Code reviewed and issue fixed.

app/services/log_service.py

@@ -54,8 +54,16 @@ def log_action(user_id, action, entity_type=None, entity_id=None, details=None):
     own business objects. This ensures the log entry is only persisted when
     the parent operation succeeds — an independent commit here would leave
     orphaned log entries for operations that were subsequently rolled back.
+
+    Error isolation
+    ---------------
+    On failure, only the log entry itself is expelled from the session via
+    expunge(). db.session.rollback() is intentionally NOT called here because
+    that would wipe the entire session — silently undoing the parent business
+    operation (ticket creation, user update, etc.) that triggered this log call.
     """
     ip = _get_real_ip()
+    entry = None
 
     try:
         entry = ActivityLog(
@@ -74,8 +82,14 @@ def log_action(user_id, action, entity_type=None, entity_id=None, details=None):
             f'user_id={user_id} ip={ip}'
         )
     except Exception as exc:
-        db.session.rollback()
-        logger.error(f'[ACTIVITY LOG ERROR] {exc}')
+        # Expunge only the failed log entry — do NOT roll back the full session,
+        # as that would undo the parent operation that called this function.
+        if entry is not None:
+            try:
+                db.session.expunge(entry)
+            except Exception:
+                pass
+        logger.error(f'[ACTIVITY LOG ERROR] action={action} entity={entity_type}:{entity_id} error={exc}')
 
 
 def log_ticket_history(ticket, field_name, old_value, new_value, changed_by_id):
@@ -85,8 +99,15 @@ def log_ticket_history(ticket, field_name, old_value, new_value, changed_by_id):
     ----------------
     Like log_action, this function does NOT commit — the caller is responsible
     for committing the session after all field changes have been recorded.
+
+    Error isolation
+    ---------------
+    On failure, only the failed history entry is expelled from the session.
+    db.session.rollback() is intentionally NOT called here — that would undo
+    the parent ticket update that triggered this history recording.
     """
     from app.models import TicketHistory
+    entry = None
     try:
         entry = TicketHistory(
             ticket_id  = ticket.id,
@@ -102,5 +123,11 @@ def log_ticket_history(ticket, field_name, old_value, new_value, changed_by_id):
             f'"{old_value}" -> "{new_value}" by user_id={changed_by_id}'
         )
     except Exception as exc:
-        db.session.rollback()
-        logger.error(f'[TICKET HISTORY ERROR] {exc}')
+        # Expunge only the failed history entry — do NOT roll back the full
+        # session, as that would undo the parent ticket update.
+        if entry is not None:
+            try:
+                db.session.expunge(entry)
+            except Exception:
+                pass
+        logger.error(f'[TICKET HISTORY ERROR] ticket_id={ticket.id} field={field_name} error={exc}')