diff --git a/lib/agent-session.sh b/lib/agent-session.sh
index c2ae7da..dcce0ff 100644
--- a/lib/agent-session.sh
+++ b/lib/agent-session.sh
@@ -114,6 +114,8 @@ monitor_phase_loop() {
 
     # Phase changed
     last_mtime="$phase_mtime"
+    # shellcheck disable=SC2034  # read by phase-handler.sh callback
+    LAST_PHASE_MTIME="$phase_mtime"
     idle_elapsed=0
 
     # Terminal phases