diff --git a/services/api/requirements-dev.txt b/services/api/requirements-dev.txt
index b22027c..3da0a04 100644
--- a/services/api/requirements-dev.txt
+++ b/services/api/requirements-dev.txt
@@ -4,5 +4,5 @@
 httpx>=0.27          # required by starlette.testclient
 pytest>=8.0          # optional: collects the run_tests gate
 pypdf>=4.0           # read generated PDFs in tests (contract documents)
-ruff>=0.6            # static-analysis gate (config in ruff.toml): dead code + real defects
+ruff>=0.15.20            # static-analysis gate (config in ruff.toml): dead code + real defects
 bandit>=1.7          # security static analysis (report-only in CI; run before shipping)