refactor(core): restore deprecated Task* schemas to neutral layer

Drops the Q1-SD2 wire/rev type-only carve-out; layering rule now zero-exception.

The 14 deprecated Task message-surface schemas (TaskSchema, TaskStatusSchema,
CreateTaskResultSchema, TaskStatusNotification*, Get/List/CancelTask*) return
to types/schemas.ts in a clearly-bannered @deprecated block. types/types.ts
now infers them from ./schemas.js like every other public type — no import
from wire/rev2025-11-25 remains outside src/wire/.

- layeringInvariants test (a) tightened to expect(offenders).toEqual([])
- eslint.config.mjs outbound rule comment + message drop the carve-out
  (allowTypeImports kept: erased-at-runtime crossings stay a lint non-event;
  the test enforces zero crossings regardless)
- wire/rev2025-11-25/schemas.ts header rewritten to point at the neutral copy
- specTypeSchema SPEC_SCHEMA_KEYS gains the 14 entries (each has a public
  type in types.ts; drift-guard contract requires it — matches the existing
  TaskMetadata/RelatedTaskMetadata/TaskAugmentedRequestParams entries)
- client.ts callTool() comment drops the stale Q1-SD2 reference

The wire-parse contract for these shapes is unchanged — the FROZEN copies in
wire/rev2025-11-25/schemas.ts remain the era registry's parse source; the
neutral-layer copies are nameable-only and appear in no role union.

Author: felixweinberger

packages/client/src/client/client.ts

@@ -2219,8 +2219,7 @@ export class Client extends Protocol<ClientContext> {
 
         // The method-keyed request() path validates the era registry's plain
         // CallToolResult schema — with the result map aligned to the typed
-        // map there is no wider union to narrow away (Q1-SD2 holds by
-        // construction).
+        // map there is no wider union to narrow away.
         let result: CallToolResult;
         try {
             result = await this.request({ method: 'tools/call', params }, await buildSendOptions());

packages/core/eslint.config.mjs

@@ -8,9 +8,9 @@ export default [
         // Wire-layer isolation, outbound direction: nothing outside src/wire/ may
         // reach into a wire revision module. The wire layer's only public surface
         // is src/wire/codec.ts (the WireCodec interface) and src/wire/bootstrap.ts.
-        // Type-only imports are exempted — the sole intended user of that exemption
-        // is types/types.ts re-exporting the deprecated Task* vocabulary as types
-        // (Q1-SD2); test/wire/layeringInvariants.test.ts pins it to that one site.
+        // test/wire/layeringInvariants.test.ts re-derives the same invariant with
+        // zero exceptions. Type-only imports are exempted at the lint layer (a
+        // type-only crossing is erased at runtime), but the test allows none.
         files: ['src/**/*.ts'],
         ignores: ['src/wire/**'],
         rules: {
@@ -21,9 +21,7 @@ export default [
                         {
                             group: ['**/wire/rev*', '**/wire/rev*/**', '@modelcontextprotocol/core/wire/rev*'],
                             allowTypeImports: true,
-                            message:
-                                'Wire revision modules are codec-private. Route through src/wire/codec.ts (WireCodec) instead. ' +
-                                'The only permitted crossing is the type-only Task* re-export in types/types.ts (Q1-SD2).'
+                            message: 'Wire revision modules are codec-private. Route through src/wire/codec.ts (WireCodec) instead.'
                         }
                     ]
                 }

packages/core/src/types/schemas.ts

@@ -2154,13 +2154,182 @@ export const RootsListChangedNotificationSchema = NotificationSchema.extend({
     params: NotificationsParamsSchema.optional()
 });
 
