diff --git a/docs/ENGINEERING_HARNESS.md b/docs/ENGINEERING_HARNESS.md
index bf516b8..434dcef 100644
--- a/docs/ENGINEERING_HARNESS.md
+++ b/docs/ENGINEERING_HARNESS.md
@@ -66,6 +66,10 @@ dotnet watch run --project .\src\TaxBaik.Web\TaxBaik.Web.csproj
 - 로그인 검증:
   - 마이그레이션으로 시드된 실제 관리자 계정 `admin`
   - 로그인 실패 시 DB 연결 오류와 자격 증명 오류를 구분해서 본다
+- 로컬 DB 시드 확인:
+```bash
+./scripts/validate_admin_seed.sh "$DB_CONNECTION_STRING"
+```
 
 ### Production
 
diff --git a/scripts/run_local_tests.py b/scripts/run_local_tests.py
index 6cfa686..bdce319 100644
--- a/scripts/run_local_tests.py
+++ b/scripts/run_local_tests.py
@@ -115,8 +115,8 @@ def main():
     test_env["E2E_BASE_URL"] = base_url
     test_env["EVIDENCE_ROOT"] = "evidence"
     # Set default test credentials
-    test_env["E2E_ADMIN_USERNAME"] = "admin"
-    test_env["E2E_ADMIN_PASSWORD"] = "Admin123!@#456"
+    test_env["E2E_ADMIN_USERNAME"] = os.environ.get("E2E_ADMIN_USERNAME", "admin")
+    test_env["E2E_ADMIN_PASSWORD"] = os.environ.get("E2E_ADMIN_PASSWORD", "")
     
     # Run playwright test command
     # Local 1차 검증은 Desktop Chrome만 대상으로 잡아 불필요한 브라우저 설치 의존을 줄인다.
diff --git a/scripts/validate_admin_seed.sh b/scripts/validate_admin_seed.sh
new file mode 100644
index 0000000..7f7e4dc
--- /dev/null
+++ b/scripts/validate_admin_seed.sh
@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+DB_CONNECTION_STRING="${1:-}"
+
+if [ -z "$DB_CONNECTION_STRING" ]; then
+  echo "Usage: $0 <db-connection-string>" >&2
+  exit 1
+fi
+
+if ! command -v psql >/dev/null 2>&1; then
+  echo "psql is required." >&2
+  exit 1
+fi
+
+echo "Checking admin seed..."
+psql "$DB_CONNECTION_STRING" -Atc "SELECT username FROM admin_users WHERE username = 'admin';" | grep -qx 'admin'
+echo "Checking schema migrations..."
+psql "$DB_CONNECTION_STRING" -Atc "SELECT 1 FROM schema_migrations WHERE version = '003';" >/dev/null
+echo "Admin seed validation passed."