diff --git a/README.md b/README.md
index a89004c..6e7f564 100644
--- a/README.md
+++ b/README.md
@@ -72,12 +72,19 @@ from aio_lib_sandbox import Sandbox
 sandbox = await Sandbox.create(
     name="my-sandbox",
     type="cpu:default",
+    idle_timeout=900,
     max_lifetime=3600,
     ports=[3000, 8080],
     envs={"API_KEY": "your-api-key"},
 )
 ```
 
+#### Sandbox lifetime model
+
+A sandbox is always deleted when `max_lifetime` has elapsed. It will also be deleted after the `idle_timeout` has elapsed, if there has been no activity.
+
+To keep a sandbox alive, send at least one command or check the status every `idle_timeout` seconds.
+
 ### Get Status
 
 ```python
diff --git a/src/aio_lib_sandbox/sandbox.py b/src/aio_lib_sandbox/sandbox.py
index 5b6880c..3f392a8 100644
--- a/src/aio_lib_sandbox/sandbox.py
+++ b/src/aio_lib_sandbox/sandbox.py
@@ -53,6 +53,7 @@ def __init__(
         status: str,
         cluster: str | None = None,
         region: str | None = None,
+        idle_timeout: int = 900,
         max_lifetime: int = 3600,
         namespace: str,
         api_host: str,
@@ -67,6 +68,7 @@ def __init__(
         self.status = status
         self.cluster = cluster
         self.region = region
+        self.idle_timeout = idle_timeout
         self.max_lifetime = max_lifetime
 
         self.namespace = namespace
@@ -93,6 +95,7 @@ async def create(
         auth: str | None = None,
         type: str = "cpu:default",
         size: str | dict[str, Any] | None = None,
+        idle_timeout: int = 900,
         max_lifetime: int = 3600,
         ports: list[int] | None = None,
         envs: dict[str, str] | None = None,
@@ -119,7 +122,10 @@ async def create(
             auth: Runtime API key (overrides ``__OW_API_KEY``).
             type: Sandbox type (default: ``'cpu:default'``).
             size: Size tier name or spec dict.
-            max_lifetime: Maximum lifetime in seconds.
+            idle_timeout: Seconds of inactivity before the sandbox is terminated
+                (default: 900, max: 10800). The idle timer resets on every
+                WebSocket message or status-check request.
+            max_lifetime: Maximum lifetime in seconds (default: 3600, max: 10800).
             ports: TCP ports to expose via preview URLs (default: ``[]``).
             envs: Environment variables to inject into the sandbox.
             policy: Network policy (e.g. egress allowlist).
@@ -137,6 +143,7 @@ async def create(
             "name": name,
             "size": normalize_size(size),
             "type": type,
+            "idleTimeout": idle_timeout,
             "maxLifetime": max_lifetime,
         }
         if cluster is not None:
@@ -170,6 +177,7 @@ async def create(
             status=payload.get("status", ""),
             cluster=payload.get("cluster"),
             region=payload.get("region"),
+            idle_timeout=payload.get("idleTimeout", 900),
             max_lifetime=payload.get("maxLifetime", 3600),
             preview_urls=_parse_preview_urls(payload.get("previewUrls")),
             management_endpoint=payload.get("managementEndpoint"),
@@ -191,17 +199,23 @@ async def get(
         api_host: str | None = None,
         namespace: str | None = None,
         auth: str | None = None,
+        management_endpoint: str | None = None,
         verify_ssl: bool = True,
     ) -> "Sandbox":
         """Fetch the current status of an existing sandbox.
 
         Credentials are read from the environment automatically.
 
+        Pass the management endpoint so the request is sent to the correct host;
+        falls back to ``api_host`` when omitted.
+
         Args:
             sandbox_id: ID of the sandbox to look up.
             api_host: Runtime API host override.
             namespace: Runtime namespace override.
             auth: Runtime API key override.
+            management_endpoint: Per-sandbox management endpoint returned by
+                :meth:`create`. Falls back to ``api_host`` otherwise.
             verify_ssl: Whether to verify TLS certificates.
 
         Returns:
@@ -209,7 +223,8 @@ async def get(
             This instance is **not** WebSocket-connected.
         """
         creds = cls.resolve_credentials(api_host=api_host, namespace=namespace, auth=auth)
-        url = f"{creds['api_host']}/api/v1/namespaces/{creds['namespace']}/sandboxes/{sandbox_id}"
+        base = management_endpoint or creds["api_host"]
+        url = f"{base}/api/v1/namespaces/{creds['namespace']}/sandboxes/{sandbox_id}"
         payload = await api_request(
             "GET",
             url,
@@ -224,7 +239,9 @@ async def get(
             status=payload.get("status", ""),
             cluster=payload.get("cluster"),
             region=payload.get("region"),
+            idle_timeout=payload.get("idleTimeout", 900),
             max_lifetime=payload.get("maxLifetime", 3600),
+            management_endpoint=payload.get("managementEndpoint") or management_endpoint,
             preview_urls=_parse_preview_urls(payload.get("previewUrls")),
             namespace=creds["namespace"],
             api_host=creds["api_host"],
diff --git a/tests/test_sandbox.py b/tests/test_sandbox.py
index 8ed39d8..94c2f03 100644
--- a/tests/test_sandbox.py
+++ b/tests/test_sandbox.py
@@ -326,6 +326,83 @@ async def test_create_forwards_ports_and_parses_preview_urls(self):
         }
         assert sandbox.get_url(3000) == "https://sb-ports-3000.preview.example.net"
 
