fix: update the draft wire version to 2026-07-28 (#331)

* chore: sync spec-types to modelcontextprotocol@0168c57f

Refreshes the vendored schema copies via npm run sync-schema. The draft
schema now declares LATEST_PROTOCOL_VERSION = "2026-07-28" (previously
the DRAFT-2026-v1 placeholder) and picks up the latest draft doc-comment
and type updates. The dated schemas are unchanged.

* fix: update the draft wire version to 2026-07-28

The spec repo's draft schema now declares
LATEST_PROTOCOL_VERSION = "2026-07-28", but the harness still asserted
the old DRAFT-2026-v1 placeholder, so an SDK that sends the version the
draft spec actually declares cannot pass the draft suite.

- bump DRAFT_PROTOCOL_VERSION in src/types.ts to 2026-07-28
- update the hard-coded literals in tests, example servers, and README
- add src/types.test.ts pinning DRAFT_PROTOCOL_VERSION to the vendored
  draft schema's LATEST_PROTOCOL_VERSION so the two cannot drift, and
  asserting the draft identifier stays distinct from the dated versions

src/connection/connection.test.ts

@@ -20,8 +20,8 @@ describe('connectFor', () => {
     // version through), so identity with connectStateless no longer holds;
     // assert it did not select the stateful implementation. The wire-level
     // behaviour of the wrapper is covered in stateless.test.ts.
-    expect(connectFor('DRAFT-2026-v1')).not.toBe(connectStateful);
-    expect(connectFor('DRAFT-2026-v1')).not.toBe(connectStateless);
+    expect(connectFor('2026-07-28')).not.toBe(connectStateful);
+    expect(connectFor('2026-07-28')).not.toBe(connectStateless);
   });
 });
 
@@ -64,10 +64,10 @@ describe('connectStateless', () => {
     await conn.request('tools/list');
 
     const [, init] = mockFetch.mock.calls[0];
-    expect(init.headers['MCP-Protocol-Version']).toBe('DRAFT-2026-v1');
+    expect(init.headers['MCP-Protocol-Version']).toBe('2026-07-28');
     const sent = JSON.parse(init.body);
     expect(sent.params._meta['io.modelcontextprotocol/protocolVersion']).toBe(
-      'DRAFT-2026-v1'
+      '2026-07-28'
     );
     expect(
       sent.params._meta['io.modelcontextprotocol/clientInfo']

src/scenarios/client/http-standard-headers.test.ts

@@ -24,7 +24,7 @@ describe('HttpStandardHeadersScenario (SEP-2243) — negative', () => {
         id: 1,
         method: 'initialize',
         params: {
-          protocolVersion: 'DRAFT-2026-v1',
+          protocolVersion: '2026-07-28',
           clientInfo: { name: 'neg-test', version: '0' },
           capabilities: {}
         }

src/scenarios/client/request-metadata.test.ts

@@ -26,7 +26,7 @@ async function badClient(serverUrl: string) {
 }
 
 const goodMeta = {
-  'io.modelcontextprotocol/protocolVersion': 'DRAFT-2026-v1',
+  'io.modelcontextprotocol/protocolVersion': '2026-07-28',
   'io.modelcontextprotocol/clientInfo': { name: 'test', version: '1.0' },
   'io.modelcontextprotocol/clientCapabilities': {}
 };
@@ -70,7 +70,7 @@ async function nonRetryingClient(serverUrl: string) {
     method: 'POST',
     headers: {
       'Content-Type': 'application/json',
-      'MCP-Protocol-Version': 'DRAFT-2026-v1'
+      'MCP-Protocol-Version': '2026-07-28'
     },
     body: JSON.stringify({
       jsonrpc: '2.0',
@@ -118,7 +118,7 @@ async function malformedCapabilitiesClient(serverUrl: string) {
     method: 'POST',
     headers: {
       'Content-Type': 'application/json',
-      'MCP-Protocol-Version': 'DRAFT-2026-v1'
+      'MCP-Protocol-Version': '2026-07-28'
     },
     body: JSON.stringify({
       jsonrpc: '2.0',

