _context, options) => {
-    captured.headers = options?.headers;
-    options?.onPayload?.({}, model);
-    return createAssistantMessageEventStream();
-  };
-  const agent = { streamFn: baseStreamFn };
-
-  applyExtraParamsToAgent(agent, undefined, params.provider, params.modelId);
-
-  const model = {
-    api: "openai-responses",
-    provider: params.provider,
-    id: params.modelId,
-    baseUrl: params.baseUrl,
-  } as Model<"openai-responses">;
-  const context: Context = { messages: [] };
-
-  void agent.streamFn?.(model, context, { headers: params.callerHeaders });
-
-  return captured;
+}) {
+  return runExtraParamsCase({
+    applyModelId: params.modelId,
+    applyProvider: params.provider,
+    callerHeaders: params.callerHeaders,
+    model: {
+      api: "openai-responses",
+      provider: params.provider,
+      id: params.modelId,
+      baseUrl: params.baseUrl,
+    } as Model<"openai-responses">,
+    payload: {},
+  });
 }
 
 describe("extra-params: OpenAI attribution", () => {
diff --git a/src/agents/pi-embedded-runner/extra-params.openrouter-cache-control.test.ts b/src/agents/pi-embedded-runner/extra-params.openrouter-cache-control.test.ts
index 8a09d9af547..08010bb0b20 100644
--- a/src/agents/pi-embedded-runner/extra-params.openrouter-cache-control.test.ts
+++ b/src/agents/pi-embedded-runner/extra-params.openrouter-cache-control.test.ts
@@ -1,9 +1,6 @@
-import type { StreamFn } from "@mariozechner/pi-agent-core";
-import type { Context, Model } from "@mariozechner/pi-ai";
-import { createAssistantMessageEventStream } from "@mariozechner/pi-ai";
+import type { Model } from "@mariozechner/pi-ai";
 import { describe, expect, it } from "vitest";
-import type { OpenClawConfig } from "../../config/config.js";
-import { applyExtraParamsToAgent } from "./extra-params.js";
+import { runExtraParamsCase } from "./extra-params.test-support.js";
 
 type StreamPayload = {
   messages: Array<{
@@ -13,31 +10,23 @@ type StreamPayload = {
 };
 
 function runOpenRouterPayload(payload: StreamPayload, modelId: string) {
-  const baseStreamFn: StreamFn = (model, _context, options) => {
-    options?.onPayload?.(payload, model);
-    return createAssistantMessageEventStream();
-  };
-  const agent = { streamFn: baseStreamFn };
-  const cfg = {
-    plugins: {
-      entries: {
-        openrouter: {
-          enabled: true,
+  runExtraParamsCase({
+    cfg: {
+      plugins: {
+        entries: {
+          openrouter: {
+            enabled: true,
+          },
         },
       },
     },
-  } satisfies OpenClawConfig;
-
-  applyExtraParamsToAgent(agent, cfg, "openrouter", modelId);
-
-  const model = {
-    api: "openai-completions",
-    provider: "openrouter",
-    id: modelId,
-  } as Model<"openai-completions">;
-  const context: Context = { messages: [] };
-
-  void agent.streamFn?.(model, context, {});
+    model: {
+      api: "openai-completions",
+      provider: "openrouter",
+      id: modelId,
+    } as Model<"openai-completions">,
+    payload,
+  });
 }
 
