Add SSE envelope helpers under app.services.streaming.

surfsense_backend/app/services/streaming/envelope/identifiers.py

@@ -0,0 +1,25 @@
+"""Prefixed UUID generators for stream parts."""
+
+from __future__ import annotations
+
+import uuid
+
+
+def generate_message_id() -> str:
+    return f"msg_{uuid.uuid4().hex}"
+
+
+def generate_text_id() -> str:
+    return f"text_{uuid.uuid4().hex}"
+
+
+def generate_reasoning_id() -> str:
+    return f"reasoning_{uuid.uuid4().hex}"
+
+
+def generate_tool_call_id() -> str:
+    return f"call_{uuid.uuid4().hex}"
+
+
+def generate_subagent_run_id() -> str:
+    return f"subagent_{uuid.uuid4().hex}"