diff --git a/gardener/gardener-agent.sh b/gardener/gardener-agent.sh
index 5402df9..7591cba 100644
--- a/gardener/gardener-agent.sh
+++ b/gardener/gardener-agent.sh
@@ -290,15 +290,15 @@ gardener_phase_callback() {
       log "WARNING: tmux session died unexpectedly — attempting recovery"
       rm -f "$RESULT_FILE"
       touch "$RESULT_FILE"
-      if create_agent_session "$SESSION_NAME" "$PROJECT_REPO_ROOT" 2>/dev/null; then
-        agent_inject_into_session "$SESSION_NAME" "$PROMPT"
+      if create_agent_session "${_MONITOR_SESSION:-$SESSION_NAME}" "$PROJECT_REPO_ROOT" 2>/dev/null; then
+        agent_inject_into_session "${_MONITOR_SESSION:-$SESSION_NAME}" "$PROMPT"
         log "Recovery session started"
       else
         log "ERROR: could not restart session after crash"
       fi
       ;;
     PHASE:done|PHASE:failed|PHASE:needs_human|PHASE:merged)
-      agent_kill_session "$SESSION_NAME"
+      agent_kill_session "${_MONITOR_SESSION:-$SESSION_NAME}"
       ;;
   esac
 }
diff --git a/lib/agent-session.sh b/lib/agent-session.sh
index 5499273..11d819b 100644
--- a/lib/agent-session.sh
+++ b/lib/agent-session.sh
@@ -61,6 +61,8 @@ inject_formula() {
 
 # Monitor a phase file, calling a callback on changes and handling idle timeout.
 # Sets _MONITOR_LOOP_EXIT to the exit reason (idle_timeout, done, failed, break).
+# Sets _MONITOR_SESSION to the resolved session name (arg 4 or $SESSION_NAME).
+#   Callbacks should reference _MONITOR_SESSION instead of $SESSION_NAME directly.
 # Args: phase_file idle_timeout_secs callback_fn [session_name]
 #   session_name — tmux session to health-check; falls back to $SESSION_NAME global
 monitor_phase_loop() {
@@ -68,6 +70,9 @@ monitor_phase_loop() {
   local idle_timeout="$2"
   local callback="$3"
   local _session="${4:-${SESSION_NAME:-}}"
+  # Export resolved session name so callbacks can reference it regardless of
+  # which session was passed to monitor_phase_loop (analogous to _MONITOR_LOOP_EXIT).
+  export _MONITOR_SESSION="$_session"
   local poll_interval="${PHASE_POLL_INTERVAL:-10}"
   local last_mtime=0
   local idle_elapsed=0