Structura

A transparent stdio proxy that sits between AI clients and Razorpay's official Model Context Protocol (MCP) server to enforce deterministic runtime safety on financial tool execution.

Live Demo: https://structura-mlsv.onrender.com

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Why It Exists

Autonomous AI agents executing financial actions cannot rely on prompt-based guardrails. Furthermore, Razorpay's official MCP server offers only binary access (--read-only or unrestricted execution), and generic API gateways cannot inspect inside JSON-RPC frames or track state across multiple calls.

Structura fills this gap by providing:

1. Deterministic Policy Enforcement: Evaluates tool calls against YAML-defined rules without an LLM in the decision loop. Schema-validated via Zod; fails closed on missing or invalid configurations.
2. Transaction Structuring Detection: Detects smurfing and structuring patterns across calls. For example, five ₹10,000 refunds on the same payment_id trip a ₹15,000 threshold on the 2nd call and trigger REQUIRE_APPROVAL, whereas five ₹10,000 refunds spread across five different payments pass (ALLOW).
3. Human Approval Queue: Intercepted calls enter an SQLite queue reviewable in an embedded React + Vite dashboard before downstream execution.
4. Tamper-Evident Audit Chain: Every inbound frame, decision, and payload hash is committed to an SQLite hash-chain (SHA-256). A standalone CLI verifier (structura verify-audit-log) detects edited rows, deleted rows, and recomputed hashes.

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Policy Rules Example (policy.yaml)

rules:
  - tool: create_refund
    action: REQUIRE_APPROVAL
    conditions:
      amount: { gt: 1000000 } # Subunits: > ₹10,000 triggers human review

structuring:
  - tool: create_refund
    group_by: payment_id
    threshold: 1500000        # Cumulative > ₹15,000 triggers REQUIRE_APPROVAL
    window_hours: 24

Decisions resolve strictly to ALLOW, DENY, or REQUIRE_APPROVAL.

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Tech Stack

• Runtime & Language: Node.js 22, TypeScript
• Validation: Zod (fail-closed schema enforcement)
• Database & Storage: SQLite (better-sqlite3)
• Dashboard UI: React, Vite, Tailwind CSS
• Protocol: Model Context Protocol (MCP) JSON-RPC 2.0 over stdio

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Setup & Quick Start

# 1. Clone & install
git clone https://github.com/CodeWithRJ006/Structura.git
cd Structura && npm install

# 2. Build proxy & dashboard
npm run build

# 3. Run proxy (wraps Razorpay MCP on stdio)
npm start

# 4. Verify cryptographic audit log integrity
npx structura verify-audit-log