diff --git a/DOCS.md b/DOCS.md
index ade1baa..4a3281c 100644
--- a/DOCS.md
+++ b/DOCS.md
@@ -251,7 +251,7 @@ All options are set via **Settings → Apps/Add-ons → OpenClaw Assistant → C
 
 When `gateway_auth_mode: trusted-proxy` is used, the add-on sets `gateway.auth.trustedProxy.userHeader` to `x-forwarded-user` by default.
 | `force_ipv4_dns` | bool | `false` | Force IPv4-first DNS ordering for Node network calls. Useful if IPv6 DNS resolves but IPv6 egress is broken (can affect Telegram API polling). |
-| `gateway_env_vars` | map(string) | `{}` | Environment variables exported to the gateway process at startup. Use YAML map format (for example `OPENAI_API_KEY: "sk-..."`). Limits: max 50 vars, key length 255, value length 10000. |
+| `gateway_env_vars` | map(string) | `{}` | Environment variables exported to the gateway process at startup. Use YAML map format (for example `SERVICE_API_KEY: "..."`). Limits: max 50 vars, key length 255, value length 10000. Reserved runtime keys are blocked (for example `PATH`, `HOME`, `NODE_OPTIONS`, `NODE_PATH`, `OPENCLAW_*`, proxy vars). |
 
 ### Terminal
 
diff --git a/openclaw_assistant/CHANGELOG.md b/openclaw_assistant/CHANGELOG.md
index 4020249..4a3dc20 100644
--- a/openclaw_assistant/CHANGELOG.md
+++ b/openclaw_assistant/CHANGELOG.md
@@ -6,6 +6,7 @@ All notable changes to the OpenClaw Assistant Home Assistant Add-on will be docu
 
 ### Fixed
 - **`web_fetch failed: fetch failed`**: changed `force_ipv4_dns` default to **true**. Node 22 tries IPv6 first; most HAOS VMs lack IPv6 egress, causing outbound `web_fetch` / HTTP tool calls to time out.
+- **`gateway_env_vars` safety**: block overrides for reserved runtime variables (for example `PATH`, `HOME`, `NODE_OPTIONS`, `NODE_PATH`, `OPENCLAW_*`, proxy vars) to prevent accidental startup/security regressions.
 
 ### Added
 - **`nginx_log_level` option** (`minimal` / `full`, default `minimal`): suppresses repetitive Home Assistant health-check and polling requests (`GET /`, `GET /v1/models`, `POST /tools/invoke`) from the nginx access log.
diff --git a/openclaw_assistant/config.yaml b/openclaw_assistant/config.yaml
index efdd48b..0c6b651 100644
--- a/openclaw_assistant/config.yaml
+++ b/openclaw_assistant/config.yaml
@@ -116,6 +116,8 @@ options:
   #   Feature flags:
   #     FEATURE_FLAG_X: "1"
   #     FEATURE_FLAG_Y: "0"
+  # Reserved keys are blocked to protect runtime/security
+  # (e.g. PATH, HOME, NODE_OPTIONS, NODE_PATH, OPENCLAW_*, proxy vars).
   # Limits: max 50 variables, max key length 255 chars, max value length 10000 chars
   gateway_env_vars: {}
 
diff --git a/openclaw_assistant/run.sh b/openclaw_assistant/run.sh
index 45eb713..b58bcf5 100644
--- a/openclaw_assistant/run.sh
+++ b/openclaw_assistant/run.sh
@@ -190,6 +190,27 @@ export PNPM_HOME="${PERSISTENT_NODE_GLOBAL}/pnpm"
 mkdir -p "$PNPM_HOME"
 export PATH="${PNPM_HOME}:${PATH}"
 
+# Protect critical runtime variables from accidental override via gateway_env_vars.
+is_reserved_gateway_env_var() {
+  case "$1" in
+    # Critical runtime paths/process vars.
+    HOME|PATH|PWD|OLDPWD|SHLVL|TZ|XDG_CONFIG_HOME|PNPM_HOME|NODE_PATH|NODE_OPTIONS|NODE_NO_WARNINGS)
+      return 0
+      ;;
+    # Proxy vars managed by add-on options.
+    HTTP_PROXY|HTTPS_PROXY|NO_PROXY|http_proxy|https_proxy|no_proxy)
+      return 0
+      ;;
+    # Add-on internal control vars.
+    OPENCLAW_*)
+      return 0
+      ;;
+    *)
+      return 1
+      ;;
+  esac
+}
+
 # Export gateway environment variables from add-on config
 # These are user-defined variables that should be available to the gateway process
 if [ "$GW_ENV_VARS" != "{}" ] && [ -n "$GW_ENV_VARS" ]; then
@@ -212,6 +233,12 @@ if [ "$GW_ENV_VARS" != "{}" ] && [ -n "$GW_ENV_VARS" ]; then
         continue
       fi
 
+      # Protect critical runtime variables from accidental override.
+      if is_reserved_gateway_env_var "$key"; then
+        echo "WARN: Reserved environment variable '$key' cannot be overridden via gateway_env_vars (skip)"
+        continue
+      fi
+
       # Enforce max variable name length
       if [ ${#key} -gt $max_var_name_size ]; then
         echo "WARN: Environment variable name too long: '$key' (max $max_var_name_size chars, skip)"