fix(frontend): make the dashboard build pass again (26 type errors since April)

The frontend build gate added on 2026-09-23 (166091b) has failed on every
main run since: five April PRs left code that never compiled — imports of
shadcn components that were never added (ui/alert, ui/textarea), seven
example widgets that never existed (CustomElementHost), react-router-dom
(not a dependency), a useSSE call written for a different hook, a wrong
ChatMessages prop set, and unused locals under noUnusedLocals.

- add the standard shadcn alert and textarea components
- CustomElementHost: empty registry instead of imports of missing widgets
- useWindowMessage: small local EventSource hook for /sse/window-message
- SharedThread: read the token from /shared/{token}; pass the props
  ChatMessages takes; type messages as ChatMessage[]
- drop unused imports/locals

None of these files are imported by the app today, so nothing users see
changes; the gate now builds and catches real breakage again.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

src/frontend/src/chat/ActionButtons.tsx

@@ -38,7 +38,7 @@ interface ActionButtonsProps {
  */
 export function ActionButtons({ actions, messageId, sessionId }: ActionButtonsProps) {
     const [pendingActions, setPendingActions] = useState<Set<string>>(new Set())
-    const [hiddenActions, setHiddenActions] = useState<Set<string>>(new Set())
+    const [hiddenActions] = useState<Set<string>>(new Set())
 
     const handleActionClick = useCallback(async (action: ActionButton) => {
         if (pendingActions.has(action.id) || hiddenActions.has(action.id)) {

src/frontend/src/chat/AskActionPrompt.tsx

@@ -73,7 +73,7 @@ export function AskActionPrompt({
 
             {/* Action buttons */}
             <div className="space-y-3">
-                {actions.map((action, index) => (
+                {actions.map((action) => (
                     <button
                         key={action.name}
                         type="button"

src/frontend/src/chat/ChatSettingsPanel.tsx

@@ -15,7 +15,7 @@ import { Textarea } from '../components/ui/textarea';
 import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from '../components/ui/select';
 import { Slider } from '../components/ui/slider';
 import { Switch } from '../components/ui/switch';
-import { Card, CardContent, CardHeader, CardTitle, CardDescription } from '../components/ui/card';
+import { Card, CardContent } from '../components/ui/card';
 import { Sheet, SheetContent, SheetHeader, SheetTitle, SheetDescription } from '../components/ui/sheet';
 
 interface SettingsWidget {
@@ -74,7 +74,7 @@ const WidgetRenderer: React.FC<{
               id={name}
               placeholder={placeholder}
               value={value || ''}
-              onChange={(e) => onChange(e.target.value)}
+              onChange={(e: React.ChangeEvent<HTMLTextAreaElement>) => onChange(e.target.value)}
               maxLength={widget.maxLength}
               rows={4}
             />

src/frontend/src/chat/CustomElementHost.tsx

@@ -20,43 +20,16 @@ interface CustomElementProps {
   onError?: (error: Error) => void;
 }
 
-interface CustomComponentModule {
-  default: React.ComponentType<any>;
-}
-
 // Registry of loaded components (cache)
 const componentCache = new Map<string, Promise<React.ComponentType<any>>>();
 
-// List of available custom components (in practice, this would be populated from backend)
-const availableComponents = new Set([
-  'ExampleWidget',
-  'UserCard',
-  'DataChart', 
-  'FormBuilder',
-  'CodeEditor',
-  'ImageGallery',
-  'ChatEmbed'
-]);
-
-// Static imports for build-tool compatibility
-const ExampleWidget = React.lazy(() => import('../components/custom/ExampleWidget'));
-const UserCard = React.lazy(() => import('../components/custom/UserCard'));
-const DataChart = React.lazy(() => import('../components/custom/DataChart'));
-const FormBuilder = React.lazy(() => import('../components/custom/FormBuilder'));
-const CodeEditor = React.lazy(() => import('../components/custom/CodeEditor'));
-const ImageGallery = React.lazy(() => import('../components/custom/ImageGallery'));
-const ChatEmbed = React.lazy(() => import('../components/custom/ChatEmbed'));
-
-// Static mapping of component names to imports
-const componentMap: Record<string, React.ComponentType<any>> = {
-  ExampleWidget,
-  UserCard,
-  DataChart,
-  FormBuilder,
-  CodeEditor,
-  ImageGallery,
-  ChatEmbed,
-};
+// Custom components available to <CustomElementHost name="..." />. The example
+// widgets this once listed (ExampleWidget, UserCard, ...) were never added, and
+// importing them broke the build. Register real components here as they land:
+//   const MyWidget = React.lazy(() => import('../components/custom/MyWidget'));
+//   componentMap.MyWidget = MyWidget;
+const componentMap: Record<string, React.ComponentType<any>> = {};
+const availableComponents = new Set(Object.keys(componentMap));
 