src/scenarios/server/caching.ts

@@ -99,7 +99,7 @@ Servers MUST include \`ttlMs\` (integer >= 0) and \`cacheScope\` ("public" or "p
     // SEP-2549 only exists in the draft spec, so each cacheable endpoint is
     // queried over the version-appropriate connection. Under --spec-version
     // draft that resolves to the stateless impl (SEP-2575): protocolVersion
-    // DRAFT-2026-v1 plus the cross-cutting _meta and standard headers
+    // 2026-07-28 plus the cross-cutting _meta and standard headers
     // (issue #315).
     let conn: Connection;
     try {

src/scenarios/server/stateless.test.ts

@@ -101,7 +101,7 @@ describe('Stateless Server Scenario Negative Tests', () => {
             jsonrpc: '2.0',
             id: reqBody.id,
             result: {
-              supportedVersions: ['DRAFT-2026-v1'],
+              supportedVersions: ['2026-07-28'],
               capabilities: {},
               serverInfo: { name: 'bad-meta-server', version: '1.0.0' }
             }
@@ -341,7 +341,7 @@ describe('Stateless Server Scenario Negative Tests', () => {
             jsonrpc: '2.0',
             id: reqBody.id,
             result: {
-              supportedVersions: ['DRAFT-2026-v1'],
+              supportedVersions: ['2026-07-28'],
               capabilities: {
                 tools: { listChanged: true },
                 prompts: { listChanged: true }

src/spec-types/SOURCE

@@ -1 +1 @@
-modelcontextprotocol@33c3724972e6a87a8ad153e3f8a0d4714b0b9536
+modelcontextprotocol@0168c57fc74aba6e6dcf8f0b7191db3caaa5ad65

src/spec-types/draft.ts

@@ -34,7 +34,7 @@ export type JSONRPCMessage =
   | JSONRPCResponse;
 
 /** @internal */
-export const LATEST_PROTOCOL_VERSION = "DRAFT-2026-v1";
+export const LATEST_PROTOCOL_VERSION = "2026-07-28";
 /** @internal */
 export const JSONRPC_VERSION = "2.0";
 
@@ -102,6 +102,10 @@ export interface RequestMetaObject extends MetaObject {
    * If absent, the server MUST NOT send any {@link LoggingMessageNotification | notifications/message}
    * notifications for this request. The client opts in to log messages by
    * explicitly setting a level. Replaces the former `logging/setLevel` RPC.
+   *
+   * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+   * Remains in the specification for at least twelve months; see the
+   * deprecated features registry.
    */
   "io.modelcontextprotocol/logLevel"?: LoggingLevel;
 }
@@ -162,7 +166,7 @@ export interface Notification {
  * input_required - the request requires additional input and the result contains an {@link InputRequiredResult} object with instructions for the client to provide additional input before retrying the original request.
  * @category Common Types
  */
-export type ResultType = "complete" | "input_required";
+export type ResultType = "complete" | "input_required" | string;
 
