diff --git a/run_agent.py b/run_agent.py
index 61263d4ebf..67eac17cf7 100644
--- a/run_agent.py
+++ b/run_agent.py
@@ -404,6 +404,8 @@ class AIAgent(
 
         # Turn counter (added after reset_session_state was first written — #2635)
         self._user_turn_count = 0
+        # The drifted-prompt compaction INFO is once per session, so a /new or /resume re-arms it.
+        self._compaction_prompt_drift_logged = False
         # Who wrote the current turn. build_turn_context() sets it at the start of every turn.
         self._turn_author = None
         # Copilot x-initiator: True for the first API call of a user turn, False for tool-loop follow-ups.