diff --git a/src/agents/sandbox-paths.test.ts b/src/agents/sandbox-paths.test.ts
index b31c22a53df..20b5938ffc2 100644
--- a/src/agents/sandbox-paths.test.ts
+++ b/src/agents/sandbox-paths.test.ts
@@ -5,148 +5,100 @@ import { pathToFileURL } from "node:url";
 import { describe, expect, it } from "vitest";
 import { resolveSandboxedMediaSource } from "./sandbox-paths.js";
 
+async function withSandboxRoot<T>(run: (sandboxDir: string) => Promise<T>) {
+  const sandboxDir = await fs.mkdtemp(path.join(os.tmpdir(), "sandbox-media-"));
+  try {
+    return await run(sandboxDir);
+  } finally {
+    await fs.rm(sandboxDir, { recursive: true, force: true });
+  }
+}
+
+async function expectSandboxRejection(media: string, sandboxRoot: string, pattern: RegExp) {
+  await expect(resolveSandboxedMediaSource({ media, sandboxRoot })).rejects.toThrow(pattern);
+}
+
 describe("resolveSandboxedMediaSource", () => {
   // Group 1: /tmp paths (the bug fix)
-  it("allows absolute paths under os.tmpdir()", async () => {
-    const sandboxDir = await fs.mkdtemp(path.join(os.tmpdir(), "sandbox-media-"));
-    try {
+  it.each([
+    {
+      name: "absolute paths under os.tmpdir()",
+      media: path.join(os.tmpdir(), "image.png"),
+      expected: path.join(os.tmpdir(), "image.png"),
+    },
+    {
+      name: "file:// URLs pointing to os.tmpdir()",
+      media: pathToFileURL(path.join(os.tmpdir(), "photo.png")).href,
+      expected: path.join(os.tmpdir(), "photo.png"),
+    },
+    {
+      name: "nested paths under os.tmpdir()",
+      media: path.join(os.tmpdir(), "subdir", "deep", "file.png"),
+      expected: path.join(os.tmpdir(), "subdir", "deep", "file.png"),
+    },
+  ])("allows $name", async ({ media, expected }) => {
+    await withSandboxRoot(async (sandboxDir) => {
       const result = await resolveSandboxedMediaSource({
-        media: path.join(os.tmpdir(), "image.png"),
+        media,
         sandboxRoot: sandboxDir,
       });
-      expect(result).toBe(path.join(os.tmpdir(), "image.png"));
-    } finally {
-      await fs.rm(sandboxDir, { recursive: true, force: true });
-    }
-  });
-
-  it("allows file:// URLs pointing to os.tmpdir()", async () => {
-    const sandboxDir = await fs.mkdtemp(path.join(os.tmpdir(), "sandbox-media-"));
-    try {
-      const tmpFile = path.join(os.tmpdir(), "photo.png");
-      const fileUrl = pathToFileURL(tmpFile).href;
-      const result = await resolveSandboxedMediaSource({
-        media: fileUrl,
-        sandboxRoot: sandboxDir,
-      });
-      expect(result).toBe(tmpFile);
-    } finally {
-      await fs.rm(sandboxDir, { recursive: true, force: true });
-    }
-  });
-
-  it("allows nested paths under os.tmpdir()", async () => {
-    const sandboxDir = await fs.mkdtemp(path.join(os.tmpdir(), "sandbox-media-"));
-    try {
-      const result = await resolveSandboxedMediaSource({
-        media: path.join(os.tmpdir(), "subdir", "deep", "file.png"),
-        sandboxRoot: sandboxDir,
-      });
-      expect(result).toBe(path.join(os.tmpdir(), "subdir", "deep", "file.png"));
-    } finally {
-      await fs.rm(sandboxDir, { recursive: true, force: true });
-    }
+      expect(result).toBe(expected);
+    });
   });
 
   // Group 2: Sandbox-relative paths (existing behavior)
   it("resolves sandbox-relative paths", async () => {
-    const sandboxDir = await fs.mkdtemp(path.join(os.tmpdir(), "sandbox-media-"));
-    try {
+    await withSandboxRoot(async (sandboxDir) => {
       const result = await resolveSandboxedMediaSource({
         media: "./data/file.txt",
         sandboxRoot: sandboxDir,
       });
       expect(result).toBe(path.join(sandboxDir, "data", "file.txt"));
-    } finally {
-      await fs.rm(sandboxDir, { recursive: true, force: true });
-    }
+    });
   });
 
   // Group 3: Rejections (security)
-  it("rejects paths outside sandbox root and tmpdir", async () => {
-    const sandboxDir = await fs.mkdtemp(path.join(os.tmpdir(), "sandbox-media-"));
-    try {
-      await expect(
-        resolveSandboxedMediaSource({ media: "/etc/passwd", sandboxRoot: sandboxDir }),
-      ).rejects.toThrow(/sandbox/i);
-    } finally {
-      await fs.rm(sandboxDir, { recursive: true, force: true });
-    }
-  });
-
-  it("rejects path traversal through tmpdir", async () => {
-    const sandboxDir = await fs.mkdtemp(path.join(os.tmpdir(), "sandbox-media-"));
-    try {
-      await expect(
-        resolveSandboxedMediaSource({
-          media: path.join(os.tmpdir(), "..", "etc", "passwd"),
-          sandboxRoot: sandboxDir,
-        }),
-      ).rejects.toThrow(/sandbox/i);
-    } finally {
-      await fs.rm(sandboxDir, { recursive: true, force: true });
-    }
-  });
-
-  it("rejects relative traversal outside sandbox even when sandbox root is under tmpdir", async () => {
-    const sandboxDir = await fs.mkdtemp(path.join(os.tmpdir(), "sandbox-media-"));
-    try {
-      await expect(
-        resolveSandboxedMediaSource({
-          media: "../outside-sandbox.png",
-          sandboxRoot: sandboxDir,
-        }),
-      ).rejects.toThrow(/sandbox/i);
-    } finally {
-      await fs.rm(sandboxDir, { recursive: true, force: true });
-    }
+  it.each([
+    {
+      name: "paths outside sandbox root and tmpdir",
+      media: "/etc/passwd",
+      expected: /sandbox/i,
+    },
+    {
+      name: "path traversal through tmpdir",
+      media: path.join(os.tmpdir(), "..", "etc", "passwd"),
+      expected: /sandbox/i,
+    },
+    {
+      name: "relative traversal outside sandbox",
+      media: "../outside-sandbox.png",
+      expected: /sandbox/i,
+    },
+    {
+      name: "file:// URLs outside sandbox",
+      media: "file:///etc/passwd",
+      expected: /sandbox/i,
+    },
+    {
+      name: "invalid file:// URLs",
+      media: "file://not a valid url\x00",
+      expected: /Invalid file:\/\/ URL/,
+    },
+  ])("rejects $name", async ({ media, expected }) => {
+    await withSandboxRoot(async (sandboxDir) => {
+      await expectSandboxRejection(media, sandboxDir, expected);
+    });
   });
 
   it("rejects symlinked tmpdir paths escaping tmpdir", async () => {
     if (process.platform === "win32") {
       return;
     }
-    const sandboxDir = await fs.mkdtemp(path.join(os.tmpdir(), "sandbox-media-"));
-    const symlinkPath = path.join(sandboxDir, "tmp-link-escape");
-    try {
+    await withSandboxRoot(async (sandboxDir) => {
+      const symlinkPath = path.join(sandboxDir, "tmp-link-escape");
       await fs.symlink("/etc/passwd", symlinkPath);
-      await expect(
-        resolveSandboxedMediaSource({
-          media: symlinkPath,
-          sandboxRoot: sandboxDir,
-        }),
-      ).rejects.toThrow(/symlink|sandbox/i);
-    } finally {
-      await fs.rm(sandboxDir, { recursive: true, force: true });
-    }
-  });
-
-  it("rejects file:// URLs outside sandbox", async () => {
-    const sandboxDir = await fs.mkdtemp(path.join(os.tmpdir(), "sandbox-media-"));
-    try {
-      await expect(
-        resolveSandboxedMediaSource({
-          media: "file:///etc/passwd",
-          sandboxRoot: sandboxDir,
-        }),
-      ).rejects.toThrow(/sandbox/i);
-    } finally {
-      await fs.rm(sandboxDir, { recursive: true, force: true });
-    }
-  });
-
-  it("throws on invalid file:// URLs", async () => {
-    const sandboxDir = await fs.mkdtemp(path.join(os.tmpdir(), "sandbox-media-"));
-    try {
-      await expect(
-        resolveSandboxedMediaSource({
-          media: "file://not a valid url\x00",
-          sandboxRoot: sandboxDir,
-        }),
-      ).rejects.toThrow(/Invalid file:\/\/ URL/);
-    } finally {
-      await fs.rm(sandboxDir, { recursive: true, force: true });
-    }
+      await expectSandboxRejection(symlinkPath, sandboxDir, /symlink|sandbox/i);
+    });
   });
 
   // Group 4: Passthrough