feat: inject proper params typing into Request and Notification interfaces

Update pre-processing to transform Request.params and Notification.params:
- Request.params: { [key: string]: any } → RequestParams & { [key: string]: any }
- Notification.params: { [key: string]: any } → NotificationParams & { [key: string]: any }

This allows RequestSchema, NotificationSchema, and ResultSchema to be
re-exported from generated schemas with proper _meta typing.

Total schemas re-exported: 36
Lines saved: ~368 (2600 → 2232)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: ochafik

scripts/generate-schemas.ts

@@ -106,6 +106,7 @@ const RELATED_TASK_META_KEY = 'io.modelcontextprotocol/related-task';
  * 1. `extends JSONRPCRequest` → `extends Request`
  * 2. `extends JSONRPCNotification` → `extends Notification`
  * 3. Add RELATED_TASK_META_KEY to RequestParams._meta
+ * 4. Change Request.params type to use RequestParams (for proper _meta typing)
  */
 function preProcessTypes(content: string): string {
     const project = new Project({ useInMemoryFileSystem: true });
@@ -120,6 +121,9 @@ function preProcessTypes(content: string): string {
     // Transform 3: Add RELATED_TASK_META_KEY to RequestParams._meta
     injectRelatedTaskMetaKey(sourceFile);
 
+    // Transform 4: Update Request.params to use RequestParams
+    updateRequestParamsType(sourceFile);
+
     return sourceFile.getFullText();
 }
 
@@ -208,6 +212,39 @@ function injectRelatedTaskMetaKey(sourceFile: SourceFile): void {
     console.log('    ✓ Injected RELATED_TASK_META_KEY into RequestParams._meta');
 }
 
+/**
+ * Update Request.params and Notification.params to use proper param types.
+ *
+ * Before:
+ *   interface Request { params?: { [key: string]: any }; }
+ *   interface Notification { params?: { [key: string]: any }; }
+ *
+ * After:
+ *   interface Request { params?: RequestParams & { [key: string]: any }; }
+ *   interface Notification { params?: NotificationParams & { [key: string]: any }; }
+ */
+function updateRequestParamsType(sourceFile: SourceFile): void {
+    // Update Request.params
+    const requestInterface = sourceFile.getInterface('Request');
+    if (requestInterface) {
+        const paramsProp = requestInterface.getProperty('params');
+        if (paramsProp) {
+            paramsProp.setType('RequestParams & { [key: string]: any }');
+            console.log('    ✓ Updated Request.params to include RequestParams');
+        }
+    }
+
+    // Update Notification.params
+    const notificationInterface = sourceFile.getInterface('Notification');
+    if (notificationInterface) {
+        const paramsProp = notificationInterface.getProperty('params');
+        if (paramsProp) {
+            paramsProp.setType('NotificationParams & { [key: string]: any }');
+            console.log('    ✓ Updated Notification.params to include NotificationParams');
+        }
+    }
+}
+
 // =============================================================================
 // Post-processing: AST-based transforms using ts-morph
 // =============================================================================

src/generated/sdk.schemas.ts

@@ -43,12 +43,27 @@ export const RelatedTaskMetadataSchema = z.object({
     taskId: z.string()
 });
 
-/** @internal */
-export const RequestSchema = z.object({
-    method: z.string(),
-    // Allow unofficial extensions of `Request.params` without impacting `RequestParams`.
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    params: z.record(z.string(), z.any()).optional()
+/**
+ * Common params for any request.
+ *
+ * @internal
+ */
+export const RequestParamsSchema = z.object({
+    /**
+     * See [General fields: `_meta`](/specification/draft/basic/index#meta) for notes on `_meta` usage.
+     */
+    _meta: z
+        .looseObject({
+            /**
+             * If specified, the caller is requesting out-of-band progress notifications for this request (as represented by notifications/progress). The value of this parameter is an opaque token that will be attached to any subsequent notifications. The receiver is not obligated to provide these notifications.
+             */
+            progressToken: ProgressTokenSchema.optional(),
+            /**
+             * If specified, this request is related to the provided task.
+             */
+            'io.modelcontextprotocol/related-task': RelatedTaskMetadataSchema.optional()
+        })
+        .optional()
 });
 
