diff --git a/backend/src/utilities/tshark_manager.py b/backend/src/utilities/tshark_manager.py
index 1316229..73af08e 100644
--- a/backend/src/utilities/tshark_manager.py
+++ b/backend/src/utilities/tshark_manager.py
@@ -288,6 +288,10 @@ def _eth_type_from_protocol_stack(protocol_stack: List[str]) -> Optional[int]:
     return None
 
 
+def _is_generic_stream_protocol(protocol_name: Optional[str]) -> bool:
+    return str(protocol_name or "").replace("-", "_").replace(".", "_").lower() in _GENERIC_PROTOCOLS
+
+
 def _http_metadata(layers: Dict[str, Any]) -> Dict[str, Any]:
     http_layer = layers.get("http")
     if not isinstance(http_layer, dict):
@@ -532,15 +536,36 @@ def _build_enrichment(event: Dict[str, Any], flow_context: Optional[Dict[str, An
     derived_context = _derive_flow_context(event)
     protocol_stack = list(event.get("protocol_stack") or [])
 
-    app_protocol = derived_context.get("app_protocol") or flow_context.get("app_protocol")
-    app_category = derived_context.get("app_category") or flow_context.get("app_category")
+    derived_protocol = _safe_text(derived_context.get("app_protocol"))
+    flow_protocol = _safe_text(flow_context.get("app_protocol"))
+    prefer_flow_context = (
+        flow_protocol is not None
+        and not _is_generic_stream_protocol(flow_protocol)
+        and derived_protocol is not None
+        and _is_generic_stream_protocol(derived_protocol)
+    )
+
+    app_protocol = flow_protocol if prefer_flow_context else (derived_protocol or flow_protocol)
+    app_category = (
+        flow_context.get("app_category") or derived_context.get("app_category")
+        if prefer_flow_context
+        else (derived_context.get("app_category") or flow_context.get("app_category"))
+    )
     app_hostname = derived_context.get("app_hostname") or flow_context.get("app_hostname")
     app_is_encrypted = (
-        derived_context.get("app_is_encrypted")
-        if derived_context.get("app_is_encrypted") is not None
-        else flow_context.get("app_is_encrypted")
+        flow_context.get("app_is_encrypted")
+        if prefer_flow_context and flow_context.get("app_is_encrypted") is not None
+        else (
+            derived_context.get("app_is_encrypted")
+            if derived_context.get("app_is_encrypted") is not None
+            else flow_context.get("app_is_encrypted")
+        )
+    )
+    app_confidence = (
+        flow_context.get("app_confidence") or derived_context.get("app_confidence")
+        if prefer_flow_context
+        else (derived_context.get("app_confidence") or flow_context.get("app_confidence"))
     )
-    app_confidence = derived_context.get("app_confidence") or flow_context.get("app_confidence")
 
     tcp_flags = _safe_int(event.get("tcp_flags"))
     tcp_len = int(event.get("tcp_len") or 0)
@@ -631,8 +656,34 @@ def _build_stream_enrichment(flow_context: Dict[str, Any]) -> Dict[str, Any]:
     }
 
 
-def _is_generic_stream_protocol(protocol_name: Optional[str]) -> bool:
-    return str(protocol_name or "").replace("-", "_").replace(".", "_").lower() in _GENERIC_PROTOCOLS
+def _merge_flow_context(existing: Optional[Dict[str, Any]], incoming: Optional[Dict[str, Any]]) -> Dict[str, Any]:
+    merged = dict(existing or {})
+    incoming_context = dict(incoming or {})
+    existing_protocol = _safe_text(merged.get("app_protocol"))
+    incoming_protocol = _safe_text(incoming_context.get("app_protocol"))
+    preserve_existing_protocol = (
+        existing_protocol is not None
+        and not _is_generic_stream_protocol(existing_protocol)
+        and incoming_protocol is not None
+        and _is_generic_stream_protocol(incoming_protocol)
+    )
+
+    for key, value in incoming_context.items():
+        if value is None:
+            continue
+        if preserve_existing_protocol and key in {
+            "app_protocol",
+            "app_master_protocol",
+            "app_category",
+            "app_confidence",
+            "app_is_encrypted",
+        }:
+            continue
+        merged[key] = value
+
+    if merged.get("app_master_protocol") is None and merged.get("app_protocol") is not None:
+        merged["app_master_protocol"] = merged["app_protocol"]
+    return merged
 
 
 class TsharkManager:
@@ -864,8 +915,7 @@ class TsharkManager:
                     flow_context = dict(self._flow_context.get(stream_key) or {})
                 derived_context = _derive_flow_context(event)
                 if stream_key is not None and derived_context.get("app_protocol") is not None:
-                    merged_context = dict(flow_context or {})
-                    merged_context.update({key: value for key, value in derived_context.items() if value is not None})
+                    merged_context = _merge_flow_context(flow_context, derived_context)
                     self._flow_context[stream_key] = merged_context
                     flow_context = merged_context
                 entries = self._cache.setdefault(signature, [])