diff --git a/web/src/app.css b/web/src/app.css
index 9f7bc10..15d792b 100644
--- a/web/src/app.css
+++ b/web/src/app.css
@@ -254,6 +254,77 @@
   cursor: not-allowed;
 }
 
+/* ---------- modal ---------- */
+
+.modal-overlay {
+  position: fixed;
+  inset: 0;
+  z-index: 100;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 24px;
+  background: rgba(4, 7, 5, 0.72);
+  backdrop-filter: blur(2px);
+  animation: modal-fade 0.12s ease-out;
+}
+
+.modal-dialog {
+  width: 100%;
+  max-width: 440px;
+  background: var(--bg-panel-raised);
+  border: 1px solid var(--border-bright);
+  box-shadow: 0 18px 48px rgba(0, 0, 0, 0.55);
+  padding: 22px 24px;
+  outline: none;
+  animation: modal-rise 0.14s ease-out;
+}
+
+.modal-title {
+  font-family: var(--font-mono);
+  font-size: 12px;
+  letter-spacing: 0.14em;
+  text-transform: uppercase;
+  color: var(--accent);
+  margin-bottom: 14px;
+}
+
+.confirm-message {
+  margin: 0 0 20px;
+  color: var(--fg);
+  font-size: 14px;
+  line-height: 1.5;
+}
+
+.modal-actions {
+  display: flex;
+  justify-content: flex-end;
+  gap: 10px;
+}
+
+.btn-danger {
+  border-color: var(--fail-dim);
+  color: var(--fail);
+}
+
+.btn-danger:hover:not(:disabled) {
+  background: var(--fail-dim);
+  color: var(--fail);
+}
+
+@keyframes modal-fade {
+  from {
+    opacity: 0;
+  }
+}
+
+@keyframes modal-rise {
+  from {
+    opacity: 0;
+    transform: translateY(6px);
+  }
+}
+
 /* ---------- buttons ---------- */
 
