diff --git a/apps/sim/app/(auth)/verify/otp-error-source.test.tsx b/apps/sim/app/(auth)/verify/otp-error-source.test.tsx
new file mode 100644
index 00000000000..f81caafe77f
--- /dev/null
+++ b/apps/sim/app/(auth)/verify/otp-error-source.test.tsx
@@ -0,0 +1,174 @@
+/** @vitest-environment jsdom */
+import { act, type ButtonHTMLAttributes, type InputHTMLAttributes, type ReactNode } from 'react'
+import { createRoot, type Root } from 'react-dom/client'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+
+const mocks = vi.hoisted(() => ({
+  chatRequest: vi.fn(),
+  chatVerify: vi.fn(),
+  fileRequest: vi.fn(),
+  fileVerify: vi.fn(),
+  refresh: vi.fn(),
+}))
+
+vi.mock('@sim/emcn', () => ({
+  cn: (...values: Array<string | false | null | undefined>) => values.filter(Boolean).join(' '),
+  ChipInput: ({
+    error: _error,
+    size: _size,
+    ...props
+  }: Omit<InputHTMLAttributes<HTMLInputElement>, 'size'> & {
+    error?: boolean
+    size?: string
+  }) => <input {...props} />,
+  Label: ({ children, htmlFor }: { children: ReactNode; htmlFor?: string }) => (
+    <label htmlFor={htmlFor}>{children}</label>
+  ),
+  InputOTP: ({
+    children,
+    value,
+    onChange,
+    'aria-invalid': invalid,
+  }: {
+    children: ReactNode
+    value: string
+    onChange: (value: string) => void
+    'aria-invalid'?: boolean
+  }) => (
+    <div>
+      <input
+        data-testid='otp-code'
+        aria-invalid={invalid}
+        value={value}
+        onChange={(event) => onChange(event.target.value)}
+      />
+      {children}
+    </div>
+  ),
+  InputOTPGroup: ({ children }: { children: ReactNode }) => <div>{children}</div>,
+  InputOTPSlot: ({ invalid, index }: { invalid?: boolean; index: number }) => (
+    <span data-otp-slot={index} data-invalid={invalid} />
+  ),
+}))
+vi.mock('@/lib/messaging/email/validation', () => ({
+  quickValidateEmail: () => ({ isValid: true }),
+}))
+vi.mock('@/app/(auth)/components', () => ({
+  AuthSubmitButton: ({
+    children,
+    loading: _loading,
+    loadingLabel: _loadingLabel,
+    ...props
+  }: ButtonHTMLAttributes<HTMLButtonElement> & {
+    loading?: boolean
+    loadingLabel?: string
+  }) => (
+    <button type='submit' {...props}>
+      {children}
+    </button>
+  ),
+}))
+vi.mock('@/app/(auth)/components/auth-button-classes', () => ({ AUTH_TEXT_LINK: '' }))
+vi.mock('@/components/auth/public-auth-header', () => ({
+  PublicAuthHeader: ({ title }: { title: string }) => <h1>{title}</h1>,
+}))
+vi.mock('@/app/f/[token]/public-file-auth-shell', () => ({
+  PublicFileAuthShell: ({ children }: { children: ReactNode }) => <div>{children}</div>,
+}))
+vi.mock('next/navigation', () => ({ useRouter: () => ({ refresh: mocks.refresh }) }))
+vi.mock('@/hooks/queries/chats', () => ({
+  useChatEmailOtpRequest: () => ({ mutateAsync: mocks.chatRequest, isPending: false }),
+  useChatEmailOtpVerify: () => ({ mutateAsync: mocks.chatVerify, isPending: false }),
+}))
+vi.mock('@/hooks/queries/public-shares', () => ({
+  usePublicFileOtpRequest: () => ({ mutateAsync: mocks.fileRequest, isPending: false }),
+  usePublicFileOtpVerify: () => ({ mutateAsync: mocks.fileVerify, isPending: false }),
+}))
+
+import EmailAuth from '@/app/(interfaces)/chat/components/auth/email/email-auth'
+import { PublicFileEmailAuth } from '@/app/f/[token]/public-file-email-auth'
+
+let root: Root
+let container: HTMLDivElement
+
