fix: revert out-of-scope SdkError, add ctx.mcpReq.send to changeset + tests

Author: felixweinberger

.changeset/custom-method-overloads.md

@@ -3,4 +3,4 @@
 '@modelcontextprotocol/server': minor
 ---
 
-`setRequestHandler`/`setNotificationHandler` accept the v1 `(ZodSchema, handler)` form as a first-class alternative to `(methodString, handler)`. `request()` accepts an explicit result schema (`request(req, resultSchema, options?)`) and has a method-keyed return type for spec methods. `callTool(params, resultSchema?)` accepts the v1 schema arg (ignored). `removeRequestHandler`/`removeNotificationHandler`/`assertCanSetRequestHandler` accept any method string.
+`setRequestHandler`/`setNotificationHandler` accept the v1 `(ZodSchema, handler)` form as a first-class alternative to `(methodString, handler)`. `request()` and `ctx.mcpReq.send()` accept an explicit result schema (`request(req, resultSchema, options?)`) and have method-keyed return types for spec methods. `callTool(params, resultSchema?)` accepts the v1 schema arg (ignored). `removeRequestHandler`/`removeNotificationHandler`/`assertCanSetRequestHandler` accept any method string.

packages/core/src/shared/protocol.ts

@@ -837,7 +837,7 @@ export abstract class Protocol<ContextT extends BaseContext> {
             };
 
             if (!this._transport) {
-                earlyReject(new SdkError(SdkErrorCode.NotConnected, 'Not connected'));
+                earlyReject(new Error('Not connected'));
                 return;
             }
 

packages/core/test/shared/customMethods.test.ts

@@ -108,6 +108,32 @@ describe('request() — explicit result schema overload', () => {
     });
 });
 
+describe('ctx.mcpReq.send() — explicit result schema overload', () => {
+    it('forwards to a related request and validates result via the supplied schema', async () => {
+        const { a, b } = await makePair();
+        a.setRequestHandler(EchoRequest, req => ({ reply: req.params.msg }));
+        let captured: unknown;
+        b.setRequestHandler(z.object({ method: z.literal('acme/outer') }), async (_req, ctx) => {
+            captured = await ctx.mcpReq.send({ method: 'acme/echo', params: { msg: 'via-send' } }, z.object({ reply: z.string() }));
+            return {};
+        });
+        await a.request({ method: 'acme/outer' }, z.object({}));
+        expect(captured).toEqual({ reply: 'via-send' });
+    });
+
+    it('spec-method form (no schema) uses method-keyed return', async () => {
+        const { a, b } = await makePair();
+        a.setRequestHandler('ping', () => ({}));
+        let pingResult: unknown;
+        b.setRequestHandler(z.object({ method: z.literal('acme/outer') }), async (_req, ctx) => {
+            pingResult = await ctx.mcpReq.send({ method: 'ping' });
+            return {};
+        });
+        await a.request({ method: 'acme/outer' }, z.object({}));
+        expect(pingResult).toEqual({});
+    });
+});
+
 describe('notification() mock-assignability', () => {
     it('single-signature notification() is assignable from a simple mock (compile-time check)', () => {
         const p = new TestProtocol();