 /**
  * Common result fields.
@@ -292,15 +296,14 @@ export interface InvalidRequestError extends Error {
 /**
  * A JSON-RPC error indicating that the requested method does not exist or is not available.
  *
- * In MCP, this error is returned when a request is made for a method that requires a capability that has not been declared. This can occur in either direction:
+ * In MCP, a server returns this error when a client invokes a method the server does not implement — either a genuinely unknown method, or one gated behind a server capability the server did not advertise (e.g., calling `prompts/list` when the `prompts` capability was not advertised).
  *
- * - A server returning this error when the client requests a capability it doesn't support (e.g., requesting completions when the `completions` capability was not advertised)
- * - A client returning this error when the server requests a capability it doesn't support (e.g., requesting roots when the client did not declare the `roots` capability)
+ * A request that requires a client capability the client did not declare is signalled instead by {@link MissingRequiredClientCapabilityError} (`-32003`).
  *
  * @see {@link https://www.jsonrpc.org/specification#error_object | JSON-RPC 2.0 Error Object}
  *
- * @example Roots not supported
- * {@includeCode ./examples/MethodNotFoundError/roots-not-supported.json}
+ * @example Prompts not supported
+ * {@includeCode ./examples/MethodNotFoundError/prompts-not-supported.json}
  *
  * @category Errors
  */
@@ -578,7 +581,7 @@ export interface DiscoverRequest extends JSONRPCRequest {
  *
  * @category `server/discover`
  */
-export interface DiscoverResult extends Result {
+export interface DiscoverResult extends CacheableResult {
   /**
    * MCP Protocol Versions this server supports. The client should choose a
    * version from this list for use in subsequent requests.
@@ -628,6 +631,10 @@ export interface ClientCapabilities {
   /**
    * Present if the client supports listing roots.
    *
+   * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+   * Remains in the specification for at least twelve months; see the
+   * deprecated features registry.
+   *
    * @example Roots — minimum baseline support
    * {@includeCode ./examples/ClientCapabilities/roots-minimum-baseline-support.json}
    */
@@ -636,14 +643,18 @@ export interface ClientCapabilities {
   /**
    * Present if the client supports sampling from an LLM.
    *
+   * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+   * Remains in the specification for at least twelve months; see the
+   * deprecated features registry.
+   *
    * @example Sampling — minimum baseline support
    * {@includeCode ./examples/ClientCapabilities/sampling-minimum-baseline-support.json}
    *
    * @example Sampling — tool use support
    * {@includeCode ./examples/ClientCapabilities/sampling-tool-use-support.json}
    *
-   * @example Sampling — context inclusion support (soft-deprecated)
-   * {@includeCode ./examples/ClientCapabilities/sampling-context-inclusion-support-soft-deprecated.json}
+   * @example Sampling — context inclusion support (deprecated)
+   * {@includeCode ./examples/ClientCapabilities/sampling-context-inclusion-support-deprecated.json}
    */
   sampling?: {
     /**
@@ -675,7 +686,10 @@ export interface ClientCapabilities {
    * (e.g., "io.modelcontextprotocol/oauth-client-credentials"), and values are
    * per-extension settings objects. An empty object indicates support with no settings.
    *
-   * @example Extensions — UI extension with MIME type support
+   * Keys MUST follow the {@link MetaObject | `_meta` key naming rules}, with a
+   * mandatory prefix.
+   *
+   * @example Extensions — MCP Apps (UI) extension with MIME type support
    * {@includeCode ./examples/ClientCapabilities/extensions-ui-mime-types.json}
    */
   extensions?: { [key: string]: JSONObject };
@@ -694,6 +708,10 @@ export interface ServerCapabilities {
   /**
    * Present if the server supports sending log messages to the client.
    *
+   * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+   * Remains in the specification for at least twelve months; see the
+   * deprecated features registry.
+   *
    * @example Logging — minimum baseline support
    * {@includeCode ./examples/ServerCapabilities/logging-minimum-baseline-support.json}
    */
@@ -762,11 +780,14 @@ export interface ServerCapabilities {
   };
   /**
    * Optional MCP extensions that the server supports. Keys are extension identifiers
-   * (e.g., "io.modelcontextprotocol/apps"), and values are per-extension settings
+   * (e.g., "io.modelcontextprotocol/tasks"), and values are per-extension settings
    * objects. An empty object indicates support with no settings.
    *
-   * @example Extensions — UI extension support
-   * {@includeCode ./examples/ServerCapabilities/extensions-ui.json}
+   * Keys MUST follow the {@link MetaObject | `_meta` key naming rules}, with a
+   * mandatory prefix.
+   *
+   * @example Extensions — Tasks extension support
+   * {@includeCode ./examples/ServerCapabilities/extensions-tasks.json}
    */
   extensions?: { [key: string]: JSONObject };
 }
@@ -1848,6 +1869,10 @@ export interface Tool extends BaseMetadata, Icons {
 /**
  * Parameters for a `notifications/message` notification.
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @example Log database connection failed
  * {@includeCode ./examples/LoggingMessageNotificationParams/log-database-connection-failed.json}
  *
@@ -1871,6 +1896,10 @@ export interface LoggingMessageNotificationParams extends NotificationParams {
 /**
  * JSONRPCNotification of a log message passed from server to client. The client opts in by setting `"io.modelcontextprotocol/logLevel"` in a request's `_meta`.
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @example Log database connection failed
  * {@includeCode ./examples/LoggingMessageNotification/log-database-connection-failed.json}
  *
@@ -1887,6 +1916,10 @@ export interface LoggingMessageNotification extends JSONRPCNotification {
  * These map to syslog message severities, as specified in RFC-5424:
  * https://datatracker.ietf.org/doc/html/rfc5424#section-6.2.1
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @category Common Types
  */
 export type LoggingLevel =
@@ -1912,6 +1945,10 @@ export type LoggingLevel =
  * @example Follow-up request with tool results
  * {@includeCode ./examples/CreateMessageRequestParams/follow-up-with-tool-results.json}
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @category `sampling/createMessage`
  */
 export interface CreateMessageRequestParams {
@@ -1928,8 +1965,12 @@ export interface CreateMessageRequestParams {
    * A request to include context from one or more MCP servers (including the caller), to be attached to the prompt.
    * The client MAY ignore this request.
    *
-   * Default is `"none"`. Values `"thisServer"` and `"allServers"` are soft-deprecated. Servers SHOULD only use these values if the client
-   * declares {@link ClientCapabilities.sampling.context}. These values may be removed in future spec releases.
+   * Default is `"none"`. The values `"thisServer"` and `"allServers"` are deprecated (SEP-2596): servers SHOULD
+   * omit this field or use `"none"`, and SHOULD only use the deprecated values if the client declares
+   * {@link ClientCapabilities.sampling.context}.
+   *
+   * @deprecated The `"thisServer"` and `"allServers"` values are deprecated as of protocol version 2025-11-25
+   * (SEP-2596) and will be removed no later than the Sampling feature itself (SEP-2577). Omit this field or use `"none"`.
    */
   includeContext?: "none" | "thisServer" | "allServers";
   /**
@@ -1963,6 +2004,10 @@ export interface CreateMessageRequestParams {
 /**
  * Controls tool selection behavior for sampling requests.
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @category `sampling/createMessage`
  */
 export interface ToolChoice {
@@ -1981,6 +2026,10 @@ export interface ToolChoice {
  * @example Sampling request
  * {@includeCode ./examples/CreateMessageRequest/sampling-request.json}
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @category `sampling/createMessage`
  */
 export interface CreateMessageRequest {
@@ -2002,6 +2051,10 @@ export interface CreateMessageRequest {
  * @example Final response after tool use
  * {@includeCode ./examples/CreateMessageResult/final-response.json}
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @category `sampling/createMessage`
  */
 export interface CreateMessageResult extends SamplingMessage {
@@ -2033,6 +2086,10 @@ export interface CreateMessageResult extends SamplingMessage {
  * @example Multiple content blocks
  * {@includeCode ./examples/SamplingMessage/multiple-content-blocks.json}
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @category `sampling/createMessage`
  */
 export interface SamplingMessage {
@@ -2042,6 +2099,10 @@ export interface SamplingMessage {
 }
 
