refactor(chat): clean up the deployed chat surface

Eight-angle cleanup pass over the full contents of the chat surface and
the speech code that survived the voice-mode removal.

Dead code
- enforceChatRateLimit: added for the TTS relay in #6212, orphaned when
  #6215 deleted that route. Zero consumers.
- ChatToolCallStatus, ChatErrorType, and six unused CHAT_ERROR_MESSAGES
  keys (only GENERIC_ERROR and CHAT_UNAVAILABLE are read).
- scrollToMessage was declared and destructured by ChatMessageContainer
  but never used in its body; removing the prop also made the
  scrollToShowOnlyMessage branch unreachable, since the sole caller
  passed true.
- permissionState and the language prop on useSpeechToText: both
  write-only across the repo.
- The image branch in ChatFileDownload's renderIcon returned the same
  DefaultFileIcon at the same size as the fallback.
- chatKeys.status/detail: aliases of deploymentKeys nothing imported,
  and misleading since they root under a different key namespace.

Redundant state
- password-auth and email-auth each kept a boolean in lockstep with
  `errors.length > 0`; email-auth also validated on every keystroke and
  then immediately hid the result.
- file-download tracked hover in state to drive one opacity class; now
  group-hover. Verified emcn Button sets no `group` class of its own.

Memoization
- ChatMessageContainer's memo() could never bail: chat.tsx passes an
  inline arrow for scrollToBottom and displayMessages is a fresh array.
  Four of the five things that re-render ChatClient are its props
  anyway, so the memo is dropped rather than propped up.
- ClientChatMessage keeps its memo — it blocks markdown re-parsing —
  but loses the custom comparator, which compared proxies (a
  key:status fingerprint, files by length) and ignored attachments and
  type entirely. Default shallow compare on its single prop is both
  simpler and stricter.
- Six useCallbacks whose consumers are native DOM handlers or inline
  arrows, so nothing observed their identity.

Effects
- The scroll listener attached in an effect keyed on [chatConfig,
  authRequired] — values it never reads, standing in for "the container
  has mounted". It now attaches via a ref callback, so it no longer
  re-attaches on every config refetch.

Design system and a11y
- z-[100] -> z-[var(--z-dropdown)] (same value), shadow-lg ->
  shadow-medium, list styles from inline style to Tailwind classes,
  hover: -> hover-hover: on touch-reachable targets, Check sourced from
  emcn alongside its Duplicate pair.
- Accessible names on the remove-attachment, stop, and send buttons,
  which announced only as "button".
- Dropped a keyboard handler on a role='group' div with no tabIndex,
  where target === currentTarget was unreachable, and the Tooltip
  Provider wrappers and delayDuration, which emcn documents as
  no-op passthroughs.

Author: waleedlatif1

apps/sim/app/(interfaces)/chat/[identifier]/chat.tsx

@@ -1,6 +1,6 @@
 'use client'
 
-import { type RefObject, useCallback, useEffect, useMemo, useRef, useState } from 'react'
+import { type RefObject, useCallback, useMemo, useRef, useState } from 'react'
 import { createLogger } from '@sim/logger'
 import { generateId } from '@sim/utils/id'
 import {
@@ -26,6 +26,8 @@ import { useGitHubStars } from '@/hooks/queries/github-stars'
 
 const logger = createLogger('ChatClient')
 
+const NEAR_BOTTOM_THRESHOLD_PX = 100
+
 interface ChatRequestFile {
   name: string
   size: number
@@ -87,13 +89,11 @@ export default function ChatClient({ identifier }: { identifier: string }) {
   const { isStreamingResponse, abortControllerRef, stopStreaming, handleStreamedResponse } =
     useChatStreaming()
 
-  const NEAR_BOTTOM_THRESHOLD_PX = 100
-
   /**
    * ChatGPT-style scroll. Without `force`, no-ops when the user has scrolled away.
    * With `force` (jump button), re-pins to bottom.
    */
-  const scrollToBottom = useCallback((options?: { behavior?: ScrollBehavior; force?: boolean }) => {
+  const scrollToBottom = (options?: { behavior?: ScrollBehavior; force?: boolean }) => {
     const behavior = options?.behavior ?? 'smooth'
     const force = options?.force === true
     if (!force && !stickToBottomRef.current) return
@@ -112,52 +112,46 @@ export default function ChatClient({ identifier }: { identifier: string }) {
       },
       behavior === 'smooth' ? 400 : 50
     )
-  }, [])
+  }
 
-  const scrollToMessage = useCallback(
-    (messageId: string, scrollToShowOnlyMessage = false) => {
-      const messageElement = document.querySelector(`[data-message-id="${messageId}"]`)
-      if (messageElement && messagesContainerRef.current) {
-        const container = messagesContainerRef.current
-        const containerRect = container.getBoundingClientRect()
-        const messageRect = messageElement.getBoundingClientRect()
-
-        if (scrollToShowOnlyMessage) {
-          const scrollTop = container.scrollTop + messageRect.top - containerRect.top
-
-          container.scrollTo({
-            top: scrollTop,
-            behavior: 'smooth',
-          })
-        } else {
-          const scrollTop = container.scrollTop + messageRect.top - containerRect.top - 80
-
-          container.scrollTo({
-            top: scrollTop,
-            behavior: 'smooth',
-          })
-        }
-      }
-    },
-    [messagesContainerRef]
-  )
+  const scrollToMessage = (messageId: string) => {
+    const messageElement = document.querySelector(`[data-message-id="${messageId}"]`)
+    if (!messageElement || !messagesContainerRef.current) return
 
