Guide: name @modelcontextprotocol/express in the server-author row, say
the two SDKs share no types rather than "do not interoperate" (they speak
the same wire protocol), note zod 4.0/4.1 lack ~standard.jsonSchema, list
the full 1.x-shaped extra, cover tool callbacks in the handler-context
bullet, document that the double-registration guard now covers the base
Protocol's notifications/progress and notifications/cancelled handlers,
mention ResourceNotFoundError, add the Express row to the import map, and
add a "What stays the same" section.
The @deprecated tag on the legacy setRequestHandler / setNotificationHandler
overload sat on the parameter inside an intersection type, which TypeScript
does not report. The overload now comes from LegacyRequestHandlerSetter /
LegacyNotificationHandlerSetter, named types with a documented call
signature, so editors flag the 1.x call and not the 2.x forms.
README links to the quickstart use the lowercase slug typedoc emits.
Consumers on 1.x wrote setRequestHandler(Schema, handler) and
setNotificationHandler(Schema, handler) with a whole-message Zod schema.
SDK 2.0 keys handlers by method name, so App and AppBridge now accept
that form as a third, deprecated overload: a small helper detects the
schema, extracts the method literal, forwards to the 2.x
(method, { params }, handler) form, and hands the legacy handler the
reassembled { method, params } message plus a 1.x-shaped extra
(signal, requestId, sessionId, _meta). A one-time console warning
points at the new form. The double-registration guard applies to both
forms.
The AppRequest, AppNotification and AppResult unions that 1.x fed to
the SDK's Protocol generics come back as deprecated type aliases, since
they leaked through the root entry and cost nothing to keep.
Both go away in 3.0.
- pdf-server build-mcpb.mjs packs the ext-apps build from this checkout
into the staging dir instead of asking the registry for ^2.0.0, which
is not published yet; CI's "Build MCPB bundle" step failed on ETARGET.
- Claim notifications/cancelled and notifications/progress in the
MethodRegistry right after super() so a direct setNotificationHandler
cannot silently replace the base Protocol's own handlers.
- Migration guide and add-app-to-server skill: custom methods use the
three-argument setRequestHandler("m", { params }, handler) form (the
two-argument form is only for spec methods); zod schemas live in
@modelcontextprotocol/core, not client/server; it is
toolInfo.tool.outputSchema that loosened in schema.json, and the
recursive JSON-value def is nested under three definitions; core is a
required peer that client already depends on.
- app-bridge.ts: fix "forthe"/"forresult" typos in @see links, update
three JSDoc examples to the method-string setNotificationHandler form,
move the UntypedHandlerSetter type below the import block (same in
app.ts).
- wire-compat.test.ts: say the fixtures are 1.x-shaped, not captures.
Install instructions now list the split base MCP SDK packages at ^2.0.0
by role (core comes in transitively, server only for server authors),
require Node 20+, and state that the wire protocol is unchanged so 2.x
Views and 1.x hosts interoperate. The agent skills lose the exact
prerelease wording and add-app-to-server gains a v1 to v2 import
mapping. docs/migrate-to-2.md lists the breaking changes, the peer
matrix and the host-side error deltas.
