Version Packages (beta)

github-actions[bot] · github-actions[bot] · commit da4653dd9d3e · 2026-07-21T12:07:45.000Z
diff --git a/.changeset/pre.json b/.changeset/pre.json
@@ -35,15 +35,19 @@
     "content-type-media-type-validation",
     "cross-bundle-error-instanceof",
     "examples-protected-wiring",
+    "export-protocol-class",
     "initialize-session-hygiene",
     "lazy-ajv-engine",
     "lazy-era-wire-schemas",
     "malformed-resource-uri-invalid-params",
     "post-dispatch-32021-http-400",
+    "prior-legacy-verdict",
+    "probe-close-handling",
     "probe-window-handler-restore",
     "response-cache-document-codec",
     "schemas-source-home",
     "silent-validators-wave",
+    "spec-3002-servinfo-meta",
     "standard-header-ows",
     "standard-schema-elicitation",
     "web-standard-bearer-auth",
diff --git a/packages/client/CHANGELOG.md b/packages/client/CHANGELOG.md
@@ -1,5 +1,32 @@
 # @modelcontextprotocol/client
 
+## 2.0.0-beta.5
+
+### Minor Changes
+
+- [#2501](https://github.com/modelcontextprotocol/typescript-sdk/pull/2501) [`1480241`](https://github.com/modelcontextprotocol/typescript-sdk/commit/1480241e2a2a7f0ceee8e7723b2adcf88579bb36) Thanks [@felixweinberger](https://github.com/felixweinberger)! - Export the `Protocol` base class and `mergeCapabilities` from the `@modelcontextprotocol/client` and `@modelcontextprotocol/server` package roots, restoring the v1 import for consumers that subclass `Protocol` (e.g. the MCP Apps SDK). The client and server packages each bundle their own compiled copy of the class, so import it from one package consistently within a process.
+
+    The codemod now rewrites `Protocol` and `mergeCapabilities` imports from `shared/protocol.js` to the client or server package root, like the module's other symbols, instead of dropping them with an action-required marker.
+
+- [#2511](https://github.com/modelcontextprotocol/typescript-sdk/pull/2511) [`f60dff0`](https://github.com/modelcontextprotocol/typescript-sdk/commit/f60dff0674954ab516739f21ad9905349c8e9249) Thanks [@felixweinberger](https://github.com/felixweinberger)! - `ConnectOptions.prior` accepts a cached era verdict — the new exported type `PriorDiscovery`. `{ kind: 'modern', discover }` adopts a previously obtained `DiscoverResult` with zero round trips; `{ kind: 'legacy' }` skips the `server/discover` probe and runs the plain `initialize` handshake directly, for servers known out-of-band to be legacy — without pinning the client to `mode: 'legacy'`: stop supplying the verdict and `connect()` falls back to the configured `versionNegotiation` mode (under `'auto'`, it re-probes and rediscovers an upgraded server). Freshness is the supplying host's responsibility — a stale legacy verdict succeeds silently against an upgraded server, so hosts must date cached legacy verdicts in their own storage and stop supplying them past their policy horizon. Persisted-blob plumbing is hardened: `prior: null` is treated as absent, the modern arm's `discover` payload is schema-validated before any connection state changes, and an unrecognized shape rejects with a typed `SdkError(EraNegotiationFailed)` instead of a `TypeError`.
+
+- [#2513](https://github.com/modelcontextprotocol/typescript-sdk/pull/2513) [`f413763`](https://github.com/modelcontextprotocol/typescript-sdk/commit/f4137630c05dc9a4fb14d4d3777f5cb167bd6313) Thanks [@felixweinberger](https://github.com/felixweinberger)! - Align the 2026-07-28 wire with the final revision (spec PR #3002): `serverInfo` moves from the `DiscoverResult` body to the result `_meta`, and the per-request envelope's `clientInfo` demotes from required to SHOULD.
+
+    Before this change the SDK shipped the pre-#3002 shape in both directions: the client hard-rejected a conforming server's `DiscoverResult` (missing body `serverInfo` failed parse, so the probe misclassified the server as legacy and attempted an `initialize` handshake against it — a hard connect failure against a modern-only server such as go-sdk v1.7.0-pre.3), and the server rejected conforming clients that omit `clientInfo`.
+
+    Now:
+    - The 2026 wire schemas are the final revision exactly: no body `serverInfo` on `DiscoverResult`, envelope `clientInfo` optional (a present-but-malformed value still fails validation).
+    - Servers stamp `_meta['io.modelcontextprotocol/serverInfo']` on every 2026-era response (spec SHOULD; a handler-authored value wins, the 2025-era wire is untouched). This includes the entry-built `subscriptions/listen` graceful-close results — the spec's `SubscriptionsListenResultMeta` extends `ResultMetaObject`.
+    - Clients keep sending `clientInfo` and read server identity from the discover result's `_meta` only. A server that stamps no identity is anonymous: `getServerVersion()` is `undefined` and the response cache partitions under a per-connection surrogate. A malformed `_meta` serverInfo value is treated as absent on receive (the spec marks the field self-reported, unverified, and display-only).
+    - Breaking type changes: `DiscoverResult` no longer declares `serverInfo`; `RequestMetaEnvelope`'s `clientInfo` is optional. New public constant `SERVER_INFO_META_KEY` (`'io.modelcontextprotocol/serverInfo'`).
+
+### Patch Changes
+
+- [#2514](https://github.com/modelcontextprotocol/typescript-sdk/pull/2514) [`6fe1963`](https://github.com/modelcontextprotocol/typescript-sdk/commit/6fe196310ddba95a9f9655facb6b7c1ab503d346) Thanks [@felixweinberger](https://github.com/felixweinberger)! - Probe stdio servers on a disposable sibling process. Some stdio servers exit on any pre-`initialize` request (servers built on the official Rust SDK, rmcp, behave this way), so under `versionNegotiation: { mode: 'auto' }` the `server/discover` probe previously killed the server and `connect()` hard-failed. The probe now runs on a short-lived sibling spawned from the same parameters — its stderr is discarded and it is reaped once the era is known — and the caller's transport spawns exactly once, afterwards: a legacy verdict connects with the plain `initialize` handshake (byte-identical to `mode: 'legacy'`), a modern verdict is adopted directly, and the session wire never carries `server/discover`. Closing the caller's transport during the probe aborts `connect()` with the typed `SdkError(EraNegotiationFailed)` and the session child is never spawned. On HTTP — and on custom stdio-shaped transports, which probe in place — a mid-probe connection close keeps rejecting with the typed connect error, now naming the close in pin-mode and modern-only diagnostics.
+
+- Updated dependencies [[`f413763`](https://github.com/modelcontextprotocol/typescript-sdk/commit/f4137630c05dc9a4fb14d4d3777f5cb167bd6313)]:
+    - @modelcontextprotocol/core@2.0.0-beta.5
+
 ## 2.0.0-beta.4
 