 /** @internal */
@@ -64,7 +79,7 @@ export const NotificationSchema = z.object({
     method: z.string(),
     // Allow unofficial extensions of `Notification.params` without impacting `NotificationParams`.
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    params: z.record(z.string(), z.any()).optional()
+    params: NotificationParamsSchema.and(z.record(z.string(), z.any())).optional()
 });
 
 /**
@@ -102,14 +117,12 @@ export const ErrorSchema = z.object({
  */
 export const RequestIdSchema = z.union([z.string(), z.number().int()]);
 
-/**
- * A request that expects a response.
- *
- * @category JSON-RPC
- */
-export const JSONRPCRequestSchema = RequestSchema.extend({
-    jsonrpc: z.literal('2.0'),
-    id: RequestIdSchema
+/** @internal */
+export const RequestSchema = z.object({
+    method: z.string(),
+    // Allow unofficial extensions of `Request.params` without impacting `RequestParams`.
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    params: RequestParamsSchema.and(z.record(z.string(), z.any())).optional()
 });
 
 /**
@@ -195,29 +208,6 @@ export const CancelledNotificationSchema = NotificationSchema.extend({
     params: CancelledNotificationParamsSchema
 });
 
-/**
- * Common params for any request.
- *
- * @internal
- */
-export const RequestParamsSchema = z.object({
-    /**
-     * See [General fields: `_meta`](/specification/draft/basic/index#meta) for notes on `_meta` usage.
-     */
-    _meta: z
-        .looseObject({
-            /**
-             * If specified, the caller is requesting out-of-band progress notifications for this request (as represented by notifications/progress). The value of this parameter is an opaque token that will be attached to any subsequent notifications. The receiver is not obligated to provide these notifications.
-             */
-            progressToken: ProgressTokenSchema.optional(),
-            /**
-             * If specified, this request is related to the provided task.
-             */
-            'io.modelcontextprotocol/related-task': RelatedTaskMetadataSchema.optional()
-        })
-        .optional()
-});
-
 /**
  * Capabilities a client may support. Known capabilities are defined here, in this schema, but this is not a closed set: any client can define its own, additional capabilities.
  *
@@ -1967,21 +1957,14 @@ export const ListToolsResultSchema = PaginatedResultSchema.extend({
 });
 
 /**
- * This file is automatically generated from the Model Context Protocol specification.
- *
- * Source: https://github.com/modelcontextprotocol/modelcontextprotocol
- * Pulled from: https://raw.githubusercontent.com/modelcontextprotocol/modelcontextprotocol/main/schema/draft/schema.ts
- * Last updated from commit: 35fa160caf287a9c48696e3ae452c0645c713669
- *
- * DO NOT EDIT THIS FILE MANUALLY. Changes will be overwritten by automated updates.
- * To update this file, run: npm run fetch:spec-types
- */ /* JSON-RPC types */
-/**
- * Refers to any valid JSON-RPC object that can be decoded off the wire, or encoded to be sent.
+ * A request that expects a response.
  *
  * @category JSON-RPC
  */
-export const JSONRPCMessageSchema = z.union([JSONRPCRequestSchema, JSONRPCNotificationSchema, JSONRPCResponseSchema]);
+export const JSONRPCRequestSchema = RequestSchema.extend({
+    jsonrpc: z.literal('2.0'),
+    id: RequestIdSchema
+});
 
 /**
  * An error response that indicates that the server requires the client to provide additional information via an elicitation request.
@@ -2367,6 +2350,23 @@ export const CallToolResultSchema = ResultSchema.extend({
     isError: z.boolean().optional()
 });
 