+/* ───────────────────────────────────────────────────────────────────────────
+ * Tasks (2025-11-25 wire vocabulary, DEPRECATED)
+ *
+ * The task message surface defined by the 2025-11-25 protocol revision. These
+ * schemas are kept in the neutral layer so the public Task* types stay
+ * nameable without a cross-layer import into wire/rev*; the wire-parse
+ * contract for them is the FROZEN copy in wire/rev2025-11-25/schemas.ts.
+ *
+ * They appear in NO role aggregate below and no API signature — nameable-only
+ * vocabulary for interop with task-capable 2025 peers (#2248). Removable at
+ * the major version that drops 2025-era support.
+ * ─────────────────────────────────────────────────────────────────────────── */
+
+/**
+ * Task creation parameters, used to ask that the server create a task to represent a request.
+ *
+ * @deprecated 2025-11-25 wire vocabulary with no SDK runtime; kept importable for interoperability only.
+ */
+export const TaskCreationParamsSchema = z.looseObject({
+    /**
+     * Requested duration in milliseconds to retain task from creation.
+     */
+    ttl: z.number().optional(),
+
+    /**
+     * Time in milliseconds to wait between task status requests.
+     */
+    pollInterval: z.number().optional()
+});
+
+/**
+ * The status of a task.
+ *
+ * @deprecated 2025-11-25 wire vocabulary with no SDK runtime; kept importable for interoperability only.
+ */
+export const TaskStatusSchema = z.enum(['working', 'input_required', 'completed', 'failed', 'cancelled']);
+
+/**
+ * A pollable state object associated with a request.
+ *
+ * @deprecated 2025-11-25 wire vocabulary with no SDK runtime; kept importable for interoperability only.
+ */
+export const TaskSchema = z.object({
+    taskId: z.string(),
+    status: TaskStatusSchema,
+    /**
+     * Time in milliseconds to keep task results available after completion.
+     * If `null`, the task has unlimited lifetime until manually cleaned up.
+     */
+    ttl: z.union([z.number(), z.null()]),
+    /**
+     * ISO 8601 timestamp when the task was created.
+     */
+    createdAt: z.string(),
+    /**
+     * ISO 8601 timestamp when the task was last updated.
+     */
+    lastUpdatedAt: z.string(),
+    pollInterval: z.optional(z.number()),
+    /**
+     * Optional diagnostic message for failed tasks or other status information.
+     */
+    statusMessage: z.optional(z.string())
+});
+
+/**
+ * Result returned when a task is created, containing the task data wrapped in a `task` field.
+ *
+ * @deprecated 2025-11-25 wire vocabulary with no SDK runtime; kept importable for interoperability only.
+ */
+export const CreateTaskResultSchema = ResultSchema.extend({
+    task: TaskSchema
+});
+
+/**
+ * Parameters for task status notification.
+ *
+ * @deprecated 2025-11-25 wire vocabulary with no SDK runtime; kept importable for interoperability only.
+ */
+export const TaskStatusNotificationParamsSchema = NotificationsParamsSchema.merge(TaskSchema);
+
+/**
+ * A notification sent when a task's status changes.
+ *
+ * @deprecated 2025-11-25 wire vocabulary with no SDK runtime; kept importable for interoperability only.
+ */
+export const TaskStatusNotificationSchema = NotificationSchema.extend({
+    method: z.literal('notifications/tasks/status'),
+    params: TaskStatusNotificationParamsSchema
+});
+
+/**
+ * A request to get the state of a specific task.
+ *
+ * @deprecated 2025-11-25 wire vocabulary with no SDK runtime; kept importable for interoperability only.
+ */
+export const GetTaskRequestSchema = RequestSchema.extend({
+    method: z.literal('tasks/get'),
+    params: BaseRequestParamsSchema.extend({
+        taskId: z.string()
+    })
+});
+
+/**
+ * The response to a {@linkcode GetTaskRequest | tasks/get} request.
+ *
+ * @deprecated 2025-11-25 wire vocabulary with no SDK runtime; kept importable for interoperability only.
+ */
+export const GetTaskResultSchema = ResultSchema.merge(TaskSchema);
+
+/**
+ * A request to get the result of a specific task.
+ *
+ * @deprecated 2025-11-25 wire vocabulary with no SDK runtime; kept importable for interoperability only.
+ */
+export const GetTaskPayloadRequestSchema = RequestSchema.extend({
+    method: z.literal('tasks/result'),
+    params: BaseRequestParamsSchema.extend({
+        taskId: z.string()
+    })
+});
+
+/**
+ * The response to a `tasks/result` request.
+ * The structure matches the result type of the original request.
+ * For example, a {@linkcode CallToolRequest | tools/call} task would return the `CallToolResult` structure.
+ *
+ *
+ * @deprecated 2025-11-25 wire vocabulary with no SDK runtime; kept importable for interoperability only.
+ */
+export const GetTaskPayloadResultSchema = ResultSchema.loose();
+
+/**
+ * A request to list tasks.
+ *
+ * @deprecated 2025-11-25 wire vocabulary with no SDK runtime; kept importable for interoperability only.
+ */
+export const ListTasksRequestSchema = PaginatedRequestSchema.extend({
+    method: z.literal('tasks/list')
+});
+
+/**
+ * The response to a {@linkcode ListTasksRequest | tasks/list} request.
+ *
+ * @deprecated 2025-11-25 wire vocabulary with no SDK runtime; kept importable for interoperability only.
+ */
+export const ListTasksResultSchema = PaginatedResultSchema.extend({
+    tasks: z.array(TaskSchema)
+});
+
+/**
+ * A request to cancel a specific task.
+ *
+ * @deprecated 2025-11-25 wire vocabulary with no SDK runtime; kept importable for interoperability only.
+ */
+export const CancelTaskRequestSchema = RequestSchema.extend({
+    method: z.literal('tasks/cancel'),
+    params: BaseRequestParamsSchema.extend({
+        taskId: z.string()
+    })
+});
+
+/**
+ * The response to a {@linkcode CancelTaskRequest | tasks/cancel} request.
+ *
+ * @deprecated 2025-11-25 wire vocabulary with no SDK runtime; kept importable for interoperability only.
+ */
+export const CancelTaskResultSchema = ResultSchema.merge(TaskSchema);
+
 /* Client messages */
 // NOTE (Q1 increment 2): the role unions below are the NEUTRAL message sets.
 // The 2025-era task vocabulary (tasks/* methods, task results, the task
-// status notification) is 2025-only WIRE vocabulary and now lives in
-// `wire/rev2025-11-25/schemas.ts`, which also exports the era's full wire
-// role unions. The deprecated Task* types remain importable from the types
-// barrel (Q1-SD2); they appear in no role aggregate and no API signature.
+// status notification) is 2025-only WIRE vocabulary; the deprecated Task*
+// schemas above are nameable-only and appear in NO role aggregate and no API
+// signature. The era's full wire role unions live in
+// `wire/rev2025-11-25/schemas.ts`.
 export const ClientRequestSchema = z.union([
     PingRequestSchema,
     InitializeRequestSchema,

