diff --git a/CHANGELOG.md b/CHANGELOG.md
index 52b2b8145..d83913104 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,7 @@ Docs: https://docs.openclaw.ai
 
 ### Fixes
 
+- Agents/Tools/exec: add a preflight guard that detects likely shell env var injection (e.g. `$DM_JSON`, `$TMPDIR`) in Python/Node scripts before execution, preventing recurring cron failures and wasted tokens when models emit mixed shell+language source. (#12836)
 - Security/Sessions: create new session transcript JSONL files with user-only (`0o600`) permissions and extend `openclaw security audit --fix` to remediate existing transcript file permissions.
 - Infra/Fetch: ensure foreign abort-signal listener cleanup never masks original fetch successes/failures, while still preventing detached-finally unhandled rejection noise in `wrapFetchWithAbortSignal`. Thanks @Jackten.
 - Gateway/Config: prevent `config.patch` object-array merges from falling back to full-array replacement when some patch entries lack `id`, so partial `agents.list` updates no longer drop unrelated agents. (#17989) Thanks @stakeswky.
diff --git a/src/agents/bash-tools.exec.script-preflight.test.ts b/src/agents/bash-tools.exec.script-preflight.test.ts
new file mode 100644
index 000000000..8174093d2
--- /dev/null
+++ b/src/agents/bash-tools.exec.script-preflight.test.ts
@@ -0,0 +1,65 @@
+import fs from "node:fs/promises";
+import os from "node:os";
+import path from "node:path";
+import { describe, expect, it } from "vitest";
+
+const isWin = process.platform === "win32";
+
+describe("exec script preflight", () => {
+  it("blocks shell env var injection tokens in python scripts before execution", async () => {
+    if (isWin) {
+      return;
+    }
+
+    const tmp = await fs.mkdtemp(path.join(os.tmpdir(), "openclaw-exec-preflight-"));
+    const pyPath = path.join(tmp, "bad.py");
+
+    await fs.writeFile(
+      pyPath,
+      [
+        "import json",
+        "# model accidentally wrote shell syntax:",
+        "payload = $DM_JSON",
+        "print(payload)",
+      ].join("\n"),
+      "utf-8",
+    );
+
+    const { createExecTool } = await import("./bash-tools.exec.js");
+    const tool = createExecTool({ host: "gateway", security: "full", ask: "off" });
+
+    await expect(
+      tool.execute("call1", {
+        command: "python bad.py",
+        workdir: tmp,
+      }),
+    ).rejects.toThrow(/exec preflight: detected likely shell variable injection \(\$DM_JSON\)/);
+  });
+
+  it("blocks obvious shell-as-js output before node execution", async () => {
+    if (isWin) {
+      return;
+    }
+
+    const tmp = await fs.mkdtemp(path.join(os.tmpdir(), "openclaw-exec-preflight-"));
+    const jsPath = path.join(tmp, "bad.js");
+
+    await fs.writeFile(
+      jsPath,
+      ['NODE "$TMPDIR/hot.json"', "console.log('hi')"].join("\n"),
+      "utf-8",
+    );
+
+    const { createExecTool } = await import("./bash-tools.exec.js");
+    const tool = createExecTool({ host: "gateway", security: "full", ask: "off" });
+
+    await expect(
+      tool.execute("call1", {
+        command: "node bad.js",
+        workdir: tmp,
+      }),
+    ).rejects.toThrow(
+      /exec preflight: (detected likely shell variable injection|JS file starts with shell syntax)/,
+    );
+  });
+});
diff --git a/src/agents/bash-tools.exec.ts b/src/agents/bash-tools.exec.ts
index b9a7e83b2..e0fba6ea2 100644
--- a/src/agents/bash-tools.exec.ts
+++ b/src/agents/bash-tools.exec.ts
@@ -1,5 +1,7 @@
 import type { AgentTool, AgentToolResult } from "@mariozechner/pi-agent-core";
 import crypto from "node:crypto";
+import fs from "node:fs/promises";
+import path from "node:path";
 import type { BashSandboxConfig } from "./bash-tools.shared.js";
 import {
   type ExecAsk,
@@ -118,6 +120,97 @@ export type ExecToolDetails =
       nodeId?: string;
     };
 