+function changeInput(input: HTMLInputElement, value: string) {
+  Object.getOwnPropertyDescriptor(HTMLInputElement.prototype, 'value')?.set?.call(input, value)
+  input.dispatchEvent(new Event('input', { bubbles: true }))
+}
+
+function button(label: string) {
+  const found = Array.from(container.querySelectorAll('button')).find(
+    (candidate) => candidate.textContent?.trim() === label
+  )
+  if (!found) throw new Error(`Missing button: ${label}`)
+  return found
+}
+
+function expectOtpInvalid(invalid: boolean) {
+  expect(container.querySelector('[data-testid="otp-code"]')?.getAttribute('aria-invalid')).toBe(
+    String(invalid)
+  )
+  const slots = container.querySelectorAll('[data-otp-slot]')
+  expect(slots).toHaveLength(6)
+  for (const slot of slots) expect(slot.getAttribute('data-invalid')).toBe(String(invalid))
+}
+
+beforeEach(() => {
+  vi.clearAllMocks()
+  vi.stubGlobal('IS_REACT_ACT_ENVIRONMENT', true)
+  mocks.chatRequest.mockResolvedValue({})
+  mocks.chatVerify.mockResolvedValue({})
+  mocks.fileRequest.mockResolvedValue({})
+  mocks.fileVerify.mockResolvedValue({})
+  container = document.createElement('div')
+  document.body.appendChild(container)
+  root = createRoot(container)
+})
+
+afterEach(() => {
+  act(() => root.unmount())
+  container.remove()
+  vi.unstubAllGlobals()
+})
+
+describe('OTP error provenance', () => {
+  it('keeps the chat code valid on resend failure and marks only a failed verification invalid', async () => {
+    act(() => root.render(<EmailAuth identifier='chat-1' />))
+    act(() =>
+      changeInput(container.querySelector<HTMLInputElement>('#email')!, 'member@example.com')
+    )
+    await act(async () => button('Continue').click())
+
+    mocks.chatRequest.mockRejectedValueOnce(new Error('Delivery failed'))
+    await act(async () => button('Resend').click())
+    expect(container.textContent).toContain('Delivery failed')
+    expectOtpInvalid(false)
+
+    mocks.chatVerify.mockRejectedValueOnce(new Error('Incorrect code'))
+    await act(async () =>
+      changeInput(container.querySelector<HTMLInputElement>('[data-testid="otp-code"]')!, '123456')
+    )
+    expect(container.textContent).toContain('Incorrect code')
+    expectOtpInvalid(true)
+  })
+
+  it('keeps the public-file code valid on resend failure and marks only a failed verification invalid', async () => {
+    act(() => root.render(<PublicFileEmailAuth token='share-1' />))
+    act(() =>
+      changeInput(container.querySelector<HTMLInputElement>('#email')!, 'member@example.com')
+    )
+    await act(async () => button('Continue').click())
+
+    mocks.fileRequest.mockRejectedValueOnce(new Error('Delivery failed'))
+    await act(async () => button('Resend').click())
+    expect(container.textContent).toContain('Delivery failed')
+    expectOtpInvalid(false)
+
+    mocks.fileVerify.mockRejectedValueOnce(new Error('Incorrect code'))
+    await act(async () =>
+      changeInput(container.querySelector<HTMLInputElement>('[data-testid="otp-code"]')!, '123456')
+    )
+    expect(container.textContent).toContain('Incorrect code')
+    expectOtpInvalid(true)
+  })
+})
diff --git a/apps/sim/app/(auth)/verify/verify-content.tsx b/apps/sim/app/(auth)/verify/verify-content.tsx
index 88d1c2e9d67..4e13de53044 100644
--- a/apps/sim/app/(auth)/verify/verify-content.tsx
+++ b/apps/sim/app/(auth)/verify/verify-content.tsx
@@ -1,7 +1,7 @@
 'use client'
 
