diff --git a/src/apps/app_sdk/apps/definition.ts b/src/apps/app_sdk/apps/definition.ts
index 120e8686..baaaa067 100644
--- a/src/apps/app_sdk/apps/definition.ts
+++ b/src/apps/app_sdk/apps/definition.ts
@@ -11,6 +11,8 @@ export interface AppDefinition {
   migrations: boolean;
   // If adding, updating, or removing this app requires a session restart
   restartOnChange: boolean;
+  // If only one instance of this app is allowed per session
+  unique: boolean;
 }
 
 // All Apps
@@ -21,6 +23,7 @@ export const APPS: Record<AppName, AppDefinition> = {
     queue: false,
     migrations: false,
     restartOnChange: true,
+    unique: true,
   },
   [AppName.chatwoot]: {
     name: AppName.chatwoot,
@@ -28,6 +31,7 @@ export const APPS: Record<AppName, AppDefinition> = {
     queue: true,
     migrations: true,
     restartOnChange: true,
+    unique: true,
   },
   [AppName.mcp]: {
     name: AppName.mcp,
@@ -35,6 +39,7 @@ export const APPS: Record<AppName, AppDefinition> = {
     queue: false,
     migrations: false,
     restartOnChange: false,
+    unique: false,
   },
   [AppName.brazilianPhoneNumbers]: {
     name: AppName.brazilianPhoneNumbers,
@@ -42,5 +47,27 @@ export const APPS: Record<AppName, AppDefinition> = {
     queue: false,
     migrations: true,
     restartOnChange: true,
+    unique: true,
   },
 };
+
+export function isUniqueApp(name: AppName): boolean {
+  return APPS[name]?.unique === true;
+}
+
+// Returns the first unique AppName that appears more than once in the list, or null
+export function findDuplicateUniqueApp(
+  apps: Array<{ app: AppName }>,
+): AppName | null {
+  const seen = new Set<AppName>();
+  for (const app of apps) {
+    if (!isUniqueApp(app.app)) {
+      continue;
+    }
+    if (seen.has(app.app)) {
+      return app.app;
+    }
+    seen.add(app.app);
+  }
+  return null;
+}
diff --git a/src/apps/app_sdk/services/AppsEnabledService.ts b/src/apps/app_sdk/services/AppsEnabledService.ts
index 3d1c7052..5bc94e46 100644
--- a/src/apps/app_sdk/services/AppsEnabledService.ts
+++ b/src/apps/app_sdk/services/AppsEnabledService.ts
@@ -22,6 +22,10 @@ import { App } from '../dto/app.dto';
 import { AppRepository } from '../storage/AppRepository';
 import { AppName } from '@waha/apps/app_sdk/apps/name';
 import { AppRuntimeConfig } from '@waha/apps/app_sdk/apps/AppRuntime';
+import {
+  findDuplicateUniqueApp,
+  isUniqueApp,
+} from '@waha/apps/app_sdk/apps/definition';
 
 export class AppDisableError extends UnprocessableEntityException {
   constructor(app: string) {
@@ -31,6 +35,15 @@ export class AppDisableError extends UnprocessableEntityException {
   }
 }
 
+export class AppUniquePerSessionError extends UnprocessableEntityException {
+  constructor(app: string, session: string, existingAppId: string) {
+    super(
+      `Only one '${app}' app is allowed per session. ` +
+        `Session '${session}' already has a '${app}' app with ID '${existingAppId}'.`,
+    );
+  }
+}
+
 @Injectable()
 export class AppsEnabledService implements IAppsService {
   constructor(
@@ -67,47 +80,17 @@ export class AppsEnabledService implements IAppsService {
       throw new Error(`App with ID '${app.id}' already exists.`);
     }
 
-    let existingApps: App[] = [];
-    if (
-      app.app === AppName.chatwoot ||
-      app.app === AppName.calls ||
-      app.app === AppName.brazilianPhoneNumbers
-    ) {
-      existingApps = await repo.getAllBySession(app.session);
-    }
-    // Validate only one Chatwoot app per session
-    if (app.app === AppName.chatwoot) {
-      const existingChatwootApp = existingApps.find(
-        (existingApp) => existingApp.app === AppName.chatwoot,
+    // Validate only one instance of a unique app per session
+    if (isUniqueApp(app.app)) {
+      const existingApps = await repo.getAllBySession(app.session);
+      const duplicateApp = existingApps.find(
+        (existingApp) => existingApp.app === app.app,
       );
-
-      if (existingChatwootApp) {
-        throw new Error(
-          `Only one Chatwoot app is allowed per session. Session '${app.session}' already has a Chatwoot app with ID '${existingChatwootApp.id}'.`,
-        );
-      }
-    }
-    // Validate only one Calls app per session
-    if (app.app === AppName.calls) {
-      const existingCallsApp = existingApps.find(
-        (existingApp) => existingApp.app === AppName.calls,
-      );
-
-      if (existingCallsApp) {
-        throw new Error(
-          `Only one Calls app is allowed per session. Session '${app.session}' already has a Calls app with ID '${existingCallsApp.id}'.`,
-        );
-      }
-    }
-    // Validate only one Brazilian Phone Numbers app per session
-    if (app.app === AppName.brazilianPhoneNumbers) {
-      const existingBrazilianPhoneNumbersApp = existingApps.find(
-        (existingApp) => existingApp.app === AppName.brazilianPhoneNumbers,
-      );
-
-      if (existingBrazilianPhoneNumbersApp) {
-        throw new Error(
-          `Only one Brazilian Phone Numbers app is allowed per session. Session '${app.session}' already has a Brazilian Phone Numbers app with ID '${existingBrazilianPhoneNumbersApp.id}'.`,
+      if (duplicateApp) {
+        throw new AppUniquePerSessionError(
+          app.app,
+          app.session,
+          duplicateApp.id,
         );
       }
     }
@@ -257,6 +240,15 @@ export class AppsEnabledService implements IAppsService {
     session: string,
     apps: App[],
   ): Promise<void> {
+    // Reject duplicate unique apps in the payload before any writes,
+    // otherwise the by-type matching below binds them to the same app
+    const duplicateUniqueApp = findDuplicateUniqueApp(apps);
+    if (duplicateUniqueApp !== null) {
+      throw new UnprocessableEntityException(
+        `Only one '${duplicateUniqueApp}' app is allowed per session - remove duplicate entries from 'apps'.`,
+      );
+    }
+
     const existing = await this.list(manager, session);
     const ids = new Set<string>();