feat: add AgentTrust Action Provider for on-chain reputation.

[remangazo]

PR Pitch: AgentTrust Action Provider for Coinbase AgentKit 🛡️🏛️
Title Proposal: feat: add AgentTrust Action Provider for on-chain reputation and risk scoring

Description
This PR introduces the AgentTrust Action Provider, a machine-native credit bureau for autonomous agents on the Base network.

As the agentic economy scales, agents need a trustless way to evaluate the counterparty risk of wallets before executing transactions, lending funds, or interacting with other agents. AgentTrust provides a real-time, 5-factor scoring system (Age, Volume, Success Rate, Diversity, and Consistency) to give agents an actionable "Trust Grade" (AAA to C).

Key Features
Automated x402 Handshake: The provider natively handles the HTTP 402 (Payment Required) protocol. If a request requires payment, the agent automatically executes the USDC transfer on Base and retries the query with the transaction hash — all without human intervention.
Ecosystem Aligned: Specifically optimized for Base Mainnet and Sepolia.
Developer-Friendly Schema: Uses Zod for strict parameter validation and supports both basic scores and full risk reports.
Standardized Output: Returns concise, machine-readable summaries designed for LLM reasoning and decision-making.
Motivation
In a decentralized world of autonomous agents, reputation is the primary bottleneck for complex interactions (uncollateralized lending, service marketplaces, bot-to-bot commerce). By integrating AgentTrust into AgentKit, we provide builders with a "standard tool" to build safer, more reliable agentic workflows.

Technical Details
Protocol: x402 for automated value exchange.
Network: Base (8453).
Security: Strict type-checking and schema validation for address inputs.
Verification Results
Automated Tests
Unit tests included in
test/agentTrust.test.ts
verify network support and schema validation.
Validated automated encoding of ERC20 USDC transfers for the x402 flow.
Manual Verification
Verified integration with a standalone AgentKit instance on Base Sepolia.
Confirmed that the agent successfully transitions from a 402 error to a successful score retrieval after automated payment.
Built with 🛡️ by the AgentTrust Team Powered by @base

[cb-heimdall]

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[douglasborthwick-crypto]

Related work: we shipped POST /v1/trust on InsumerAPI, which returns a signed multi-dimensional wallet fact profile. 14 checks across stablecoins, governance tokens, and NFTs on 31 EVM chains. ECDSA P-256 signatures, JWKS at /.well-known/jwks.json, 30-minute expiry. Three credits per call.

The difference from a single-number score: the response is a structured fact profile with per-check results, so the consuming agent can reason over individual dimensions rather than a composite grade. An agent deciding whether to extend credit cares about stablecoin holdings; one joining a DAO cares about governance tokens. Same endpoint, different decision logic.

AI Agent Verification API guide · MCP server: mcp-server-insumer (18 tools, stdio transport)
LangChain: langchain-insumer
Spec: insumermodel.com/openapi.yaml