When the agent has its own SessionDB reference (_session_db is not None),
_flush_messages_to_session_db() persists user messages to SQLite during the
agent run. Two gateway fallback paths also wrote the same user message
without skip_db=True, creating duplicate entries in state.db:
1. agent_failed_early path (transient 429/timeout failures)
2. not-new-messages path (history_offset >= len(messages) edge case)
Move agent_persisted flag definition to before the if/elif/else block so
all paths can use it, and pass skip_db=agent_persisted to every fallback
append_to_transcript() call.
Fixes#42039
liuhao1024
8e4c447e5f