fix(scripts): bound Docker E2E JSON helpers

scripts/docker-e2e.mjs

@@ -2,6 +2,10 @@
 // Converts scheduler JSON into GitHub Actions outputs and compact markdown
 // summaries so the workflow does not duplicate Docker E2E planning logic.
 import fs from "node:fs";
+import { parsePositiveInt } from "./lib/numeric-options.mjs";
+
+const JSON_ARTIFACT_MAX_BYTES_ENV = "OPENCLAW_DOCKER_E2E_JSON_ARTIFACT_MAX_BYTES";
+const DEFAULT_JSON_ARTIFACT_MAX_BYTES = 16 * 1024 * 1024;
 
 function usage() {
   return [
@@ -13,7 +17,29 @@ function usage() {
 }
 
 function readJson(file) {
-  return JSON.parse(fs.readFileSync(file, "utf8"));
+  return JSON.parse(readJsonArtifactText(file));
+}
+
+function readJsonArtifactText(file) {
+  const maxBytes = readPositiveIntEnv(JSON_ARTIFACT_MAX_BYTES_ENV, DEFAULT_JSON_ARTIFACT_MAX_BYTES);
+  const stat = fs.statSync(file);
+  if (!stat.isFile()) {
+    throw new Error(`JSON artifact is not a file: ${file}`);
+  }
+  if (stat.size > maxBytes) {
+    throw new Error(`JSON artifact exceeded ${maxBytes} bytes: ${file} (${stat.size} bytes)`);
+  }
+  const text = fs.readFileSync(file, "utf8");
+  const bytes = Buffer.byteLength(text, "utf8");
+  if (bytes > maxBytes) {
+    throw new Error(`JSON artifact exceeded ${maxBytes} bytes: ${file} (${bytes} bytes)`);
+  }
+  return text;
+}
+
+function readPositiveIntEnv(name, fallback) {
+  const raw = process.env[name];
+  return raw === undefined || raw === "" ? fallback : parsePositiveInt(raw, name);
 }
 
 function boolOutput(value) {