Upstream 20260501

[andylim-duo]

Summary

Merge upstream modelcontextprotocol/python-sdk main (as of 2026-05-01) into our fork, preserving multi-tenant isolation features.

Upstream changes included

• OpenTelemetry tracing — basic client/server request tracing with W3C trace context propagation via _meta (Add basic OpenTelemetry tracing for client and server requests modelcontextprotocol/python-sdk#2381)
• Context-aware streams — contextvars.Context propagation through anyio memory streams (Propagate contextvars.Context through anyio streams without modifying SessionMessage modelcontextprotocol/python-sdk#2298)
• resources parameter on MCPServer — bulk resource init at construction (Add resources parameter to MCPServer modelcontextprotocol/python-sdk#2414)
• dependencies parameter restored on MCPServer (feat(server): restore dependencies parameter on MCPServer modelcontextprotocol/python-sdk#2358)
• Sync resource/prompt functions no longer block the event loop (Don't block the event loop on sync resource and prompt functions modelcontextprotocol/python-sdk#2380)
• Shared is_async_callable replaces inspect.iscoroutinefunction (Use shared is_async_callable instead of inspect.iscoroutinefunction modelcontextprotocol/python-sdk#2389)
• Auth fixes — empty-string URL coercion in OAuthClientMetadata (fix(auth): coerce empty-string optional URL fields to None in OAuthClientMetadata modelcontextprotocol/python-sdk#2404), refresh token guidance (SEP-2207: Refresh token guidance modelcontextprotocol/python-sdk#2039)
• Pydantic 2.13 compat — catch PydanticUserError in output schema generation (fix: catch PydanticUserError when generating output schema (pydantic 2.13 compat) modelcontextprotocol/python-sdk#2434)
• Dep bumps — cryptography 46.0.7, requests 2.33.0, httpx <1.0.0 restriction
• CI — removed claude-code-review workflow, skip claude.yml on @claude review comments
• Docs — AGENTS.md replaces CLAUDE.md guidelines, migration guide gap fills

Merge conflict resolutions

Four files had conflicts between upstream's structural changes and our tenant-scoped storage model:

File	Resolution
src/mcp/server/lowlevel/server.py	Kept upstream's OTel span structure; grafted tenant_id_var propagation into the new _handle_request; removed duplicate handler block from conflict
src/mcp/server/mcpserver/resources/resource_manager.py	Kept tenant-scoped dict[str | None, dict[str, Resource]] type; added upstream's resources= constructor parameter with bulk init
src/mcp/server/mcpserver/tools/tool_manager.py	Same pattern — kept tenant-scoped dict, adopted upstream's tools= constructor kwarg
tests/server/mcpserver/resources/test_resource_manager.py	Replaced class-method tests with upstream's top-level functions; ported tenant template-duplicate tests; fixed _templates direct write to use add_template()

Context merging fix

Upstream's context-aware streams propagate the sender's (client-side) contextvars.Context to server handlers for OTel trace correlation. This shadowed our tenant_id_var (set server-side) in the in-memory transport.

Fix: Added merge_contexts(sender, server) in src/mcp/shared/_context.py — creates a new context using the sender as base with server-side vars overlaid. Server wins on conflict, preventing clients from spoofing tenant_id_var.

Documentation updates

• docs/multi-tenancy.md — added Context Merging architecture section, security notes on ctx.meta being client-controlled, documented decorator/constructor global-scope limitations
• docs/migration.md — added bug fix entry for context propagation with link to multi-tenancy guide

Test plan

• All 9 multi-tenancy E2E tests pass (6 were previously broken by context propagation change)
• 7 new merge_contexts unit tests (sender-only, server-only, both, conflict, tenant spoof, empty cases)
• New integration test: test_sender_context_and_tenant_id_coexist verifies both client contextvar and server tenant_id_var visible in handler
• Upstream test_context_propagation still passes
• Full suite: 1282 passed, 98 skipped, 1 xfailed, 0 failed
• pyright: 0 errors
• ruff: all checks passed
• markdownlint: passed