 /**
  * Load a custom component with static mapping for build-tool compatibility

src/frontend/src/chat/TaskSidebar.tsx

@@ -4,7 +4,6 @@
  * Shows live-updating task lists with states, progress bars, and click-to-jump functionality.
  */
 
-import React from 'react'
 import { ChevronRight, ChevronDown, CheckCircle, Clock, XCircle, Circle, ExternalLink } from 'lucide-react'
 import { useTaskState, setTasksCollapsed, type Task, type TaskList, type TaskStatus } from '../state/tasks'
 import { cn } from '../lib/utils'

src/frontend/src/components/ui/alert.tsx

@@ -0,0 +1,44 @@
+import * as React from "react"
+import { cva, type VariantProps } from "class-variance-authority"
+
+import { cn } from "@/lib/utils"
+
+const alertVariants = cva(
+  "relative w-full rounded-lg border px-4 py-3 text-sm [&>svg+div]:translate-y-[-3px] [&>svg]:absolute [&>svg]:left-4 [&>svg]:top-4 [&>svg]:text-foreground [&>svg~*]:pl-7",
+  {
+    variants: {
+      variant: {
+        default: "bg-background text-foreground",
+        destructive:
+          "border-destructive/50 text-destructive dark:border-destructive [&>svg]:text-destructive",
+      },
+    },
+    defaultVariants: {
+      variant: "default",
+    },
+  }
+)
+
+const Alert = React.forwardRef<
+  HTMLDivElement,
+  React.HTMLAttributes<HTMLDivElement> & VariantProps<typeof alertVariants>
+>(({ className, variant, ...props }, ref) => (
+  <div ref={ref} role="alert" className={cn(alertVariants({ variant }), className)} {...props} />
+))
+Alert.displayName = "Alert"
+
+const AlertTitle = React.forwardRef<HTMLParagraphElement, React.HTMLAttributes<HTMLHeadingElement>>(
+  ({ className, ...props }, ref) => (
+    <h5 ref={ref} className={cn("mb-1 font-medium leading-none tracking-tight", className)} {...props} />
+  )
+)
+AlertTitle.displayName = "AlertTitle"
+
+const AlertDescription = React.forwardRef<HTMLParagraphElement, React.HTMLAttributes<HTMLParagraphElement>>(
+  ({ className, ...props }, ref) => (
+    <div ref={ref} className={cn("text-sm [&_p]:leading-relaxed", className)} {...props} />
+  )
+)
+AlertDescription.displayName = "AlertDescription"
+
+export { Alert, AlertTitle, AlertDescription }

src/frontend/src/components/ui/textarea.tsx

@@ -0,0 +1,19 @@
+import * as React from "react"
+
+import { cn } from "@/lib/utils"
+
+const Textarea = React.forwardRef<HTMLTextAreaElement, React.ComponentProps<"textarea">>(
+  ({ className, ...props }, ref) => (
+    <textarea
+      className={cn(
+        "flex min-h-[60px] w-full rounded-md border border-input bg-transparent px-3 py-2 text-base shadow-sm placeholder:text-muted-foreground focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-ring disabled:cursor-not-allowed disabled:opacity-50 md:text-sm",
+        className
+      )}
+      ref={ref}
+      {...props}
+    />
+  )
+)
+Textarea.displayName = "Textarea"
+
+export { Textarea }

src/frontend/src/hooks/useMicStream.ts

@@ -183,7 +183,7 @@ export function useMicStream(options: UseMicStreamOptions = {}): UseMicStreamRet
       onConnectionChangeRef.current?.(false);
     };
     
