feat: add stop execution with hybrid graceful/force abort

Implement a stop execution feature that allows users to abort ongoing LLM
streaming, kill running tool calls, and clear pending permission/human input
requests. Uses a hybrid approach: first click sends graceful SIGTERM, second
click within 2s sends SIGKILL and force-closes MCP clients.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/x/apps/main/src/ipc.ts

@@ -295,7 +295,7 @@ export function setupIpcHandlers() {
       return { success: true };
     },
     'runs:stop': async (_event, args) => {
-      await runsCore.stop(args.runId);
+      await runsCore.stop(args.runId, args.force);
       return { success: true };
     },
     'runs:fetch': async (_event, args) => {

apps/x/apps/renderer/src/App.tsx

@@ -6,7 +6,7 @@ import type { LanguageModelUsage, ToolUIPart } from 'ai';
 import './App.css'
 import z from 'zod';
 import { Button } from './components/ui/button';
-import { CheckIcon, LoaderIcon, ArrowUp, PanelRightIcon, SquarePen } from 'lucide-react';
+import { CheckIcon, LoaderIcon, ArrowUp, PanelRightIcon, SquarePen, Square } from 'lucide-react';
 import { cn } from '@/lib/utils';
 import { MarkdownEditor } from './components/markdown-editor';
 import { ChatInputBar } from './components/chat-button';
@@ -279,7 +279,9 @@ const collectFilePaths = (nodes: TreeNode[]): string[] =>
 // Inner component that uses the controller to access mentions
 interface ChatInputInnerProps {
   onSubmit: (message: PromptInputMessage, mentions?: FileMention[]) => void
+  onStop?: () => void
   isProcessing: boolean
+  isStopping?: boolean
   presetMessage?: string
   onPresetMessageConsumed?: () => void
   runId?: string | null
@@ -287,7 +289,9 @@ interface ChatInputInnerProps {
 
 function ChatInputInner({
   onSubmit,
+  onStop,
   isProcessing,
+  isStopping,
   presetMessage,
   onPresetMessageConsumed,
   runId,
@@ -327,19 +331,39 @@ function ChatInputInner({
         focusTrigger={runId}
         className="min-h-6 py-0 border-0 shadow-none focus-visible:ring-0 rounded-none"
       />
-      <Button
-        size="icon"
-        onClick={handleSubmit}
-        disabled={!canSubmit}
-        className={cn(
-          "h-7 w-7 rounded-full shrink-0 transition-all",
-          canSubmit
-            ? "bg-primary text-primary-foreground hover:bg-primary/90"
-            : "bg-muted text-muted-foreground"
-        )}
-      >
-        <ArrowUp className="h-4 w-4" />
-      </Button>
+      {isProcessing ? (
+        <Button
+          size="icon"
+          onClick={onStop}
+          title={isStopping ? "Click again to force stop" : "Stop generation"}
+          className={cn(
+            "h-7 w-7 rounded-full shrink-0 transition-all",
+            isStopping
+              ? "bg-destructive text-destructive-foreground hover:bg-destructive/90"
+              : "bg-primary text-primary-foreground hover:bg-primary/90"
+          )}
+        >
+          {isStopping ? (
+            <LoaderIcon className="h-4 w-4 animate-spin" />
+          ) : (
+            <Square className="h-3 w-3 fill-current" />
+          )}
+        </Button>
+      ) : (
+        <Button
+          size="icon"
+          onClick={handleSubmit}
+          disabled={!canSubmit}
+          className={cn(
+            "h-7 w-7 rounded-full shrink-0 transition-all",
+            canSubmit
+              ? "bg-primary text-primary-foreground hover:bg-primary/90"
+              : "bg-muted text-muted-foreground"
+          )}
+        >
+          <ArrowUp className="h-4 w-4" />
+        </Button>
+      )}
     </div>
   )
 }
@@ -350,7 +374,9 @@ interface ChatInputWithMentionsProps {
   recentFiles: string[]
   visibleFiles: string[]
   onSubmit: (message: PromptInputMessage, mentions?: FileMention[]) => void
+  onStop?: () => void
   isProcessing: boolean
+  isStopping?: boolean
   presetMessage?: string
   onPresetMessageConsumed?: () => void
   runId?: string | null
@@ -361,7 +387,9 @@ function ChatInputWithMentions({
   recentFiles,
   visibleFiles,
   onSubmit,
+  onStop,
   isProcessing,
+  isStopping,
   presetMessage,
   onPresetMessageConsumed,
   runId,
@@ -370,7 +398,9 @@ function ChatInputWithMentions({
     <PromptInputProvider knowledgeFiles={knowledgeFiles} recentFiles={recentFiles} visibleFiles={visibleFiles}>
       <ChatInputInner
         onSubmit={onSubmit}
+        onStop={onStop}
         isProcessing={isProcessing}
+        isStopping={isStopping}
         presetMessage={presetMessage}
         onPresetMessageConsumed={onPresetMessageConsumed}
         runId={runId}
@@ -414,6 +444,8 @@ function App() {
   const [runId, setRunId] = useState<string | null>(null)
   const runIdRef = useRef<string | null>(null)
   const [isProcessing, setIsProcessing] = useState(false)
+  const [isStopping, setIsStopping] = useState(false)
+  const [stopClickedAt, setStopClickedAt] = useState<number | null>(null)
   const [agentId] = useState<string>('copilot')
   const [presetMessage, setPresetMessage] = useState<string | undefined>(undefined)
 
