diff --git a/README.md b/README.md
index eef192a..ae170c7 100644
--- a/README.md
+++ b/README.md
@@ -32,6 +32,7 @@ Repo 內提供：
 # 例：用一次性 URL 安裝 vault-pass.txt
 INSTALL_VAULT_PASS_METHOD=url \
 VAULT_PASS_URL="https://example.com/one-time/vault-pass.txt" \
+./scripts/install-vault-pass.sh --check-env
 ./scripts/install-vault-pass.sh
 ```
 
diff --git a/docs/agent-install-runbook.md b/docs/agent-install-runbook.md
index c7098fa..97c701d 100644
--- a/docs/agent-install-runbook.md
+++ b/docs/agent-install-runbook.md
@@ -93,6 +93,14 @@ INSTALL_ENV_FILE=install.local.env ./scripts/install-vault-pass.sh
 
 不要把含真實密碼/token 的 env 檔 commit。
 
+執行安裝前可先檢查 env 是否足夠非互動安裝：
+
+```bash
+./scripts/install-vault-pass.sh --check-env
+```
+
+若輸出顯示 env 不足，installer 會在正式安裝時進入互動提示或列出缺少欄位。
+
 ## 3. 安裝 vault password file
 
 標準位置：
diff --git a/docs/human-guide.md b/docs/human-guide.md
index 47f3fa0..d6e1fc1 100644
--- a/docs/human-guide.md
+++ b/docs/human-guide.md
@@ -28,6 +28,7 @@ cd agent-secret-vault
 接著安裝 vault password file：
 
 ```bash
+./scripts/install-vault-pass.sh --check-env
 ./scripts/install-vault-pass.sh
 ```
 
@@ -74,6 +75,7 @@ git push
 cd ~/projects/agent-secret-vault
 cp -n install.env.example install.env
 editor install.env
+./scripts/install-vault-pass.sh --check-env
 ./scripts/install-vault-pass.sh
 ```
 
@@ -87,7 +89,8 @@ editor install.env
 若 env 內含真實 secrets，不要 commit。可改用 `install.local.env`，再執行：
 
 ```bash
-INSTALL_ENV_FILE=install.local.env ./scripts/install-vault-pass.sh
+INSTALL_ENV_FILE=install.local.env ./scripts/install-vault-pass.sh --check-env
+./scripts/install-vault-pass.sh
 ```
 