 describe("extra-params: OpenRouter Anthropic cache_control", () => {
diff --git a/src/agents/pi-embedded-runner/extra-params.test-support.ts b/src/agents/pi-embedded-runner/extra-params.test-support.ts
new file mode 100644
index 00000000000..ae4fdb9edc3
--- /dev/null
+++ b/src/agents/pi-embedded-runner/extra-params.test-support.ts
@@ -0,0 +1,56 @@
+import type { StreamFn } from "@mariozechner/pi-agent-core";
+import type { Context, Model, SimpleStreamOptions } from "@mariozechner/pi-ai";
+import type { OpenClawConfig } from "../../config/config.js";
+import { applyExtraParamsToAgent } from "./extra-params.js";
+
+export type ExtraParamsCapture<TPayload extends Record<string, unknown>> = {
+  headers?: Record<string, string>;
+  payload: TPayload;
+};
+
+type RunExtraParamsCaseParams<
+  TApi extends "openai-completions" | "openai-responses",
+  TPayload extends Record<string, unknown>,
+> = {
+  applyModelId?: string;
+  applyProvider?: string;
+  callerHeaders?: Record<string, string>;
+  cfg?: OpenClawConfig;
+  model: Model<TApi>;
+  options?: SimpleStreamOptions;
+  payload: TPayload;
+  thinkingLevel?: "minimal" | "low" | "medium" | "high";
+};
+
+export function runExtraParamsCase<
+  TApi extends "openai-completions" | "openai-responses",
+  TPayload extends Record<string, unknown>,
+>(params: RunExtraParamsCaseParams<TApi, TPayload>): ExtraParamsCapture<TPayload> {
+  const captured: ExtraParamsCapture<TPayload> = {
+    payload: params.payload,
+  };
+
+  const baseStreamFn: StreamFn = (model, _context, options) => {
+    captured.headers = options?.headers;
+    options?.onPayload?.(params.payload, model);
+    return {} as ReturnType<StreamFn>;
+  };
+  const agent = { streamFn: baseStreamFn };
+
+  applyExtraParamsToAgent(
+    agent,
+    params.cfg,
+    params.applyProvider ?? params.model.provider,
+    params.applyModelId ?? params.model.id,
+    undefined,
+    params.thinkingLevel,
+  );
+
+  const context: Context = { messages: [] };
+  void agent.streamFn?.(params.model, context, {
+    ...params.options,
+    headers: params.callerHeaders ?? params.options?.headers,
+  });
+
+  return captured;
+}
diff --git a/src/agents/pi-embedded-runner/extra-params.zai-tool-stream.test.ts b/src/agents/pi-embedded-runner/extra-params.zai-tool-stream.test.ts
index f7262a66798..b22be4231b8 100644
--- a/src/agents/pi-embedded-runner/extra-params.zai-tool-stream.test.ts
+++ b/src/agents/pi-embedded-runner/extra-params.zai-tool-stream.test.ts
@@ -1,7 +1,7 @@
-import type { StreamFn } from "@mariozechner/pi-agent-core";
-import type { Context, Model, SimpleStreamOptions } from "@mariozechner/pi-ai";
+import type { Model, SimpleStreamOptions } from "@mariozechner/pi-ai";
 import { describe, expect, it, vi } from "vitest";
-import { applyExtraParamsToAgent } from "./extra-params.js";
+import type { OpenClawConfig } from "../../config/config.js";
+import { runExtraParamsCase } from "./extra-params.test-support.js";
 
 // Mock streamSimple for testing
 vi.mock("@mariozechner/pi-ai", () => ({
@@ -15,24 +15,19 @@ type ToolStreamCase = {
   applyProvider: string;
   applyModelId: string;
   model: Model<"openai-completions">;
-  cfg?: Parameters<typeof applyExtraParamsToAgent>[1];
+  cfg?: OpenClawConfig;
   options?: SimpleStreamOptions;
 };
 
 function runToolStreamCase(params: ToolStreamCase) {
-  const payload: Record<string, unknown> = { model: params.model.id, messages: [] };
-  const baseStreamFn: StreamFn = (model, _context, options) => {
-    options?.onPayload?.(payload, model);
-    return {} as ReturnType<StreamFn>;
-  };
-  const agent = { streamFn: baseStreamFn };
-
-  applyExtraParamsToAgent(agent, params.cfg, params.applyProvider, params.applyModelId);
-
-  const context: Context = { messages: [] };
-  void agent.streamFn?.(params.model, context, params.options ?? {});
-
-  return payload;
+  return runExtraParamsCase({
+    applyModelId: params.applyModelId,
+    applyProvider: params.applyProvider,
+    cfg: params.cfg,
+    model: params.model,
+    options: params.options,
+    payload: { model: params.model.id, messages: [] },
+  }).payload;
 }
 
 describe("extra-params: Z.AI tool_stream support", () => {