diff --git a/app/utils/logging.py b/app/utils/logging.py
index e56f2ed6..57db13f7 100644
--- a/app/utils/logging.py
+++ b/app/utils/logging.py
@@ -25,7 +25,7 @@ class TaskLogCollector(logging.Handler):
         try:
             msg = self.format(record)
             # Extract task_id from messages formatted as "[task_id] ..."
-            if msg and "[" in msg:
+            if msg and "[" in msg and "]" in msg:
                 start = msg.index("[")
                 end = msg.index("]", start)
                 task_id = msg[start + 1 : end].strip()
@@ -76,7 +76,7 @@ def log_task_progress(task_id, step_name, status, message=None, file_id=None, de
                 If not provided, buffered logger output is used automatically.
     """
     # Auto-capture buffered log output when no explicit detail is given
-    if detail is None and task_id:
+    if not detail and task_id:
         _ensure_collector_installed()
         collected = _collector.drain(task_id)
         if collected:
diff --git a/tests/test_logging_utils.py b/tests/test_logging_utils.py
index 26ce24e5..a4906841 100644
--- a/tests/test_logging_utils.py
+++ b/tests/test_logging_utils.py
@@ -257,3 +257,23 @@ class TestTaskLogCollector:
         assert collector.drain("OK") == ""
 
         logger.removeHandler(collector)
+
+    def test_collector_handles_malformed_brackets(self):
+        """Test that the collector handles messages with [ but no ]."""
+        from app.utils.logging import TaskLogCollector
+
+        collector = TaskLogCollector()
+        collector.setFormatter(logging.Formatter("%(message)s"))
+
+        logger = logging.getLogger("test_malformed")
+        logger.addHandler(collector)
+        logger.setLevel(logging.DEBUG)
+
+        logger.info("[no closing bracket")
+        logger.info("no brackets at all")
+        logger.info("")
+
+        # Should not raise and should not buffer anything
+        assert collector.drain("no closing bracket") == ""
+
+        logger.removeHandler(collector)