🛡️ Bulwark (TypeScript)

An open-source safeguard against prompt injection in AI summarization.

Summarizing untrusted content (web pages, emails, PDFs, search results) with an LLM is dangerous: hidden instructions in that content can hijack the model. Bulwark wraps any model in five layers of defense — sanitize, detect, spotlight, harden, validate — so the content gets summarized and the attack inside it doesn't.

Isomorphic (Node 18+, edge, browser), zero runtime dependencies. Full docs, threat model, and architecture: https://github.com/Myrhex-x/bulwark

Install

npm install bulwark-guard

Use

import { Bulwark } from "bulwark-guard";

const guard = new Bulwark();

const myModel = async (messages) => {
  // call OpenAI / Anthropic / a local model — anything
  return summaryText;
};

const result = await guard.summarize(untrustedPage, myModel);
console.log(result.summary); // cleaned, validated summary (or null if blocked)
console.log(result.report);  // what was caught

Detection only (no model):

import { scan } from "bulwark-guard";
if (scan(text).injected) {
  // ...
}

Presets

import { Bulwark, strictConfig, paranoidConfig } from "bulwark-guard";
new Bulwark(strictConfig());    // delimiting + data-marking, blocks on critical
new Bulwark(paranoidConfig());  // base64 isolation, blocks on high

No prompt-injection defense is perfect. Bulwark applies every robust mitigation at once and validates the model's output, but you should still keep your summarizer read-only and gate downstream actions. See the threat model.

MIT licensed — free for any use, including commercial.