@@ -758,6 +790,8 @@ function App() {
 
       case 'run-processing-end':
         setIsProcessing(false)
+        setIsStopping(false)
+        setStopClickedAt(null)
         break
 
       case 'start':
@@ -936,8 +970,32 @@ function App() {
         break
       }
 
+      case 'run-stopped':
+        setIsProcessing(false)
+        setIsStopping(false)
+        setStopClickedAt(null)
+        // Clear pending requests since they've been aborted
+        setPendingPermissionRequests(new Map())
+        setPendingAskHumanRequests(new Map())
+        // Flush any streaming content as a message
+        setCurrentAssistantMessage(currentMsg => {
+          if (currentMsg) {
+            setConversation(prev => [...prev, {
+              id: `assistant-stopped-${Date.now()}`,
+              role: 'assistant',
+              content: currentMsg,
+              timestamp: Date.now(),
+            }])
+          }
+          return ''
+        })
+        setCurrentReasoning('')
+        break
+
       case 'error':
         setIsProcessing(false)
+        setIsStopping(false)
+        setStopClickedAt(null)
         console.error('Run error:', event.error)
         break
     }
@@ -1009,6 +1067,21 @@ function App() {
     }
   }
 
+  const handleStop = useCallback(async () => {
+    if (!runId) return
+    const now = Date.now()
+    const isForce = isStopping && stopClickedAt !== null && (now - stopClickedAt) < 2000
+
+    setStopClickedAt(now)
+    setIsStopping(true)
+
+    try {
+      await window.ipc.invoke('runs:stop', { runId, force: isForce })
+    } catch (error) {
+      console.error('Failed to stop run:', error)
+    }
+  }, [runId, isStopping, stopClickedAt])
+
   const handlePermissionResponse = useCallback(async (toolCallId: string, subflow: string[], response: 'approve' | 'deny') => {
     if (!runId) return
     
@@ -1779,7 +1852,9 @@ function App() {
                       recentFiles={recentWikiFiles}
                       visibleFiles={visibleKnowledgeFiles}
                       onSubmit={handlePromptSubmit}
+                      onStop={handleStop}
                       isProcessing={isProcessing}
+                      isStopping={isStopping}
                       presetMessage={presetMessage}
                       onPresetMessageConsumed={() => setPresetMessage(undefined)}
                       runId={runId}
@@ -1801,6 +1876,8 @@ function App() {
                 currentAssistantMessage={currentAssistantMessage}
                 currentReasoning={currentReasoning}
                 isProcessing={isProcessing}
+                isStopping={isStopping}
+                onStop={handleStop}
                 message={message}
                 onMessageChange={setMessage}
                 onSubmit={handlePromptSubmit}

apps/x/apps/renderer/src/components/chat-sidebar.tsx

@@ -1,5 +1,5 @@
 import { useCallback, useEffect, useMemo, useRef, useState } from 'react'
-import { ArrowUp, Expand, Plus } from 'lucide-react'
+import { ArrowUp, Expand, LoaderIcon, Plus, Square } from 'lucide-react'
 import type { ToolUIPart } from 'ai'
 import { Button } from '@/components/ui/button'
 import { cn } from '@/lib/utils'
@@ -115,6 +115,8 @@ interface ChatSidebarProps {
   currentAssistantMessage: string
   currentReasoning: string
   isProcessing: boolean
+  isStopping?: boolean
+  onStop?: () => void
   message: string
   onMessageChange: (message: string) => void
   onSubmit: (message: PromptInputMessage, mentions?: FileMention[]) => void
@@ -139,6 +141,8 @@ export function ChatSidebar({
   currentAssistantMessage,
   currentReasoning,
   isProcessing,
+  isStopping,
+  onStop,
   message,
   onMessageChange,
   onSubmit,
@@ -595,19 +599,39 @@ export function ChatSidebar({
                 style={{ fieldSizing: 'content' } as React.CSSProperties}
               />
             </div>
-            <Button
-              size="icon"
-              onClick={handleSubmit}
-              disabled={!canSubmit}
-              className={cn(
-                "h-7 w-7 rounded-full shrink-0 transition-all",
-                canSubmit
-                  ? "bg-primary text-primary-foreground hover:bg-primary/90"
-                  : "bg-muted text-muted-foreground"
-              )}
-            >
-              <ArrowUp className="h-4 w-4" />
-            </Button>
+            {isProcessing ? (
+              <Button
+                size="icon"
+                onClick={onStop}
+                title={isStopping ? "Click again to force stop" : "Stop generation"}
+                className={cn(
+                  "h-7 w-7 rounded-full shrink-0 transition-all",
+                  isStopping
+                    ? "bg-destructive text-destructive-foreground hover:bg-destructive/90"
+                    : "bg-primary text-primary-foreground hover:bg-primary/90"
+                )}
+              >
+                {isStopping ? (
+                  <LoaderIcon className="h-4 w-4 animate-spin" />
+                ) : (
+                  <Square className="h-3 w-3 fill-current" />
+                )}
+              </Button>
+            ) : (
+              <Button
+                size="icon"
+                onClick={handleSubmit}
+                disabled={!canSubmit}
+                className={cn(
+                  "h-7 w-7 rounded-full shrink-0 transition-all",
+                  canSubmit
+                    ? "bg-primary text-primary-foreground hover:bg-primary/90"
+                    : "bg-muted text-muted-foreground"
+                )}
+              >
+                <ArrowUp className="h-4 w-4" />
+              </Button>
+            )}
           </div>
           {knowledgeFiles.length > 0 && (
             <MentionPopover