feat: Add BlockRun action provider for pay-per-request LLM access

[1bcMax]

Summary

Add BlockRun action provider enabling AI agents to access multiple LLM providers (OpenAI, Anthropic, Google, DeepSeek) using pay-per-request USDC micropayments on Base chain via the x402 protocol.

Why BlockRun?

• Multi-provider access: GPT-4o, Claude, Gemini, DeepSeek via single integration
• Pay-per-request: No monthly subscriptions - pay only for what you use in USDC
• Secure: Uses AgentKit's wallet provider - private keys never exposed
• Native x402: Built on Coinbase's x402 protocol using wallet_provider.to_signer()

Changes

• Added BlockrunActionProvider with chat_completion, list_models, and get_usdc_balance actions
• Uses x402 library with AgentKit's wallet provider (same pattern as x402_action_provider)
• Added USDC balance check before chat completion requests
• No external SDK dependency - uses built-in x402 support
• Comprehensive unit tests (32 tests) and e2e test setup

Actions Provided

Action	Description
chat_completion	Send chat completion requests to LLMs via x402 micropayments
list_models	List available models (GPT-4o, Claude, Gemini, DeepSeek)
get_usdc_balance	Check wallet's USDC balance on Base before making requests

Architecture

┌─────────────────┐     ┌──────────────────┐     ┌─────────────────┐
│   AgentKit      │     │    BlockRun      │     │   LLM Provider  │
│                 │     │    Action        │     │   (OpenAI,      │
│  WalletProvider │────▶│    Provider      │────▶│   Anthropic,    │
│  .to_signer()   │     │                  │     │   Google, etc)  │
└─────────────────┘     └──────────────────┘     └─────────────────┘
        │                       │
        │                       │ x402 micropayment
        │                       │ (USDC on Base)
        ▼                       ▼
┌─────────────────────────────────────────────┐
│              x402 Protocol                   │
│  - EIP-712 signing via wallet provider       │
│  - Automatic payment handling                │
└─────────────────────────────────────────────┘

Usage Example

from coinbase_agentkit import (
    AgentKit,
    AgentKitConfig,
    blockrun_action_provider,
)

# Works with any EVM wallet provider (CDP, local, etc.)
agentkit = AgentKit(AgentKitConfig(
    wallet_provider=wallet_provider,
    action_providers=[blockrun_action_provider()],
))

# Check balance before making requests
balance = agentkit.run_action("get_usdc_balance", {})

# Make a chat completion request
response = agentkit.run_action("chat_completion", {
    "prompt": "What is the capital of France?",
    "model": "openai/gpt-4o-mini"
})

Testing

• 32 unit tests pass
• Ruff linting passes
• E2E test setup with CDP wallet provider
• Follows existing action provider patterns (same as x402_action_provider)

Wallet Provider Compatibility

Provider	Supported	Notes
CdpEvmWalletProvider	✅	Recommended - keys managed server-side
EvmWalletProvider	✅	Local wallet with private key
Any EVM provider with to_signer()	✅	Uses standard interface

Links

• BlockRun Documentation
• x402 Protocol

[cb-heimdall]

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