diff --git a/scripts/run_guard3b_overnight_spark.sh b/scripts/run_guard3b_overnight_spark.sh
index 77c9ff0..883e073 100755
--- a/scripts/run_guard3b_overnight_spark.sh
+++ b/scripts/run_guard3b_overnight_spark.sh
@@ -50,6 +50,10 @@ train() {
 
 docker wait "$CANARY" > "$RUN_ROOT/canary_exit_code.txt"
 docker logs "$CANARY" > "$RUN_ROOT/canary_training.log" 2>&1
+if [[ "$(cat "$RUN_ROOT/canary_exit_code.txt")" != "0" ]]; then
+  printf '{"finished_at":"%s","status":"CANARY_FAILED"}\n' "$(date -Iseconds)" > "$RUN_ROOT/program_state.json"
+  exit 1
+fi
 cp "$PROJECT/artifex_overnight/guard3b_v03_canary/pilot_metrics.json" "$RUN_ROOT/canary_metrics.json"
 
 # Base and the initial Challenger use the identical fixed harness/version.