 ### Minor Changes
diff --git a/packages/client/package.json b/packages/client/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@modelcontextprotocol/client",
-    "version": "2.0.0-beta.4",
+    "version": "2.0.0-beta.5",
     "description": "Model Context Protocol implementation for TypeScript - Client package",
     "license": "MIT",
     "author": "Anthropic, PBC (https://anthropic.com)",
diff --git a/packages/codemod/CHANGELOG.md b/packages/codemod/CHANGELOG.md
@@ -1,5 +1,13 @@
 # @modelcontextprotocol/codemod
 
+## 2.0.0-beta.5
+
+### Patch Changes
+
+- [#2501](https://github.com/modelcontextprotocol/typescript-sdk/pull/2501) [`1480241`](https://github.com/modelcontextprotocol/typescript-sdk/commit/1480241e2a2a7f0ceee8e7723b2adcf88579bb36) Thanks [@felixweinberger](https://github.com/felixweinberger)! - Export the `Protocol` base class and `mergeCapabilities` from the `@modelcontextprotocol/client` and `@modelcontextprotocol/server` package roots, restoring the v1 import for consumers that subclass `Protocol` (e.g. the MCP Apps SDK). The client and server packages each bundle their own compiled copy of the class, so import it from one package consistently within a process.
+
+    The codemod now rewrites `Protocol` and `mergeCapabilities` imports from `shared/protocol.js` to the client or server package root, like the module's other symbols, instead of dropping them with an action-required marker.
+
 ## 2.0.0-beta.4
 
