fix: add validation to check for duplicate roles

src/types/plugin-input.ts

@@ -1,6 +1,7 @@
 import { SupportedEvents, SupportedEventsU } from "./context";
-import { StaticDecode, Type as T } from "@sinclair/typebox";
+import { Static, Type as T } from "@sinclair/typebox";
 import { StandardValidator } from "typebox-validators";
+import { validateSchemaForDuplicateRoles } from "../utils/validate-schema-for-duplicate-roles";
 
 export interface PluginInputs<T extends SupportedEventsU = SupportedEventsU, TU extends SupportedEvents[T] = SupportedEvents[T]> {
   stateId: string;

src/utils/validate-schema-for-duplicate-roles.ts

@@ -0,0 +1,37 @@
+import { Static, TSchema } from "@sinclair/typebox";
+import { startStopSchema } from "../types";
+
+class DuplicateRoleError extends Error {
+    constructor(message: string) {
+      super(message);
+      this.name = "DuplicateRoleError";
+    }
+  }
+
+ export function validateSchemaForDuplicateRoles<T extends TSchema>(schema: T): T {
+    return {
+      ...schema,
+      decode(value: unknown) {
+        try {
+          const decodedValue = value as Static<typeof startStopSchema>;
+
+          const taskRoles = decodedValue.miscellaneous.maxConcurrentTasks.map((task) => task.role);
+          const uniqueRoles = new Set(taskRoles);
+
+          if (taskRoles.length !== uniqueRoles.size) {
+            throw new DuplicateRoleError("Duplicate roles found in maxConcurrentTasks.");
+          }
+
+          return decodedValue;
+        } catch (error) {
+          if (error instanceof DuplicateRoleError) {
+            console.error(error.message);
+            throw error;
+          } else {
+            console.error("An unexpected error occurred during decoding:", error);
+            throw error;
+          }
+        }
+      },
+    } as T;
+  }