feat: add spraay crypto payments agent example

examples/spraay_crypto_payments/README.md

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+# Spraay Crypto Payments Agent
+
+An AI agent that executes cryptocurrency payments across 13 blockchains using the [Spraay x402 gateway](https://gateway.spraay.app). The agent can batch-send tokens, create escrow contracts, check balances, get token prices, and hire robots via the Robot Task Protocol (RTP).
+
+## Overview
+
+This example demonstrates how to build a **crypto payment agent** using NeMo Agent Toolkit with custom tools that interact with the Spraay x402 protocol gateway. The agent uses a ReAct pattern to reason about payment tasks and execute them via HTTP API calls.
+
+### What is x402?
+
+The [x402 protocol](https://www.x402.org) enables AI agents to pay for API services using USDC micropayments over HTTP. When an agent calls a paid endpoint, the server returns HTTP 402 (Payment Required) with payment details. The agent signs a USDC transaction, resends the request with the payment proof, and the server executes the operation.
+
+### Supported Chains
+
+Base · Ethereum · Arbitrum · Polygon · BNB Chain · Avalanche · Solana · Bitcoin · Stacks · Unichain · Plasma · BOB · Bittensor
+
+## Prerequisites
+
+- Python 3.11+
+- [uv](https://docs.astral.sh/uv/) package manager
+- NVIDIA API key from [build.nvidia.com](https://build.nvidia.com)
+
+## Setup
+
+1. Clone this repository and navigate to the example:
+
+```bash
+cd examples/spraay_crypto_payments
+```
+
+2. Install dependencies:
+
+```bash
+uv venv --python 3.12 --seed .venv
+source .venv/bin/activate  # Linux/Mac
+# .venv\Scripts\activate   # Windows
+uv pip install nvidia-nat httpx
+```
+
+3. Set environment variables:
+
+```bash
+export NVIDIA_API_KEY=<your-nvidia-api-key>
+export SPRAAY_GATEWAY_URL=https://gateway.spraay.app
+```
+
+## Running the Example
+
+### Using the CLI
+
+```bash
+nat run --config_file configs/config.yml --input "What chains does Spraay support and what is the current price of ETH on Base?"
+```
+
+### Example Prompts
+
+- `"Check the USDC balance for address 0xAd62f03C7514bb8c51f1eA70C2b75C37404695c8 on Base"`
+- `"What is the current price of ETH on Base?"`
+- `"List all available Spraay gateway routes and their pricing"`
+- `"Discover available robots on the RTP network"`
+
+## Architecture
+
+```
+┌─────────────────────────────────────────┐
+│         NeMo Agent Toolkit              │
+│                                         │
+│  ┌───────────────────────────────────┐  │
+│  │      ReAct Agent (Nemotron)       │  │
+│  │                                   │  │
+│  │  Tools:                           │  │
+│  │  ├── spraay_health                │  │
+│  │  ├── spraay_routes                │  │
+│  │  ├── spraay_chains                │  │
+│  │  ├── spraay_balance               │  │
+│  │  ├── spraay_price                 │  │
+│  │  ├── spraay_batch_send            │  │
+│  │  ├── spraay_escrow_create         │  │
+│  │  └── spraay_rtp_discover          │  │
+│  └──────────────┬────────────────────┘  │
+│                 │                        │
+└─────────────────┼────────────────────────┘
+                  │ HTTP + x402
+                  ▼
+     ┌────────────────────────┐
+     │  Spraay x402 Gateway   │
+     │  gateway.spraay.app    │
+     │                        │
+     │  76+ paid endpoints    │
+     │  13 blockchains        │
+     │  USDC micropayments    │
+     └────────────────────────┘
+```
+
+## Files
+
+| File | Description |
+|------|-------------|
+| `configs/config.yml` | NeMo Agent Toolkit workflow configuration |
+| `src/spraay_crypto_payments/spraay_tools.py` | Custom Spraay gateway tools |
+| `src/spraay_crypto_payments/__init__.py` | Package init with tool registration |
+| `pyproject.toml` | Project dependencies |
+
+## Links
+
+- [Spraay Gateway Docs](https://docs.spraay.app)
+- [x402 Protocol](https://www.x402.org)
+- [Spraay MCP Server](https://smithery.ai/server/@plagtech/spraay-x402-mcp)
+- [NeMo Agent Toolkit Docs](https://docs.nvidia.com/nemo/agent-toolkit/latest/)
+- [Spraay on OpenShell](https://github.com/NVIDIA/OpenShell-Community/pull/50)

