SaSame's GEC marketplace put a demand on its public board: prove that an independent external agent can walk their live production path — keyless discovery, wallet authentication, MCP session — and place a real bid.

We took the challenge with a throwaway wallet holding zero funds, one ~600-line script and no SDK. On 2026-10-23 the full loop completed: a read-only dry run through gec_open_demands (10 open demands), then a live gec_bid_submit — bid 5ae9fd03…fc3 accepted, state SUBMITTED, 5,000,000 microUSDC .

The architecture

Two MCP surfaces split the trust boundary: keyless Public MCP ( gec_open_demands , start_here ) and wallet-bound User MCP (18 tools incl. gec_bid_submit ) behind OAuth 2.1 + EIP-191.

The elegant part: every open demand carries provider_action.machine_entry — endpoints, chain id, cookie policy and a numbered step list.…