 ### Patch Changes
diff --git a/packages/codemod/package.json b/packages/codemod/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@modelcontextprotocol/codemod",
-    "version": "2.0.0-beta.4",
+    "version": "2.0.0-beta.5",
     "description": "Codemod to migrate MCP TypeScript SDK code from v1 to v2",
     "license": "MIT",
     "author": "Anthropic, PBC (https://anthropic.com)",
diff --git a/packages/core-internal/CHANGELOG.md b/packages/core-internal/CHANGELOG.md
@@ -1,5 +1,28 @@
 # @modelcontextprotocol/core-internal
 
+## 2.0.0-beta.4
+
+### Minor Changes
+
+- [#2501](https://github.com/modelcontextprotocol/typescript-sdk/pull/2501) [`1480241`](https://github.com/modelcontextprotocol/typescript-sdk/commit/1480241e2a2a7f0ceee8e7723b2adcf88579bb36) Thanks [@felixweinberger](https://github.com/felixweinberger)! - Export the `Protocol` base class and `mergeCapabilities` from the `@modelcontextprotocol/client` and `@modelcontextprotocol/server` package roots, restoring the v1 import for consumers that subclass `Protocol` (e.g. the MCP Apps SDK). The client and server packages each bundle their own compiled copy of the class, so import it from one package consistently within a process.
+
+    The codemod now rewrites `Protocol` and `mergeCapabilities` imports from `shared/protocol.js` to the client or server package root, like the module's other symbols, instead of dropping them with an action-required marker.
+
+- [#2513](https://github.com/modelcontextprotocol/typescript-sdk/pull/2513) [`f413763`](https://github.com/modelcontextprotocol/typescript-sdk/commit/f4137630c05dc9a4fb14d4d3777f5cb167bd6313) Thanks [@felixweinberger](https://github.com/felixweinberger)! - Align the 2026-07-28 wire with the final revision (spec PR #3002): `serverInfo` moves from the `DiscoverResult` body to the result `_meta`, and the per-request envelope's `clientInfo` demotes from required to SHOULD.
+
+    Before this change the SDK shipped the pre-#3002 shape in both directions: the client hard-rejected a conforming server's `DiscoverResult` (missing body `serverInfo` failed parse, so the probe misclassified the server as legacy and attempted an `initialize` handshake against it — a hard connect failure against a modern-only server such as go-sdk v1.7.0-pre.3), and the server rejected conforming clients that omit `clientInfo`.
+
+    Now:
+    - The 2026 wire schemas are the final revision exactly: no body `serverInfo` on `DiscoverResult`, envelope `clientInfo` optional (a present-but-malformed value still fails validation).
+    - Servers stamp `_meta['io.modelcontextprotocol/serverInfo']` on every 2026-era response (spec SHOULD; a handler-authored value wins, the 2025-era wire is untouched). This includes the entry-built `subscriptions/listen` graceful-close results — the spec's `SubscriptionsListenResultMeta` extends `ResultMetaObject`.
+    - Clients keep sending `clientInfo` and read server identity from the discover result's `_meta` only. A server that stamps no identity is anonymous: `getServerVersion()` is `undefined` and the response cache partitions under a per-connection surrogate. A malformed `_meta` serverInfo value is treated as absent on receive (the spec marks the field self-reported, unverified, and display-only).
+    - Breaking type changes: `DiscoverResult` no longer declares `serverInfo`; `RequestMetaEnvelope`'s `clientInfo` is optional. New public constant `SERVER_INFO_META_KEY` (`'io.modelcontextprotocol/serverInfo'`).
+
+### Patch Changes
+
+- Updated dependencies [[`f413763`](https://github.com/modelcontextprotocol/typescript-sdk/commit/f4137630c05dc9a4fb14d4d3777f5cb167bd6313)]:
+    - @modelcontextprotocol/core@2.0.0-beta.5
+
 ## 2.0.0-beta.3
 