 import { Suspense, useEffect, useState } from 'react'
-import { cn, InputOTP, InputOTPGroup, InputOTPSlot } from '@sim/emcn'
+import { InputOTP, InputOTPGroup, InputOTPSlot } from '@sim/emcn'
 import { POST_AUTH_REDIRECT_STORAGE_KEY } from '@/app/(auth)/auth-redirect'
 import {
   AuthFormMessage,
@@ -84,14 +84,16 @@ function VerificationForm({
             </p>
 
             <div className='flex justify-center'>
-              <InputOTP maxLength={6} value={otp} onChange={handleOtpChange} disabled={isLoading}>
+              <InputOTP
+                maxLength={6}
+                value={otp}
+                onChange={handleOtpChange}
+                disabled={isLoading}
+                aria-invalid={isInvalidOtp}
+              >
                 <InputOTPGroup>
                   {OTP_SLOTS.map((index) => (
-                    <InputOTPSlot
-                      key={index}
-                      index={index}
-                      className={cn(isInvalidOtp && 'border-[var(--text-error)]')}
-                    />
+                    <InputOTPSlot key={index} index={index} invalid={isInvalidOtp} />
                   ))}
                 </InputOTPGroup>
               </InputOTP>
diff --git a/apps/sim/app/(interfaces)/chat/components/auth/email/email-auth.tsx b/apps/sim/app/(interfaces)/chat/components/auth/email/email-auth.tsx
index 2781d70779b..190dfbaf917 100644
--- a/apps/sim/app/(interfaces)/chat/components/auth/email/email-auth.tsx
+++ b/apps/sim/app/(interfaces)/chat/components/auth/email/email-auth.tsx
@@ -34,13 +34,17 @@ const validateEmailField = (emailValue: string): string[] => {
 
 export default function EmailAuth({ identifier }: EmailAuthProps) {
   const [email, setEmail] = useState('')
-  const [authError, setAuthError] = useState<string | null>(null)
+  const [authError, setAuthError] = useState<{
+    kind: 'verification' | 'request'
+    message: string
+  } | null>(null)
   const [emailErrors, setEmailErrors] = useState<string[]>([])
   const hasEmailError = emailErrors.length > 0
 
   const [showOtpVerification, setShowOtpVerification] = useState(false)
   const [otpValue, setOtpValue] = useState('')
   const [countdown, setCountdown] = useState(0)
+  const isInvalidOtp = authError?.kind === 'verification'
 
   const requestOtp = useChatEmailOtpRequest(identifier)
   const verifyOtp = useChatEmailOtpVerify(identifier)
@@ -89,7 +93,10 @@ export default function EmailAuth({ identifier }: EmailAuthProps) {
       await verifyOtp.mutateAsync({ email, otp: codeToVerify })
     } catch (error) {
       logger.error('Error verifying OTP:', error)
-      setAuthError(toError(error).message || 'Invalid verification code')
+      setAuthError({
+        kind: 'verification',
+        message: toError(error).message || 'Invalid verification code',
+      })
     }
   }
 
@@ -102,7 +109,10 @@ export default function EmailAuth({ identifier }: EmailAuthProps) {
       setOtpValue('')
     } catch (error) {
       logger.error('Error resending OTP:', error)
-      setAuthError(toError(error).message || 'Failed to resend verification code')
+      setAuthError({
+        kind: 'request',
+        message: toError(error).message || 'Failed to resend verification code',
+      })
       setCountdown(0)
     }
   }
@@ -181,15 +191,12 @@ export default function EmailAuth({ identifier }: EmailAuthProps) {
                       }
                     }}
                     disabled={verifyOtp.isPending}
-                    className={cn('gap-2', authError && 'otp-error')}
+                    className={cn('gap-2', isInvalidOtp && 'otp-error')}
+                    aria-invalid={isInvalidOtp}
                   >
                     <InputOTPGroup>
                       {[0, 1, 2, 3, 4, 5].map((index) => (
-                        <InputOTPSlot
-                          key={index}
-                          index={index}
-                          className={cn(authError && 'border-[var(--text-error)]')}
-                        />
+                        <InputOTPSlot key={index} index={index} invalid={isInvalidOtp} />
                       ))}
                     </InputOTPGroup>
                   </InputOTP>
@@ -197,7 +204,7 @@ export default function EmailAuth({ identifier }: EmailAuthProps) {
 