+/**
+ * This file is automatically generated from the Model Context Protocol specification.
+ *
+ * Source: https://github.com/modelcontextprotocol/modelcontextprotocol
+ * Pulled from: https://raw.githubusercontent.com/modelcontextprotocol/modelcontextprotocol/main/schema/draft/schema.ts
+ * Last updated from commit: 35fa160caf287a9c48696e3ae452c0645c713669
+ *
+ * DO NOT EDIT THIS FILE MANUALLY. Changes will be overwritten by automated updates.
+ * To update this file, run: npm run fetch:spec-types
+ */ /* JSON-RPC types */
+/**
+ * Refers to any valid JSON-RPC object that can be decoded off the wire, or encoded to be sent.
+ *
+ * @category JSON-RPC
+ */
+export const JSONRPCMessageSchema = z.union([JSONRPCRequestSchema, JSONRPCNotificationSchema, JSONRPCResponseSchema]);
+
 /**
  * Describes a message returned as part of a prompt.
  *

src/generated/sdk.types.ts

@@ -81,7 +81,7 @@ export interface Request {
     method: string;
     // Allow unofficial extensions of `Request.params` without impacting `RequestParams`.
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    params?: { [key: string]: any };
+    params?: RequestParams & { [key: string]: any };
 }
 
 /** @internal */
@@ -97,7 +97,7 @@ export interface Notification {
     method: string;
     // Allow unofficial extensions of `Notification.params` without impacting `NotificationParams`.
     // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    params?: { [key: string]: any };
+    params?: NotificationParams & { [key: string]: any };
 }
 
 /**

src/types.ts

@@ -54,10 +54,17 @@ import {
     // Request/notification base schemas (with RELATED_TASK_META_KEY injected)
     RequestParamsSchema,
     TaskAugmentedRequestParamsSchema,
+    NotificationParamsSchema,
+    // Core request/notification schemas (params include proper _meta typing)
+    RequestSchema,
+    NotificationSchema,
+    ResultSchema,
 } from './generated/sdk.schemas.js';
 
 // Alias RequestParamsSchema to BaseRequestParamsSchema for internal use
 const BaseRequestParamsSchema = RequestParamsSchema;
+// Alias NotificationParamsSchema to NotificationsParamsSchema (plural) for backwards compat
+const NotificationsParamsSchema = NotificationParamsSchema;
 
 export {
     ProgressTokenSchema,
@@ -91,6 +98,10 @@ export {
     ResourceContentsSchema,
     TextResourceContentsSchema,
     BlobResourceContentsSchema,
+    // Core protocol schemas
+    RequestSchema,
+    NotificationSchema,
+    ResultSchema,
 };
 
 export const LATEST_PROTOCOL_VERSION = '2025-11-25';
@@ -151,31 +162,8 @@ const RequestMetaSchema = z.looseObject({
 export const isTaskAugmentedRequestParams = (value: unknown): value is TaskAugmentedRequestParams =>
     TaskAugmentedRequestParamsSchema.safeParse(value).success;
 
-export const RequestSchema = z.object({
-    method: z.string(),
-    params: BaseRequestParamsSchema.loose().optional()
-});
-
-const NotificationsParamsSchema = z.object({
-    /**
-     * See [MCP specification](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/47339c03c143bb4ec01a26e721a1b8fe66634ebe/docs/specification/draft/basic/index.mdx#general-fields)
-     * for notes on _meta usage.
-     */
-    _meta: RequestMetaSchema.optional()
-});
-
-export const NotificationSchema = z.object({
-    method: z.string(),
-    params: NotificationsParamsSchema.loose().optional()
-});
-
-export const ResultSchema = z.looseObject({
-    /**
-     * See [MCP specification](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/47339c03c143bb4ec01a26e721a1b8fe66634ebe/docs/specification/draft/basic/index.mdx#general-fields)
-     * for notes on _meta usage.
-     */
-    _meta: RequestMetaSchema.optional()
-});
+// Note: RequestSchema, NotificationSchema, ResultSchema are re-exported from generated.
+// They include proper _meta typing with RELATED_TASK_META_KEY.
 
 /**
  * A request that expects a response.