+function extractScriptTargetFromCommand(
+  command: string,
+): { kind: "python"; relOrAbsPath: string } | { kind: "node"; relOrAbsPath: string } | null {
+  const raw = command.trim();
+  if (!raw) {
+    return null;
+  }
+
+  // Intentionally simple parsing: we only support common forms like
+  //   python file.py
+  //   python3 -u file.py
+  //   node --experimental-something file.js
+  // If the command is more complex (pipes, heredocs, quoted paths with spaces), skip preflight.
+  const pythonMatch = raw.match(/^\s*(python3?|python)\s+(?:-[^\s]+\s+)*([^\s]+\.py)\b/i);
+  if (pythonMatch?.[2]) {
+    return { kind: "python", relOrAbsPath: pythonMatch[2] };
+  }
+  const nodeMatch = raw.match(/^\s*(node)\s+(?:--[^\s]+\s+)*([^\s]+\.js)\b/i);
+  if (nodeMatch?.[2]) {
+    return { kind: "node", relOrAbsPath: nodeMatch[2] };
+  }
+
+  return null;
+}
+
+async function validateScriptFileForShellBleed(params: {
+  command: string;
+  workdir: string;
+}): Promise<void> {
+  const target = extractScriptTargetFromCommand(params.command);
+  if (!target) {
+    return;
+  }
+
+  const absPath = path.isAbsolute(target.relOrAbsPath)
+    ? path.resolve(target.relOrAbsPath)
+    : path.resolve(params.workdir, target.relOrAbsPath);
+
+  // Best-effort: only validate if file exists and is reasonably small.
+  let stat: { isFile(): boolean; size: number };
+  try {
+    stat = await fs.stat(absPath);
+  } catch {
+    return;
+  }
+  if (!stat.isFile()) {
+    return;
+  }
+  if (stat.size > 512 * 1024) {
+    return;
+  }
+
+  const content = await fs.readFile(absPath, "utf-8");
+
+  // Common failure mode: shell env var syntax leaking into Python/JS.
+  // We deliberately match all-caps/underscore vars to avoid false positives with `$` as a JS identifier.
+  const envVarRegex = /\$[A-Z_][A-Z0-9_]{1,}/g;
+  const first = envVarRegex.exec(content);
+  if (first) {
+    const idx = first.index;
+    const before = content.slice(0, idx);
+    const line = before.split("\n").length;
+    const token = first[0];
+    throw new Error(
+      [
+        `exec preflight: detected likely shell variable injection (${token}) in ${target.kind} script: ${path.basename(
+          absPath,
+        )}:${line}.`,
+        target.kind === "python"
+          ? `In Python, use os.environ.get(${JSON.stringify(token.slice(1))}) instead of raw ${token}.`
+          : `In Node.js, use process.env[${JSON.stringify(token.slice(1))}] instead of raw ${token}.`,
+        "(If this is inside a string literal on purpose, escape it or restructure the code.)",
+      ].join("\n"),
+    );
+  }
+
+  // Another recurring pattern from the issue: shell commands accidentally emitted as JS.
+  if (target.kind === "node") {
+    const firstNonEmpty = content
+      .split(/\r?\n/)
+      .map((l) => l.trim())
+      .find((l) => l.length > 0);
+    if (firstNonEmpty && /^NODE\b/.test(firstNonEmpty)) {
+      throw new Error(
+        `exec preflight: JS file starts with shell syntax (${firstNonEmpty}). ` +
+          `This looks like a shell command, not JavaScript.`,
+      );
+    }
+  }
+}
+
 export function createExecTool(
   defaults?: ExecToolDefaults,
   // oxlint-disable-next-line typescript/no-explicit-any
@@ -874,6 +967,11 @@ export function createExecTool(
         typeof params.timeout === "number" ? params.timeout : defaultTimeoutSec;
       const getWarningText = () => (warnings.length ? `${warnings.join("\n")}\n\n` : "");
       const usePty = params.pty === true && !sandbox;
+
+      // Preflight: catch a common model failure mode (shell syntax leaking into Python/JS sources)
+      // before we execute and burn tokens in cron loops.
+      await validateScriptFileForShellBleed({ command: params.command, workdir });
+
       const run = await runExecProcess({
         command: params.command,
         execCommand: execCommandOverride,
diff --git a/src/agents/pi-embedded-runner-extraparams.e2e.test.ts b/src/agents/pi-embedded-runner-extraparams.e2e.test.ts
index b425f33c7..bec5e67f6 100644
--- a/src/agents/pi-embedded-runner-extraparams.e2e.test.ts
+++ b/src/agents/pi-embedded-runner-extraparams.e2e.test.ts
@@ -154,4 +154,27 @@ describe("applyExtraParamsToAgent", () => {
     });
     expect(payload.store).toBe(false);
   });
+
+  it("does not force store=true for Codex responses (Codex requires store=false)", () => {
+    const payload = { store: false };
+    const baseStreamFn: StreamFn = (_model, _context, options) => {
+      options?.onPayload?.(payload);
+      return new AssistantMessageEventStream();
+    };
+    const agent = { streamFn: baseStreamFn };
+
+    applyExtraParamsToAgent(agent, undefined, "openai-codex", "codex-mini-latest");
+
+    const model = {
+      api: "openai-codex-responses",
+      provider: "openai-codex",
+      id: "codex-mini-latest",
+      baseUrl: "https://chatgpt.com/backend-api/codex/responses",
+    } as Model<"openai-codex-responses">;
+    const context: Context = { messages: [] };
+
+    void agent.streamFn?.(model, context, {});
+
+    expect(payload.store).toBe(false);
+  });
 });