 /**
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @category `sampling/createMessage`
  */
 export type SamplingMessageContentBlock =
@@ -2190,6 +2251,10 @@ export interface AudioContent {
  * @example `get_weather` tool use
  * {@includeCode ./examples/ToolUseContent/get-weather-tool-use.json}
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @category `sampling/createMessage`
  */
 export interface ToolUseContent {
@@ -2225,6 +2290,10 @@ export interface ToolUseContent {
  * @example `get_weather` tool result
  * {@includeCode ./examples/ToolResultContent/get-weather-tool-result.json}
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @category `sampling/createMessage`
  */
 export interface ToolResultContent {
@@ -2284,6 +2353,10 @@ export interface ToolResultContent {
  * @example With hints and priorities
  * {@includeCode ./examples/ModelPreferences/with-hints-and-priorities.json}
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @category `sampling/createMessage`
  */
 export interface ModelPreferences {
@@ -2338,6 +2411,10 @@ export interface ModelPreferences {
  * Keys not declared here are currently left unspecified by the spec and are up
  * to the client to interpret.
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @category `sampling/createMessage`
  */
 export interface ModelHint {
@@ -2486,6 +2563,10 @@ export interface PromptReference extends BaseMetadata {
  * @example List roots request
  * {@includeCode ./examples/ListRootsRequest/list-roots-request.json}
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @category `roots/list`
  */
 export interface ListRootsRequest {
@@ -2504,6 +2585,10 @@ export interface ListRootsRequest {
  * @example Multiple root directories
  * {@includeCode ./examples/ListRootsResult/multiple-root-directories.json}
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @category `roots/list`
  */
 export interface ListRootsResult {
@@ -2516,6 +2601,10 @@ export interface ListRootsResult {
  * @example Project directory root
  * {@includeCode ./examples/Root/project-directory.json}
  *
+ * @deprecated Deprecated as of protocol version 2026-07-28 (SEP-2577).
+ * Remains in the specification for at least twelve months; see the
+ * deprecated features registry.
+ *
  * @category `roots/list`
  */
 export interface Root {
@@ -2666,8 +2755,17 @@ export interface NumberSchema {
   type: "number" | "integer";
   title?: string;
   description?: string;
+  /**
+   * @TJS-type number
+   */
   minimum?: number;
+  /**
+   * @TJS-type number
+   */
   maximum?: number;
+  /**
+   * @TJS-type number
+   */
   default?: number;
 }
 
