diff --git a/backend/python/app/api/admin/dashboard.py b/backend/python/app/api/admin/dashboard.py
index 729ad2a..9f99f28 100644
--- a/backend/python/app/api/admin/dashboard.py
+++ b/backend/python/app/api/admin/dashboard.py
@@ -85,12 +85,14 @@ async def get_recent_logs(
 
 
 def _format_cst(dt_value):
-    """Format UTC naive datetime to CST ISO string"""
+    """Format datetime to CST ISO string.
+    DB values are written by cst_now() as CST time (stored naive by MySQL).
+    No UTC conversion needed - treat naive values as CST directly.
+    """
     if dt_value is None:
         return None
-    utc_dt = dt_value.replace(tzinfo=timezone.utc)
-    cst_dt = utc_dt.astimezone(CST_TZ)
-    return cst_dt.isoformat()
+    # DB naive values are already CST (written by cst_now()), just attach tz
+    return dt_value.replace(tzinfo=CST_TZ).isoformat()
 
 @router.get("/recent-audit")
 async def get_recent_audit(
@@ -117,9 +119,11 @@ async def get_recent_audit(
 
 
 def _format_cst(dt_value):
-    """Format UTC naive datetime to CST ISO string"""
+    """Format datetime to CST ISO string.
+    DB values are written by cst_now() as CST time (stored naive by MySQL).
+    No UTC conversion needed - treat naive values as CST directly.
+    """
     if dt_value is None:
         return None
-    utc_dt = dt_value.replace(tzinfo=timezone.utc)
-    cst_dt = utc_dt.astimezone(CST_TZ)
-    return cst_dt.isoformat()
\ No newline at end of file
+    # DB naive values are already CST (written by cst_now()), just attach tz
+    return dt_value.replace(tzinfo=CST_TZ).isoformat()
\ No newline at end of file
diff --git a/backend/python/app/api/market.py b/backend/python/app/api/market.py
index fa2e862..7f07b82 100644
--- a/backend/python/app/api/market.py
+++ b/backend/python/app/api/market.py
@@ -387,9 +387,6 @@ def uninstall_app(
             app.install_count = app.install_count - 1
 
     # 将应用状态标记为未安装(对于skill类型)
-    if app.type == "skill" and app.is_active:
-        app.is_active = False
-
     app.updated_at = datetime.now()
 
     db.commit()
diff --git a/backend/python/app/api/token_usage.py b/backend/python/app/api/token_usage.py
index b547162..5256ac1 100644
--- a/backend/python/app/api/token_usage.py
+++ b/backend/python/app/api/token_usage.py
@@ -252,10 +252,11 @@ def recharge(
 
 
 def _format_cst_time(dt_value):
-    """Format datetime to CST ISO string. Input is UTC naive datetime from DB."""
+    """Format datetime to CST ISO string.
+    DB values are written by cst_now() as CST time (stored naive by MySQL).
+    No UTC conversion needed - treat naive values as CST directly.
+    """
     if dt_value is None:
         return None
-    # DB stores UTC naive datetime, convert to CST
-    utc_dt = dt_value.replace(tzinfo=timezone.utc)
-    cst_dt = utc_dt.astimezone(CST_TZ)
-    return cst_dt.isoformat()
+    # DB naive values are already CST (written by cst_now()), just attach tz
+    return dt_value.replace(tzinfo=CST_TZ).isoformat()