 ### Patch Changes
diff --git a/packages/core-internal/package.json b/packages/core-internal/package.json
@@ -1,7 +1,7 @@
 {
     "name": "@modelcontextprotocol/core-internal",
     "private": true,
-    "version": "2.0.0-beta.3",
+    "version": "2.0.0-beta.4",
     "description": "Model Context Protocol implementation for TypeScript - Core package",
     "license": "MIT",
     "author": "Anthropic, PBC (https://anthropic.com)",
diff --git a/packages/core/CHANGELOG.md b/packages/core/CHANGELOG.md
@@ -1,5 +1,19 @@
 # @modelcontextprotocol/core
 
+## 2.0.0-beta.5
+
+### Minor Changes
+
+- [#2513](https://github.com/modelcontextprotocol/typescript-sdk/pull/2513) [`f413763`](https://github.com/modelcontextprotocol/typescript-sdk/commit/f4137630c05dc9a4fb14d4d3777f5cb167bd6313) Thanks [@felixweinberger](https://github.com/felixweinberger)! - Align the 2026-07-28 wire with the final revision (spec PR #3002): `serverInfo` moves from the `DiscoverResult` body to the result `_meta`, and the per-request envelope's `clientInfo` demotes from required to SHOULD.
+
+    Before this change the SDK shipped the pre-#3002 shape in both directions: the client hard-rejected a conforming server's `DiscoverResult` (missing body `serverInfo` failed parse, so the probe misclassified the server as legacy and attempted an `initialize` handshake against it — a hard connect failure against a modern-only server such as go-sdk v1.7.0-pre.3), and the server rejected conforming clients that omit `clientInfo`.
+
+    Now:
+    - The 2026 wire schemas are the final revision exactly: no body `serverInfo` on `DiscoverResult`, envelope `clientInfo` optional (a present-but-malformed value still fails validation).
+    - Servers stamp `_meta['io.modelcontextprotocol/serverInfo']` on every 2026-era response (spec SHOULD; a handler-authored value wins, the 2025-era wire is untouched). This includes the entry-built `subscriptions/listen` graceful-close results — the spec's `SubscriptionsListenResultMeta` extends `ResultMetaObject`.
+    - Clients keep sending `clientInfo` and read server identity from the discover result's `_meta` only. A server that stamps no identity is anonymous: `getServerVersion()` is `undefined` and the response cache partitions under a per-connection surrogate. A malformed `_meta` serverInfo value is treated as absent on receive (the spec marks the field self-reported, unverified, and display-only).
+    - Breaking type changes: `DiscoverResult` no longer declares `serverInfo`; `RequestMetaEnvelope`'s `clientInfo` is optional. New public constant `SERVER_INFO_META_KEY` (`'io.modelcontextprotocol/serverInfo'`).
+
 ## 2.0.0-beta.4
 
 ### Minor Changes
diff --git a/packages/core/package.json b/packages/core/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@modelcontextprotocol/core",
-    "version": "2.0.0-beta.4",
+    "version": "2.0.0-beta.5",
     "description": "Model Context Protocol for TypeScript — public Zod schemas (spec + OAuth/OpenID)",
     "license": "MIT",
     "author": "Anthropic, PBC (https://anthropic.com)",
diff --git a/packages/middleware/express/CHANGELOG.md b/packages/middleware/express/CHANGELOG.md
@@ -1,5 +1,12 @@
 # @modelcontextprotocol/express
 
+## 2.0.0-beta.5
+
+### Patch Changes
+
+- Updated dependencies [[`1480241`](https://github.com/modelcontextprotocol/typescript-sdk/commit/1480241e2a2a7f0ceee8e7723b2adcf88579bb36), [`f413763`](https://github.com/modelcontextprotocol/typescript-sdk/commit/f4137630c05dc9a4fb14d4d3777f5cb167bd6313)]:
+    - @modelcontextprotocol/server@2.0.0-beta.5
+
 ## 2.0.0-beta.4
 
