diff --git a/scripts/run-with-env.mjs b/scripts/run-with-env.mjs
index 602c62dd6e5f..2fc4b88984ba 100644
--- a/scripts/run-with-env.mjs
+++ b/scripts/run-with-env.mjs
@@ -61,6 +61,25 @@ export function resolveSpawnCommand(command, args, execPath = process.execPath)
   };
 }
 
+/**
+ * Reads the signal-forwarding force-kill grace period.
+ */
+export function resolveForceKillDelayMs(env = process.env) {
+  const raw = env.OPENCLAW_RUN_WITH_ENV_FORCE_KILL_MS;
+  if (raw === undefined || raw === "") {
+    return 5_000;
+  }
+  const text = raw.trim();
+  if (!/^\d+$/u.test(text)) {
+    throw new Error("OPENCLAW_RUN_WITH_ENV_FORCE_KILL_MS must be a positive integer");
+  }
+  const parsed = Number(text);
+  if (!Number.isSafeInteger(parsed) || parsed < 1) {
+    throw new Error("OPENCLAW_RUN_WITH_ENV_FORCE_KILL_MS must be a positive integer");
+  }
+  return parsed;
+}
+
 function main(argv = process.argv.slice(2)) {
   if (isRunWithEnvHelpRequest(argv)) {
     console.log(USAGE);
@@ -75,6 +94,14 @@ function main(argv = process.argv.slice(2)) {
     process.exit(2);
   }
 
+  let forceKillDelayMs;
+  try {
+    forceKillDelayMs = resolveForceKillDelayMs();
+  } catch (error) {
+    console.error(error instanceof Error ? error.message : String(error));
+    process.exit(2);
+  }
+
   const spawnCommand = resolveSpawnCommand(parsed.command, parsed.args);
   const useChildProcessGroup = process.platform !== "win32" && !process.stdin.isTTY;
   const child = spawn(spawnCommand.command, spawnCommand.args, {
@@ -85,10 +112,6 @@ function main(argv = process.argv.slice(2)) {
     },
     stdio: "inherit",
   });
-  const forceKillDelayMs = Math.max(
-    1,
-    Number.parseInt(process.env.OPENCLAW_RUN_WITH_ENV_FORCE_KILL_MS ?? "5000", 10) || 5_000,
-  );
   let forwardedSignal = null;
   let forceKillTimer = null;
   // Keep the child in the foreground process group so TTY signals such as
diff --git a/test/scripts/run-with-env.test.ts b/test/scripts/run-with-env.test.ts
index 740602a7d13a..068e7acde618 100644
--- a/test/scripts/run-with-env.test.ts
+++ b/test/scripts/run-with-env.test.ts
@@ -7,6 +7,7 @@ import { describe, expect, it } from "vitest";
 import {
   isRunWithEnvHelpRequest,
   parseRunWithEnvArgs,
+  resolveForceKillDelayMs,
   resolveSpawnCommand,
 } from "../../scripts/run-with-env.mjs";
 
@@ -124,6 +125,39 @@ describe("run-with-env", () => {
     });
   });
 
+  it("rejects malformed force-kill grace configuration before spawning", () => {
+    expect(resolveForceKillDelayMs({})).toBe(5_000);
+    expect(resolveForceKillDelayMs({ OPENCLAW_RUN_WITH_ENV_FORCE_KILL_MS: "250" })).toBe(250);
+    for (const value of ["0", "-1", "1e3", "100ms"]) {
+      expect(() => resolveForceKillDelayMs({ OPENCLAW_RUN_WITH_ENV_FORCE_KILL_MS: value })).toThrow(
+        "OPENCLAW_RUN_WITH_ENV_FORCE_KILL_MS must be a positive integer",
+      );
+    }
+
+    const result = spawnSync(
+      process.execPath,
+      [
+        "scripts/run-with-env.mjs",
+        "OPENCLAW_RUN_WITH_ENV_SIGNAL_TEST=1",
+        "--",
+        "node",
+        "-e",
+        "process.stdout.write('spawned')",
+      ],
+      {
+        cwd: process.cwd(),
+        encoding: "utf8",
+        env: { ...process.env, OPENCLAW_RUN_WITH_ENV_FORCE_KILL_MS: "100ms" },
+      },
+    );
+
+    expect(result.status).toBe(2);
+    expect(result.stdout).toBe("");
+    expect(result.stderr).toContain(
+      "OPENCLAW_RUN_WITH_ENV_FORCE_KILL_MS must be a positive integer",
+    );
+  });
+
   it.runIf(process.platform !== "win32").each(["SIGTERM", "SIGHUP", "SIGINT"] as const)(
     "forwards parent %s to the wrapped command",
     async (signal) => {