diff --git a/packages/js-sdk/tests/volume/mount.test.ts b/packages/js-sdk/tests/volume/mount.test.ts
new file mode 100644
index 0000000000..17774059c1
--- /dev/null
+++ b/packages/js-sdk/tests/volume/mount.test.ts
@@ -0,0 +1,39 @@
+import { assert } from 'vitest'
+
+import { Sandbox, Volume } from '../../src'
+import { hostedTest, template } from '../setup'
+
+/**
+ * Volume content persisting across sandboxes is server-side behavior — the
+ * mount happens on real compute, so this is the one volume test that can't be
+ * mocked. Everything else about volumes (CRUD, pagination, error mapping, the
+ * content API) is asserted against a mocked transport in the unit tier.
+ */
+hostedTest('a mounted volume persists content across sandboxes', async () => {
+  const volume = await Volume.create(`test-mount-${Date.now()}`)
+
+  try {
+    const writer = await Sandbox.create(template, {
+      volumeMounts: { '/mnt/data': volume },
+    })
+    try {
+      await writer.files.write('/mnt/data/hello.txt', 'written by the writer')
+    } finally {
+      await writer.kill()
+    }
+
+    const reader = await Sandbox.create(template, {
+      volumeMounts: { '/mnt/data': volume },
+    })
+    try {
+      assert.equal(
+        await reader.files.read('/mnt/data/hello.txt'),
+        'written by the writer'
+      )
+    } finally {
+      await reader.kill()
+    }
+  } finally {
+    await Volume.destroy(volume.volumeId)
+  }
+})
diff --git a/packages/js-sdk/tests/volume/mountPayload.test.ts b/packages/js-sdk/tests/volume/mountPayload.test.ts
new file mode 100644
index 0000000000..0a62aeaf07
--- /dev/null
+++ b/packages/js-sdk/tests/volume/mountPayload.test.ts
@@ -0,0 +1,56 @@
+import { afterAll, afterEach, beforeAll, expect, test } from 'vitest'
+import { http, HttpResponse } from 'msw'
+import { setupServer } from 'msw/node'
+
+import { Sandbox, Volume } from '../../src'
+import { apiUrl, TEST_API_KEY } from '../setup'
+
+let lastCreateBody: Record<string, unknown> | undefined
+
+const server = setupServer(
+  http.post(apiUrl('/sandboxes'), async ({ request }) => {
+    lastCreateBody = (await request.json()) as Record<string, unknown>
+    return HttpResponse.json({
+      sandboxID: 'test-sandbox-id',
+      templateID: 'base',
+      envdVersion: '0.2.4',
+    })
+  })
+)
+
+beforeAll(() => server.listen({ onUnhandledRequest: 'error' }))
+afterAll(() => server.close())
+afterEach(() => {
+  lastCreateBody = undefined
+  server.resetHandlers()
+})
+
+test('Sandbox.create omits volumeMounts when none are requested', async () => {
+  await Sandbox.create('base', { apiKey: TEST_API_KEY })
+
+  expect(lastCreateBody).not.toHaveProperty('volumeMounts')
+})
+
+test('Sandbox.create maps mount paths to named volume mounts', async () => {
+  await Sandbox.create('base', {
+    apiKey: TEST_API_KEY,
+    volumeMounts: { '/mnt/data': 'my-volume' },
+  })
+
+  expect(lastCreateBody?.volumeMounts).toEqual([
+    { name: 'my-volume', path: '/mnt/data' },
+  ])
+})
+
+test('Sandbox.create accepts a Volume instance as the mount source', async () => {
+  const volume = new Volume('vol-1', 'my-volume', 'volume-token')
+
+  await Sandbox.create('base', {
+    apiKey: TEST_API_KEY,
+    volumeMounts: { '/mnt/data': volume },
+  })
+
+  expect(lastCreateBody?.volumeMounts).toEqual([
+    { name: 'my-volume', path: '/mnt/data' },
+  ])
+})
diff --git a/packages/python-sdk/tests/async/volume_async/test_mount.py b/packages/python-sdk/tests/async/volume_async/test_mount.py
new file mode 100644
index 0000000000..ab6616a184
--- /dev/null
+++ b/packages/python-sdk/tests/async/volume_async/test_mount.py
@@ -0,0 +1,35 @@
+"""Async counterpart of `tests/sync/volume_sync/test_mount.py`."""
+
+from uuid import uuid4
+
+import pytest
+
+from e2b import AsyncSandbox, AsyncVolume
+
+
+@pytest.mark.e2e
+@pytest.mark.skip_debug()
+async def test_mounted_volume_persists_content_across_sandboxes(template):
+    volume = await AsyncVolume.create(f"test-mount-{uuid4()}")
+
+    try:
+        writer = await AsyncSandbox.create(
+            template, volume_mounts={"/mnt/data": volume}
+        )
+        try:
+            await writer.files.write("/mnt/data/hello.txt", "written by the writer")
+        finally:
+            await writer.kill()
+
+        reader = await AsyncSandbox.create(
+            template, volume_mounts={"/mnt/data": volume}
+        )
+        try:
+            assert (
+                await reader.files.read("/mnt/data/hello.txt")
+                == "written by the writer"
+            )
+        finally:
+            await reader.kill()
+    finally:
+        await AsyncVolume.destroy(volume.volume_id)
diff --git a/packages/python-sdk/tests/shared/volume/test_mount_payload.py b/packages/python-sdk/tests/shared/volume/test_mount_payload.py
new file mode 100644
index 0000000000..b25e528a9e
--- /dev/null
+++ b/packages/python-sdk/tests/shared/volume/test_mount_payload.py
@@ -0,0 +1,77 @@
+"""Volume mounts in the sandbox create request — pure client-side shaping.