 ### Patch Changes
diff --git a/packages/middleware/express/package.json b/packages/middleware/express/package.json
@@ -1,7 +1,7 @@
 {
     "name": "@modelcontextprotocol/express",
     "private": false,
-    "version": "2.0.0-beta.4",
+    "version": "2.0.0-beta.5",
     "description": "Express adapters for the Model Context Protocol TypeScript server SDK - Express middleware",
     "license": "MIT",
     "author": "Anthropic, PBC (https://anthropic.com)",
diff --git a/packages/middleware/fastify/CHANGELOG.md b/packages/middleware/fastify/CHANGELOG.md
@@ -1,5 +1,12 @@
 # @modelcontextprotocol/fastify
 
+## 2.0.0-beta.5
+
+### Patch Changes
+
+- Updated dependencies [[`1480241`](https://github.com/modelcontextprotocol/typescript-sdk/commit/1480241e2a2a7f0ceee8e7723b2adcf88579bb36), [`f413763`](https://github.com/modelcontextprotocol/typescript-sdk/commit/f4137630c05dc9a4fb14d4d3777f5cb167bd6313)]:
+    - @modelcontextprotocol/server@2.0.0-beta.5
+
 ## 2.0.0-beta.4
 
 ### Patch Changes
diff --git a/packages/middleware/fastify/package.json b/packages/middleware/fastify/package.json
@@ -1,7 +1,7 @@
 {
     "name": "@modelcontextprotocol/fastify",
     "private": false,
-    "version": "2.0.0-beta.4",
+    "version": "2.0.0-beta.5",
     "description": "Fastify adapters for the Model Context Protocol TypeScript server SDK - Fastify middleware",
     "license": "MIT",
     "author": "Anthropic, PBC (https://anthropic.com)",
diff --git a/packages/middleware/hono/CHANGELOG.md b/packages/middleware/hono/CHANGELOG.md
@@ -1,5 +1,12 @@
 # @modelcontextprotocol/hono
 
+## 2.0.0-beta.5
+
+### Patch Changes
+
+- Updated dependencies [[`1480241`](https://github.com/modelcontextprotocol/typescript-sdk/commit/1480241e2a2a7f0ceee8e7723b2adcf88579bb36), [`f413763`](https://github.com/modelcontextprotocol/typescript-sdk/commit/f4137630c05dc9a4fb14d4d3777f5cb167bd6313)]:
+    - @modelcontextprotocol/server@2.0.0-beta.5
+
 ## 2.0.0-beta.4
 
 ### Patch Changes
diff --git a/packages/middleware/hono/package.json b/packages/middleware/hono/package.json
@@ -1,7 +1,7 @@
 {
     "name": "@modelcontextprotocol/hono",
     "private": false,
-    "version": "2.0.0-beta.4",
+    "version": "2.0.0-beta.5",
     "description": "Hono adapters for the Model Context Protocol TypeScript server SDK - Hono middleware",
     "license": "MIT",
     "author": "Anthropic, PBC (https://anthropic.com)",
diff --git a/packages/middleware/node/CHANGELOG.md b/packages/middleware/node/CHANGELOG.md
@@ -1,5 +1,12 @@
 # @modelcontextprotocol/node
 
+## 2.0.0-beta.5
+
+### Patch Changes
+
+- Updated dependencies [[`1480241`](https://github.com/modelcontextprotocol/typescript-sdk/commit/1480241e2a2a7f0ceee8e7723b2adcf88579bb36), [`f413763`](https://github.com/modelcontextprotocol/typescript-sdk/commit/f4137630c05dc9a4fb14d4d3777f5cb167bd6313)]:
+    - @modelcontextprotocol/server@2.0.0-beta.5
+
 ## 2.0.0-beta.4
 
