diff --git a/backend/Dockerfile b/backend/Dockerfile
index 8d4a54c..2bfd8ee 100644
--- a/backend/Dockerfile
+++ b/backend/Dockerfile
@@ -20,4 +20,12 @@ EXPOSE 5000
 
 # instance/ (sqlite db) and uploads/ (receipt photos) should be mounted as
 # volumes - see docker-compose.yml - so they survive a container rebuild.
-CMD ["gunicorn", "--bind", "0.0.0.0:5000", "--workers", "2", "--timeout", "60", "run:app"]
+#
+# --workers 1: the Login Flow v2 poll state (app/auth.py _pending_flows) is
+# an in-memory dict, not shared across processes - with >1 worker,
+# /auth/login/start and the follow-up /auth/login/poll calls can land on
+# different worker processes, which never see each other's flow_id, so
+# login intermittently/always times out. Single worker (+ threads for
+# concurrency) keeps that state actually shared. Fine for this scale
+# (household tool, already SQLite-backed).
+CMD ["gunicorn", "--bind", "0.0.0.0:5000", "--workers", "1", "--threads", "4", "--timeout", "60", "run:app"]