fix(web): address PR review feedback for Nexus AI stop

Guard stream cleanup against Stop-then-Send races, remove dead cancelled
handler, tighten abort error detection, add stopped tool-call status, and
extend abort unit tests. Fixes #1615.

gitnexus-web/src/components/ToolCallCard.tsx

@@ -13,6 +13,7 @@ import {
   Check,
   Loader2,
   AlertCircle,
+  Square,
 } from '@/lib/lucide-icons';
 import type { ToolCallInfo } from '../core/llm/types';
 import type { TFunction } from 'i18next';
@@ -77,6 +78,13 @@ const getStatusDisplay = (status: ToolCallInfo['status']) => {
         bgColor: 'bg-rose-500/10',
         borderColor: 'border-rose-500/30',
       };
+    case 'stopped':
+      return {
+        icon: <Square className="h-3.5 w-3.5 fill-current" />,
+        color: 'text-amber-300',
+        bgColor: 'bg-amber-500/10',
+        borderColor: 'border-amber-500/30',
+      };
     default:
       return {
         icon: <Sparkles className="h-3.5 w-3.5" />,

gitnexus-web/src/core/llm/agent.ts

@@ -367,11 +367,11 @@ export interface AgentRuntimeOptions {
   signal?: AbortSignal;
 }
 
-const isAbortError = (error: unknown): boolean => {
+const isAbortError = (error: unknown, signal?: AbortSignal): boolean => {
+  if (signal?.aborted) return true;
   if (error instanceof DOMException && error.name === 'AbortError') return true;
   if (error instanceof Error && error.name === 'AbortError') return true;
-  const message = error instanceof Error ? error.message : String(error);
-  return /aborted|abort/i.test(message);
+  return false;
 };
 
 export const buildLangChainMessages = (messages: AgentMessage[]): BaseMessage[] =>
@@ -662,7 +662,7 @@ export async function* streamAgentResponse(
           : undefined,
     };
   } catch (error) {
-    if (options.signal?.aborted || isAbortError(error)) {
+    if (isAbortError(error, options.signal)) {
       yield { type: 'cancelled' };
       return;
     }

gitnexus-web/src/core/llm/types.ts

@@ -254,7 +254,7 @@ export interface ToolCallInfo {
   name: string;
   args: Record<string, unknown>;
   result?: string;
-  status: 'pending' | 'running' | 'completed' | 'error';
+  status: 'pending' | 'running' | 'completed' | 'error' | 'stopped';
 }
 
 /**

gitnexus-web/src/hooks/useAppState.tsx

@@ -1017,39 +1017,6 @@ const AppStateProviderInner = ({ children }: { children: ReactNode }) => {
               // Finalize the assistant message - just call updateMessage one more time
               scheduleMessageUpdate();
               break;
-
-            case 'cancelled': {
-              const stoppedLabel = i18n.t('chat:stopped');
-              for (let i = 0; i < toolCallsForMessage.length; i++) {
-                const tc = toolCallsForMessage[i];
-                if (tc.status === 'running' || tc.status === 'pending') {
-                  toolCallsForMessage[i] = {
-                    ...tc,
-                    status: 'error',
-                    result: stoppedLabel,
-                  };
-                }
-              }
-              for (let i = 0; i < stepsForMessage.length; i++) {
-                const step = stepsForMessage[i];
-                if (
-                  step.type === 'tool_call' &&
-                  step.toolCall &&
-                  (step.toolCall.status === 'running' || step.toolCall.status === 'pending')
-                ) {
-                  stepsForMessage[i] = {
-                    ...step,
-                    toolCall: {
-                      ...step.toolCall,
-                      status: 'error',
-                      result: stoppedLabel,
-                    },
-                  };
-                }
-              }
-              scheduleMessageUpdate();
-              break;
-            }
           }
         };
 
