diff --git a/ci-runner.sh b/ci-runner.sh
index 63e4e18..b0a965e 100755
--- a/ci-runner.sh
+++ b/ci-runner.sh
@@ -31,6 +31,11 @@ if ! flock -n 200; then
   exit 0
 fi
 
+# Serialize all CI runs to avoid DB connection contention
+GLOBAL_LOCK="/tmp/tsharps-ci-global.lock"
+exec 201>"$GLOBAL_LOCK"
+flock 201
+
 echo "=== TSHARPS CI Runner ==="
 echo "Branch: $BRANCH"
 echo "Commit: $COMMIT"