diff --git a/src/agents/sandbox/fs-bridge.anchored-ops.test.ts b/src/agents/sandbox/fs-bridge.anchored-ops.test.ts
index 48e7e9e23f8..f92e99cc3c6 100644
--- a/src/agents/sandbox/fs-bridge.anchored-ops.test.ts
+++ b/src/agents/sandbox/fs-bridge.anchored-ops.test.ts
@@ -4,6 +4,7 @@ import { describe, expect, it } from "vitest";
 import {
   createSandbox,
   createSandboxFsBridge,
+  createSeededSandboxFsBridge,
   dockerExecResult,
   findCallsByScriptFragment,
   findCallByDockerArg,
@@ -103,17 +104,7 @@ describe("sandbox fs bridge anchored ops", () => {
 
   it.each(pinnedCases)("$name", async (testCase) => {
     await withTempDir("openclaw-fs-bridge-contract-write-", async (stateDir) => {
-      const workspaceDir = path.join(stateDir, "workspace");
-      await fs.mkdir(path.join(workspaceDir, "nested"), { recursive: true });
-      await fs.writeFile(path.join(workspaceDir, "from.txt"), "hello", "utf8");
-      await fs.writeFile(path.join(workspaceDir, "nested", "file.txt"), "bye", "utf8");
-
-      const bridge = createSandboxFsBridge({
-        sandbox: createSandbox({
-          workspaceDir,
-          agentWorkspaceDir: workspaceDir,
-        }),
-      });
+      const { bridge } = await createSeededSandboxFsBridge(stateDir);
 
       await testCase.invoke(bridge);
 
diff --git a/src/agents/sandbox/fs-bridge.shell.test.ts b/src/agents/sandbox/fs-bridge.shell.test.ts
index 1685759ad38..1e870ef0268 100644
--- a/src/agents/sandbox/fs-bridge.shell.test.ts
+++ b/src/agents/sandbox/fs-bridge.shell.test.ts
@@ -4,6 +4,7 @@ import { describe, expect, it } from "vitest";
 import {
   createSandbox,
   createSandboxFsBridge,
+  createSeededSandboxFsBridge,
   getScriptsFromCalls,
   installFsBridgeTestHarness,
   mockedExecDockerRaw,
@@ -140,16 +141,8 @@ describe("sandbox fs bridge shell compatibility", () => {
 
   it("routes mkdirp, remove, and rename through the pinned mutation helper", async () => {
     await withTempDir("openclaw-fs-bridge-shell-write-", async (stateDir) => {
-      const workspaceDir = path.join(stateDir, "workspace");
-      await fs.mkdir(path.join(workspaceDir, "nested"), { recursive: true });
-      await fs.writeFile(path.join(workspaceDir, "a.txt"), "hello", "utf8");
-      await fs.writeFile(path.join(workspaceDir, "nested", "file.txt"), "bye", "utf8");
-
-      const bridge = createSandboxFsBridge({
-        sandbox: createSandbox({
-          workspaceDir,
-          agentWorkspaceDir: workspaceDir,
-        }),
+      const { bridge } = await createSeededSandboxFsBridge(stateDir, {
+        rootFileName: "a.txt",
       });
 
       await bridge.mkdirp({ filePath: "nested" });
diff --git a/src/agents/sandbox/fs-bridge.test-helpers.ts b/src/agents/sandbox/fs-bridge.test-helpers.ts
index 87a184154af..0747371478d 100644
--- a/src/agents/sandbox/fs-bridge.test-helpers.ts
+++ b/src/agents/sandbox/fs-bridge.test-helpers.ts
@@ -79,6 +79,36 @@ export function createSandbox(overrides?: Partial<SandboxContext>): SandboxConte
   });
 }
 
+export async function createSeededSandboxFsBridge(
+  stateDir: string,
+  params?: {
+    rootFileName?: string;
+    rootContents?: string;
+    nestedFileName?: string;
+    nestedContents?: string;
+  },
+) {
+  const workspaceDir = path.join(stateDir, "workspace");
+  await fs.mkdir(path.join(workspaceDir, "nested"), { recursive: true });
+  await fs.writeFile(
+    path.join(workspaceDir, params?.rootFileName ?? "from.txt"),
+    params?.rootContents ?? "hello",
+    "utf8",
+  );
+  await fs.writeFile(
+    path.join(workspaceDir, "nested", params?.nestedFileName ?? "file.txt"),
+    params?.nestedContents ?? "bye",
+    "utf8",
+  );
+  const bridge = createSandboxFsBridge({
+    sandbox: createSandbox({
+      workspaceDir,
+      agentWorkspaceDir: workspaceDir,
+    }),
+  });
+  return { workspaceDir, bridge };
+}
+
 export async function withTempDir<T>(
   prefix: string,
   run: (stateDir: string) => Promise<T>,