fix: AI chat not showing credits exhausted or API key errors to user

Root cause: AgentChatResolver was missing @UseInterceptors, so domain
exceptions were never converted to typed GraphQL errors. They fell through
to generateGraphQLErrorFromError which created a BaseGraphQLError from
error.message (a string), losing the CustomException's subCode and
userFriendlyMessage.

Changes:
- generate-graphql-error-from-error.util.ts: Pass CustomException directly
  to BaseGraphQLError constructor (which already handles it properly)
  instead of extracting message as string and duck-typing fields after
- agent-chat.resolver.ts: Add @UseInterceptors(AgentGraphqlApiExceptionInterceptor)
- agent-graphql-api-exception-handler.util.ts: Map API_KEY_NOT_CONFIGURED
  to ForbiddenError instead of re-throwing raw
- useAgentChat.ts: Catch block now normalizes mutation errors and sets
  the error atom (same pattern as stream error handler)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/twenty-front/src/modules/ai/hooks/useAgentChat.ts

@@ -1,3 +1,4 @@
+import { CombinedGraphQLErrors } from '@apollo/client/errors';
 import { useApolloClient } from '@apollo/client/react';
 import { useStore } from 'jotai';
 import { useCallback, useState } from 'react';
@@ -18,6 +19,7 @@ import {
 import { agentChatInputState } from '@/ai/states/agentChatInputState';
 import { agentChatSelectedFilesState } from '@/ai/states/agentChatSelectedFilesState';
 import { agentChatUploadedFilesState } from '@/ai/states/agentChatUploadedFilesState';
+import { agentChatErrorComponentFamilyState } from '@/ai/states/agentChatErrorComponentFamilyState';
 import { agentChatMessagesComponentFamilyState } from '@/ai/states/agentChatMessagesComponentFamilyState';
 import { currentAIChatThreadState } from '@/ai/states/currentAIChatThreadState';
 import { useGetBrowsingContext } from '@/ai/hooks/useBrowsingContext';
@@ -110,6 +112,13 @@ export const useAgentChat = (
       familyKey: { threadId },
     });
 
+    const errorAtom = agentChatErrorComponentFamilyState.atomFamily({
+      instanceId: AGENT_CHAT_INSTANCE_ID,
+      familyKey: { threadId },
+    });
+
+    store.set(errorAtom, null);
+
     const currentMessages = store.get(messagesAtom);
 
     store.set(messagesAtom, [...currentMessages, optimisticUserMessage]);
@@ -155,7 +164,7 @@ export const useAgentChat = (
 
         return null;
       });
-    } catch {
+    } catch (error) {
       setAgentChatInput(contentToSend);
       setAgentChatDraftsByThreadId((prev) => ({
         ...prev,
@@ -168,6 +177,17 @@ export const useAgentChat = (
         messagesAtom,
         latestMessages.filter((message) => message.id !== messageId),
       );
+
+      if (CombinedGraphQLErrors.is(error)) {
+        const subCode = error.errors[0]?.extensions?.subCode;
+        const mutationError = new Error(error.message) as Error & {
+          code?: string;
+        };
+
+        mutationError.code =
+          typeof subCode === 'string' ? subCode : undefined;
+        store.set(errorAtom, mutationError);
+      }
     }
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [

packages/twenty-server/src/engine/core-modules/graphql/utils/generate-graphql-error-from-error.util.ts

@@ -1,6 +1,6 @@
 import { HttpException } from '@nestjs/common';
 
-import { type I18n, type MessageDescriptor } from '@lingui/core';
+import { type I18n } from '@lingui/core';
 import { msg } from '@lingui/core/macro';
 
 import {
@@ -8,22 +8,29 @@ import {
   ErrorCode,
 } from 'src/engine/core-modules/graphql/utils/graphql-errors.util';
 import { convertExceptionToGraphQLError } from 'src/engine/utils/global-exception-handler.util';
+import { CustomException } from 'src/utils/custom-exception';
 
 export const generateGraphQLErrorFromError = (error: Error, i18n: I18n) => {
-  const graphqlError =
-    error instanceof HttpException
-      ? convertExceptionToGraphQLError(error)
-      : new BaseGraphQLError(error.message, ErrorCode.INTERNAL_SERVER_ERROR);
+  let graphqlError: BaseGraphQLError;
+
+  if (error instanceof HttpException) {
+    graphqlError = convertExceptionToGraphQLError(error);
+  } else if (error instanceof CustomException) {
+    graphqlError = new BaseGraphQLError(
+      error,
+      ErrorCode.INTERNAL_SERVER_ERROR,
+    );
+  } else {
+    graphqlError = new BaseGraphQLError(
+      error.message,
+      ErrorCode.INTERNAL_SERVER_ERROR,
+    );
+  }
 
   const defaultErrorMessage = msg`An error occurred.`;
 
-  const userFriendlyMessage =
-    'userFriendlyMessage' in error
-      ? (error.userFriendlyMessage as MessageDescriptor)
-      : undefined;
-
   graphqlError.extensions.userFriendlyMessage = i18n._(
-    userFriendlyMessage ?? defaultErrorMessage,
+    graphqlError.extensions.userFriendlyMessage ?? defaultErrorMessage,
   );
 
   return graphqlError;

packages/twenty-server/src/engine/metadata-modules/ai/ai-agent/utils/agent-graphql-api-exception-handler.util.ts

@@ -24,8 +24,9 @@ export const agentGraphqlApiExceptionHandler = (error: Error) => {
       case AgentExceptionCode.AGENT_IS_STANDARD:
       case AgentExceptionCode.ROLE_CANNOT_BE_ASSIGNED_TO_AGENTS:
         throw new ForbiddenError(error);
-      case AgentExceptionCode.AGENT_EXECUTION_FAILED:
       case AgentExceptionCode.API_KEY_NOT_CONFIGURED:
+        throw new ForbiddenError(error);
+      case AgentExceptionCode.AGENT_EXECUTION_FAILED:
       case AgentExceptionCode.USER_WORKSPACE_ID_NOT_FOUND:
         throw error;
       default: {

packages/twenty-server/src/engine/metadata-modules/ai/ai-chat/resolvers/agent-chat.resolver.ts

@@ -1,4 +1,4 @@
-import { UseGuards } from '@nestjs/common';
+import { UseGuards, UseInterceptors } from '@nestjs/common';
 import {
   Args,
   Float,
@@ -51,6 +51,7 @@ import { AgentChatStreamingService } from 'src/engine/metadata-modules/ai/ai-cha
 import { AgentChatService } from 'src/engine/metadata-modules/ai/ai-chat/services/agent-chat.service';
 import { getCancelChannel } from 'src/engine/metadata-modules/ai/ai-chat/utils/get-cancel-channel.util';
 import { SystemPromptBuilderService } from 'src/engine/metadata-modules/ai/ai-chat/services/system-prompt-builder.service';
+import { AgentGraphqlApiExceptionInterceptor } from 'src/engine/metadata-modules/ai/ai-agent/interceptors/agent-graphql-api-exception.interceptor';
 import { AiModelRegistryService } from 'src/engine/metadata-modules/ai/ai-models/services/ai-model-registry.service';
 
 @UseGuards(
@@ -58,6 +59,7 @@ import { AiModelRegistryService } from 'src/engine/metadata-modules/ai/ai-models
   FeatureFlagGuard,
   SettingsPermissionGuard(PermissionFlagType.AI),
 )
+@UseInterceptors(AgentGraphqlApiExceptionInterceptor)
 @MetadataResolver(() => AgentChatThreadDTO)
 export class AgentChatResolver {
   constructor(