diff --git a/CUSTOMIZATION.md b/CUSTOMIZATION.md
index 859e6e57..4cbc5054 100644
--- a/CUSTOMIZATION.md
+++ b/CUSTOMIZATION.md
@@ -37,7 +37,7 @@ DEFAULT_SANDBOX_SNAPSHOT_ID="<snapshot-uuid>"                      # Required
 DEFAULT_SANDBOX_SNAPSHOT_FS_CAPACITY_BYTES="34359738368"           # Optional, default 32 GiB
 DEFAULT_SANDBOX_VCPUS="4"                                          # Optional, default 4
 DEFAULT_SANDBOX_MEM_BYTES="16106127360"                            # Optional, default 15 GiB
-DEFAULT_SANDBOX_IDLE_TTL_SECONDS="600"                             # Optional, default 600 (10 min); 0 disables
+DEFAULT_SANDBOX_IDLE_TTL_SECONDS="7200"                            # Optional, default 7200 (2 h); 0 disables
 DEFAULT_SANDBOX_DELETE_AFTER_STOP_SECONDS="86400"                  # Optional, default 86400 (24 h); 0 disables
 ```
 
diff --git a/INSTALLATION.md b/INSTALLATION.md
index 73dbc4c2..ec91bff1 100644
--- a/INSTALLATION.md
+++ b/INSTALLATION.md
@@ -208,8 +208,8 @@ DEFAULT_SANDBOX_SNAPSHOT_FS_CAPACITY_BYTES="34359738368"
 DEFAULT_SANDBOX_VCPUS="4"
 # Optional; memory in bytes per sandbox. Default is 15 GiB.
 DEFAULT_SANDBOX_MEM_BYTES="16106127360"
-# Optional; auto-stop a sandbox after this many seconds of inactivity. Default is 600 (10 min). 0 disables.
-DEFAULT_SANDBOX_IDLE_TTL_SECONDS="600"
+# Optional; auto-stop a sandbox after this many seconds of inactivity. Default is 7200 (2 hours). 0 disables.
+DEFAULT_SANDBOX_IDLE_TTL_SECONDS="7200"
 # Optional; delete a stopped sandbox after this many seconds. Default is 86400 (24 hours). 0 disables.
 DEFAULT_SANDBOX_DELETE_AFTER_STOP_SECONDS="86400"
 ```
@@ -513,7 +513,7 @@ DEFAULT_SANDBOX_SNAPSHOT_ID=""         # Required when SANDBOX_TYPE=langsmith (s
 DEFAULT_SANDBOX_SNAPSHOT_FS_CAPACITY_BYTES=""  # Root FS size in bytes (default: 32 GiB)
 DEFAULT_SANDBOX_VCPUS=""               # vCPUs per sandbox (default: 4)
 DEFAULT_SANDBOX_MEM_BYTES=""           # Memory in bytes per sandbox (default: 15 GiB)
-DEFAULT_SANDBOX_IDLE_TTL_SECONDS=""    # Auto-stop after N seconds idle (default: 600; 0 disables)
+DEFAULT_SANDBOX_IDLE_TTL_SECONDS=""    # Auto-stop after N seconds idle (default: 7200; 0 disables)
 DEFAULT_SANDBOX_DELETE_AFTER_STOP_SECONDS=""  # Delete N seconds after stop (default: 86400; 0 disables)
 
 # === Token Encryption ===
diff --git a/agent/integrations/langsmith.py b/agent/integrations/langsmith.py
index 794f4e94..04e0ada0 100644
--- a/agent/integrations/langsmith.py
+++ b/agent/integrations/langsmith.py
@@ -27,7 +27,7 @@ logger = logging.getLogger(__name__)
 DEFAULT_SNAPSHOT_FS_CAPACITY_BYTES = 32 * 1024**3
 DEFAULT_SANDBOX_VCPUS = 2
 DEFAULT_SANDBOX_MEM_BYTES = 7936 * 1024**2  # 7936 MiB ("large" tier cap)
-DEFAULT_SANDBOX_IDLE_TTL_SECONDS = 10 * 60  # 10 minutes
+DEFAULT_SANDBOX_IDLE_TTL_SECONDS = 2 * 60 * 60  # 2 hours
 DEFAULT_SANDBOX_DELETE_AFTER_STOP_SECONDS = 24 * 60 * 60  # 24 hours
 PROXY_CONFIG_MAX_ATTEMPTS = 3
 PROXY_CONFIG_TIMEOUT_SECONDS = 10.0