 .btn {
diff --git a/web/src/components/ConfirmProvider.tsx b/web/src/components/ConfirmProvider.tsx
new file mode 100644
index 0000000..fa8bf3b
--- /dev/null
+++ b/web/src/components/ConfirmProvider.tsx
@@ -0,0 +1,73 @@
+import { createContext, useCallback, useContext, useRef, useState, type ReactNode } from 'react'
+import { Modal } from './Modal'
+
+export type ConfirmOptions = {
+  title?: string
+  message: string
+  confirmLabel?: string
+  cancelLabel?: string
+  danger?: boolean
+}
+
+type ConfirmFn = (opts: ConfirmOptions) => Promise<boolean>
+
+const ConfirmContext = createContext<ConfirmFn | null>(null)
+
+// Drop-in async replacement for window.confirm(): `await confirm({ message })`.
+export function useConfirm(): ConfirmFn {
+  const ctx = useContext(ConfirmContext)
+  if (!ctx) throw new Error('useConfirm must be used within <ConfirmProvider>')
+  return ctx
+}
+
+export function ConfirmProvider({ children }: { children: ReactNode }) {
+  const [opts, setOpts] = useState<ConfirmOptions | null>(null)
+  const resolver = useRef<(v: boolean) => void>(() => {})
+
+  const confirm = useCallback<ConfirmFn>((o) => {
+    setOpts(o)
+    return new Promise<boolean>((resolve) => {
+      resolver.current = resolve
+    })
+  }, [])
+
+  const finish = useCallback((result: boolean) => {
+    resolver.current(result)
+    resolver.current = () => {}
+    setOpts(null)
+  }, [])
+
+  return (
+    <ConfirmContext.Provider value={confirm}>
+      {children}
+      <Modal open={opts !== null} title={opts?.title ?? 'Confirm'} onClose={() => finish(false)}>
+        {opts && (
+          <div
+            className="confirm-body"
+            onKeyDown={(e) => {
+              if (e.key === 'Enter') {
+                e.preventDefault()
+                finish(true)
+              }
+            }}
+          >
+            <p className="confirm-message">{opts.message}</p>
+            <div className="modal-actions">
+              <button type="button" className="btn" onClick={() => finish(false)}>
+                {opts.cancelLabel ?? 'Cancel'}
+              </button>
+              <button
+                type="button"
+                className={opts.danger ? 'btn btn-danger' : 'btn btn-primary'}
+                data-modal-autofocus
+                onClick={() => finish(true)}
+              >
+                {opts.confirmLabel ?? 'Confirm'}
+              </button>
+            </div>
+          </div>
+        )}
+      </Modal>
+    </ConfirmContext.Provider>
+  )
+}
diff --git a/web/src/components/Modal.tsx b/web/src/components/Modal.tsx
new file mode 100644
index 0000000..322d546
--- /dev/null
+++ b/web/src/components/Modal.tsx
@@ -0,0 +1,88 @@
+import { useEffect, useRef, type ReactNode } from 'react'
+import { createPortal } from 'react-dom'
+
+type ModalProps = {
+  open: boolean
+  title?: string
+  onClose: () => void
+  children: ReactNode
+}
+
+function focusable(root: HTMLElement | null): HTMLElement[] {
+  if (!root) return []
+  const sel = 'button, [href], input, select, textarea, [tabindex]:not([tabindex="-1"])'
+  return Array.from(root.querySelectorAll<HTMLElement>(sel)).filter(
+    (el) => !el.hasAttribute('disabled') && el.getAttribute('aria-hidden') !== 'true',
+  )
+}
+
+// Reusable modal shell: portal to <body>, ESC to close, Tab focus-trap,
+// focus-on-open (prefers [data-modal-autofocus]), focus restore on close,
+// click-on-overlay to close, and body scroll lock while open.
+export function Modal({ open, title, onClose, children }: ModalProps) {
+  const dialogRef = useRef<HTMLDivElement>(null)
+  const prevFocus = useRef<HTMLElement | null>(null)
+  const onCloseRef = useRef(onClose)
+  onCloseRef.current = onClose
+
+  useEffect(() => {
+    if (!open) return
+    prevFocus.current = document.activeElement as HTMLElement | null
+
+    const auto = dialogRef.current?.querySelector<HTMLElement>('[data-modal-autofocus]')
+    ;(auto ?? focusable(dialogRef.current)[0] ?? dialogRef.current)?.focus()
+
+    function onKeyDown(e: KeyboardEvent) {
+      if (e.key === 'Escape') {
+        e.preventDefault()
+        onCloseRef.current()
+        return
+      }
+      if (e.key !== 'Tab') return
+      const items = focusable(dialogRef.current)
+      if (items.length === 0) {
+        e.preventDefault()
+        return
+      }
+      const first = items[0]
+      const last = items[items.length - 1]
+      const active = document.activeElement as HTMLElement | null
+      const inside = dialogRef.current?.contains(active)
+      if (e.shiftKey) {
+        if (active === first || !inside) {
+          e.preventDefault()
+          last.focus()
+        }
+      } else if (active === last || !inside) {
+        e.preventDefault()
+        first.focus()
+      }
+    }
+
+    document.addEventListener('keydown', onKeyDown, true)
+    const prevOverflow = document.body.style.overflow
+    document.body.style.overflow = 'hidden'
+    return () => {
+      document.removeEventListener('keydown', onKeyDown, true)
+      document.body.style.overflow = prevOverflow
+      prevFocus.current?.focus?.()
+    }
+  }, [open])
+
+  if (!open) return null
+
+  return createPortal(
+    <div
+      className="modal-overlay"
+      onMouseDown={(e) => {
+        if (e.target === e.currentTarget) onClose()
+      }}
+    >
+      <div className="modal-dialog" role="dialog" aria-modal="true" aria-label={title} ref={dialogRef} tabIndex={-1}>
+        {title && <div className="modal-title">{title}</div>}
+        {children}
+      </div>
+    </div>,
+    document.body,
+  )
+}
diff --git a/web/src/main.tsx b/web/src/main.tsx
index bef5202..129cdbd 100644
--- a/web/src/main.tsx
+++ b/web/src/main.tsx
@@ -2,9 +2,12 @@ import { StrictMode } from 'react'
 import { createRoot } from 'react-dom/client'
 import './index.css'
 import App from './App.tsx'
+import { ConfirmProvider } from './components/ConfirmProvider'
 