examples/spraay_crypto_payments/configs/config.yml

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+# Spraay Crypto Payments Agent
+# NeMo Agent Toolkit workflow configuration
+#
+# This agent uses the Spraay x402 gateway to execute cryptocurrency
+# payments across 13 blockchains via USDC micropayments.
+
+functions:
+  # Query tools (free endpoints — no x402 payment required)
+  spraay_health:
+    _type: spraay_health
+    description: "Check the health status of the Spraay x402 gateway"
+
+  spraay_routes:
+    _type: spraay_routes
+    description: "List all available Spraay gateway routes with pricing info"
+
+  spraay_chains:
+    _type: spraay_chains
+    description: "List all supported blockchains on the Spraay gateway"
+
+  spraay_balance:
+    _type: spraay_balance
+    description: "Check the token balance of a wallet address on a specific chain"
+
+  spraay_price:
+    _type: spraay_price
+    description: "Get the current price of a token on a specific chain"
+
+  # Action tools (paid endpoints — requires x402 USDC payment)
+  spraay_batch_send:
+    _type: spraay_batch_send
+    description: "Send tokens to multiple recipients in a single batch transaction"
+
+  spraay_escrow_create:
+    _type: spraay_escrow_create
+    description: "Create an escrow contract with milestone-based fund releases"
+
+  spraay_rtp_discover:
+    _type: spraay_rtp_discover
+    description: "Discover available robots and IoT devices on the RTP network"
+
+llms:
+  nim_llm:
+    _type: nim
+    model_name: nvidia/nemotron-3-nano-30b-a3b
+    temperature: 0.0
+    chat_template_kwargs:
+      enable_thinking: false
+
+workflow:
+  _type: react_agent
+  tool_names:
+    - spraay_health
+    - spraay_routes
+    - spraay_chains
+    - spraay_balance
+    - spraay_price
+    - spraay_batch_send
+    - spraay_escrow_create
+    - spraay_rtp_discover
+  llm_name: nim_llm
+  verbose: true
+  parse_agent_response_max_retries: 3

examples/spraay_crypto_payments/pyproject.toml

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+[project]
+name = "spraay-crypto-payments"
+version = "0.1.0"
+description = "Spraay x402 crypto payment tools for NVIDIA NeMo Agent Toolkit"
+readme = "README.md"
+license = { text = "Apache-2.0" }
+requires-python = ">=3.11,<3.14"
+dependencies = [
+    "nvidia-nat>=1.5.0",
+    "httpx>=0.27.0",
+]
+
+[build-system]
+requires = ["setuptools>=75.0"]
+build-backend = "setuptools.build_meta"
+
+[tool.setuptools.packages.find]
+where = ["src"]

examples/spraay_crypto_payments/src/spraay_crypto_payments/__init__.py

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+# SPDX-FileCopyrightText: Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES.
+# SPDX-License-Identifier: Apache-2.0
+
+"""Spraay Crypto Payments — NeMo Agent Toolkit plugin.
+
+Registers Spraay x402 gateway tools for use in NeMo Agent Toolkit workflows.
+"""
+
+from nat.components.functions.tool import tool
+from nat.registry import register
+
+from .spraay_tools import (
+    spraay_balance,
+    spraay_batch_send,
+    spraay_chains,
+    spraay_escrow_create,
+    spraay_health,
+    spraay_price,
+    spraay_routes,
+    spraay_rtp_discover,
+)
+
+
+@register("spraay_health")
+def _register_health(**kwargs):
+    return tool(spraay_health, description=kwargs.get("description", ""))
+
+
+@register("spraay_routes")
+def _register_routes(**kwargs):
+    return tool(spraay_routes, description=kwargs.get("description", ""))
+
+
+@register("spraay_chains")
+def _register_chains(**kwargs):
+    return tool(spraay_chains, description=kwargs.get("description", ""))
+
+
+@register("spraay_balance")
+def _register_balance(**kwargs):
+    return tool(spraay_balance, description=kwargs.get("description", ""))
+
+
+@register("spraay_price")
+def _register_price(**kwargs):
+    return tool(spraay_price, description=kwargs.get("description", ""))
+
+
+@register("spraay_batch_send")
+def _register_batch_send(**kwargs):
+    return tool(spraay_batch_send, description=kwargs.get("description", ""))
+
+
+@register("spraay_escrow_create")
+def _register_escrow_create(**kwargs):
+    return tool(spraay_escrow_create, description=kwargs.get("description", ""))
+
+
+@register("spraay_rtp_discover")
+def _register_rtp_discover(**kwargs):
+    return tool(spraay_rtp_discover, description=kwargs.get("description", ""))