packages/core/src/types/specTypeSchema.ts

@@ -41,6 +41,8 @@ const SPEC_SCHEMA_KEYS = [
     'CallToolResultSchema',
     'CancelledNotificationSchema',
     'CancelledNotificationParamsSchema',
+    'CancelTaskRequestSchema',
+    'CancelTaskResultSchema',
     'ClientCapabilitiesSchema',
     'ClientNotificationSchema',
     'ClientRequestSchema',
@@ -54,6 +56,7 @@ const SPEC_SCHEMA_KEYS = [
     'CreateMessageRequestParamsSchema',
     'CreateMessageResultSchema',
     'CreateMessageResultWithToolsSchema',
+    'CreateTaskResultSchema',
     'CursorSchema',
     'DiscoverRequestSchema',
     'DiscoverResultSchema',
@@ -70,6 +73,10 @@ const SPEC_SCHEMA_KEYS = [
     'GetPromptRequestSchema',
     'GetPromptRequestParamsSchema',
     'GetPromptResultSchema',
+    'GetTaskPayloadRequestSchema',
+    'GetTaskPayloadResultSchema',
+    'GetTaskRequestSchema',
+    'GetTaskResultSchema',
     'IconSchema',
     'IconsSchema',
     'ImageContentSchema',
@@ -96,6 +103,8 @@ const SPEC_SCHEMA_KEYS = [
     'ListResourceTemplatesResultSchema',
     'ListRootsRequestSchema',
     'ListRootsResultSchema',
+    'ListTasksRequestSchema',
+    'ListTasksResultSchema',
     'ListToolsRequestSchema',
     'ListToolsResultSchema',
     'LoggingLevelSchema',
@@ -159,7 +168,12 @@ const SPEC_SCHEMA_KEYS = [
     'SubscriptionsListenRequestSchema',
     'SubscriptionsListenRequestParamsSchema',
     'TaskAugmentedRequestParamsSchema',
+    'TaskCreationParamsSchema',
     'TaskMetadataSchema',
+    'TaskSchema',
+    'TaskStatusSchema',
+    'TaskStatusNotificationSchema',
+    'TaskStatusNotificationParamsSchema',
     'TextContentSchema',
     'TextResourceContentsSchema',
     'TitledMultiSelectEnumSchemaSchema',

packages/core/src/types/types.ts

@@ -4,26 +4,6 @@
 
 import type * as z from 'zod/v4';
 
