diff --git a/scripts/e2e/lib/upgrade-survivor/probe-gateway.mjs b/scripts/e2e/lib/upgrade-survivor/probe-gateway.mjs
index cabdb324361..a3202262003 100644
--- a/scripts/e2e/lib/upgrade-survivor/probe-gateway.mjs
+++ b/scripts/e2e/lib/upgrade-survivor/probe-gateway.mjs
@@ -17,11 +17,37 @@ function option(name, fallback) {
   return value;
 }
 
+function optionValue(name, envName, fallback) {
+  const index = args.indexOf(name);
+  if (index !== -1) {
+    return {
+      label: name,
+      value: option(name),
+    };
+  }
+  return {
+    label: envName,
+    value: process.env[envName] ?? fallback,
+  };
+}
+
 function writeJson(file, value) {
   fs.mkdirSync(path.dirname(file), { recursive: true });
   fs.writeFileSync(file, `${JSON.stringify(value, null, 2)}\n`);
 }
 
+function readStrictInteger({ allowZero = false, label, value }) {
+  const text = String(value ?? "").trim();
+  if (!/^\d+$/u.test(text)) {
+    throw new Error(`invalid ${label}: ${text}`);
+  }
+  const parsed = Number(text);
+  if (!Number.isSafeInteger(parsed) || (allowZero ? parsed < 0 : parsed <= 0)) {
+    throw new Error(`invalid ${label}: ${text}`);
+  }
+  return parsed;
+}
+
 const baseUrl = option("--base-url");
 const probePath = option("--path");
 const expectKind = option("--expect");
@@ -32,35 +58,25 @@ const allowFailing = new Set(
     .map((entry) => entry.trim())
     .filter(Boolean),
 );
-const timeoutMs = Number.parseInt(
-  option("--timeout-ms", process.env.OPENCLAW_UPGRADE_SURVIVOR_PROBE_TIMEOUT_MS || "60000"),
-  10,
+const timeoutOption = optionValue(
+  "--timeout-ms",
+  "OPENCLAW_UPGRADE_SURVIVOR_PROBE_TIMEOUT_MS",
+  "60000",
 );
-const attemptTimeoutMs = Number.parseInt(
-  option(
-    "--attempt-timeout-ms",
-    process.env.OPENCLAW_UPGRADE_SURVIVOR_PROBE_ATTEMPT_TIMEOUT_MS || "5000",
-  ),
-  10,
+const attemptTimeoutOption = optionValue(
+  "--attempt-timeout-ms",
+  "OPENCLAW_UPGRADE_SURVIVOR_PROBE_ATTEMPT_TIMEOUT_MS",
+  "5000",
 );
-const maxBodyBytes = Number.parseInt(
-  option(
-    "--max-body-bytes",
-    process.env.OPENCLAW_UPGRADE_SURVIVOR_PROBE_MAX_BODY_BYTES || "1048576",
-  ),
-  10,
+const maxBodyOption = optionValue(
+  "--max-body-bytes",
+  "OPENCLAW_UPGRADE_SURVIVOR_PROBE_MAX_BODY_BYTES",
+  "1048576",
 );
+const timeoutMs = readStrictInteger({ ...timeoutOption, allowZero: true });
+const attemptTimeoutMs = readStrictInteger(attemptTimeoutOption);
+const maxBodyBytes = readStrictInteger(maxBodyOption);
 const url = new URL(probePath, baseUrl).toString();
-
-if (!Number.isFinite(timeoutMs) || timeoutMs < 0) {
-  throw new Error(`invalid --timeout-ms: ${String(timeoutMs)}`);
-}
-if (!Number.isFinite(attemptTimeoutMs) || attemptTimeoutMs <= 0) {
-  throw new Error(`invalid --attempt-timeout-ms: ${String(attemptTimeoutMs)}`);
-}
-if (!Number.isFinite(maxBodyBytes) || maxBodyBytes <= 0) {
-  throw new Error(`invalid --max-body-bytes: ${String(maxBodyBytes)}`);
-}
 if (expectKind !== "live" && expectKind !== "ready") {
   throw new Error(`unknown probe expectation: ${expectKind}`);
 }
diff --git a/test/scripts/upgrade-survivor-probe-gateway.test.ts b/test/scripts/upgrade-survivor-probe-gateway.test.ts
index 82a7dcfb018..3564ff970ed 100644
--- a/test/scripts/upgrade-survivor-probe-gateway.test.ts
+++ b/test/scripts/upgrade-survivor-probe-gateway.test.ts
@@ -23,9 +23,14 @@ interface ProbeResult {
   stdout: string;
 }
 
-function runProbe(args: string[], timeout = 5_000): Promise<ProbeResult> {
+function runProbe(
+  args: string[],
+  timeout = 5_000,
+  env: NodeJS.ProcessEnv = {},
+): Promise<ProbeResult> {
   return new Promise((resolve) => {
     const child = spawn(process.execPath, [probePath, ...args], {
+      env: { ...process.env, ...env },
       stdio: ["ignore", "pipe", "pipe"],
     });
     let stdout = "";
@@ -82,6 +87,47 @@ afterEach(() => {
 });
 
 describe("scripts/e2e/lib/upgrade-survivor/probe-gateway.mjs", () => {
+  it("rejects loose numeric probe limits instead of parsing prefixes", async () => {
+    const out = path.join(makeTempDir(), "invalid.json");
+    const timeoutResult = await runProbe([
+      "--base-url",
+      "http://127.0.0.1:9",
+      "--path",
+      "/readyz",
+      "--expect",
+      "ready",
+      "--out",
+      out,
+      "--timeout-ms",
+      "1e3",
+    ]);
+
+    expect(timeoutResult.status).not.toBe(0);
+    expect(timeoutResult.stderr).toContain("invalid --timeout-ms: 1e3");
+
+    const bodyLimitResult = await runProbe(
+      [
+        "--base-url",
+        "http://127.0.0.1:9",
+        "--path",
+        "/readyz",
+        "--expect",
+        "ready",
+        "--out",
+        out,
+      ],
+      5_000,
+      {
+        OPENCLAW_UPGRADE_SURVIVOR_PROBE_MAX_BODY_BYTES: "64bytes",
+      },
+    );
+
+    expect(bodyLimitResult.status).not.toBe(0);
+    expect(bodyLimitResult.stderr).toContain(
+      "invalid OPENCLAW_UPGRADE_SURVIVOR_PROBE_MAX_BODY_BYTES: 64bytes",
+    );
+  });
+
   it("writes a result when the ready probe matches", async () => {
     const server = createHttpServer((_request, response) => {
       response.writeHead(200, { "content-type": "application/json" });