diff --git a/.claude/hooks/check-on-stop.sh b/.claude/hooks/check-on-stop.sh
new file mode 100755
index 0000000..318c0e3
--- /dev/null
+++ b/.claude/hooks/check-on-stop.sh
@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+# Stop hook: run the quality gate. On failure, exit 2 so Claude Code blocks the
+# stop and hands the output back to the agent to fix; on success, exit 0 to let
+# the turn end. It keeps retrying until green — interrupt to break out, or guard
+# on the input's stop_hook_active to cap it at one attempt.
+set -uo pipefail
+
+cd "${CLAUDE_PROJECT_DIR:-.}" || exit 0
+
+if ! output=$(make check 2>&1); then
+  printf '%s\n' "$output" >&2
+  exit 2
+fi
diff --git a/.claude/settings.json b/.claude/settings.json
index 953faad..ed666b4 100644
--- a/.claude/settings.json
+++ b/.claude/settings.json
@@ -5,7 +5,7 @@
         "hooks": [
           {
             "type": "command",
-            "command": "cd \"$CLAUDE_PROJECT_DIR\" && make check"
+            "command": "\"$CLAUDE_PROJECT_DIR/.claude/hooks/check-on-stop.sh\""
           }
         ]
       }