@@ -1062,9 +1029,6 @@ const AppStateProviderInner = ({ children }: { children: ReactNode }) => {
           captureHistory: providerCapabilities.preserveAssistantTranscript,
           signal: chatAbortController.signal,
         })) {
-          if (chatAbortController.signal.aborted) {
-            break;
-          }
           onChunk(chunk);
           if (chunk.type === 'cancelled') {
             break;
@@ -1078,9 +1042,13 @@ const AppStateProviderInner = ({ children }: { children: ReactNode }) => {
       } finally {
         if (chatAbortRef.current === chatAbortController) {
           chatAbortRef.current = null;
+          setIsChatLoading(false);
+          setCurrentToolCalls([]);
+        } else if (!chatAbortRef.current) {
+          // Stopped with no new turn started — safe to clear loading UI
+          setIsChatLoading(false);
+          setCurrentToolCalls([]);
         }
-        setIsChatLoading(false);
-        setCurrentToolCalls([]);
       }
     },
     [
@@ -1105,13 +1073,12 @@ const AppStateProviderInner = ({ children }: { children: ReactNode }) => {
     chatAbortRef.current = null;
 
     const stoppedLabel = i18n.t('chat:stopped');
-    setCurrentToolCalls((prev) =>
-      prev.map((tc) =>
-        tc.status === 'running' || tc.status === 'pending'
-          ? { ...tc, status: 'error', result: stoppedLabel }
-          : tc,
-      ),
-    );
+    const markStoppedToolCall = (tc: ToolCallInfo): ToolCallInfo =>
+      tc.status === 'running' || tc.status === 'pending'
+        ? { ...tc, status: 'stopped', result: stoppedLabel }
+        : tc;
+
+    setCurrentToolCalls((prev) => prev.map(markStoppedToolCall));
 
     setChatMessages((prev) => {
       const lastAssistantIdx = [...prev]
@@ -1121,10 +1088,7 @@ const AppStateProviderInner = ({ children }: { children: ReactNode }) => {
       if (lastAssistantIdx === undefined) return prev;
 
       const message = prev[lastAssistantIdx];
-      const markStopped = (tc: ToolCallInfo): ToolCallInfo =>
-        tc.status === 'running' || tc.status === 'pending'
-          ? { ...tc, status: 'error', result: stoppedLabel }
-          : tc;
+      const markStopped = markStoppedToolCall;
 
       const updated: ChatMessage = {
         ...message,

gitnexus-web/src/locales/en/graph.json

@@ -10,7 +10,8 @@
     "status": {
       "running": "running",
       "completed": "completed",
-      "error": "error"
+      "error": "error",
+      "stopped": "stopped"
     },
     "tools": {
       "search": "🔍 Search Code",

gitnexus-web/src/locales/zh-CN/graph.json

@@ -10,7 +10,8 @@
     "status": {
       "running": "运行中",
       "completed": "已完成",
-      "error": "错误"
+      "error": "错误",
+      "stopped": "已停止"
     },
     "tools": {
       "search": "🔍 搜索代码",

gitnexus-web/test/unit/agent-abort.test.ts

@@ -27,7 +27,6 @@ describe('streamAgentResponse abort', () => {
       stream: async function* () {
         yield ['values', { messages: [] }];
         controller.abort();
-        // Simulate a long-running graph step after abort
         for (let i = 0; i < 100; i++) {
           yield ['messages', [{ _getType: () => 'ai', content: 'still going' }]];
         }
@@ -45,4 +44,41 @@ describe('streamAgentResponse abort', () => {
     expect(chunks.some((c) => c.type === 'cancelled')).toBe(true);
     expect(chunks.some((c) => c.type === 'error')).toBe(false);
   });
+
+  it('passes AbortSignal to agent.stream config', async () => {
+    const controller = new AbortController();
+    let capturedConfig: Record<string, unknown> | undefined;
+
+    const agent = {
+      stream: async (_input: unknown, config: Record<string, unknown>) => {
+        capturedConfig = config;
+        throw new DOMException('aborted', 'AbortError');
+      },
+    };
+
+    for await (const _chunk of streamAgentResponse(agent as any, userMessage, {
+      signal: controller.signal,
+    })) {
+      // drain
+    }
+
+    expect(capturedConfig?.signal).toBe(controller.signal);
+  });
+
+  it('does not treat unrelated errors mentioning abort as cancellation', async () => {
+    const agent = {
+      stream: async () => {
+        throw new Error('Cannot abort the current transaction');
+      },
+    };
+
+    const chunks = [];
+    for await (const chunk of streamAgentResponse(agent as any, userMessage)) {
+      chunks.push(chunk);
+    }
+
+    expect(chunks).toEqual([
+      { type: 'error', error: 'Cannot abort the current transaction' },
+    ]);
+  });
 });