Shared core enables cross-language feature parity
By moving state management (target handling, frame tracking, CDP dispatch) into a browser extension, Stagehand v4 reduces each SDK to a thin RPC client—enabling simultaneous TypeScript, Python, and Go releases and maintaining feature parity with single-core updates.
Supporting evidence
Introducing Stagehand v4: The SDK for browser agents.
Original excerpt
By putting it in the extension, each SDK becomes a thin client over one RPC boundary. We ship a feature to the core implementation once and every language has it immediately, which is what made launching TypeScript, Python, and Go together possible and what keeps them at parity afterward.