feat: add Hydrex Base MCP plugin

[CottonEyeBro]

Summary

This PR adds a plugin for Hydrex, an Omni-Liquidity MetaDEX on Base that delivers the best swap rates on Base and supports concentrated liquidity position management.

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What This Adds

skills/base-mcp/plugins/hydrex.md — a complete send_calls-based plugin covering:

• DEX swaps with best available routing on Base
• Concentrated liquidity position management — open and close positions
• Read endpoints for live quotes, wallet portfolio, open positions, and trade history
• Full orchestration patterns for harness surfaces (Claude Code, Cursor, Codex) and chat-only surfaces (Claude.ai, ChatGPT)
• Price impact guard — warns the user and requires explicit confirmation before executing any swap with price impact > 5%
• Slippage defaults (50 bps) with user-overridable parameters on all write operations

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Infrastructure

The plugin is backed by a dedicated prepare server hosted at https://hydrex-agent.com, built on the hydrex-base-mcp Express server running against Base mainnet (chainId: 8453).

Allowlist Request

Please add hydrex-agent.com to the web_request allowlist so the plugin works natively on Claude.ai and ChatGPT consumer surfaces. On harness surfaces the plugin works today via direct HTTP tool calls without allowlisting.

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Endpoints

Endpoint	Type	Description
GET /health	Read	Server health check
GET /state/quote	Read	Best available swap quote on Base
GET /state/portfolio	Read	Token balances and LP positions for a wallet
GET /state/positions	Read	Open concentrated liquidity positions
GET /state/trade-history	Read	Past swaps executed through Hydrex
GET /prepare/swap	Prepare	Returns unsigned swap calldata
GET /prepare/add-liquidity	Prepare	Returns unsigned approve + mint calldata
GET /prepare/remove-liquidity	Prepare	Returns unsigned remove-liquidity calldata

All prepare endpoints return a transactions[] array ready to pass directly to send_calls.

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Testing

Health check:

GET https://hydrex-agent.com/health

{"ok":true,"service":"hydrex-base-skill-server","chainId":8453}

Sample quote — 10 USDC → WETH:

GET https://hydrex-agent.com/state/quote?tokenIn=0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913&tokenOut=0x4200000000000000000000000000000000000006&amount=10000000&recipient=0x0000000000000000000000000000000000000001

[cb-heimdall]

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