-// Wire-module schema imports, TYPE-ONLY (erased at runtime): the deprecated
-// task vocabulary and the per-request envelope are wire-era artifacts whose
-// schemas live in the codec modules; their inferred TYPES stay importable
-// from this neutral layer (Q1-SD2).
-import type {
-    CancelTaskRequestSchema,
-    CancelTaskResultSchema,
-    CreateTaskResultSchema,
-    GetTaskPayloadRequestSchema,
-    GetTaskPayloadResultSchema,
-    GetTaskRequestSchema,
-    GetTaskResultSchema,
-    ListTasksRequestSchema,
-    ListTasksResultSchema,
-    TaskCreationParamsSchema,
-    TaskSchema,
-    TaskStatusNotificationParamsSchema,
-    TaskStatusNotificationSchema,
-    TaskStatusSchema
-} from '../wire/rev2025-11-25/schemas.js';
 import type {
     CLIENT_CAPABILITIES_META_KEY,
     CLIENT_INFO_META_KEY,
@@ -47,6 +27,8 @@ import type {
     CallToolResultSchema,
     CancelledNotificationParamsSchema,
     CancelledNotificationSchema,
+    CancelTaskRequestSchema,
+    CancelTaskResultSchema,
     ClientCapabilitiesSchema,
     ClientNotificationSchema,
     ClientRequestSchema,
@@ -60,6 +42,7 @@ import type {
     CreateMessageRequestSchema,
     CreateMessageResultSchema,
     CreateMessageResultWithToolsSchema,
+    CreateTaskResultSchema,
     CursorSchema,
     DiscoverRequestSchema,
     DiscoverResultSchema,
@@ -76,6 +59,10 @@ import type {
     GetPromptRequestParamsSchema,
     GetPromptRequestSchema,
     GetPromptResultSchema,
+    GetTaskPayloadRequestSchema,
+    GetTaskPayloadResultSchema,
+    GetTaskRequestSchema,
+    GetTaskResultSchema,
     IconSchema,
     IconsSchema,
     ImageContentSchema,
@@ -97,6 +84,8 @@ import type {
     ListResourceTemplatesResultSchema,
     ListRootsRequestSchema,
     ListRootsResultSchema,
+    ListTasksRequestSchema,
+    ListTasksResultSchema,
     ListToolsRequestSchema,
     ListToolsResultSchema,
     LoggingLevelSchema,
@@ -161,7 +150,12 @@ import type {
     SubscriptionsListenRequestParamsSchema,
     SubscriptionsListenRequestSchema,
     TaskAugmentedRequestParamsSchema,
+    TaskCreationParamsSchema,
     TaskMetadataSchema,
+    TaskSchema,
+    TaskStatusNotificationParamsSchema,
+    TaskStatusNotificationSchema,
+    TaskStatusSchema,
     TextContentSchema,
     TextResourceContentsSchema,
     TitledMultiSelectEnumSchemaSchema,
@@ -247,9 +241,8 @@ export type NotificationParams = Infer<typeof NotificationsParamsSchema>;
  *
  * Neutral hand-written shape keyed by the public meta-key constants — never
  * inferred from a wire-module schema (this neutral layer does not import from
- * `wire/rev*` for runtime types; the deprecated 2025-11-25 task vocabulary
- * above is the sole, type-only carve-out). A `type` alias rather than an
- * interface so it stays assignable to `_meta`'s string-indexed object slot.
+ * `wire/rev*`). A `type` alias rather than an interface so it stays assignable
+ * to `_meta`'s string-indexed object slot.
  */
 export type RequestMetaEnvelope = {
     [PROTOCOL_VERSION_META_KEY]: string;

packages/core/src/wire/rev2025-11-25/schemas.ts

@@ -12,9 +12,11 @@
  *
  * The 2025-only delta (the task message surface, restored types-only by #2248
  * for interop with task-capable 2025 peers) is parsed ONLY through this era's
- * registry; the deprecated Task* TYPES remain importable from the types barrel
- * (Q1-SD2: nameability is constant, runtime availability is version-keyed) but
- * appear in no API signature. Q1 increment 2 — deletions are physical: the
+ * registry; the deprecated Task* schemas also live (marked `@deprecated`) in
+ * the neutral schema layer so the public types stay nameable without a
+ * cross-layer import — nameability is constant, runtime availability is
+ * version-keyed — but appear in no API signature. Q1 increment 2 — deletions
+ * are physical: the
  * 2026-era REGISTRY has no Task* methods (its frozen building-block copies do
  * carry the deprecated Task* sub-schemas by composition — soft contamination,
  * tracked for anchor-exactness adjudication).