@@ -2916,6 +3014,18 @@ export interface ElicitResult {
   content?: { [key: string]: string | number | boolean | string[] };
 }
 
+/**
+ * Parameters for a {@link ElicitationCompleteNotification | notifications/elicitation/complete} notification.
+ *
+ * @category `notifications/elicitation/complete`
+ */
+export interface ElicitationCompleteNotificationParams extends NotificationParams {
+  /**
+   * The ID of the elicitation that completed.
+   */
+  elicitationId: string;
+}
+
 /**
  * An optional notification from the server to the client, informing it of a completion of a out-of-band elicitation request.
  *
@@ -2926,12 +3036,7 @@ export interface ElicitResult {
  */
 export interface ElicitationCompleteNotification extends JSONRPCNotification {
   method: "notifications/elicitation/complete";
-  params: {
-    /**
-     * The ID of the elicitation that completed.
-     */
-    elicitationId: string;
-  };
+  params: ElicitationCompleteNotificationParams;
 }
 
 /* Client messages */

src/types.test.ts

@@ -0,0 +1,19 @@
+import { describe, it, expect } from 'vitest';
+import { LATEST_PROTOCOL_VERSION } from './spec-types/draft';
+import { DATED_SPEC_VERSIONS, DRAFT_PROTOCOL_VERSION } from './types';
+
+describe('DRAFT_PROTOCOL_VERSION', () => {
+  it('mirrors LATEST_PROTOCOL_VERSION from the vendored draft schema', () => {
+    // DRAFT_PROTOCOL_VERSION is the wire protocolVersion the harness asserts
+    // for draft-spec scenarios. It must match what the spec's draft schema
+    // declares, or SDKs implementing the draft cannot pass the draft suite.
+    expect(DRAFT_PROTOCOL_VERSION).toBe(LATEST_PROTOCOL_VERSION);
+  });
+
+  it('is distinct from every dated spec version', () => {
+    // Scenario applicability (introducedIn/removedIn) and --spec-version
+    // resolution rely on the draft identifier not colliding with a released
+    // version.
+    expect(DATED_SPEC_VERSIONS).not.toContain(DRAFT_PROTOCOL_VERSION);
+  });
+});

src/types.ts

@@ -41,7 +41,7 @@ export const LATEST_SPEC_VERSION: DatedSpecVersion = '2025-11-25';
  * `LATEST_PROTOCOL_VERSION` in the spec repo's `schema/draft/schema.ts`;
  * bump when that constant changes.
  */
-export const DRAFT_PROTOCOL_VERSION = 'DRAFT-2026-v1';
+export const DRAFT_PROTOCOL_VERSION = '2026-07-28';
 
 // Wire protocolVersion strings the mock server will negotiate on initialize.
 export const NEGOTIABLE_PROTOCOL_VERSIONS: readonly string[] = [