 createRoot(document.getElementById('root')!).render(
   <StrictMode>
-    <App />
+    <ConfirmProvider>
+      <App />
+    </ConfirmProvider>
   </StrictMode>,
 )
diff --git a/web/src/pages/TaskDetail.tsx b/web/src/pages/TaskDetail.tsx
index 3e1cc05..4d8532e 100644
--- a/web/src/pages/TaskDetail.tsx
+++ b/web/src/pages/TaskDetail.tsx
@@ -2,6 +2,7 @@ import { useEffect, useRef, useState, type ChangeEvent, type FormEvent } from 'r
 import { createAccount, deleteAccount, getTask, importCSV, runTask, testAccounts, type TaskDetail as TaskDetailData } from '../api'
 import { connectTaskWS, type TaskEvent } from '../ws'
 import { StatusBadge } from '../components/StatusBadge'
+import { useConfirm } from '../components/ConfirmProvider'
 
 const emptyAccount = { src_login: '', src_pass: '', dst_login: '', dst_pass: '' }
 
@@ -40,6 +41,7 @@ export function TaskDetail({ id }: { id: number }) {
   const [log, setLog] = useState<{ type: string; text: string }[]>([])
   const [form, setForm] = useState(emptyAccount)
   const [busy, setBusy] = useState<'test' | 'run' | 'add' | 'import' | 'delete' | null>(null)
+  const confirm = useConfirm()
   const [error, setError] = useState<string | null>(null)
   const fileInputRef = useRef<HTMLInputElement>(null)
 
@@ -111,7 +113,13 @@ export function TaskDetail({ id }: { id: number }) {
   }
 
   async function onDeleteAccount(accId: number, login: string) {
-    if (!confirm(`Remove account "${login}" from this task?`)) return
+    const ok = await confirm({
+      title: 'Remove account',
+      message: `Remove account "${login}" from this task?`,
+      confirmLabel: 'Remove',
+      danger: true,
+    })
+    if (!ok) return
     setBusy('delete')
     setError(null)
     try {
diff --git a/web/src/pages/Tasks.tsx b/web/src/pages/Tasks.tsx
index 83f2c7a..8fc127c 100644
--- a/web/src/pages/Tasks.tsx
+++ b/web/src/pages/Tasks.tsx
@@ -1,6 +1,7 @@
 import { useEffect, useState, type FormEvent } from 'react'
 import { createTask, deleteTask, listEndpoints, listTasks, type Endpoint, type Task } from '../api'
 import { StatusBadge } from '../components/StatusBadge'
+import { useConfirm } from '../components/ConfirmProvider'
 
 export function Tasks() {
   const [tasks, setTasks] = useState<Task[] | null>(null)
@@ -10,6 +11,7 @@ export function Tasks() {
   const [dstId, setDstId] = useState('')
   const [error, setError] = useState<string | null>(null)
   const [busy, setBusy] = useState(false)
+  const confirm = useConfirm()
 
   function reload() {
     listTasks()
@@ -23,7 +25,13 @@ export function Tasks() {
   }, [])
 
   async function onDeleteTask(id: number, taskName: string) {
-    if (!confirm(`Delete task "${taskName}" and all its accounts?`)) return
+    const ok = await confirm({
+      title: 'Delete task',
+      message: `Delete task "${taskName}" and all its accounts?`,
+      confirmLabel: 'Delete',
+      danger: true,
+    })
+    if (!ok) return
     setError(null)
     try {
       await deleteTask(id)