+
+Mirrors `tests/volume/mountPayload.test.ts` in the JS SDK. The mount itself is
+server-side behavior and is covered by the e2e tier (`test_mount.py`).
+"""
+
+from types import SimpleNamespace
+from typing import Any, Dict
+from unittest.mock import AsyncMock, Mock
+
+from e2b import AsyncSandbox, Sandbox, Volume
+from e2b.api.client.api.sandboxes import post_sandboxes
+from e2b.api.client.models import Sandbox as SandboxModel
+
+
+def _created_sandbox():
+    return SimpleNamespace(
+        status_code=200,
+        parsed=SandboxModel(
+            client_id="client-id",
+            envd_version="0.2.4",
+            sandbox_id="sbx-test",
+            template_id="template-id",
+        ),
+    )
+
+
+def _sync_request_body(monkeypatch, api_key: str, volume_mounts) -> Dict[str, Any]:
+    request = Mock(return_value=_created_sandbox())
+    monkeypatch.setattr(post_sandboxes, "sync_detailed", request)
+
+    Sandbox.create(api_key=api_key, volume_mounts=volume_mounts)
+
+    return request.call_args.kwargs["body"].to_dict()
+
+
+async def _async_request_body(
+    monkeypatch, api_key: str, volume_mounts
+) -> Dict[str, Any]:
+    request = AsyncMock(return_value=_created_sandbox())
+    monkeypatch.setattr(post_sandboxes, "asyncio_detailed", request)
+
+    await AsyncSandbox.create(api_key=api_key, volume_mounts=volume_mounts)
+
+    return request.call_args.kwargs["body"].to_dict()
+
+
+def test_create_omits_volume_mounts_when_none_are_requested(monkeypatch, test_api_key):
+    body = _sync_request_body(monkeypatch, test_api_key, None)
+
+    assert "volumeMounts" not in body
+
+
+def test_create_maps_mount_paths_to_named_volume_mounts(monkeypatch, test_api_key):
+    body = _sync_request_body(monkeypatch, test_api_key, {"/mnt/data": "my-volume"})
+
+    assert body["volumeMounts"] == [{"name": "my-volume", "path": "/mnt/data"}]
+
+
+def test_create_accepts_a_volume_instance_as_the_mount_source(
+    monkeypatch, test_api_key
+):
+    volume = Volume("vol-1", "my-volume", "volume-token")
+
+    body = _sync_request_body(monkeypatch, test_api_key, {"/mnt/data": volume})
+
+    assert body["volumeMounts"] == [{"name": "my-volume", "path": "/mnt/data"}]
+
+
+async def test_async_create_maps_mount_paths_to_named_volume_mounts(
+    monkeypatch, test_api_key
+):
+    body = await _async_request_body(
+        monkeypatch, test_api_key, {"/mnt/data": "my-volume"}
+    )
+
+    assert body["volumeMounts"] == [{"name": "my-volume", "path": "/mnt/data"}]
diff --git a/packages/python-sdk/tests/sync/volume_sync/test_mount.py b/packages/python-sdk/tests/sync/volume_sync/test_mount.py
new file mode 100644
index 0000000000..8f52894c08
--- /dev/null
+++ b/packages/python-sdk/tests/sync/volume_sync/test_mount.py
@@ -0,0 +1,33 @@
+"""Volume content persisting across sandboxes — real mounts, real compute.
+
+Everything else about volumes (CRUD, pagination, error mapping, the content
+API) is asserted against a mocked transport in the default tier; only the mount
+behavior needs live infrastructure. Mirrors `tests/volume/mount.test.ts`.
+"""
+
+from uuid import uuid4
+
+import pytest
+
+from e2b import Sandbox, Volume
+
+
+@pytest.mark.e2e
+@pytest.mark.skip_debug()
+def test_mounted_volume_persists_content_across_sandboxes(template):
+    volume = Volume.create(f"test-mount-{uuid4()}")
+
+    try:
+        writer = Sandbox.create(template, volume_mounts={"/mnt/data": volume})
+        try:
+            writer.files.write("/mnt/data/hello.txt", "written by the writer")
+        finally:
+            writer.kill()
+
+        reader = Sandbox.create(template, volume_mounts={"/mnt/data": volume})
+        try:
+            assert reader.files.read("/mnt/data/hello.txt") == "written by the writer"
+        finally:
+            reader.kill()
+    finally:
+        Volume.destroy(volume.volume_id)