-  useEffect(() => {
     const container = messagesContainerRef.current
-    if (!container) return
+    const containerRect = container.getBoundingClientRect()
+    const messageRect = messageElement.getBoundingClientRect()
+
+    container.scrollTo({
+      top: container.scrollTop + messageRect.top - containerRect.top,
+      behavior: 'smooth',
+    })
+  }
+
+  /**
+   * Attaches on mount via a ref callback rather than an effect: the container
+   * renders only after the auth/loading early returns, so an effect would need
+   * unrelated render values as a stand-in for "the node exists yet".
+   */
+  const attachMessagesContainer = useCallback((node: HTMLDivElement | null) => {
+    messagesContainerRef.current = node
+    if (!node) return
 
     const handleScroll = () => {
       if (ignoreScrollRef.current) return
-      const { scrollTop, scrollHeight, clientHeight } = container
+      const { scrollTop, scrollHeight, clientHeight } = node
       const distanceFromBottom = scrollHeight - scrollTop - clientHeight
       const nearBottom = distanceFromBottom <= NEAR_BOTTOM_THRESHOLD_PX
       stickToBottomRef.current = nearBottom
       setShowScrollButton(!nearBottom)
     }
 
-    container.addEventListener('scroll', handleScroll, { passive: true })
-    return () => container.removeEventListener('scroll', handleScroll)
-  }, [chatConfig, authRequired])
+    node.addEventListener('scroll', handleScroll, { passive: true })
+    return () => {
+      node.removeEventListener('scroll', handleScroll)
+      messagesContainerRef.current = null
+    }
+  }, [])
 
   const handleSendMessage = async (
     messageToSend: string,
@@ -199,7 +193,7 @@ export default function ChatClient({ identifier }: { identifier: string }) {
     setIsLoading(true)
 
     setTimeout(() => {
-      scrollToMessage(userMessage.id, true)
+      scrollToMessage(userMessage.id)
     }, 100)
 
     // One AbortController for fetch + SSE body reads so Stop cancels server work too.
@@ -314,18 +308,17 @@ export default function ChatClient({ identifier }: { identifier: string }) {
   }
 
   return (
-    <div className='light desktop-title-bar-page fixed inset-0 z-[100] flex flex-col bg-[var(--bg)] text-[var(--text-primary)]'>
+    <div className='light desktop-title-bar-page fixed inset-0 z-[var(--z-dropdown)] flex flex-col bg-[var(--bg)] text-[var(--text-primary)]'>
       <DesktopTitleBarLane />
       <ChatHeader chatConfig={chatConfig} starCount={starCount} />
 
       <ChatMessageContainer
         messages={displayMessages}
         isLoading={isLoading}
         showScrollButton={showScrollButton}
-        messagesContainerRef={messagesContainerRef as RefObject<HTMLDivElement>}
+        messagesContainerRef={attachMessagesContainer}
         messagesEndRef={messagesEndRef as RefObject<HTMLDivElement>}
         scrollToBottom={() => scrollToBottom({ behavior: 'smooth', force: true })}
-        scrollToMessage={scrollToMessage}
         chatConfig={chatConfig}
       />
 

apps/sim/app/(interfaces)/chat/[identifier]/loading.tsx

@@ -3,7 +3,7 @@ import { DesktopTitleBarLane } from '@/app/_shell/desktop-title-bar'
 
 export default function ChatLoading() {
   return (
-    <div className='light desktop-title-bar-page fixed inset-0 z-[100] flex flex-col bg-[var(--bg)] text-[var(--text-primary)]'>
+    <div className='light desktop-title-bar-page fixed inset-0 z-[var(--z-dropdown)] flex flex-col bg-[var(--bg)] text-[var(--text-primary)]'>
       <DesktopTitleBarLane />
       <div className='border-[var(--border-1)] border-b px-4 py-3'>
         <div className='mx-auto flex max-w-3xl items-center justify-between'>

apps/sim/app/(interfaces)/chat/components/auth/email/email-auth.tsx

@@ -35,7 +35,7 @@ export default function EmailAuth({ identifier }: EmailAuthProps) {
   const [email, setEmail] = useState('')
   const [authError, setAuthError] = useState<string | null>(null)
   const [emailErrors, setEmailErrors] = useState<string[]>([])
-  const [showEmailValidationError, setShowEmailValidationError] = useState(false)
+  const hasEmailError = emailErrors.length > 0
 
