feat: PeerMixin, BaseContext, Connection, server Context#2460
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maxisbey wants to merge 5 commits intomaxisbey/v2-jsonrpc-dispatcherfrom
Draft
feat: PeerMixin, BaseContext, Connection, server Context#2460maxisbey wants to merge 5 commits intomaxisbey/v2-jsonrpc-dispatcherfrom
maxisbey wants to merge 5 commits intomaxisbey/v2-jsonrpc-dispatcherfrom
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PeerMixin defines the typed server-to-client request methods (sample with overloads, elicit_form, elicit_url, list_roots, ping) once. Each method constrains `self: Outbound` so any class with send_request/notify can mix it in — pyright checks the host structurally at the call site. The mixin does no capability gating; that's the host's send_request's job. Peer is a trivial standalone wrapper for when you have a bare Outbound (e.g. a dispatcher) and want the typed sugar without writing your own host class. 6 tests over DirectDispatcher, 0.03s.
Composition over a DispatchContext: forwards transport/cancel_requested/ send_request/notify/progress and adds meta. Satisfies Outbound so PeerMixin works on it (proven by Peer(bctx).ping() round-tripping). The server Context (next commit) extends this with lifespan/connection; ClientContext will be an alias once ClientSession is reworked.
…ntext PeerMixin methods and Peer/BaseContext now call/expose send_raw_request. The typed send_request lands on Connection/Context in the next commit.
TypedServerRequestMixin (server/_typed_request.py) provides shape-2 typed send_request: per-spec overloads (CreateMessage/Elicit/ListRoots/Ping) infer the result type; custom requests pass result_type explicitly. Mixed into both Connection and the server Context. Connection (server/connection.py) wraps an Outbound for the standalone stream. notify is best-effort (never raises); send_raw_request gated on has_standalone_channel; check_capability mirrors v1 for now (FOLLOWUP). Holds peer info populated at initialize time and the per-connection lifespan state. Context (server/context.py, alongside v1's ServerRequestContext) composes BaseContext + PeerMixin + TypedServerRequestMixin and adds lifespan/connection. Request-scoped log() rides the request's back-channel; ctx.connection.log() uses the standalone stream. dump_params(model, meta) merges user-supplied meta into _meta; threaded through every PeerMixin and Connection convenience method. 31 tests, 0.06s.
- Connection.check_capability per-field branches (parametrized) - Context.log with logger and meta supplied - Peer.notify forwards to wrapped Outbound
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Stacked on #2458. The MCP-type layer that sits above the dispatcher: typed request sugar, the per-request
Context, and the per-connectionConnection.Motivation and Context
Outbound(from #2452) is the rawsend_raw_request(method, params) -> dictchannel. This PR builds the typed surface on top:PeerMixin(shared/peer.py) — kwarg-style typed methods (sample,elicit_form,elicit_url,list_roots,ping) defined once. Each constrainsself: Outboundso any class withsend_raw_request/notifygets them.Peeris a standalone wrapper for bare dispatchers.BaseContext[TT](shared/context.py) — composition over aDispatchContext. Forwardstransport/cancel_requested/send_raw_request/notify/report_progress; addsmeta. SatisfiesOutbound.TypedServerRequestMixin(server/_typed_request.py) — typedsend_request(req) -> Resultwith per-spec overloads (CreateMessageRequest/ElicitRequest/ListRootsRequest/PingRequest) plus aresult_type=fallback for custom requests.Connection(server/connection.py) — per-client state and the standalone-streamOutbound. Best-effortnotify(never raises);send_raw_requestgated onhas_standalone_channel; convenience notifications (log,send_*_list_changed,send_resource_updated). Mixes inTypedServerRequestMixin.Context[LifespanT, TT](server/context.py, alongside v1'sServerRequestContext) —BaseContext+PeerMixin+TypedServerRequestMixin+lifespan/connection. WhatServerRunner(next PR) hands to user handlers.dump_params(model, meta)merges user-suppliedmetainto_meta; threaded through every convenience method.How Has This Been Tested?
tests/shared/test_peer.py(8),tests/shared/test_context.py(5),tests/server/test_connection.py(14),tests/server/test_server_context.py(4) — all overDirectDispatcher. 31 tests, 0.06s.Breaking Changes
None. New code only; v1's
ServerRequestContext/ClientRequestContextare untouched.Types of changes
Checklist
Additional context
Stack:
The typed
send_requestis shape 2 (per-spec overloads) for now. AHasResult[R]protocol (__mcp_result__ClassVar on each Request type, one generic signature, O(1) maintenance) is the cleaner long-term shape and would also handle MRTR/Tasks via discriminated unions — tracked as a follow-up onceClient(PR7) lands and the overload duplication becomes visible.AI Disclaimer