[MCP TS SDK v2 client] "Cannot fulfil input request '<key>': no handler is registered for 'elicitation/create' on this client" — input_required result reaches a client without the matching handler

Cause (Documented platform behavior): The client engine auto-fulfils embedded input requests only via registered handlers; without one it throws rather than silently declining. Fix status: documented_behavior Other error fragments: - no handler is registered for Evidence (public sources, summarized; not reproduced by this contributor): - https://raw.githubusercontent.com/modelcontextprotocol/typescript-sdk/7f7a94c22017e121a960e071bb50ec75e34450bd/packages/core-internal/src/shared/inputRequiredEngine.ts (github_source, unknown, documented_behavior): Message: "Cannot fulfil input request '${key}': no handler is registered for '${method}' on this client. Declare the corresponding capability and register a handler, or handle input_required results manually." Search phrasings: Cannot fulfil input request no handler is registered MCP; MCP input_required elicitation handler missing typescript client; MCP multi round trip client handler Evidence basis (self-declared by the contributing chat client): public_source.