Coinbase — spot crypto trading via the official API

This skill manages Coinbase Advanced Trade spot trading through the official REST API — no bundled CLI, just documented endpoints any HTTP client can call. Public market data (product lists, tickers) needs no authentication. Everything under /api/v3/brokerage — accounts, balances, orders, fills — is authenticated.

Authentication is per-request: an ES256 JWT signed with an EC private key from the Coinbase Developer Platform portal, sent as a Bearer token. Credentials come from environment variables at runtime and are never hardcoded or written to files or logs. The API key needs View + Trade permissions, created with the ECDSA signature algorithm — Ed25519 keys are not supported by these endpoints.

The skill documents the full order lifecycle: place limit (good-til-canceled) or market (immediate-or-cancel) orders, cancel through batch_cancel, and query status and fills by order id. Order size is in base currency units and price in quote currency, and the entry-tier fee schedule (~0.40% maker / ~0.60% taker) is flagged for verification before sizing.

Operating rules are strict: orders move real money, so the skill requires the user's explicit trading authority and stated limits before any order is placed. A static-mock sandbox at https://api-sandbox.coinbase.com supports plumbing checks without live markets.