diff --git a/.agents/scripts/gate.sh b/.agents/scripts/gate.sh
index 1732354..344f8c0 100755
--- a/.agents/scripts/gate.sh
+++ b/.agents/scripts/gate.sh
@@ -43,7 +43,20 @@ step "types"
 pnpm exec astro check
 
 step "build"
-pnpm run build
+# `astro build` exits 0 even when vite fails to resolve an asset: the cutover
+# left a stale `@import` in a moved stylesheet and every gate stayed green for
+# it. Treat a logged error as a failed build.
+build_log=$(mktemp)
+if ! pnpm run build 2>&1 | tee "$build_log"; then
+  rm -f "$build_log"
+  exit 1
+fi
+if grep -q '\[ERROR\]' "$build_log"; then
+  echo "gate: astro build logged an error and still exited 0. See above." >&2
+  rm -f "$build_log"
+  exit 1
+fi
+rm -f "$build_log"
 
 step "content contracts"
 pnpm run verify