                 {authError && (
                   <div className='mt-1 space-y-1 text-center text-[var(--text-error)] text-xs'>
-                    <p>{authError}</p>
+                    <p>{authError.message}</p>
                   </div>
                 )}
 
diff --git a/apps/sim/app/f/[token]/public-file-email-auth.tsx b/apps/sim/app/f/[token]/public-file-email-auth.tsx
index a674db4ffcb..198fea32ae5 100644
--- a/apps/sim/app/f/[token]/public-file-email-auth.tsx
+++ b/apps/sim/app/f/[token]/public-file-email-auth.tsx
@@ -28,8 +28,12 @@ export function PublicFileEmailAuth({ token }: PublicFileEmailAuthProps) {
   const [email, setEmail] = useState('')
   const [otp, setOtp] = useState('')
   const [sent, setSent] = useState(false)
-  const [error, setError] = useState<string | null>(null)
+  const [error, setError] = useState<{
+    kind: 'verification' | 'request'
+    message: string
+  } | null>(null)
   const [countdown, setCountdown] = useState(0)
+  const isInvalidOtp = error?.kind === 'verification'
 
   useEffect(() => {
     if (countdown <= 0) return
@@ -39,7 +43,7 @@ export function PublicFileEmailAuth({ token }: PublicFileEmailAuthProps) {
 
   const sendCode = async () => {
     if (!quickValidateEmail(normalizeEmail(email)).isValid) {
-      setError('Please enter a valid email address.')
+      setError({ kind: 'request', message: 'Please enter a valid email address.' })
       return
     }
     setError(null)
@@ -48,7 +52,10 @@ export function PublicFileEmailAuth({ token }: PublicFileEmailAuthProps) {
       setSent(true)
       setOtp('')
     } catch (err) {
-      setError(getErrorMessage(err, 'Failed to send verification code'))
+      setError({
+        kind: 'request',
+        message: getErrorMessage(err, 'Failed to send verification code'),
+      })
     }
   }
 
@@ -59,7 +66,7 @@ export function PublicFileEmailAuth({ token }: PublicFileEmailAuthProps) {
       await verifyOtp.mutateAsync({ email: normalizeEmail(email), otp: code })
       router.refresh()
     } catch (err) {
-      setError(getErrorMessage(err, 'Invalid verification code'))
+      setError({ kind: 'verification', message: getErrorMessage(err, 'Invalid verification code') })
     }
   }
 
@@ -71,7 +78,10 @@ export function PublicFileEmailAuth({ token }: PublicFileEmailAuthProps) {
       setError(null)
     } catch (err) {
       setCountdown(0)
-      setError(getErrorMessage(err, 'Failed to resend verification code'))
+      setError({
+        kind: 'request',
+        message: getErrorMessage(err, 'Failed to resend verification code'),
+      })
     }
   }
 
@@ -107,7 +117,7 @@ export function PublicFileEmailAuth({ token }: PublicFileEmailAuthProps) {
               size='lg'
               error={Boolean(error)}
             />
-            {error ? <p className='text-[var(--text-error)] text-xs'>{error}</p> : null}
+            {error ? <p className='text-[var(--text-error)] text-xs'>{error.message}</p> : null}
           </div>
 
