diff --git a/create-domain/action.yml b/create-domain/action.yml
index eebb85b..e669bdb 100644
--- a/create-domain/action.yml
+++ b/create-domain/action.yml
@@ -82,25 +82,45 @@ runs:
         FORWARD_SCHEME="http"                        # 대상 프로토콜 http 고정
         EMAIL="$NPM_USER"                            # Let's Encrypt 이메일 = NPM 계정
 
+        # NPM API 호출 헬퍼: 응답 본문과 상태코드를 분리해, 2xx가 아니면
+        # NPM이 보낸 에러 본문을 그대로 출력하고 실패시킵니다.
+        # 사용법: api <METHOD> <PATH> [JSON_DATA]   (성공 시 응답 본문을 stdout으로)
+        api() {
+          local method="$1" path="$2" data="${3:-}" resp code body
+          if [ -n "$data" ]; then
+            resp=$(curl -sS -w $'\n%{http_code}' -X "$method" "${BASE}${path}" \
+              -H "$AUTH" -H "Content-Type: application/json" -d "$data")
+          else
+            resp=$(curl -sS -w $'\n%{http_code}' -X "$method" "${BASE}${path}" -H "$AUTH")
+          fi
+          code="${resp##*$'\n'}"
+          body="${resp%$'\n'*}"
+          if [ "$code" -lt 200 ] || [ "$code" -ge 300 ]; then
+            echo "API 오류 [$method $path] HTTP $code: $body" >&2
+            return 1
+          fi
+          printf '%s' "$body"
+        }
+
         # ---------------------------------------------------------------
         # 1. 토큰 발급 (로그인)
         # ---------------------------------------------------------------
-        TOKEN=$(curl -fsS -X POST "${BASE}/tokens" \
+        TOKEN_RESP=$(curl -sS -w $'\n%{http_code}' -X POST "${BASE}/tokens" \
           -H "Content-Type: application/json" \
-          -d "$(jq -nc --arg i "$NPM_USER" --arg s "$NPM_PASS" \
-                '{identity:$i, secret:$s}')" \
-          | jq -r '.token')
-
-        if [ -z "$TOKEN" ] || [ "$TOKEN" = "null" ]; then
-          echo "NPM 토큰 발급 실패: 자격증명을 확인하세요"
+          -d "$(jq -nc --arg i "$NPM_USER" --arg s "$NPM_PASS" '{identity:$i, secret:$s}')")
+        TOKEN_CODE="${TOKEN_RESP##*$'\n'}"
+        TOKEN_BODY="${TOKEN_RESP%$'\n'*}"
+        if [ "$TOKEN_CODE" != "200" ]; then
+          echo "NPM 토큰 발급 실패 (HTTP $TOKEN_CODE): $TOKEN_BODY"
           exit 1
         fi
+        TOKEN=$(printf '%s' "$TOKEN_BODY" | jq -r '.token')
         AUTH="Authorization: Bearer ${TOKEN}"
 
         # ---------------------------------------------------------------
         # 2. 도메인 중복 체크 (2번째 실행 대응)
         # ---------------------------------------------------------------
-        HOST_ID=$(curl -fsS "${BASE}/nginx/proxy-hosts" -H "$AUTH" \
+        HOST_ID=$(api GET "/nginx/proxy-hosts" \
           | jq -r --arg d "$DOMAIN" \
             'map(select(.domain_names | index($d))) | .[0].id // empty')
 
@@ -115,15 +135,14 @@ runs:
         # 3. Let's Encrypt 인증서 발급 — 인증서도 멱등 처리
         # ---------------------------------------------------------------
         # 같은 도메인의 기존 인증서가 있으면 재사용합니다.
-        CERT_ID=$(curl -fsS "${BASE}/nginx/certificates" -H "$AUTH" \
+        CERT_ID=$(api GET "/nginx/certificates" \
           | jq -r --arg d "$DOMAIN" \
             'map(select(.provider=="letsencrypt" and (.domain_names | index($d)))) | .[0].id // empty')
 
         if [ -z "$CERT_ID" ]; then
           echo "Let's Encrypt 인증서 발급 중: ${DOMAIN}"
-          CERT_ID=$(curl -fsS -X POST "${BASE}/nginx/certificates" \
-            -H "$AUTH" -H "Content-Type: application/json" \
-            -d "$(jq -nc --arg d "$DOMAIN" --arg e "$EMAIL" \
+          CERT_ID=$(api POST "/nginx/certificates" \
+            "$(jq -nc --arg d "$DOMAIN" --arg e "$EMAIL" \
                   '{provider:"letsencrypt",
                     domain_names:[$d],
                     meta:{letsencrypt_email:$e, letsencrypt_agree:true, dns_challenge:false}}')" \
@@ -168,9 +187,7 @@ runs:
             locations:[],
             meta:{}}')
 
-        HOST_ID=$(curl -fsS -X POST "${BASE}/nginx/proxy-hosts" \
-          -H "$AUTH" -H "Content-Type: application/json" \
-          -d "$PAYLOAD" | jq -r '.id')
+        HOST_ID=$(api POST "/nginx/proxy-hosts" "$PAYLOAD" | jq -r '.id')
 
         if [ -z "$HOST_ID" ] || [ "$HOST_ID" = "null" ]; then
           echo "프록시 호스트 생성 실패: ${DOMAIN}"