diff --git a/.claude/JOURNAL.md b/.claude/JOURNAL.md
index 715bf29..0c9e8ec 100644
--- a/.claude/JOURNAL.md
+++ b/.claude/JOURNAL.md
@@ -174,3 +174,6 @@ This journal tracks substantive work on documents, diagrams, and documentation c
 
 57. **Task - Harmonize env settings across files**: Ensured all env settings are consistent in compose.yml, Dockerfile, and config<br>
     **Result**: Added all missing ENV defaults to Dockerfile (ADMIN, BASE_URL, SSL_ENABLED, NOTEBOOK_IMAGE, NETWORK_NAME, GPU_ENABLED, NVIDIA_IMAGE, SERVICE_MLFLOW/RESOURCES_MONITOR/TENSORBOARD, all IDLE_CULLER settings, TF_CPP_MIN_LOG_LEVEL), added AUTOGENERATED_PASSWORD_WORDS/DELIMITER to compose.yml, standardized logo setting as JUPYTERHUB_LOGO_URI with file:// prefix (supports external http/https URIs), updated NVIDIA_IMAGE to nvidia/cuda:13.0.2-base-ubuntu24.04 across all files (compose.yml, jupyterhub_config.py, Dockerfile, settings_dictionary.yml, README.md, CLAUDE.md), config now strips file:// prefix for local files while allowing external URI support in templates
+
+58. **Task - Improve session extension UI**: Changed extension input from dropdown to numeric and added explanatory note<br>
+    **Result**: Replaced dropdown with numeric input (min=1, max set dynamically to available hours), renamed card title to "Idle Session Timeout", added explanatory note "Your server will be stopped after a period of inactivity to free up resources", added input validation for minimum 1 hour, button text shortened to "Extend"
diff --git a/project.env b/project.env
index e458a04..b9a8c1b 100644
--- a/project.env
+++ b/project.env
@@ -3,7 +3,7 @@ PROJECT_NAME="stellars-jupyterhub-ds"
 PROJECT_DESCRIPTION="Multi-user JupyterHub 4 deployment platform with data science stack, GPU auto-detection, NativeAuthenticator, and isolated per-user environments spawned via DockerSpawner"
 
 # Version
-VERSION="3.6.15_cuda-13.0.2_jh-5.4.2"
+VERSION="3.6.16_cuda-13.0.2_jh-5.4.2"
 VERSION_COMMENT="Standardize env vars with JUPYTERHUB_ prefix, admin settings page"
 RELEASE_TAG="RELEASE_3.2.11"
 RELEASE_DATE="2025-11-09"
diff --git a/services/jupyterhub/conf/bin/custom_handlers.py b/services/jupyterhub/conf/bin/custom_handlers.py
index a69b440..093feb4 100755
--- a/services/jupyterhub/conf/bin/custom_handlers.py
+++ b/services/jupyterhub/conf/bin/custom_handlers.py
@@ -720,8 +720,9 @@ class ExtendSessionHandler(BaseHandler):
             })
 
         # Update last_activity to reset the idle timer
-        from datetime import datetime, timezone
-        now = datetime.now(timezone.utc)
+        # Use utcnow() without timezone info to match JupyterHub's internal format
+        from datetime import datetime
+        now = datetime.utcnow()
         user.last_activity = now
         self.db.commit()