pop-pay

Point One Percent — pop-pay

it only takes 0.1% of Hallucination to drain 100% of your wallet.

The runtime security layer for AI agent commerce. Drop-in CLI + MCP server. Card credentials are injected directly into the browser DOM via CDP — they never enter the agent's context window. One hallucinated prompt can't drain a wallet it can't see.

Install

Choose your preferred method:

Homebrew (macOS)

brew install 100xpercent/tap/pop-pay

curl (Linux / macOS) — bootstraps via npm; requires Node.js 18+

curl -fsSL https://raw.githubusercontent.com/100xPercent/pop-pay/main/install.sh | sh

npm (global)

npm install -g pop-pay

npx (no install — one-off runs)

npx -y pop-pay <command>

All install paths expose the same binaries: pop-pay, pop-launch, pop-init-vault, pop-unlock.

Also available as @100xpercent/mcp-server-pop-pay — identical package under the MCP @scope/mcp-server-<name> convention. Tracks the same version on every release.

Using Python? Check out pop-pay-python — pip install pop-pay. Same security model, same vault format, independent release cycle — safe to switch between runtimes.

Quick Start (CLI)

1. Initialize the encrypted credential vault

pop-pay init-vault

This encrypts your card credentials into ~/.config/pop-pay/vault.enc (AES-256-GCM). For stronger protection (blocks agents with shell access):

pop-pay init-vault --passphrase   # one-time setup
pop-pay unlock                     # run once per session

2. Launch Chrome with CDP remote debugging

pop-pay launch

This opens a Chromium instance on http://localhost:9222 that pop-pay injects credentials into. Your agent (via MCP, browser automation, or x402) then drives the checkout flow — card details never leave the browser process.

3. Plug into your agent

The CLI launches infrastructure; the actual payment tool calls come from your agent. Two supported paths:

• MCP server — add pop-pay to any MCP-compatible client (Claude Code, Cursor, Windsurf, OpenClaw). See MCP Server below.
• x402 HTTP — pay for API calls via the x402 payment protocol.

Full CLI reference: pop-pay --help.

MCP Server (optional)

Add to your MCP client

Standard config for any MCP-compatible client:

{
  "mcpServers": {
    "pop-pay": {
      "command": "npx",
      "args": ["-y", "pop-pay", "launch-mcp"],
      "env": {
        "POP_CDP_URL": "http://localhost:9222"
      }
    }
  }
}

Claude Code

Claude Code uses its own CLI — the JSON config above is not needed.

claude mcp add --scope user pop-pay -- npx -y pop-pay launch-mcp

--scope user makes it available across all projects. To remove: claude mcp remove pop-pay

Cursor / Windsurf / VS Code

Add the JSON config above to:

• Cursor: ~/.cursor/mcp.json
• Windsurf: ~/.codeium/windsurf/mcp_config.json
• VS Code (Copilot): .vscode/mcp.json in project root

OpenClaw / NemoClaw

OpenClaw has its own CLI — the JSON config above is not needed.

openclaw mcp add pop-pay -- npx -y pop-pay launch-mcp

Or add to ~/.openclaw/mcp_servers.json using the JSON config above.

For System Prompt templates and NemoClaw sandbox setup, see Integration Guide §4.

Docker

docker-compose up -d

Runs the MCP server + headless Chromium with CDP. Mount your encrypted vault from the host.

MCP Tools

Tool	Description
request_virtual_card	Issue a virtual card and inject credentials into the checkout page via CDP. Automatically scans the page for hidden prompt injections.
request_purchaser_info	Auto-fill billing/contact info (name, address, email, phone). Automatically scans the page for hidden prompt injections.
request_x402_payment	Pay for API calls via the x402 HTTP payment protocol.

Tip for Claude Code users: Add the following to your project's CLAUDE.md to help the agent know when to call pop-pay: "When you encounter a payment form or checkout page, use the request_virtual_card tool. For billing/contact info forms, use request_purchaser_info first."

Configuration

Core variables in ~/.config/pop-pay/.env. See ENV_REFERENCE.md for the full list.

Variable	Default	Description
POP_ALLOWED_CATEGORIES	["aws","cloudflare"]	Approved vendor categories — see Categories Cookbook
POP_MAX_PER_TX	100.0	Max USD per transaction
POP_MAX_DAILY	500.0	Max USD per day
POP_BLOCK_LOOPS	true	Block hallucination/retry loops
POP_AUTO_INJECT	true	Enable CDP card injection
POP_GUARDRAIL_ENGINE	keyword	keyword (zero-cost) or llm (semantic)

Guardrail Mode

	keyword (default)	llm
Mechanism	Keyword matching on reasoning string	Semantic analysis via LLM
Cost	Zero — no API calls	One LLM call per request
Best for	Development, low-risk workflows	Production, high-value transactions

To enable LLM mode, see Integration Guide §1.

Providers

Provider	Description
BYOC (default)	Bring Your Own Card — encrypted vault credentials, local CDP injection.
Stripe Issuing	Real virtual cards via Stripe API. Requires POP_STRIPE_KEY.
Lithic	Multi-issuer adapter (Stripe Issuing / Lithic).
Mock	Test mode with generated card numbers for development.

Priority: Stripe Issuing → BYOC Local → Mock.

Security

Layer	Defense
Context Isolation	Card credentials never enter the agent's context window or logs
Encrypted Vault	AES-256-GCM with XOR-split salt and native scrypt key derivation (Rust)
TOCTOU Guard	Domain verified at the moment of CDP injection — blocks redirect attacks
Repr Redaction	Automatic masking (****-4242) in all MCP responses, logs, and tracebacks

See THREAT_MODEL.md for the full STRIDE analysis and COMPLIANCE_FAQ.md for enterprise details.

Architecture

• TypeScript — MCP server, CDP injection engine, guardrails, CLI
• Rust (napi-rs) — Native security layer: XOR-split salt storage, scrypt key derivation
• Node.js crypto — AES-256-GCM vault encryption (OpenSSL binding)
• Chrome DevTools Protocol — Direct DOM injection via raw WebSocket

Documentation

• Threat Model — STRIDE analysis, 5 security primitives, 10 attack scenarios
• Guardrail Benchmark — Cross-model evaluation (Anthropic / OpenAI / Gemini) across 585 payloads, 11 attack categories
• Compliance FAQ — PCI DSS, SOC 2, GDPR details
• Environment Reference — All POP_* environment variables
• Integration Guide — Setup for Claude Code, Node.js SDK, and browser agents
• Categories Cookbook — POP_ALLOWED_CATEGORIES patterns and examples

License

MIT