-    ws.onerror = (error) => {
+    ws.onerror = () => {
       onErrorRef.current?.(new Error('WebSocket error'));
       setConnected(false);
       onConnectionChangeRef.current?.(false);

src/frontend/src/hooks/useWindowMessage.ts

@@ -5,8 +5,33 @@
  * incoming messages from parent.
  */
 
-import { useEffect, useCallback, useRef } from 'react';
-import { useSSE } from './useSSE';
+import { useEffect, useCallback, useRef, useState } from 'react';
+
+interface EventSourceOptions {
+  enabled?: boolean;
+  onMessage?: (event: MessageEvent) => void;
+  onOpen?: () => void;
+  onError?: () => void;
+}
+
+/**
+ * Minimal EventSource subscription. (useSSE in this package is the chat
+ * streaming store, not a generic SSE hook, so it cannot open this stream.)
+ */
+function useEventSource(url: string, { enabled = true, onMessage, onOpen, onError }: EventSourceOptions) {
+  const [connected, setConnected] = useState(false);
+  const handlers = useRef({ onMessage, onOpen, onError });
+  handlers.current = { onMessage, onOpen, onError };
+  useEffect(() => {
+    if (!enabled || typeof EventSource === 'undefined') return;
+    const source = new EventSource(url);
+    source.onopen = () => { setConnected(true); handlers.current.onOpen?.(); };
+    source.onmessage = (event) => handlers.current.onMessage?.(event);
+    source.onerror = () => { setConnected(false); handlers.current.onError?.(); };
+    return () => { source.close(); setConnected(false); };
+  }, [url, enabled]);
+  return { connected };
+}
 
 export interface WindowMessageData {
   type: string;
@@ -85,7 +110,7 @@ export function useWindowMessage(options: UseWindowMessageOptions = {}): UseWind
   const isIframe = window !== window.parent;
   
   // SSE connection for outbound messages
-  const { connected } = useSSE('/sse/window-message', {
+  const { connected } = useEventSource('/sse/window-message', {
     enabled: enabled && isIframe,
     onMessage: (event) => {
       try {

src/frontend/src/modals/AddMCPServerModal.tsx

@@ -7,9 +7,7 @@ import React, { useState } from 'react';
 import { Button } from '../components/ui/button';
 import { Input } from '../components/ui/input';
 import { Label } from '../components/ui/label';
-import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from '../components/ui/select';
 import { Dialog, DialogContent, DialogDescription, DialogHeader, DialogTitle, DialogFooter } from '../components/ui/dialog';
-import { Separator } from '../components/ui/separator';
 import { Tabs, TabsContent, TabsList, TabsTrigger } from '../components/ui/tabs';
 
 interface AddMCPServerModalProps {

src/frontend/src/pages/SharedThread.tsx

@@ -1,7 +1,7 @@
 import { useEffect, useState } from 'react';
-import { useParams } from 'react-router-dom';
 import { Eye, AlertCircle } from 'lucide-react';
 import { ChatMessages } from '../chat/ChatMessages';
+import type { ChatMessage } from '../types';
 import { Button } from '../components/ui/button';
 
 interface SharedThreadData {
@@ -11,18 +11,13 @@ interface SharedThreadData {
     title: string;
     created_at: string;
   };
-  messages: Array<{
-    id: string;
-    role: string;
-    content: string;
-    timestamp: string;
-    toolCalls?: any[];
-  }>;
+  messages: ChatMessage[];
   read_only: boolean;
 }
 
 export function SharedThread() {
-  const { token } = useParams<{ token: string }>();
+  // Served at /shared/{token} (server.py); this app has no client-side router.
+  const token = decodeURIComponent(window.location.pathname.split('/shared/')[1]?.split('/')[0] ?? '');
   const [threadData, setThreadData] = useState<SharedThreadData | null>(null);
   const [isLoading, setIsLoading] = useState(true);
   const [error, setError] = useState<string>('');
@@ -128,10 +123,13 @@ export function SharedThread() {
         <div className="bg-white rounded-lg shadow-sm border border-gray-200 overflow-hidden">
           {threadData.messages.length > 0 ? (
             <div className="divide-y divide-gray-100">
-              <ChatMessages 
+              <ChatMessages
                 messages={threadData.messages}
                 sessionId={threadData.thread_id}
-                isSharedView={true}
+                currentResponse=""
+                thinkingSteps={[]}
+                toolCalls={[]}
+                isStreaming={false}
               />
             </div>
           ) : (