 ### Patch Changes
diff --git a/packages/middleware/node/package.json b/packages/middleware/node/package.json
@@ -1,6 +1,6 @@
 {
     "name": "@modelcontextprotocol/node",
-    "version": "2.0.0-beta.4",
+    "version": "2.0.0-beta.5",
     "description": "Model Context Protocol implementation for TypeScript - Node.js middleware",
     "license": "MIT",
     "author": "Anthropic, PBC (https://anthropic.com)",
diff --git a/packages/server-legacy/CHANGELOG.md b/packages/server-legacy/CHANGELOG.md
@@ -1,5 +1,12 @@
 # @modelcontextprotocol/server-legacy
 
+## 2.0.0-beta.5
+
+### Patch Changes
+
+- Updated dependencies [[`f413763`](https://github.com/modelcontextprotocol/typescript-sdk/commit/f4137630c05dc9a4fb14d4d3777f5cb167bd6313)]:
+    - @modelcontextprotocol/core@2.0.0-beta.5
+
 ## 2.0.0-beta.4
 
 ### Minor Changes
diff --git a/packages/server-legacy/package.json b/packages/server-legacy/package.json
@@ -1,7 +1,7 @@
 {
     "name": "@modelcontextprotocol/server-legacy",
     "private": false,
-    "version": "2.0.0-beta.4",
+    "version": "2.0.0-beta.5",
     "description": "Frozen v1 SSE transport and OAuth Authorization Server helpers for the Model Context Protocol TypeScript SDK. Deprecated; use StreamableHTTP and a dedicated OAuth server in production.",
     "deprecated": "This package is a frozen copy of v1's SSE transport and OAuth Authorization Server helpers for migration purposes only. Use StreamableHTTP from @modelcontextprotocol/server and a dedicated OAuth server in production. Will not receive new features.",
     "license": "MIT",
diff --git a/packages/server/CHANGELOG.md b/packages/server/CHANGELOG.md
diff --git a/packages/server/package.json b/packages/server/package.json

Original file line number	Diff line number	Diff line change
`@@ -1,6 +1,6 @@`
`1`	`1`	`{`
`2`	`2`	`"name": "@modelcontextprotocol/client",`
`3`		`- "version": "2.0.0-beta.4",`
	`3`	`+ "version": "2.0.0-beta.5",`
`4`	`4`	`"description": "Model Context Protocol implementation for TypeScript - Client package",`
`5`	`5`	`"license": "MIT",`
`6`	`6`	`"author": "Anthropic, PBC (https://anthropic.com)",`
Original file line number	Diff line number	Diff line change
`@@ -1,6 +1,6 @@`
`1`	`1`	`{`
`2`	`2`	`"name": "@modelcontextprotocol/codemod",`
`3`		`- "version": "2.0.0-beta.4",`
	`3`	`+ "version": "2.0.0-beta.5",`
`4`	`4`	`"description": "Codemod to migrate MCP TypeScript SDK code from v1 to v2",`
`5`	`5`	`"license": "MIT",`
`6`	`6`	`"author": "Anthropic, PBC (https://anthropic.com)",`
Original file line number	Diff line number	Diff line change
`@@ -1,7 +1,7 @@`
`1`	`1`	`{`
`2`	`2`	`"name": "@modelcontextprotocol/core-internal",`
`3`	`3`	`"private": true,`
`4`		`- "version": "2.0.0-beta.3",`
	`4`	`+ "version": "2.0.0-beta.4",`
`5`	`5`	`"description": "Model Context Protocol implementation for TypeScript - Core package",`
`6`	`6`	`"license": "MIT",`
`7`	`7`	`"author": "Anthropic, PBC (https://anthropic.com)",`
Original file line number	Diff line number	Diff line change
`@@ -1,6 +1,6 @@`
`1`	`1`	`{`
`2`	`2`	`"name": "@modelcontextprotocol/core",`
`3`		`- "version": "2.0.0-beta.4",`
	`3`	`+ "version": "2.0.0-beta.5",`
`4`	`4`	`"description": "Model Context Protocol for TypeScript — public Zod schemas (spec + OAuth/OpenID)",`
`5`	`5`	`"license": "MIT",`
`6`	`6`	`"author": "Anthropic, PBC (https://anthropic.com)",`