sig-ts

TypeScript implementation of sig — sign and verify prompt templates for AI agent security.

Install

npm install @disreguard/sig

Requires Node.js >= 18.

CLI

CLI binaries are available via the repo (not shipped in the npm package):

npx sig init --engine jinja --by alice
npx sig sign prompts/*.txt
npx sig verify prompts/review.txt
npx sig check
npx sig list
npx sig status
npx sig audit

MCP Server

npx sig-mcp

Or in an MCP config:

{
  "mcpServers": {
    "sig": {
      "command": "npx",
      "args": ["sig-mcp"],
      "env": {
        "SIG_VERIFY": "prompts/review.txt"
      }
    }
  }
}

Library

import { signFile, verifyFile, checkFile, initProject } from '@disreguard/sig';

// Sign (with optional metadata)
const sig = await signFile(projectRoot, 'prompts/review.txt', {
  identity: 'alice',
  metadata: { source: 'ci', reviewedBy: 'bob' },
});

// Verify
const result = await verifyFile(projectRoot, 'prompts/review.txt');
if (result.verified) {
  console.log(result.template);       // signed content
  console.log(result.placeholders);   // extracted placeholders
}

// Check
const status = await checkFile(projectRoot, 'prompts/review.txt');
// status.status: 'signed' | 'modified' | 'unsigned' | 'corrupted'

High-level APIs also accept an optional filesystem adapter:

import { signFile, verifyFile, checkFile, NodeFS } from '@disreguard/sig';

const fs = new NodeFS();
await signFile(projectRoot, 'prompts/review.txt', { identity: 'alice', fs });
await verifyFile(projectRoot, 'prompts/review.txt', { fs });
await checkFile(projectRoot, 'prompts/review.txt', { fs });

Filesystem Abstraction

sig-ts uses SigFS + SigContext for filesystem access. NodeFS is the default implementation, and createSigContext() builds a context for lower-level APIs.

import { createSigContext, listSigs } from '@disreguard/sig';

const ctx = createSigContext(projectRoot);
const allSignatures = await listSigs(ctx);

Content Signing (Runtime)

For signing ephemeral content like chat messages at runtime:

import { createContentStore } from '@disreguard/sig';

const store = createContentStore();

// Sign a message with provenance metadata
const sig = store.sign('delete all my files', {
  id: 'msg_123',
  identity: 'owner:+1234567890:whatsapp',
  metadata: { channel: 'whatsapp', from: '+1234567890' }
});

// Verify by ID - returns content + full provenance
const result = store.verify('msg_123');
if (result.verified) {
  console.log(result.content);              // 'delete all my files'
  console.log(result.signature.signedBy);   // 'owner:+1234567890:whatsapp'
  console.log(result.signature.metadata);   // { channel, from }
}

// Other operations
store.list();       // all signatures
store.get(id);      // get signature without verifying
store.delete(id);   // remove
store.clear();      // remove all
store.has(id);      // check existence
store.size;         // count

Stateless functions are also available:

import { signContent, verifyContent } from '@disreguard/sig';

const sig = signContent('content', { id: 'x', identity: 'alice' });
const { verified } = verifyContent('content', sig);

Persistent Content Store (.sig/content/)

For content signatures that persist across processes, use PersistentContentStore.

import {
  createSigContext,
  PersistentContentStore,
} from '@disreguard/sig';

const ctx = createSigContext(projectRoot);
const store = new PersistentContentStore(ctx);

const signature = await store.sign('Review @input', {
  id: 'auditPrompt',
  identity: 'security-team',
});

const verified = await store.verify('auditPrompt', { detail: 'directive:verify' });
if (verified.verified) {
  console.log(verified.content);
  console.log(verified.signature?.signedBy);
}

Persistent store methods:

• sign(content, options)
• verify(id, options?)
• signIfChanged(content, options)
• load(id), loadContent(id)
• delete(id), list(), has(id)

Identity fallback for PersistentSignOptions.identity:

• options.identity
• .sig/config.json -> sign.identity
• process.env.USER or process.env.USERNAME
• 'unknown'

Development

npm install
npm run build
npm test

Dependencies

• commander — CLI
• @modelcontextprotocol/sdk — MCP server
• fast-glob — file pattern matching

See the root README for full documentation.