 ## 給 agent 的全自動安裝方式
@@ -103,6 +106,7 @@ VAULT_PASS_URL="https://example.com/one-time/vault-pass.txt" \
 # 或：zip 密碼放在本機安全檔案
 INSTALL_VAULT_PASS_METHOD=archive \
 VAULT_PASS_ZIP_PASSWORD_FILE=/secure/path/zip-password.txt \
+./scripts/install-vault-pass.sh --check-env
 ./scripts/install-vault-pass.sh
 ```
 
diff --git a/scripts/install-vault-pass.sh b/scripts/install-vault-pass.sh
index 4eee773..d546591 100755
--- a/scripts/install-vault-pass.sh
+++ b/scripts/install-vault-pass.sh
@@ -56,6 +56,9 @@ Non-interactive agent mode (via install.env or environment variables):
   VAULT_PASS_ZIP_PASSWORD_FILE=/secure/pass INSTALL_VAULT_PASS_METHOD=archive ./scripts/install-vault-pass.sh
   VAULT_PASS_ZIP_PASSWORD='...' INSTALL_VAULT_PASS_METHOD=archive ./scripts/install-vault-pass.sh
 
+Check env sufficiency without installing:
+  ./scripts/install-vault-pass.sh --check-env
+
 Default archive path for method [4]:
   $REPO_DIR/secrets/vault-pass.txt.zip
 USAGE
@@ -237,6 +240,78 @@ verify_vault_readable_if_possible() {
   fi
 }
 
+
+preflight_env_config() {
+  if [ ! -f "$ENV_FILE" ]; then
+    echo "Installer env file not found: $ENV_FILE"
+    echo "Copy template first: cp install.env.example install.env"
+    return 0
+  fi
+
+  echo "Loaded installer env: $ENV_FILE"
+
+  if [ -f "$DEST" ]; then
+    echo "Preflight: vault password file already exists: $DEST"
+    return 0
+  fi
+
+  method="${INSTALL_VAULT_PASS_METHOD:-}"
+  if [ -z "$method" ]; then
+    echo "Preflight: install.env does not set INSTALL_VAULT_PASS_METHOD; interactive menu will be used."
+    return 0
+  fi
+
+  case "$method" in
+    create|1)
+      echo "Preflight: install.env is sufficient for method=create."
+      ;;
+    manual|2)
+      if [ -n "${VAULT_PASS_CONTENT:-}" ]; then
+        echo "Preflight: install.env is sufficient for method=manual (VAULT_PASS_CONTENT set)."
+      else
+        echo "Preflight: method=manual but VAULT_PASS_CONTENT is empty; hidden input will be required."
+      fi
+      ;;
+    url|3)
+      if [ -n "${VAULT_PASS_URL:-}" ]; then
+        echo "Preflight: install.env is sufficient for method=url."
+      else
+        echo "Preflight: method=url but VAULT_PASS_URL is empty; URL input will be required."
+      fi
+      ;;
+    archive|4)
+      if [ -n "${VAULT_PASS_ZIP_PASSWORD_FILE:-}" ] && [ -f "$VAULT_PASS_ZIP_PASSWORD_FILE" ]; then
+        echo "Preflight: install.env is sufficient for method=archive (password file exists)."
+      elif [ -n "${VAULT_PASS_ZIP_PASSWORD_FILE:-}" ]; then
+        echo "Preflight: method=archive but VAULT_PASS_ZIP_PASSWORD_FILE does not exist: $VAULT_PASS_ZIP_PASSWORD_FILE"
+      elif [ -n "${VAULT_PASS_ZIP_PASSWORD:-}" ]; then
+        echo "Preflight: install.env is sufficient for method=archive (inline zip password set)."
+      else
+        echo "Preflight: method=archive but no zip password is configured; unzip will prompt interactively."
+      fi
+      if [ ! -f "$ARCHIVE" ]; then
+        echo "Preflight: archive file is missing: $ARCHIVE"
+      fi
+      ;;
+    *)
+      echo "Preflight: invalid INSTALL_VAULT_PASS_METHOD: $method"
+      ;;
+  esac
+}
+
+env_has_noninteractive_config() {
+  method="${INSTALL_VAULT_PASS_METHOD:-}"
+  case "$method" in
+    create|1) return 0 ;;
+    manual|2) [ -n "${VAULT_PASS_CONTENT:-}" ] ;;
+    url|3) [ -n "${VAULT_PASS_URL:-}" ] ;;
+    archive|4)
+      { [ -n "${VAULT_PASS_ZIP_PASSWORD:-}" ] || { [ -n "${VAULT_PASS_ZIP_PASSWORD_FILE:-}" ] && [ -f "$VAULT_PASS_ZIP_PASSWORD_FILE" ]; }; } && [ -f "$ARCHIVE" ]
+      ;;
+    *) return 1 ;;
+  esac
+}
+
 run_method() {
   case "$1" in
     create|1) create_new_password ;;
@@ -252,12 +327,24 @@ if [ "${1:-}" = "-h" ] || [ "${1:-}" = "--help" ]; then
   exit 0
 fi
 
+if [ "${1:-}" = "--check-env" ]; then
+  preflight_env_config
+  exit 0
+fi
+
 if verify_existing; then
   verify_vault_readable_if_possible || true
   exit 0
 fi
 
+preflight_env_config
+
 if [ -n "${INSTALL_VAULT_PASS_METHOD:-}" ]; then
+  if env_has_noninteractive_config; then
+    echo "Using non-interactive configuration from env."
+  else
+    echo "Env is not sufficient for a fully non-interactive install; installer may prompt."
+  fi
   run_method "$INSTALL_VAULT_PASS_METHOD"
   verify_vault_readable_if_possible || true
   exit 0