diff --git a/charts/langsmith/README.md b/charts/langsmith/README.md
index 74af3d37..cfccba2c 100644
--- a/charts/langsmith/README.md
+++ b/charts/langsmith/README.md
@@ -899,7 +899,7 @@ Two things worth planning for before you enable it:
 | sandboxes.juicefs.csi.controller.serviceAccount.annotations | object | `{}` | Annotations applied to the JuiceFS CSI controller ServiceAccount. |
 | sandboxes.juicefs.csi.existingSecretName | string | `""` | Existing Secret containing JuiceFS CSI config keys `name`, `metaurl`, `storage`, and `bucket`. When set, this chart does not render the CSI config Secret and `sandboxes.juicefs.name`, `sandboxes.juicefs.storage`, `sandboxes.juicefs.bucket`, and `sandboxes.juicefs.redis.metaURL` are not used for the CSI config. |
 | sandboxes.juicefs.csi.install | bool | `true` | Install the bundled JuiceFS CSI driver. Set to false when the cluster already runs one; the chart then renders only the sandbox PV/PVCs and CSI config Secret, bound to the existing driver. |
-| sandboxes.juicefs.csi.mountPodPatch | list | `[{"mountOptions":["cache-dir=/var/cache/juicefs-csi","cache-size=51200","buffer-size=300","prefetch=3","metrics=0.0.0.0:9567"],"resources":{"limits":{"cpu":"2","memory":"4Gi"},"requests":{"cpu":"2","memory":"4Gi"}}},{"mountOptions":["cache-dir=/var/cache/juicefs-csi","cache-size=307200"],"pvcSelector":{"matchLabels":{"juicefs.langsmith.com/cache":"ssd"}}}]` | Mount pod patches used by the JuiceFS CSI driver for sandbox volumes. Override only when tuning JuiceFS mount behavior or observability. |
+| sandboxes.juicefs.csi.mountPodPatch | list | `[{"mountOptions":["cache-dir=/var/cache/juicefs-csi","cache-size=51200","buffer-size=300","prefetch=3","metrics=0.0.0.0:9567"],"resources":{"limits":{"cpu":"2","memory":"4Gi"},"requests":{"cpu":"2","memory":"4Gi"}}},{"mountOptions":["cache-dir=/var/cache/juicefs-csi","cache-size=307200","cache-large-write"],"pvcSelector":{"matchLabels":{"juicefs.langsmith.com/cache":"ssd"}}}]` | Mount pod patches used by the JuiceFS CSI driver for sandbox volumes. Override only when tuning JuiceFS mount behavior or observability. |
 | sandboxes.juicefs.csi.node.annotations | object | `{}` | Annotations applied to the JuiceFS CSI node DaemonSet and pod template. |
 | sandboxes.juicefs.csi.node.serviceAccount.annotations | object | `{}` | Annotations applied to the JuiceFS CSI node ServiceAccount. Use this for workload identity annotations such as AWS IRSA or GCP Workload Identity. |
 | sandboxes.juicefs.csi.pvName | string | `"smithbox-juicefs-csi"` |  |
diff --git a/charts/langsmith/tests/sandbox_juicefs_csi_driver_test.yaml b/charts/langsmith/tests/sandbox_juicefs_csi_driver_test.yaml
index cfe23270..cc7859ac 100644
--- a/charts/langsmith/tests/sandbox_juicefs_csi_driver_test.yaml
+++ b/charts/langsmith/tests/sandbox_juicefs_csi_driver_test.yaml
@@ -296,6 +296,15 @@ tests:
           path: metadata.name
           value: RELEASE-NAME-langsmith-juicefs-csi-driver-config
 
+  - it: should cache large writes for SSD-backed mount pods
+    values:
+      - ./values/sandboxes-enabled.yaml
+    template: sandboxes/juicefs-csi-driver/configmap.yaml
+    asserts:
+      - matchRegex:
+          path: data["config.yaml"]
+          pattern: "cache-large-write"
+
   - it: should render the JuiceFS CSIDriver when sandboxes are enabled
     values:
       - ./values/sandboxes-enabled.yaml
diff --git a/charts/langsmith/values.yaml b/charts/langsmith/values.yaml
index 87b7f6d6..161fe53a 100644
--- a/charts/langsmith/values.yaml
+++ b/charts/langsmith/values.yaml
@@ -232,6 +232,7 @@ sandboxes:
           mountOptions:
             - cache-dir=/var/cache/juicefs-csi
             - cache-size=307200
+            - cache-large-write
       pvName: "smithbox-juicefs-csi"
       pvcName: "smithbox-juicefs-csi"
   sandboxHost: