feat: Abort AI builder requests on chat stop (#17854)

packages/@n8n/ai-workflow-builder.ee/src/ai-workflow-builder-agent.service.ts

@@ -167,10 +167,10 @@ export class AiWorkflowBuilderService {
 		return this.agent;
 	}
 
-	async *chat(payload: ChatPayload, user?: IUser) {
+	async *chat(payload: ChatPayload, user?: IUser, abortSignal?: AbortSignal) {
 		const agent = await this.getAgent(user);
 
-		for await (const output of agent.chat(payload, user?.id?.toString())) {
+		for await (const output of agent.chat(payload, user?.id?.toString(), abortSignal)) {
 			yield output;
 		}
 	}

packages/@n8n/ai-workflow-builder.ee/src/workflow-builder-agent.ts

@@ -1,6 +1,7 @@
 import type { BaseChatModel } from '@langchain/core/language_models/chat_models';
-import type { AIMessage, ToolMessage } from '@langchain/core/messages';
-import { HumanMessage, RemoveMessage } from '@langchain/core/messages';
+import type { ToolMessage } from '@langchain/core/messages';
+import { AIMessage, HumanMessage, RemoveMessage } from '@langchain/core/messages';
+import type { RunnableConfig } from '@langchain/core/runnables';
 import type { LangChainTracer } from '@langchain/core/tracers/tracer_langchain';
 import { StateGraph, MemorySaver, END } from '@langchain/langgraph';
 import type { Logger } from '@n8n/backend-common';
@@ -180,71 +181,73 @@ export class WorkflowBuilderAgent {
 			: crypto.randomUUID();
 	}
 
-	async *chat(payload: ChatPayload, userId?: string) {
+	private getDefaultWorkflowJSON(payload: ChatPayload): SimpleWorkflow {
+		return (
+			(payload.workflowContext?.currentWorkflow as SimpleWorkflow) ?? {
+				nodes: [],
+				connections: {},
+			}
+		);
+	}
+
+	async *chat(payload: ChatPayload, userId?: string, abortSignal?: AbortSignal) {
 		const agent = this.createWorkflow().compile({ checkpointer: this.checkpointer });
 		const workflowId = payload.workflowContext?.currentWorkflow?.id;
 		// Generate thread ID from workflowId and userId
 		// This ensures one session per workflow per user
 		const threadId = WorkflowBuilderAgent.generateThreadId(workflowId, userId);
-
-		// Configure thread for checkpointing
-		const threadConfig = {
+		const threadConfig: RunnableConfig = {
 			configurable: {
 				thread_id: threadId,
 			},
 		};
+		const streamConfig = {
+			...threadConfig,
+			streamMode: ['updates', 'custom'],
+			recursionLimit: 30,
+			signal: abortSignal,
+			callbacks: this.tracer ? [this.tracer] : undefined,
+		} as RunnableConfig;
 
-		// Check if this is a subsequent message
-		// If so, update the workflowJSON with the current editor state
-		const existingCheckpoint = await this.checkpointer.getTuple(threadConfig);
-
-		let stream;
-
-		if (!existingCheckpoint?.checkpoint) {
-			// First message - use initial state
-			const initialState: typeof WorkflowState.State = {
+		const stream = await agent.stream(
+			{
 				messages: [new HumanMessage({ content: payload.message })],
-				workflowJSON: (payload.workflowContext?.currentWorkflow as SimpleWorkflow) ?? {
-					nodes: [],
-					connections: {},
-				},
+				workflowJSON: this.getDefaultWorkflowJSON(payload),
 				workflowOperations: [],
 				workflowContext: payload.workflowContext,
-			};
+			},
+			streamConfig,
+		);
 
-			stream = await agent.stream(initialState, {
-				...threadConfig,
-				streamMode: ['updates', 'custom'],
-				recursionLimit: 30,
-				callbacks: this.tracer ? [this.tracer] : undefined,
-			});
-		} else {
-			// Subsequent message - update the state with current workflow
-			const stateUpdate: Partial<typeof WorkflowState.State> = {
-				messages: [new HumanMessage({ content: payload.message })],
-				workflowOperations: [], // Clear any pending operations from previous message
-				workflowContext: payload.workflowContext,
-				workflowJSON: { nodes: [], connections: {} }, // Default to empty workflow
-			};
-
-			if (payload.workflowContext?.currentWorkflow) {
-				stateUpdate.workflowJSON = payload.workflowContext?.currentWorkflow as SimpleWorkflow;
+		try {
+			const streamProcessor = createStreamProcessor(stream);
+			for await (const output of streamProcessor) {
+				yield output;
 			}
+		} catch (error) {
+			if (
+				error &&
+				typeof error === 'object' &&
+				'message' in error &&
+				typeof error.message === 'string' &&
+				// This is naive, but it's all we get from LangGraph AbortError
+				['Abort', 'Aborted'].includes(error.message)
+			) {
+				// eslint-disable-next-line @typescript-eslint/no-unsafe-member-access
+				const messages = (await agent.getState(threadConfig)).values.messages as Array<
+					AIMessage | HumanMessage | ToolMessage
+				>;
 
-			// Stream with just the new message
-			stream = await agent.stream(stateUpdate, {
-				...threadConfig,
-				streamMode: ['updates', 'custom'],
-				recursionLimit: 80,
-				callbacks: this.tracer ? [this.tracer] : undefined,
-			});
-		}
-
-		// Use the stream processor utility to handle chunk processing
-		const streamProcessor = createStreamProcessor(stream);
-
-		for await (const output of streamProcessor) {
-			yield output;
+				// Handle abort errors gracefully
+				const abortedAiMessage = new AIMessage({
+					content: '[Task aborted]',
+					id: crypto.randomUUID(),
+				});
+				// TODO: Should we clear tool calls that are in progress?
+				await agent.updateState(threadConfig, { messages: [...messages, abortedAiMessage] });
+				return;
+			}
+			throw error;
 		}
 	}
 
@@ -256,7 +259,7 @@ export class WorkflowBuilderAgent {
 
 		if (workflowId) {
 			const threadId = WorkflowBuilderAgent.generateThreadId(workflowId, userId);
-			const threadConfig = {
+			const threadConfig: RunnableConfig = {
 				configurable: {
 					thread_id: threadId,
 				},

packages/cli/src/controllers/__tests__/ai.controller.test.ts

@@ -152,6 +152,7 @@ describe('AiController', () => {
 					},
 				},
 				request.user,
+				expect.any(AbortSignal),
 			);
 			expect(response.header).toHaveBeenCalledWith('Content-type', 'application/json-lines');
 			expect(response.flush).toHaveBeenCalled();
@@ -241,5 +242,157 @@ describe('AiController', () => {
 			expect(response.json).not.toHaveBeenCalled();
 			expect(response.end).toHaveBeenCalled();
 		});
+
+		describe('Abort handling', () => {
+			it('should create AbortController and handle connection close', async () => {
+				let abortHandler: (() => void) | undefined;
+				let abortSignalPassed: AbortSignal | undefined;
+
+				// Mock response.on to capture the close handler
+				response.on.mockImplementation((event: string, handler: () => void) => {
+					if (event === 'close') {
+						abortHandler = handler;
+					}
+					return response;
+				});
+
+				// Create a generator that yields once then checks for abort
+				async function* testGenerator() {
+					yield {
+						messages: [{ role: 'assistant', type: 'message', text: 'Processing...' } as const],
+					};
+					// Check if aborted and throw if so
+					if (abortSignalPassed?.aborted) {
+						throw new Error('Aborted');
+					}
+				}
+
+				workflowBuilderService.chat.mockImplementation((_payload, _user, signal) => {
+					abortSignalPassed = signal;
+					return testGenerator();
+				});
+
+				// Start the request (but don't await it)
+				const buildPromise = controller.build(request, response, payload);
+
+				// Wait a bit to ensure the generator is created and starts processing
+				await new Promise((resolve) => setTimeout(resolve, 50));
+
+				// Verify abort signal was passed to the service
+				expect(abortSignalPassed).toBeDefined();
+				expect(abortSignalPassed).toBeInstanceOf(AbortSignal);
+				expect(abortSignalPassed?.aborted).toBe(false);
+
+				// Verify close handler was registered
+				expect(response.on).toHaveBeenCalledWith('close', expect.any(Function));
+				expect(abortHandler).toBeDefined();
+
+				// Simulate connection close
+				abortHandler!();
+
+				// Verify the signal was aborted
+				expect(abortSignalPassed?.aborted).toBe(true);
+
+				// Wait for the promise to settle
+				await buildPromise.catch(() => {
+					// Expected to throw due to abort
+				});
+
+				// Verify response was ended
+				expect(response.end).toHaveBeenCalled();
+			});
+
+			it('should pass abort signal to workflow builder service', async () => {
+				let capturedSignal: AbortSignal | undefined;
+
+				async function* mockGenerator() {
+					yield { messages: [{ role: 'assistant', type: 'message', text: 'Test' } as const] };
+				}
+
+				workflowBuilderService.chat.mockImplementation((_payload, _user, signal) => {
+					capturedSignal = signal;
+					return mockGenerator();
+				});
+
+				await controller.build(request, response, payload);
+
+				expect(capturedSignal).toBeDefined();
+				expect(capturedSignal).toBeInstanceOf(AbortSignal);
+				expect(workflowBuilderService.chat).toHaveBeenCalledWith(
+					expect.any(Object),
+					request.user,
+					capturedSignal,
+				);
+			});
+
+			it('should handle stream interruption when connection closes', async () => {
+				let abortHandler: (() => void) | undefined;
+				let abortSignalPassed: AbortSignal | undefined;
+
+				response.on.mockImplementation((event: string, handler: () => void) => {
+					if (event === 'close') {
+						abortHandler = handler;
+					}
+					return response;
+				});
+
+				// Create a generator that yields multiple chunks
+				async function* mockChatGenerator() {
+					yield { messages: [{ role: 'assistant', type: 'message', text: 'Chunk 1' } as const] };
+
+					// Check if aborted before yielding next chunk
+					if (abortSignalPassed?.aborted) {
+						throw new Error('Aborted');
+					}
+
+					// This second chunk should not be reached if aborted
+					yield { messages: [{ role: 'assistant', type: 'message', text: 'Chunk 2' } as const] };
+				}
+
+				workflowBuilderService.chat.mockImplementation((_payload, _user, signal) => {
+					abortSignalPassed = signal;
+					return mockChatGenerator();
+				});
+
+				// Start the build process
+				const buildPromise = controller.build(request, response, payload);
+
+				// Wait for first chunk to be written
+				await new Promise((resolve) => setTimeout(resolve, 20));
+
+				// Should have written at least one chunk
+				expect(response.write).toHaveBeenCalled();
+				const writeCallsBeforeAbort = response.write.mock.calls.length;
+
+				// Simulate connection close
+				abortHandler!();
+
+				// Wait for the build to complete
+				await buildPromise.catch(() => {
+					// Expected to catch abort error
+				});
+
+				// Should not have written additional chunks after abort
+				expect(response.write).toHaveBeenCalledTimes(writeCallsBeforeAbort);
+				expect(response.end).toHaveBeenCalled();
+			});
+
+			it('should cleanup abort listener on successful completion', async () => {
+				const onSpy = jest.spyOn(response, 'on');
+				const offSpy = jest.spyOn(response, 'off');
+
+				async function* mockGenerator() {
+					yield { messages: [{ role: 'assistant', type: 'message', text: 'Complete' } as const] };
+				}
+
+				workflowBuilderService.chat.mockReturnValue(mockGenerator());
+
+				await controller.build(request, response, payload);
+
+				// Verify close handler was registered and then removed
+				expect(onSpy).toHaveBeenCalledWith('close', expect.any(Function));
+				expect(offSpy).toHaveBeenCalledWith('close', expect.any(Function));
+			});
+		});
 	});
 });

packages/cli/src/controllers/ai.controller.ts

@@ -46,6 +46,13 @@ export class AiController {
 		@Body payload: AiBuilderChatRequestDto,
 	) {
 		try {
+			const abortController = new AbortController();
+			const { signal } = abortController;
+
+			const handleClose = () => abortController.abort();
+
+			res.on('close', handleClose);
+
 			const { text, workflowContext } = payload.payload;
 			const aiResponse = this.workflowBuilderService.chat(
 				{
@@ -57,6 +64,7 @@ export class AiController {
 					},
 				},
 				req.user,
+				signal,
 			);
 
 			res.header('Content-type', 'application/json-lines').flush();
@@ -83,6 +91,9 @@ export class AiController {
 					],
 				};
 				res.write(JSON.stringify(errorChunk) + '⧉⇋⇋➽⌑⧉§§\n');
+			} finally {
+				// Clean up event listener
+				res.off('close', handleClose);
 			}
 
 			res.end();

packages/cli/src/services/ai-workflow-builder.service.ts

@@ -48,9 +48,9 @@ export class WorkflowBuilderService {
 		return this.service;
 	}
 
-	async *chat(payload: ChatPayload, user: IUser) {
+	async *chat(payload: ChatPayload, user: IUser, abortSignal?: AbortSignal) {
 		const service = await this.getService();
-		yield* service.chat(payload, user);
+		yield* service.chat(payload, user, abortSignal);
 	}
 
 	async getSessions(workflowId: string | undefined, user: IUser) {

packages/frontend/@n8n/design-system/src/components/AskAssistantChat/AskAssistantChat.vue

@@ -10,7 +10,6 @@ import AssistantText from '../AskAssistantText/AssistantText.vue';
 import InlineAskAssistantButton from '../InlineAskAssistantButton/InlineAskAssistantButton.vue';
 import N8nButton from '../N8nButton';
 import N8nIcon from '../N8nIcon';
-import N8nIconButton from '../N8nIconButton';
 
 const { t } = useI18n();
 
@@ -28,10 +27,12 @@ interface Props {
 	title?: string;
 	placeholder?: string;
 	scrollOnNewMessage?: boolean;
+	showStop?: boolean;
 }
 
 const emit = defineEmits<{
 	close: [];
+	stop: [];
 	message: [string, string?, boolean?];
 	codeReplace: [number];
 	codeUndo: [number];
@@ -253,11 +254,24 @@ watch(
 					@input.prevent="growInput"
 					@keydown.stop
 				/>
-				<N8nIconButton
-					:class="{ [$style.sendButton]: true }"
+				<N8nButton
+					v-if="showStop && streaming"
+					:class="$style.stopButton"
+					icon="square"
+					size="large"
+					type="danger"
+					outline
+					square
+					data-test-id="send-message-button"
+					@click="emit('stop')"
+				/>
+				<N8nButton
+					v-else
+					:class="$style.sendButton"
 					icon="send"
 					:text="true"
 					size="large"
+					square
 					data-test-id="send-message-button"
 					:disabled="sendDisabled"
 					@click="onSendMessage"
@@ -274,7 +288,9 @@ watch(
 	display: grid;
 	grid-template-rows: auto 1fr auto;
 }
-
+:root .stopButton {
+	--button-border-color: transparent;
+}
 .header {
 	height: 65px; // same as header height in editor
 	padding: 0 var(--spacing-l);

packages/frontend/@n8n/design-system/src/components/AskAssistantChat/__snapshots__/AskAssistantChat.test.ts.snap

@@ -171,15 +171,19 @@ exports[`AskAssistantChat > does not render retry button if no error is present
         rows="1"
         wrap="hard"
       />
-      <n8n-icon-button-stub
+      <n8n-button-stub
         active="false"
+        block="false"
         class="sendButton"
         data-test-id="send-message-button"
         disabled="true"
+        element="button"
         icon="send"
+        label=""
         loading="false"
         outline="false"
         size="large"
+        square="true"
         text="true"
         type="primary"
       />
@@ -988,15 +992,19 @@ Testing more code
         rows="1"
         wrap="hard"
       />
-      <n8n-icon-button-stub
+      <n8n-button-stub
         active="false"
+        block="false"
         class="sendButton"
         data-test-id="send-message-button"
         disabled="true"
+        element="button"
         icon="send"
+        label=""
         loading="false"
         outline="false"
         size="large"
+        square="true"
         text="true"
         type="primary"
       />
@@ -1169,15 +1177,19 @@ exports[`AskAssistantChat > renders default placeholder chat correctly 1`] = `
         rows="1"
         wrap="hard"
       />
-      <n8n-icon-button-stub
+      <n8n-button-stub
         active="false"
+        block="false"
         class="sendButton"
         data-test-id="send-message-button"
         disabled="true"
+        element="button"
         icon="send"
+        label=""
         loading="false"
         outline="false"
         size="large"
+        square="true"
         text="true"
         type="primary"
       />
@@ -1438,15 +1450,19 @@ exports[`AskAssistantChat > renders end of session chat correctly 1`] = `
         rows="1"
         wrap="hard"
       />
-      <n8n-icon-button-stub
+      <n8n-button-stub
         active="false"
+        block="false"
         class="sendButton"
         data-test-id="send-message-button"
         disabled="true"
+        element="button"
         icon="send"
+        label=""
         loading="false"
         outline="false"
         size="large"
+        square="true"
         text="true"
         type="primary"
       />
@@ -1641,15 +1657,19 @@ exports[`AskAssistantChat > renders error message correctly with retry button 1`
         rows="1"
         wrap="hard"
       />
-      <n8n-icon-button-stub
+      <n8n-button-stub
         active="false"
+        block="false"
         class="sendButton"
         data-test-id="send-message-button"
         disabled="true"
+        element="button"
         icon="send"
+        label=""
         loading="false"
         outline="false"
         size="large"
+        square="true"
         text="true"
         type="primary"
       />
@@ -1900,15 +1920,19 @@ catch(e) {
         rows="1"
         wrap="hard"
       />
-      <n8n-icon-button-stub
+      <n8n-button-stub
         active="false"
+        block="false"
         class="sendButton"
         data-test-id="send-message-button"
         disabled="true"
+        element="button"
         icon="send"
+        label=""
         loading="false"
         outline="false"
         size="large"
+        square="true"
         text="true"
         type="primary"
       />
@@ -2092,15 +2116,19 @@ exports[`AskAssistantChat > renders streaming chat correctly 1`] = `
         rows="1"
         wrap="hard"
       />
-      <n8n-icon-button-stub
+      <n8n-button-stub
         active="false"
+        block="false"
         class="sendButton"
         data-test-id="send-message-button"
         disabled="true"
+        element="button"
         icon="send"
+        label=""
         loading="false"
         outline="false"
         size="large"
+        square="true"
         text="true"
         type="primary"
       />

packages/frontend/@n8n/design-system/src/components/CanvasThinkingPill/CanvasThinkingPill.vue

@@ -3,11 +3,20 @@ import { useCssModule } from 'vue';
 
 import { useI18n } from '../../composables/useI18n';
 import AssistantIcon from '../AskAssistantIcon/AssistantIcon.vue';
+import N8nButton from '../N8nButton';
 
 defineOptions({
 	name: 'CanvasThinkingPill',
 });
 
+defineProps<{
+	showStop?: boolean;
+}>();
+
+const emit = defineEmits<{
+	stop: [];
+}>();
+
 const { t } = useI18n();
 const $style = useCssModule();
 </script>
@@ -17,7 +26,17 @@ const $style = useCssModule();
 		<div :class="$style.iconWrapper">
 			<AssistantIcon theme="blank" />
 		</div>
-		<span :class="$style.text">{{ t('aiAssistant.builder.canvas.thinking') }}</span>
+		<span :class="$style.text"
+			>{{ t('aiAssistant.builder.canvas.thinking') }}
+			<N8nButton
+				v-if="showStop"
+				:class="$style.stopButton"
+				:label="'Stop'"
+				type="secondary"
+				size="mini"
+				@click="emit('stop')"
+			/>
+		</span>
 	</div>
 </template>
 
@@ -28,7 +47,7 @@ const $style = useCssModule();
 	padding: 0 var(--spacing-s) 0 var(--spacing-xs);
 	justify-content: center;
 	align-items: center;
-	gap: var(--spacing-3xs);
+	gap: var(--spacing-2xs);
 	border-radius: 22px;
 	border: 1px solid var(--prim-gray-740);
 	background: rgba(65, 66, 68, 0.92);
@@ -51,6 +70,9 @@ const $style = useCssModule();
 	justify-content: center;
 }
 
+.stopButton {
+	margin-left: var(--spacing-xs);
+}
 .text {
 	color: white;
 	font-size: var(--font-size-s);

packages/frontend/@n8n/design-system/src/components/CanvasThinkingPill/__snapshots__/CanvasThinkingPill.test.ts.snap

@@ -46,7 +46,8 @@ exports[`CanvasThinkingPill > renders canvas thinking pill correctly 1`] = `
     <span
       class="text"
     >
-      Working...
+      Working... 
+      <!--v-if-->
     </span>
   </div>
 </div>

packages/frontend/@n8n/i18n/src/locales/en.json

@@ -190,6 +190,7 @@
 	"aiAssistant.builder.canvasPrompt.cancelButton": "Cancel",
 	"aiAssistant.builder.canvasPrompt.startManually.title": "Start manually",
 	"aiAssistant.builder.canvasPrompt.startManually.subTitle": "Add the first node",
+	"aiAssistant.builder.streamAbortedMessage": "[Task aborted]",
 	"aiAssistant.assistant": "AI Assistant",
 	"aiAssistant.newSessionModal.title.part1": "Start new",
 	"aiAssistant.newSessionModal.title.part2": "session",

packages/frontend/@n8n/rest-api-client/src/utils.ts

@@ -219,6 +219,7 @@ export async function streamRequest<T extends object>(
 	onDone?: () => void,
 	onError?: (e: Error) => void,
 	separator = STREAM_SEPERATOR,
+	abortSignal?: AbortSignal,
 ): Promise<void> {
 	const headers: Record<string, string> = {
 		'browser-id': getBrowserId(),
@@ -229,6 +230,7 @@ export async function streamRequest<T extends object>(
 		method: 'POST',
 		credentials: 'include',
 		body: JSON.stringify(payload),
+		signal: abortSignal,
 	};
 	try {
 		const response = await fetch(`${context.baseUrl}${apiEndpoint}`, assistantRequest);

packages/frontend/editor-ui/src/api/ai.ts

@@ -13,6 +13,7 @@ export function chatWithBuilder(
 	onMessageUpdated: (data: ChatRequest.ResponsePayload) => void,
 	onDone: () => void,
 	onError: (e: Error) => void,
+	abortSignal?: AbortSignal,
 ): void {
 	void streamRequest<ChatRequest.ResponsePayload>(
 		ctx,
@@ -21,6 +22,8 @@ export function chatWithBuilder(
 		onMessageUpdated,
 		onDone,
 		onError,
+		undefined,
+		abortSignal,
 	);
 }
 

packages/frontend/editor-ui/src/components/AskAssistant/Agent/AskAssistantBuild.vue

@@ -132,11 +132,13 @@ watch(currentRoute, () => {
 			:loading-message="loadingMessage"
 			:mode="i18n.baseText('aiAssistant.builder.mode')"
 			:title="'n8n AI'"
+			:show-stop="true"
 			:scroll-on-new-message="true"
 			:placeholder="i18n.baseText('aiAssistant.builder.placeholder')"
 			@close="emit('close')"
 			@message="onUserMessage"
 			@feedback="onFeedback"
+			@stop="builderStore.stopStreaming"
 		>
 			<template #header>
 				<slot name="header" />

packages/frontend/editor-ui/src/components/canvas/elements/nodes/render-types/CanvasNodeAIPrompt.vue

@@ -30,6 +30,7 @@ const workflowSaver = useWorkflowSaving({ router });
 const prompt = ref('');
 const userEditedPrompt = ref(false);
 const isFocused = ref(false);
+const isLoading = ref(false);
 
 // Computed properties
 const hasContent = computed(() => prompt.value.trim().length > 0);
@@ -42,6 +43,7 @@ const suggestions = ref(WORKFLOW_SUGGESTIONS);
  */
 async function onSubmit() {
 	if (!hasContent.value || builderStore.streaming) return;
+	isLoading.value = true;
 
 	const isNewWorkflow = workflowsStore.isNewWorkflow;
 
@@ -52,6 +54,7 @@ async function onSubmit() {
 
 	// Here we need to await for chat to open and session to be loaded
 	await builderStore.openChat();
+	isLoading.value = false;
 	builderStore.sendChatMessage({ text: prompt.value, source: 'canvas' });
 }
 
@@ -120,7 +123,7 @@ function onAddNodeClick() {
 					name="aiBuilderPrompt"
 					:class="$style.formTextarea"
 					type="textarea"
-					:disabled="builderStore.streaming"
+					:disabled="isLoading || builderStore.streaming"
 					:placeholder="i18n.baseText('aiAssistant.builder.placeholder')"
 					:read-only="false"
 					:rows="15"
@@ -133,6 +136,7 @@ function onAddNodeClick() {
 					<n8n-button
 						native-type="submit"
 						:disabled="!hasContent || builderStore.streaming"
+						:loading="isLoading"
 						@keydown.enter="onSubmit"
 					>
 						{{ i18n.baseText('aiAssistant.builder.canvasPrompt.buildWorkflow') }}

packages/frontend/editor-ui/src/composables/useBuilderMessages.ts

@@ -262,6 +262,16 @@ export function useBuilderMessages() {
 		} as ChatUI.AssistantMessage;
 	}
 
+	function createAssistantMessage(content: string, id: string): ChatUI.AssistantMessage {
+		return {
+			id,
+			role: 'assistant',
+			type: 'text',
+			content,
+			read: true,
+		} as ChatUI.AssistantMessage;
+	}
+
 	function createErrorMessage(
 		content: string,
 		id: string,
@@ -346,6 +356,7 @@ export function useBuilderMessages() {
 	return {
 		processAssistantMessages,
 		createUserMessage,
+		createAssistantMessage,
 		createErrorMessage,
 		clearMessages,
 		addMessages,

packages/frontend/editor-ui/src/stores/builder.store.test.ts

@@ -1,3 +1,6 @@
+/* eslint-disable @typescript-eslint/no-unused-vars */
+/* eslint-disable @typescript-eslint/no-unsafe-call */
+/* eslint-disable @typescript-eslint/no-non-null-assertion */
 import { describe, it, expect, beforeEach, vi } from 'vitest';
 import { setActivePinia, createPinia } from 'pinia';
 import { ENABLED_VIEWS, useBuilderStore } from '@/stores/builder.store';
@@ -505,4 +508,205 @@ describe('AI Builder store', () => {
 			'I can help you build a workflow',
 		);
 	});
+
+	describe('Abort functionality', () => {
+		it('should create and manage abort controller', () => {
+			const builderStore = useBuilderStore();
+
+			// Initially no abort controller (might be undefined or null)
+			expect(builderStore.streamingAbortController).toBeFalsy();
+
+			// Start streaming creates abort controller
+			apiSpy.mockImplementationOnce((_ctx, _payload, onMessage, _onDone, _onError, _signal) => {
+				// Simulate successful start of streaming
+				setTimeout(() => {
+					onMessage({
+						messages: [
+							{
+								type: 'message',
+								role: 'assistant',
+								text: 'Processing...',
+							},
+						],
+						sessionId: 'test-session',
+					});
+				}, 0);
+			});
+
+			builderStore.sendChatMessage({ text: 'test' });
+			expect(builderStore.streamingAbortController).not.toBeNull();
+			expect(builderStore.streamingAbortController).toBeInstanceOf(AbortController);
+		});
+
+		it('should call abort on existing controller when stopStreaming is called', () => {
+			const builderStore = useBuilderStore();
+
+			// First start a request to create an abort controller
+			apiSpy.mockImplementationOnce(() => {});
+			builderStore.sendChatMessage({ text: 'test' });
+
+			// Verify controller was created
+			const controller = builderStore.streamingAbortController;
+			expect(controller).toBeInstanceOf(AbortController);
+
+			// Spy on the abort method
+			const abortSpy = vi.spyOn(controller!, 'abort');
+
+			// Call stopStreaming
+			builderStore.stopStreaming();
+
+			// Verify abort was called
+			expect(abortSpy).toHaveBeenCalled();
+			expect(builderStore.streamingAbortController).toBeNull();
+			expect(builderStore.streaming).toBe(false);
+		});
+
+		it('should handle AbortError gracefully', async () => {
+			const builderStore = useBuilderStore();
+
+			// Simulate an abort error
+			const abortError = new Error('AbortError');
+			abortError.name = 'AbortError';
+
+			apiSpy.mockImplementationOnce((_ctx, _payload, _onMessage, _onDone, onError) => {
+				onError(abortError);
+			});
+
+			builderStore.sendChatMessage({ text: 'test message' });
+			await vi.waitFor(() => expect(builderStore.chatMessages.length).toBe(2));
+
+			// Should have user message and aborted message
+			expect(builderStore.chatMessages[0].role).toBe('user');
+			expect(builderStore.chatMessages[1].role).toBe('assistant');
+			expect(builderStore.chatMessages[1].type).toBe('text');
+			expect((builderStore.chatMessages[1] as ChatUI.TextMessage).content).toBe('[Task aborted]');
+
+			// Verify streaming state was reset
+			expect(builderStore.streaming).toBe(false);
+			expect(builderStore.assistantThinkingMessage).toBeUndefined();
+		});
+
+		it('should abort previous request when sending new message', () => {
+			const builderStore = useBuilderStore();
+
+			// The current implementation prevents sending a new message while streaming
+			// by checking if streaming.value is true and returning early.
+			// Mock for first request - keep it pending
+			apiSpy.mockImplementationOnce((_ctx, _payload, onMessage, _onDone) => {
+				// Don't call onDone to keep streaming active
+				setTimeout(() => {
+					onMessage({
+						messages: [
+							{
+								type: 'message',
+								role: 'assistant',
+								text: 'Processing first message...',
+							},
+						],
+						sessionId: 'test-session',
+					});
+				}, 10);
+			});
+
+			// Start first request
+			builderStore.sendChatMessage({ text: 'first message' });
+
+			// Verify streaming is active and controller was created
+			expect(builderStore.streaming).toBe(true);
+			const firstController = builderStore.streamingAbortController;
+			expect(firstController).not.toBeNull();
+			expect(firstController).toBeInstanceOf(AbortController);
+
+			// Track if abort was called
+			const abortSpy = vi.spyOn(firstController!, 'abort');
+
+			// Try to send second message while streaming - it should be ignored
+			builderStore.sendChatMessage({ text: 'second message ignored' });
+
+			// Verify the abort was NOT called and controller is the same
+			expect(abortSpy).not.toHaveBeenCalled();
+			expect(builderStore.streamingAbortController).toBe(firstController);
+
+			// Now properly stop streaming first
+			builderStore.stopStreaming();
+
+			// Verify abort was called and controller was cleared
+			expect(abortSpy).toHaveBeenCalled();
+			expect(builderStore.streamingAbortController).toBeNull();
+			expect(builderStore.streaming).toBe(false);
+
+			// Mock for second request
+			apiSpy.mockImplementationOnce(() => {});
+
+			// Now we can send a new message
+			builderStore.sendChatMessage({ text: 'second message' });
+
+			// New controller should be created
+			const secondController = builderStore.streamingAbortController;
+			expect(secondController).not.toBe(firstController);
+			expect(secondController).not.toBeNull();
+			expect(secondController).toBeInstanceOf(AbortController);
+		});
+
+		it('should pass abort signal to API call', () => {
+			const builderStore = useBuilderStore();
+
+			// Mock the API to prevent actual network calls
+			apiSpy.mockImplementationOnce(() => {});
+
+			builderStore.sendChatMessage({ text: 'test' });
+
+			// Verify the API was called with correct parameters
+			expect(apiSpy).toHaveBeenCalled();
+			const callArgs = apiSpy.mock.calls[0];
+			expect(callArgs).toHaveLength(6); // Should have 6 arguments
+
+			const signal = callArgs[5]; // The 6th argument is the abort signal
+			expect(signal).toBeDefined();
+			expect(signal).toBeInstanceOf(AbortSignal);
+
+			// Check that it's the same signal from the controller
+			const controller = builderStore.streamingAbortController;
+			expect(controller).not.toBeNull();
+			expect(controller).toBeInstanceOf(AbortController);
+			expect(signal).toBe(controller!.signal);
+		});
+
+		it('should not create error message for aborted requests', async () => {
+			const builderStore = useBuilderStore();
+
+			// Track telemetry calls
+			const telemetryTrackSpy = vi.fn();
+			track.mockImplementation(telemetryTrackSpy);
+
+			// Simulate abort error
+			const abortError = new Error('AbortError');
+			abortError.name = 'AbortError';
+
+			apiSpy.mockImplementationOnce((_ctx, _payload, _onMessage, _onDone, onError) => {
+				// Call error handler immediately
+				onError(abortError);
+			});
+
+			// Clear messages before test
+			builderStore.chatMessages.length = 0;
+
+			builderStore.sendChatMessage({ text: 'test' });
+
+			// Wait for the error to be processed
+			await vi.waitFor(() => expect(builderStore.chatMessages.length).toBeGreaterThan(1));
+
+			// Should not track error for abort
+			expect(telemetryTrackSpy).not.toHaveBeenCalledWith(
+				'Workflow generation errored',
+				expect.anything(),
+			);
+
+			// Find the assistant messages (skip user message)
+			const assistantMessages = builderStore.chatMessages.filter((msg) => msg.role === 'assistant');
+			expect(assistantMessages).toHaveLength(1);
+			expect(assistantMessages[0].type).toBe('text');
+			expect((assistantMessages[0] as ChatUI.TextMessage).content).toBe('[Task aborted]');
+		});
+	});
 });

packages/frontend/editor-ui/src/stores/builder.store.ts

@@ -36,6 +36,7 @@ export const useBuilderStore = defineStore(STORES.BUILDER, () => {
 	const chatWindowOpen = ref<boolean>(false);
 	const streaming = ref<boolean>(false);
 	const assistantThinkingMessage = ref<string | undefined>();
+	const streamingAbortController = ref<AbortController | null>(null);
 
 	// Store dependencies
 	const settings = useSettingsStore();
@@ -51,6 +52,7 @@ export const useBuilderStore = defineStore(STORES.BUILDER, () => {
 	const {
 		processAssistantMessages,
 		createUserMessage,
+		createAssistantMessage,
 		createErrorMessage,
 		clearMessages,
 		mapAssistantMessageToUI,
@@ -151,6 +153,10 @@ export const useBuilderStore = defineStore(STORES.BUILDER, () => {
 
 	function stopStreaming() {
 		streaming.value = false;
+		if (streamingAbortController.value) {
+			streamingAbortController.value.abort();
+			streamingAbortController.value = null;
+		}
 	}
 
 	// Error handling
@@ -166,11 +172,19 @@ export const useBuilderStore = defineStore(STORES.BUILDER, () => {
 		stopStreaming();
 		assistantThinkingMessage.value = undefined;
 
+		if (e.name === 'AbortError') {
+			// Handle abort errors as they are expected when stopping streaming
+			const userMsg = createAssistantMessage('[Task aborted]', 'aborted-streaming');
+			chatMessages.value = [...chatMessages.value, userMsg];
+			return;
+		}
+
 		const errorMessage = createErrorMessage(
 			locale.baseText('aiAssistant.serviceError.message', { interpolate: { message: e.message } }),
 			id,
 			retry,
 		);
+
 		chatMessages.value = [...chatMessages.value, errorMessage];
 
 		telemetry.track('Workflow generation errored', {
@@ -247,6 +261,12 @@ export const useBuilderStore = defineStore(STORES.BUILDER, () => {
 		});
 		const retry = createRetryHandler(messageId, async () => sendChatMessage(options));
 
+		// Abort previous streaming request if any
+		if (streamingAbortController.value) {
+			streamingAbortController.value.abort();
+		}
+
+		streamingAbortController.value = new AbortController();
 		try {
 			chatWithBuilder(
 				rootStore.restApiContext,
@@ -269,6 +289,7 @@ export const useBuilderStore = defineStore(STORES.BUILDER, () => {
 				},
 				() => stopStreaming(),
 				(e) => handleServiceError(e, messageId, retry),
+				streamingAbortController.value?.signal,
 			);
 		} catch (e: unknown) {
 			handleServiceError(e, messageId, retry);
@@ -393,9 +414,11 @@ export const useBuilderStore = defineStore(STORES.BUILDER, () => {
 		toolMessages,
 		workflowMessages,
 		trackingSessionId,
+		streamingAbortController,
 
 		// Methods
 		updateWindowWidth,
+		stopStreaming,
 		closeChat,
 		openChat,
 		resetBuilderChat,

packages/frontend/editor-ui/src/views/NodeView.vue

@@ -2132,7 +2132,12 @@ onBeforeUnmount(() => {
 				{{ i18n.baseText('readOnlyEnv.cantEditOrRun') }}
 			</N8nCallout>
 
-			<CanvasThinkingPill v-if="builderStore.streaming" :class="$style.thinkingPill" />
+			<CanvasThinkingPill
+				v-if="builderStore.streaming"
+				:class="$style.thinkingPill"
+				show-stop
+				@stop="builderStore.stopStreaming"
+			/>
 
 			<Suspense>
 				<LazyNodeCreation

pnpm-lock.yaml

@@ -947,7 +947,7 @@ importers:
         version: 4.3.0
       '@getzep/zep-cloud':
         specifier: 1.0.12
-        version: 1.0.12(@langchain/core@0.3.61(@opentelemetry/api@1.9.0)(@opentelemetry/sdk-trace-base@1.30.1(@opentelemetry/api@1.9.0))(openai@5.8.1(ws@8.18.2)(zod@3.25.67)))(encoding@0.1.13)(langchain@0.3.29(685a0af47c92c1c99f5d7c1501acb3dd))
+        version: 1.0.12(@langchain/core@0.3.61(@opentelemetry/api@1.9.0)(@opentelemetry/sdk-trace-base@1.30.1(@opentelemetry/api@1.9.0))(openai@5.8.1(ws@8.18.2)(zod@3.25.67)))(encoding@0.1.13)(langchain@0.3.29(e83255224da9386305dfb90eaf104268))
       '@getzep/zep-js':
         specifier: 0.9.0
         version: 0.9.0
@@ -974,7 +974,7 @@ importers:
         version: 0.3.4(@langchain/core@0.3.61(@opentelemetry/api@1.9.0)(@opentelemetry/sdk-trace-base@1.30.1(@opentelemetry/api@1.9.0))(openai@5.8.1(ws@8.18.2)(zod@3.25.67)))(encoding@0.1.13)
       '@langchain/community':
         specifier: 'catalog:'
-        version: 0.3.47(d020f0fdc951e6780c547ab03e43240e)
+        version: 0.3.47(dc9073baf40e018f46d70486a38ca362)
       '@langchain/core':
         specifier: 'catalog:'
         version: 0.3.61(@opentelemetry/api@1.9.0)(@opentelemetry/sdk-trace-base@1.30.1(@opentelemetry/api@1.9.0))(openai@5.8.1(ws@8.18.2)(zod@3.25.67))
@@ -1091,7 +1091,7 @@ importers:
         version: 23.0.1
       langchain:
         specifier: 0.3.29
-        version: 0.3.29(685a0af47c92c1c99f5d7c1501acb3dd)
+        version: 0.3.29(e83255224da9386305dfb90eaf104268)
       lodash:
         specifier: 'catalog:'
         version: 4.17.21
@@ -18429,7 +18429,7 @@ snapshots:
       '@currents/commit-info': 1.0.1-beta.0
       async-retry: 1.3.3
       axios: 1.10.0(debug@4.4.1)
-      axios-retry: 4.5.0(axios@1.10.0)
+      axios-retry: 4.5.0(axios@1.10.0(debug@4.4.1))
       c12: 1.11.2(magicast@0.3.5)
       chalk: 4.1.2
       commander: 12.1.0
@@ -18732,7 +18732,7 @@ snapshots:
   '@gar/promisify@1.1.3':
     optional: true
 
-  '@getzep/zep-cloud@1.0.12(@langchain/core@0.3.61(@opentelemetry/api@1.9.0)(@opentelemetry/sdk-trace-base@1.30.1(@opentelemetry/api@1.9.0))(openai@5.8.1(ws@8.18.2)(zod@3.25.67)))(encoding@0.1.13)(langchain@0.3.29(685a0af47c92c1c99f5d7c1501acb3dd))':
+  '@getzep/zep-cloud@1.0.12(@langchain/core@0.3.61(@opentelemetry/api@1.9.0)(@opentelemetry/sdk-trace-base@1.30.1(@opentelemetry/api@1.9.0))(openai@5.8.1(ws@8.18.2)(zod@3.25.67)))(encoding@0.1.13)(langchain@0.3.29(e83255224da9386305dfb90eaf104268))':
     dependencies:
       form-data: 4.0.4
       node-fetch: 2.7.0(encoding@0.1.13)
@@ -18741,7 +18741,7 @@ snapshots:
       zod: 3.25.67
     optionalDependencies:
       '@langchain/core': 0.3.61(@opentelemetry/api@1.9.0)(@opentelemetry/sdk-trace-base@1.30.1(@opentelemetry/api@1.9.0))(openai@5.8.1(ws@8.18.2)(zod@3.25.67))
-      langchain: 0.3.29(685a0af47c92c1c99f5d7c1501acb3dd)
+      langchain: 0.3.29(e83255224da9386305dfb90eaf104268)
     transitivePeerDependencies:
       - encoding
 
@@ -19295,7 +19295,7 @@ snapshots:
       - aws-crt
       - encoding
 
-  '@langchain/community@0.3.47(d020f0fdc951e6780c547ab03e43240e)':
+  '@langchain/community@0.3.47(dc9073baf40e018f46d70486a38ca362)':
     dependencies:
       '@browserbasehq/stagehand': 1.9.0(@playwright/test@1.53.0)(deepmerge@4.3.1)(dotenv@16.5.0)(encoding@0.1.13)(openai@5.8.1(ws@8.18.2)(zod@3.25.67))(zod@3.25.67)
       '@ibm-cloud/watsonx-ai': 1.1.2
@@ -19307,7 +19307,7 @@ snapshots:
       flat: 5.0.2
       ibm-cloud-sdk-core: 5.3.2
       js-yaml: 4.1.0
-      langchain: 0.3.29(685a0af47c92c1c99f5d7c1501acb3dd)
+      langchain: 0.3.29(e83255224da9386305dfb90eaf104268)
       langsmith: 0.3.45(@opentelemetry/api@1.9.0)(@opentelemetry/sdk-trace-base@1.30.1(@opentelemetry/api@1.9.0))(openai@5.8.1(ws@8.18.2)(zod@3.25.67))
       openai: 5.8.1(ws@8.18.2)(zod@3.25.67)
       uuid: 10.0.0
@@ -19321,7 +19321,7 @@ snapshots:
       '@aws-sdk/credential-provider-node': 3.808.0
       '@azure/storage-blob': 12.26.0
       '@browserbasehq/sdk': 2.6.0(encoding@0.1.13)
-      '@getzep/zep-cloud': 1.0.12(@langchain/core@0.3.61(@opentelemetry/api@1.9.0)(@opentelemetry/sdk-trace-base@1.30.1(@opentelemetry/api@1.9.0))(openai@5.8.1(ws@8.18.2)(zod@3.25.67)))(encoding@0.1.13)(langchain@0.3.29(685a0af47c92c1c99f5d7c1501acb3dd))
+      '@getzep/zep-cloud': 1.0.12(@langchain/core@0.3.61(@opentelemetry/api@1.9.0)(@opentelemetry/sdk-trace-base@1.30.1(@opentelemetry/api@1.9.0))(openai@5.8.1(ws@8.18.2)(zod@3.25.67)))(encoding@0.1.13)(langchain@0.3.29(e83255224da9386305dfb90eaf104268))
       '@getzep/zep-js': 0.9.0
       '@google-ai/generativelanguage': 2.6.0(encoding@0.1.13)
       '@google-cloud/storage': 7.12.1(encoding@0.1.13)
@@ -23066,6 +23066,11 @@ snapshots:
 
   axe-core@4.7.2: {}
 
+  axios-retry@4.5.0(axios@1.10.0(debug@4.4.1)):
+    dependencies:
+      axios: 1.10.0(debug@4.4.1)
+      is-retry-allowed: 2.2.0
+
   axios-retry@4.5.0(axios@1.10.0):
     dependencies:
       axios: 1.10.0
@@ -25109,7 +25114,7 @@ snapshots:
 
   eslint-import-resolver-node@0.3.9:
     dependencies:
-      debug: 3.2.7(supports-color@8.1.1)
+      debug: 3.2.7(supports-color@5.5.0)
       is-core-module: 2.16.1
       resolve: 1.22.10
     transitivePeerDependencies:
@@ -25133,7 +25138,7 @@ snapshots:
 
   eslint-module-utils@2.12.1(@typescript-eslint/parser@8.35.0(eslint@9.29.0(jiti@1.21.7))(typescript@5.8.3))(eslint-import-resolver-node@0.3.9)(eslint-import-resolver-typescript@4.4.3)(eslint@9.29.0(jiti@1.21.7)):
     dependencies:
-      debug: 3.2.7(supports-color@8.1.1)
+      debug: 3.2.7(supports-color@5.5.0)
     optionalDependencies:
       '@typescript-eslint/parser': 8.35.0(eslint@9.29.0(jiti@1.21.7))(typescript@5.8.3)
       eslint: 9.29.0(jiti@1.21.7)
@@ -25172,7 +25177,7 @@ snapshots:
       array.prototype.findlastindex: 1.2.6
       array.prototype.flat: 1.3.3
       array.prototype.flatmap: 1.3.3
-      debug: 3.2.7(supports-color@8.1.1)
+      debug: 3.2.7(supports-color@5.5.0)
       doctrine: 2.1.0
       eslint: 9.29.0(jiti@1.21.7)
       eslint-import-resolver-node: 0.3.9
@@ -26109,7 +26114,7 @@ snapshots:
       array-parallel: 0.1.3
       array-series: 0.1.5
       cross-spawn: 7.0.6
-      debug: 3.2.7(supports-color@8.1.1)
+      debug: 3.2.7(supports-color@5.5.0)
     transitivePeerDependencies:
       - supports-color
 
@@ -26451,7 +26456,7 @@ snapshots:
       '@types/debug': 4.1.12
       '@types/node': 20.19.1
       '@types/tough-cookie': 4.0.5
-      axios: 1.10.0
+      axios: 1.10.0(debug@4.4.1)
       camelcase: 6.3.0
       debug: 4.4.1(supports-color@8.1.1)
       dotenv: 16.5.0
@@ -26461,7 +26466,7 @@ snapshots:
       isstream: 0.1.2
       jsonwebtoken: 9.0.2
       mime-types: 2.1.35
-      retry-axios: 2.6.0(axios@1.10.0(debug@4.4.1))
+      retry-axios: 2.6.0(axios@1.10.0)
       tough-cookie: 4.1.4
     transitivePeerDependencies:
       - supports-color
@@ -27675,7 +27680,7 @@ snapshots:
 
   kuler@2.0.0: {}
 
-  langchain@0.3.29(685a0af47c92c1c99f5d7c1501acb3dd):
+  langchain@0.3.29(e83255224da9386305dfb90eaf104268):
     dependencies:
       '@langchain/core': 0.3.61(@opentelemetry/api@1.9.0)(@opentelemetry/sdk-trace-base@1.30.1(@opentelemetry/api@1.9.0))(openai@5.8.1(ws@8.18.2)(zod@3.25.67))
       '@langchain/openai': 0.5.16(@langchain/core@0.3.61(@opentelemetry/api@1.9.0)(@opentelemetry/sdk-trace-base@1.30.1(@opentelemetry/api@1.9.0))(openai@5.8.1(ws@8.18.2)(zod@3.25.67)))(ws@8.18.2)
@@ -29446,7 +29451,7 @@ snapshots:
 
   pdf-parse@1.1.1:
     dependencies:
-      debug: 3.2.7(supports-color@8.1.1)
+      debug: 3.2.7(supports-color@5.5.0)
       node-ensure: 0.0.0
     transitivePeerDependencies:
       - supports-color
@@ -30389,7 +30394,7 @@ snapshots:
       onetime: 5.1.2
       signal-exit: 3.0.7
 
-  retry-axios@2.6.0(axios@1.10.0(debug@4.4.1)):
+  retry-axios@2.6.0(axios@1.10.0):
     dependencies:
       axios: 1.10.0
 
@@ -30416,7 +30421,7 @@ snapshots:
 
   rhea@1.0.24:
     dependencies:
-      debug: 3.2.7(supports-color@8.1.1)
+      debug: 3.2.7(supports-color@5.5.0)
     transitivePeerDependencies:
       - supports-color