Support customizing task pollInterval on server

Author: LucaButBoring

src/examples/server/simpleStreamableHttp.ts

@@ -479,7 +479,8 @@ const getServer = () => {
                 })();
                 return await taskStore.createTask({
                     taskId,
-                    keepAlive: taskRequestedKeepAlive
+                    keepAlive: taskRequestedKeepAlive,
+                    pollInterval: 100
                 });
             },
             async getTask(_args, { taskId, taskStore }) {

src/examples/shared/inMemoryTaskStore.ts

@@ -32,7 +32,7 @@ export class InMemoryTaskStore implements TaskStore {
             taskId,
             status: 'submitted',
             keepAlive: metadata.keepAlive ?? null,
-            pollInterval: 500
+            pollInterval: metadata.pollInterval ?? 500
         };
 
         this.tasks.set(taskId, {

src/types.ts

@@ -44,7 +44,12 @@ export const TaskMetadataSchema = z
         /**
          * Time in milliseconds to ask to keep task results available after completion. Only used with taskId.
          */
-        keepAlive: z.number().optional()
+        keepAlive: z.number().optional(),
+
+        /**
+         * Time in milliseconds to wait between task status requests. Only used with taskId.
+         */
+        pollInterval: z.optional(z.number())
     })
     /**
      * Passthrough required here because we want to allow any additional fields to be added to the request meta.