+    @pytest.mark.asyncio
+    async def test_create_sends_default_idle_timeout_and_max_lifetime(self):
+        payload = {
+            "sandboxId": "sb-defaults",
+            "wsEndpoint": "wss://runtime.example.net/api/v1/namespaces/ns/sandboxes/sb-defaults/exec",
+            "status": "ready",
+            "token": "tok-defaults",
+            "idleTimeout": 900,
+            "maxLifetime": 3600,
+        }
+
+        with (
+            patch("aio_lib_sandbox.sandbox.api_request", new=AsyncMock(return_value=payload)) as mock_req,
+            patch.object(Sandbox, "connect", new=AsyncMock()),
+        ):
+            await Sandbox.create(
+                name="defaults-sandbox",
+                api_host="https://runtime.example.net",
+                namespace="ns",
+                auth="uuid:key",
+            )
+
+        _, kwargs = mock_req.call_args
+        assert kwargs["body"]["idleTimeout"] == 900
+        assert kwargs["body"]["maxLifetime"] == 3600
+
+    @pytest.mark.asyncio
+    async def test_create_forwards_explicit_idle_timeout(self):
+        payload = {
+            "sandboxId": "sb-idle",
+            "wsEndpoint": "wss://runtime.example.net/api/v1/namespaces/ns/sandboxes/sb-idle/exec",
+            "status": "ready",
+            "token": "tok-idle",
+            "idleTimeout": 1800,
+            "maxLifetime": 3600,
+        }
+
+        with (
+            patch("aio_lib_sandbox.sandbox.api_request", new=AsyncMock(return_value=payload)) as mock_req,
+            patch.object(Sandbox, "connect", new=AsyncMock()),
+        ):
+            await Sandbox.create(
+                name="idle-sandbox",
+                api_host="https://runtime.example.net",
+                namespace="ns",
+                auth="uuid:key",
+                idle_timeout=1800,
+            )
+
+        _, kwargs = mock_req.call_args
+        assert kwargs["body"]["idleTimeout"] == 1800
+
+    @pytest.mark.asyncio
+    async def test_create_stores_idle_timeout_from_response(self):
+        payload = {
+            "sandboxId": "sb-store",
+            "wsEndpoint": "wss://runtime.example.net/api/v1/namespaces/ns/sandboxes/sb-store/exec",
+            "status": "ready",
+            "token": "tok-store",
+            "idleTimeout": 1800,
+            "maxLifetime": 3600,
+        }
+
+        with (
+            patch("aio_lib_sandbox.sandbox.api_request", new=AsyncMock(return_value=payload)),
+            patch.object(Sandbox, "connect", new=AsyncMock()),
+        ):
+            sandbox = await Sandbox.create(
+                name="store-sandbox",
+                api_host="https://runtime.example.net",
+                namespace="ns",
+                auth="uuid:key",
+                idle_timeout=1800,
+            )
+
+        assert sandbox.idle_timeout == 1800
+
 
 # ---------------------------------------------------------------------------
 # WebSocket connection
@@ -532,6 +609,43 @@ async def test_get_parses_preview_urls(self):
         assert sandbox.preview_urls == {3000: "https://sb-get-3000.preview.example.net"}
         assert sandbox.get_url(3000) == "https://sb-get-3000.preview.example.net"
 
+    @pytest.mark.asyncio
+    async def test_get_stores_idle_timeout_from_response(self):
+        payload = {
+            "sandboxId": "sb-get-idle",
+            "status": "running",
+            "idleTimeout": 1200,
+            "maxLifetime": 3600,
+        }
+
+        with patch("aio_lib_sandbox.sandbox.api_request", new=AsyncMock(return_value=payload)):
+            sandbox = await Sandbox.get(
+                "sb-get-idle",
+                api_host="https://runtime.example.net",
+                namespace="ns",
+                auth="uuid:key",
+            )
+
+        assert sandbox.idle_timeout == 1200
+
+    @pytest.mark.asyncio
+    async def test_get_routes_through_management_endpoint(self):
+        payload = {"sandboxId": "sb-mgmt", "status": "running"}
+
+        with patch("aio_lib_sandbox.sandbox.api_request", new=AsyncMock(return_value=payload)) as mock_req:
+            sandbox = await Sandbox.get(
+                "sb-mgmt",
+                api_host="https://runtime.example.net",
+                namespace="ns",
+                auth="uuid:key",
+                management_endpoint="https://sb-mgmt.mgmt.example.net",
+            )
+
+        args, _ = mock_req.call_args
+        # api_request is called positionally: (method, url, ...)
+        assert args[1] == "https://sb-mgmt.mgmt.example.net/api/v1/namespaces/ns/sandboxes/sb-mgmt"
+        assert sandbox.management_endpoint == "https://sb-mgmt.mgmt.example.net"
+
     @pytest.mark.asyncio
     async def test_get_not_found_raises(self):
         with patch(