fix(agent): flush un-persisted messages before session rotation (#47202)

compress_context() rotates the session (end_session -> create_session)
mid-turn when auto-compress triggers, but never called
_flush_messages_to_session_db() first. Messages generated during the
current turn that hadn't been persisted to state.db were silently lost.

The same bug existed in cli.py:new_session() (/new command). Both paths
now flush un-persisted messages before ending the old session.

agent/conversation_compression.py

@@ -512,6 +512,16 @@ def compress_context(
             old_title = agent._session_db.get_session_title(agent.session_id)
             # Trigger memory extraction on the old session before it rotates.
             agent.commit_memory_session(messages)
+            # Flush any un-persisted messages from the current turn to the
+            # old session *before* rotating.  compress_context() can be
+            # called mid-turn (auto-compress when context exceeds threshold)
+            # at a point when _flush_messages_to_session_db() has not yet
+            # run.  Without this, messages generated during the current turn
+            # are silently lost on session rotation (#47202).
+            try:
+                agent._flush_messages_to_session_db(messages)
+            except Exception:
+                pass  # best-effort — don't block compression on a flush error
             agent._session_db.end_session(agent.session_id, "compression")
             old_session_id = agent.session_id
             agent.session_id = f"{datetime.now().strftime('%Y%m%d_%H%M%S')}_{uuid.uuid4().hex[:6]}"

cli.py

@@ -5975,6 +5975,18 @@ class HermesCLI(CLIAgentSetupMixin, CLICommandsMixin):
 
         old_session_id = self.session_id
         if self._session_db and old_session_id:
+            # Flush any un-persisted messages from the current turn to the
+            # old session *before* rotating.  /new can be called mid-turn
+            # when _flush_messages_to_session_db() has not yet run — without
+            # this, messages generated during the current turn are silently
+            # lost on session rotation (#47202).
+            if self.agent:
+                try:
+                    self.agent._flush_messages_to_session_db(
+                        self.conversation_history
+                    )
+                except Exception:
+                    pass  # best-effort
             try:
                 self._session_db.end_session(old_session_id, "new_session")
             except Exception: