feat(providers): add BlockRun x402 micropayment provider

[1bcMax]

Summary

Add BlockRun as a new provider for Rig. BlockRun offers pay-per-request access to 30+ AI models via x402 micropayments - no API keys needed, just a funded wallet with USDC on Base.

Key Features

• No API keys: Uses wallet signatures for payment instead of traditional API keys
• x402 Protocol: Implements HTTP 402 Payment Required flow with EIP-712 signed USDC authorizations
• Multi-model access: Supports Claude, GPT-4o, Gemini, DeepSeek, Grok, and more through a single provider
• Tool calling support: Full compatibility with Rig's tool/agent system

Files Changed

• rig-core/src/providers/blockrun.rs - Main provider implementation (~1400 lines)
• rig-core/src/providers/mod.rs - Added blockrun module export
• rig-core/Cargo.toml - Added blockrun feature with crypto dependencies (sha3, k256, hex, rand)
• rig-core/examples/agent_with_blockrun.rs - Example demonstrating usage

Usage Example

use rig::providers::blockrun::{self, CLAUDE_SONNET_4, GPT_4O, DEEPSEEK_CHAT};

// Create client from wallet private key (for signing payments)
let client = blockrun::Client::from_env(); // reads BLOCKRUN_WALLET_KEY

// Use any supported model
let agent = client
    .agent(CLAUDE_SONNET_4)
    .preamble("You are a helpful assistant.")
    .build();

let response = agent.prompt("Hello!").await?;

Alternative: If this PR is not merged, you can use BlockRun's fork directly:

[dependencies]
rig-core = { git = "https://github.com/BlockRunAI/rig", features = ["blockrun"] }

Test Results

Tested end-to-end with real x402 payments on Base mainnet:

Wallet address: 0x4069560641ec74acfc74ddec64181f588c64e3a7
Fund this address with USDC on Base to use BlockRun

=== Using Claude Sonnet 4 ===
Claude: X402 is a designation that could refer to various things depending on context...

=== Using GPT-4o ===
GPT-4o: The term "x402" does not have a universally recognized meaning...

=== Using DeepSeek (cost-effective) ===
DeepSeek: x402 is a proposed extension to the email protocol designed to enhance security...

=== Calculator Agent with Tools ===
Calculator: I'll calculate (15 + 7) * 3 step by step.
Therefore, (15 + 7) * 3 = 66.

On-Chain Transaction Proof (Base Mainnet)

All payments settled on Base via TransferWithAuthorization (x402 protocol):

Model	Amount	Transaction
Claude Sonnet 4	0.016239 USDC	0x6b2e42f5341...
GPT-4o	0.010821 USDC	0x2ebec29ef5b...
DeepSeek	0.001 USDC	0xb960c54e34...
Calculator (tools)	0.01621 USDC	0xf1a5c8318c1...

Wallet: 0x4069560641ec74acfc74ddec64181f588c64e3a7

Test plan

• Unit tests pass (address derivation, payment parsing, response parsing)
• End-to-end test with Claude Sonnet 4
• End-to-end test with GPT-4o
• End-to-end test with DeepSeek
• Tool calling test with calculator agent
• On-chain payment verification on Base
• Streaming test (implemented but not tested in this run)

Breaking Changes

None - this is an additive change behind a feature flag.

[joshua-mo-143]

Hi, please add this as an integration under rig-integrations rather than adding it to rig-core - we're looking to keep the primary crate lean at the moment and it looks like there are extra dependency requirements required for this to work

[joshua-mo-143]

please remove the newly created README file

[1bcMax]

Thanks for the review feedback! I've addressed both items:

1. ✅ Removed rig/README.md - Deleted as requested

2. ✅ Moved BlockRun provider to rig-integrations - Restructured as a standalone crate at rig-integrations/rig-blockrun/, following the pattern of other integration crates like rig-eternalai

The new structure:

rig-integrations/rig-blockrun/
├── Cargo.toml
├── README.md
├── src/
│   ├── lib.rs
│   └── json_utils.rs
└── examples/
    └── agent_with_blockrun.rs

All changes to rig-core have been reverted to keep the primary crate lean. The code compiles cleanly.

[1bcMax]

@joshua-mo-143 Please let me know what else you want me to do, love to this get into the main branch.. Thank you