@agent-wall/core

The core library for Agent Wall. Use this to integrate Agent Wall programmatically into your own tools.

Installation

npm install @agent-wall/core

Quick Example

import {
  PolicyEngine,
  AuditLogger,
  StdioProxy,
  ResponseScanner,
  loadPolicy,
  createTerminalPromptHandler,
} from "@agent-wall/core";

// Load policy
const { config } = loadPolicy();

// Create engine
const engine = new PolicyEngine(config);

// Create response scanner from config
const scanner = config.responseScanning?.enabled !== false
  ? new ResponseScanner(config.responseScanning)
  : undefined;

// Create proxy
const proxy = new StdioProxy({
  command: "npx",
  args: ["@modelcontextprotocol/server-filesystem", "/home/user"],
  policyEngine: engine,
  responseScanner: scanner,
  logger: new AuditLogger({ stdout: true, redact: true }),
  onPrompt: createTerminalPromptHandler(),
});

await proxy.start();

Exports

Classes

Export	Description
PolicyEngine	Evaluates tool calls against policy rules
StdioProxy	Transparent two-way stdio proxy for MCP servers
AuditLogger	Structured JSON audit logger
ResponseScanner	Scans server responses for secrets, PII, and oversize content
DashboardServer	WebSocket + HTTP server for real-time browser dashboard
ReadBuffer	Newline-delimited JSON-RPC stream parser
InjectionDetector	Prompt injection detection (30+ patterns)
EgressControl	URL/SSRF protection with IP blocking
KillSwitch	Emergency deny-all (file, signal, programmatic)
ChainDetector	Tool call sequence analysis

Functions

Export	Description
loadPolicy(path?)	Load and validate a YAML policy config
loadPolicyFile(path)	Load a specific config file
parsePolicyYaml(yaml)	Parse YAML string to config
discoverPolicyFile()	Auto-discover config file
getDefaultPolicy()	Get the built-in default policy
generateDefaultConfigYaml()	Generate default YAML config string
createTerminalPromptHandler()	Create a terminal-based approval prompt
createDefaultScanner()	Create a response scanner with sensible defaults
serializeMessage(msg)	Serialize a JSON-RPC message
deserializeMessage(str)	Parse a JSON-RPC message

Type Guards

Export	Description
isRequest(msg)	Check if message is a JSON-RPC request
isResponse(msg)	Check if message is a JSON-RPC response
isNotification(msg)	Check if message is a notification
isToolCall(msg)	Check if message is a tools/call request
isToolList(msg)	Check if message is a tools/list response
getToolCallParams(msg)	Extract tool name and arguments
createDenyResponse(id, message)	Create a deny error response (code: -32001)
createPromptResponse(id, message)	Create a prompt-pending response (code: -32002)