           <AuthSubmitButton
@@ -143,21 +153,20 @@ export function PublicFileEmailAuth({ token }: PublicFileEmailAuthProps) {
               if (value.length === 6) verifyCode(value)
             }}
             disabled={verifyOtp.isPending}
-            className={cn('gap-2', error && 'otp-error')}
+            className={cn('gap-2', isInvalidOtp && 'otp-error')}
+            aria-invalid={isInvalidOtp}
           >
             <InputOTPGroup>
               {[0, 1, 2, 3, 4, 5].map((i) => (
-                <InputOTPSlot
-                  key={i}
-                  index={i}
-                  className={cn(error && 'border-[var(--text-error)]')}
-                />
+                <InputOTPSlot key={i} index={i} invalid={isInvalidOtp} />
               ))}
             </InputOTPGroup>
           </InputOTP>
         </div>
 
-        {error ? <p className='text-center text-[var(--text-error)] text-xs'>{error}</p> : null}
+        {error ? (
+          <p className='text-center text-[var(--text-error)] text-xs'>{error.message}</p>
+        ) : null}
 
         <AuthSubmitButton
           type='button'
diff --git a/packages/emcn/src/components/index.ts b/packages/emcn/src/components/index.ts
index b194122e642..df1cea58c20 100644
--- a/packages/emcn/src/components/index.ts
+++ b/packages/emcn/src/components/index.ts
@@ -161,7 +161,13 @@ export {
   type InfoCardProps,
 } from './info-card/info-card'
 export { Input, type InputProps } from './input/input'
-export { InputOTP, InputOTPGroup, InputOTPSeparator, InputOTPSlot } from './input-otp/input-otp'
+export {
+  InputOTP,
+  InputOTPGroup,
+  InputOTPSeparator,
+  InputOTPSlot,
+  type InputOTPSlotProps,
+} from './input-otp/input-otp'
 export { Label } from './label/label'
 export { Lightbox, type LightboxProps } from './lightbox/lightbox'
 export { focusFirstTextInput, focusFirstTextInputIn } from './modal/auto-focus'
diff --git a/packages/emcn/src/components/input-otp/input-otp.test.tsx b/packages/emcn/src/components/input-otp/input-otp.test.tsx
new file mode 100644
index 00000000000..9bbb8dbd699
--- /dev/null
+++ b/packages/emcn/src/components/input-otp/input-otp.test.tsx
@@ -0,0 +1,66 @@
+/**
+ * @vitest-environment jsdom
+ */
+import { act } from 'react'
+import { createRoot, type Root } from 'react-dom/client'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { InputOTP, InputOTPGroup, InputOTPSlot } from './input-otp'
+
+let root: Root
+let host: HTMLDivElement
+
+beforeEach(() => {
+  ;(globalThis as { IS_REACT_ACT_ENVIRONMENT?: boolean }).IS_REACT_ACT_ENVIRONMENT = true
+  vi.stubGlobal(
+    'ResizeObserver',
+    class {
+      observe() {}
+      unobserve() {}
+      disconnect() {}
+    }
+  )
+  host = document.createElement('div')
+  document.body.appendChild(host)
+  root = createRoot(host)
+})
+
+afterEach(() => {
+  act(() => root.unmount())
+  host.remove()
+  vi.unstubAllGlobals()
+})
+
+function renderOtp(invalid: boolean) {
+  act(() => {
+    root.render(
+      <InputOTP maxLength={2} value='' onChange={vi.fn()} aria-invalid={invalid}>
+        <InputOTPGroup>
+          <InputOTPSlot index={0} invalid={invalid} data-testid='first-slot' />
+          <InputOTPSlot index={1} invalid={invalid} />
+        </InputOTPGroup>
+      </InputOTP>
+    )
+  })
+}
+
+describe('InputOTPSlot invalid state', () => {
+  it('keeps the standard border when valid', () => {
+    renderOtp(false)
+    const slot = host.querySelector('[data-testid="first-slot"]')
+    expect(slot?.classList.contains('border-[var(--border-1)]')).toBe(true)
+    expect(slot?.classList.contains('border-[var(--text-error)]')).toBe(false)
+    expect(host.querySelector('input')?.getAttribute('aria-invalid')).toBe('false')
+  })
+
+  it('keeps the error border while the active slot has a focus ring', () => {
+    renderOtp(true)
+    const input = host.querySelector('input')
+    expect(input?.getAttribute('aria-invalid')).toBe('true')
+
+    act(() => input?.focus())
+    const slot = host.querySelector('[data-testid="first-slot"]')
+    expect(slot?.classList.contains('border-[var(--text-error)]')).toBe(true)
+    expect(slot?.classList.contains('ring-1')).toBe(true)
+    expect(slot?.classList.contains('border-[var(--text-muted)]')).toBe(false)
+  })
+})
diff --git a/packages/emcn/src/components/input-otp/input-otp.tsx b/packages/emcn/src/components/input-otp/input-otp.tsx
index a6c5ea82fff..2c3ff3a83b7 100644
--- a/packages/emcn/src/components/input-otp/input-otp.tsx
+++ b/packages/emcn/src/components/input-otp/input-otp.tsx
@@ -66,32 +66,39 @@ InputOTPGroup.displayName = 'InputOTPGroup'
  *
  * Uses emcn design tokens for consistent styling with the Input component.
  */
-const InputOTPSlot = React.forwardRef<
-  React.ElementRef<'div'>,
-  React.ComponentPropsWithoutRef<'div'> & { index: number }
->(({ index, className, ...props }, ref) => {
-  const inputOTPContext = React.useContext(OTPInputContext)
-  const { char, hasFakeCaret, isActive } = inputOTPContext.slots[index]
+export interface InputOTPSlotProps extends React.ComponentPropsWithoutRef<'div'> {
+  /** Zero-based position of this slot in the OTP input. */
+  index: number
+  /** Keep the error border visible even while this slot is active. */
+  invalid?: boolean
+}
+
+const InputOTPSlot = React.forwardRef<React.ElementRef<'div'>, InputOTPSlotProps>(
+  ({ index, invalid = false, className, ...props }, ref) => {
+    const inputOTPContext = React.useContext(OTPInputContext)
+    const { char, hasFakeCaret, isActive } = inputOTPContext.slots[index]
 
