feat(server): expose progress_callback on ServerSession request methods#2164
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giulio-leone wants to merge 2 commits intomodelcontextprotocol:mainfrom
Closed
feat(server): expose progress_callback on ServerSession request methods#2164giulio-leone wants to merge 2 commits intomodelcontextprotocol:mainfrom
giulio-leone wants to merge 2 commits intomodelcontextprotocol:mainfrom
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added 2 commits
February 28, 2026 15:41
Add progress_callback parameter to create_message(), elicit_form(), elicit_url(), and the deprecated elicit() wrapper so that server code can receive bidirectional progress notifications from the client during sampling and elicitation requests. BaseSession.send_request() already supports progress_callback, but none of the ServerSession convenience methods forwarded it — callers had no way to pass the parameter without dropping down to send_request(). Closes modelcontextprotocol#1650
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Closing to reduce noise — focusing on the most impactful PRs. Happy to reopen if there's interest. |
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Problem
BaseSession.send_request()supports aprogress_callbackparameter for receiving bidirectional progress notifications, andClientSession.call_tool()already exposes it. However, none of theServerSessionconvenience methods (create_message(),elicit_form(),elicit_url()) forward this parameter, so server code cannot receive progress updates from clients during sampling and elicitation without dropping down to rawsend_request().The TypeScript SDK already exposes this via
RequestOptions.onprogressin bothcreateMessage()andelicitInput().Solution
Add an optional
progress_callback: ProgressFnT | None = Noneparameter (defaulting toNone) to:create_message()(all overloads + implementation)elicit_form()elicit_url()elicit()(deprecated wrapper — passes through toelicit_form())The parameter is forwarded to
send_request().Testing
All 475 server tests pass — the new parameter defaults to
None(no behavioural change for existing callers).Closes #1650