Team ProtocolSmith

ProtocolSmith is a behavior-driven API compatibility prototype that helps developers keep an existing application working after the API behind it changes. An API upgrade can return the same business information in a completely different contract. In this demonstration, the legacy v1 API accepts page_size and returns an orders array containing id, total_cents, created_at, and status, followed by next_page. The modern v2 API instead accepts limit, places the orders under data, renames id to order_id and status to state, nests money under amount.value and amount.currency, shortens the timestamp to created, and moves pagination to pagination.next_cursor. Its missing-customer behavior also changes. As a result, the unchanged legacy client cannot understand the modern response, even though the modern API returns HTTP 200. ProtocolSmith begins by sending matching requests to the preconfigured legacy and modern APIs and recording their raw behavior. Meta Muse Spark 1.3 examines this paired evidence and returns structured compatibility findings, a typed and allowlisted adapter specification, and proposals for additional experiments when the evidence is uncertain. For example, Muse proposed that the legacy page_size parameter corresponds to the modern limit parameter. ProtocolSmith did not accept that suggestion on faith. It ran six controlled cases covering a baseline, the proposed parameter, and an intentionally incorrect parameter against both APIs. All six predicted outcomes matched, allowing the experiment’s final verdict to confirm the mapping. The confirmed findings describe ten evidence-linked transformations covering request parameters, response fields, money formats, dates, pagination, and error behavior. A constrained runtime consumes the typed specification; ProtocolSmith never executes arbitrary model-generated source code. In the live dashboard, the developer chooses whether to request one or two orders and clicks Execute. ProtocolSmith then sends five real HTTP requests across three visible paths: the legacy v1 API works, direct v2 returns HTTP 200 but remains incompatible with the unchanged legacy client, and the ProtocolSmith bridge restores the legacy contract. Fifteen recorded checks verify the result. ProtocolSmith also reports limitations instead of hiding them. For example, when the modern API provides only a date, the original timestamp precision cannot be recovered safely, so that information loss is explicitly disclosed. The key difference is that ProtocolSmith does not treat AI output as truth. Muse provides structured reasoning and experiment design, while deterministic evidence, allowlisted execution, and contract verification decide what can be trusted. The controlled API laboratory, Muse workflow, typed specification, constrained compiler, compatibility bridge, automated tests, and dashboard were built during the hackathon by Muhammad Rafae Khan.