   const [showOtpVerification, setShowOtpVerification] = useState(false)
   const [otpValue, setOtpValue] = useState('')
@@ -53,15 +53,12 @@ export default function EmailAuth({ identifier }: EmailAuthProps) {
   const handleEmailChange = (e: React.ChangeEvent<HTMLInputElement>) => {
     const newEmail = e.target.value
     setEmail(newEmail)
-    const errors = validateEmailField(newEmail)
-    setEmailErrors(errors)
-    setShowEmailValidationError(false)
+    setEmailErrors([])
   }
 
   const handleSendOtp = async () => {
     const emailValidationErrors = validateEmailField(email)
     setEmailErrors(emailValidationErrors)
-    setShowEmailValidationError(emailValidationErrors.length > 0)
 
     if (emailValidationErrors.length > 0) {
       return
@@ -75,7 +72,6 @@ export default function EmailAuth({ identifier }: EmailAuthProps) {
     } catch (error) {
       logger.error('Error sending OTP:', error)
       setEmailErrors([toError(error).message || 'Failed to send verification code'])
-      setShowEmailValidationError(true)
     }
   }
 
@@ -149,12 +145,10 @@ export default function EmailAuth({ identifier }: EmailAuthProps) {
                     value={email}
                     onChange={handleEmailChange}
                     className={cn(
-                      showEmailValidationError &&
-                        emailErrors.length > 0 &&
-                        'border-[var(--text-error)] focus:border-[var(--text-error)]'
+                      hasEmailError && 'border-[var(--text-error)] focus:border-[var(--text-error)]'
                     )}
                   />
-                  {showEmailValidationError && emailErrors.length > 0 && (
+                  {hasEmailError && (
                     <div className='mt-1 space-y-1 text-[var(--text-error)] text-xs'>
                       {emailErrors.map((error) => (
                         <p key={error}>{error}</p>

apps/sim/app/(interfaces)/chat/components/auth/password/password-auth.tsx

@@ -17,21 +17,19 @@ interface PasswordAuthProps {
 export default function PasswordAuth({ identifier }: PasswordAuthProps) {
   const [password, setPassword] = useState('')
   const [showPassword, setShowPassword] = useState(false)
-  const [showValidationError, setShowValidationError] = useState(false)
   const [passwordErrors, setPasswordErrors] = useState<string[]>([])
+  const hasPasswordError = passwordErrors.length > 0
   const authenticate = useChatPasswordAuth(identifier)
 
   const handlePasswordChange = (e: React.ChangeEvent<HTMLInputElement>) => {
     const newPassword = e.target.value
     setPassword(newPassword)
-    setShowValidationError(false)
     setPasswordErrors([])
   }
 
   const handleAuthenticate = async () => {
     if (!password.trim()) {
       setPasswordErrors(['Password is required'])
-      setShowValidationError(true)
       return
     }
 
@@ -41,7 +39,6 @@ export default function PasswordAuth({ identifier }: PasswordAuthProps) {
     } catch (error) {
       logger.error('Authentication error:', error)
       setPasswordErrors([toError(error).message || 'Invalid password. Please try again.'])
-      setShowValidationError(true)
     }
   }
 
@@ -84,15 +81,14 @@ export default function PasswordAuth({ identifier }: PasswordAuthProps) {
                     onChange={handlePasswordChange}
                     className={cn(
                       'pr-10',
-                      showValidationError &&
-                        passwordErrors.length > 0 &&
+                      hasPasswordError &&
                         'border-[var(--text-error)] focus:border-[var(--text-error)]'
                     )}
                   />
                   <button
                     type='button'
                     onClick={() => setShowPassword(!showPassword)}
-                    className='-translate-y-1/2 absolute top-1/2 right-3 text-[var(--text-muted)] hover:text-[var(--text-primary)]'
+                    className='-translate-y-1/2 absolute top-1/2 right-3 text-[var(--text-muted)] hover-hover:text-[var(--text-primary)]'
                     aria-label={showPassword ? 'Hide password' : 'Show password'}
                   >
                     {showPassword ? <EyeOff size={18} /> : <Eye size={18} />}
@@ -101,9 +97,7 @@ export default function PasswordAuth({ identifier }: PasswordAuthProps) {
                 <div
                   className={cn(
                     'absolute right-0 left-0 z-10 grid transition-[grid-template-rows] duration-200 ease-out',
-                    showValidationError && passwordErrors.length > 0
-                      ? 'grid-rows-[1fr]'
-                      : 'grid-rows-[0fr]'
+                    hasPasswordError ? 'grid-rows-[1fr]' : 'grid-rows-[0fr]'
                   )}
                   aria-live='polite'
                 >

apps/sim/app/(interfaces)/chat/components/header/header.tsx

@@ -52,7 +52,7 @@ export function ChatHeader({ chatConfig, starCount }: ChatHeaderProps) {
             href='https://github.com/simstudioai/sim'
             target='_blank'
             rel='noopener noreferrer'
-            className='flex items-center gap-2 text-[var(--text-muted)] transition-colors hover:text-[var(--text-primary)]'
+            className='flex items-center gap-2 text-[var(--text-muted)] transition-colors hover-hover:text-[var(--text-primary)]'
             aria-label={`GitHub repository - ${starCount} stars`}
           >
             <GithubIcon className='size-[16px]' aria-hidden='true' />