-  return (
-    <div
-      ref={ref}
-      className={cn(
-        'relative flex h-12 w-12 items-center justify-center rounded-sm border border-[var(--border-1)] bg-[var(--surface-5)] text-[var(--text-primary)] text-lg transition-colors',
-        isActive && 'z-10 border-[var(--text-muted)] ring-1 ring-[var(--text-muted)]',
-        className
-      )}
-      {...props}
-    >
-      {char}
-      {hasFakeCaret && (
-        <div className='pointer-events-none absolute inset-0 flex items-center justify-center'>
-          <div className='h-6 w-px animate-caret-blink bg-[var(--text-primary)] duration-1000 motion-reduce:animate-none' />
-        </div>
-      )}
-    </div>
-  )
-})
+    return (
+      <div
+        ref={ref}
+        className={cn(
+          'relative flex h-12 w-12 items-center justify-center rounded-sm border border-[var(--border-1)] bg-[var(--surface-5)] text-[var(--text-primary)] text-lg transition-colors',
+          isActive && 'z-10 border-[var(--text-muted)] ring-1 ring-[var(--text-muted)]',
+          invalid && 'border-[var(--text-error)]',
+          className
+        )}
+        {...props}
+      >
+        {char}
+        {hasFakeCaret && (
+          <div className='pointer-events-none absolute inset-0 flex items-center justify-center'>
+            <div className='h-6 w-px animate-caret-blink bg-[var(--text-primary)] duration-1000 motion-reduce:animate-none' />
+          </div>
+        )}
+      </div>
+    )
+  }
+)
 InputOTPSlot.displayName = 'InputOTPSlot'
 
 /**