Add real-time reminder alerts with snooze/dismiss

- Backend: GET /api/reminders/due endpoint, PATCH snooze endpoint,
  snoozed_until column + migration
- Frontend: useAlerts hook polls every 30s, fires Sonner toasts on
  non-dashboard pages (max 3 + summary), renders AlertBanner on
  dashboard below stats row
- Dashboard Active Reminders card filters out items shown in banner

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/alembic/versions/017_add_reminder_snoozed_until.py

@@ -0,0 +1,24 @@
+"""Add snoozed_until column to reminders
+
+Revision ID: 017
+Revises: 016
+Create Date: 2026-02-23
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = "017"
+down_revision = "016"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column("reminders", sa.Column("snoozed_until", sa.DateTime(), nullable=True))
+
+
+def downgrade() -> None:
+    op.drop_column("reminders", "snoozed_until")

backend/app/models/reminder.py

@@ -14,6 +14,7 @@ class Reminder(Base):
     remind_at: Mapped[Optional[datetime]] = mapped_column(nullable=True)
     is_active: Mapped[bool] = mapped_column(Boolean, default=True)
     is_dismissed: Mapped[bool] = mapped_column(Boolean, default=False)
+    snoozed_until: Mapped[Optional[datetime]] = mapped_column(nullable=True)
     recurrence_rule: Mapped[Optional[str]] = mapped_column(String(255), nullable=True)
     created_at: Mapped[datetime] = mapped_column(default=func.now())
     updated_at: Mapped[datetime] = mapped_column(default=func.now(), onupdate=func.now())

backend/app/routers/reminders.py

@@ -1,11 +1,13 @@
+from datetime import datetime, timedelta
+
 from fastapi import APIRouter, Depends, HTTPException, Query
 from sqlalchemy.ext.asyncio import AsyncSession
-from sqlalchemy import select
+from sqlalchemy import select, and_, or_
 from typing import Optional, List
 
 from app.database import get_db
 from app.models.reminder import Reminder
-from app.schemas.reminder import ReminderCreate, ReminderUpdate, ReminderResponse
+from app.schemas.reminder import ReminderCreate, ReminderUpdate, ReminderResponse, ReminderSnooze
 from app.routers.auth import get_current_session
 from app.models.settings import Settings
 
@@ -36,6 +38,52 @@ async def get_reminders(
     return reminders
 
 
+@router.get("/due", response_model=List[ReminderResponse])
+async def get_due_reminders(
+    db: AsyncSession = Depends(get_db),
+    current_user: Settings = Depends(get_current_session)
+):
+    """Get reminders that are currently due for alerting."""
+    now = datetime.now()
+    query = select(Reminder).where(
+        and_(
+            Reminder.remind_at <= now,
+            Reminder.is_dismissed == False,
+            Reminder.is_active == True,
+            Reminder.recurrence_rule.is_(None),
+            or_(
+                Reminder.snoozed_until.is_(None),
+                Reminder.snoozed_until <= now,
+            ),
+        )
+    ).order_by(Reminder.remind_at.asc())
+
+    result = await db.execute(query)
+    return result.scalars().all()
+
+
+@router.patch("/{reminder_id}/snooze", response_model=ReminderResponse)
+async def snooze_reminder(
+    reminder_id: int,
+    body: ReminderSnooze,
+    db: AsyncSession = Depends(get_db),
+    current_user: Settings = Depends(get_current_session)
+):
+    """Snooze a reminder for N minutes from now."""
+    result = await db.execute(select(Reminder).where(Reminder.id == reminder_id))
+    reminder = result.scalar_one_or_none()
+
+    if not reminder:
+        raise HTTPException(status_code=404, detail="Reminder not found")
+
+    reminder.snoozed_until = datetime.now() + timedelta(minutes=body.minutes)
+
+    await db.commit()
+    await db.refresh(reminder)
+
+    return reminder
+
+
 @router.post("/", response_model=ReminderResponse, status_code=201)
 async def create_reminder(
     reminder: ReminderCreate,

backend/app/schemas/reminder.py

@@ -1,6 +1,6 @@
 from pydantic import BaseModel, ConfigDict
 from datetime import datetime
-from typing import Optional
+from typing import Literal, Optional
 
 
 class ReminderCreate(BaseModel):
@@ -20,6 +20,10 @@ class ReminderUpdate(BaseModel):
     recurrence_rule: Optional[str] = None
 
 
+class ReminderSnooze(BaseModel):
+    minutes: Literal[5, 10, 15]
+
+
 class ReminderResponse(BaseModel):
     id: int
     title: str
@@ -27,6 +31,7 @@ class ReminderResponse(BaseModel):
     remind_at: Optional[datetime]
     is_active: bool
     is_dismissed: bool
+    snoozed_until: Optional[datetime] = None
     recurrence_rule: Optional[str]
     created_at: datetime
     updated_at: datetime

frontend/src/components/dashboard/AlertBanner.tsx

@@ -0,0 +1,71 @@
+import { Bell, X } from 'lucide-react';
+import type { Reminder } from '@/types';
+
+interface AlertBannerProps {
+  alerts: Reminder[];
+  onDismiss: (id: number) => void;
+  onSnooze: (id: number, minutes: 5 | 10 | 15) => void;
+}
+
+export default function AlertBanner({ alerts, onDismiss, onSnooze }: AlertBannerProps) {
+  if (alerts.length === 0) return null;
+
+  return (
+    <div className="rounded-lg border border-border border-l-4 border-l-orange-500 bg-card animate-slide-up">
+      <div className="flex items-center gap-2 px-4 py-2.5 border-b border-border">
+        <div className="p-1.5 rounded-md bg-orange-500/10">
+          <Bell className="h-4 w-4 text-orange-400" />
+        </div>
+        <span className="font-heading text-sm font-semibold">Alerts</span>
+        <span className="text-[10px] px-1.5 py-0.5 rounded-full bg-orange-500/15 text-orange-400 font-medium">
+          {alerts.length}
+        </span>
+      </div>
+      <div className="divide-y divide-border">
+        {alerts.map((alert) => (
+          <div
+            key={alert.id}
+            className="flex items-center gap-3 px-4 py-2 hover:bg-card-elevated transition-colors duration-150"
+          >
+            <div className="w-1.5 h-1.5 rounded-full bg-orange-400 shrink-0" />
+            <span className="text-sm font-medium truncate flex-1 min-w-0">{alert.title}</span>
+            <span className="text-[11px] text-muted-foreground shrink-0 whitespace-nowrap">
+              {alert.remind_at ? getRelativeTime(alert.remind_at) : ''}
+            </span>
+            <div className="flex items-center gap-0.5 text-[11px] shrink-0">
+              {([5, 10, 15] as const).map((m) => (
+                <button
+                  key={m}
+                  onClick={() => onSnooze(alert.id, m)}
+                  className="px-1.5 py-0.5 rounded bg-secondary hover:bg-accent/10 hover:text-accent text-muted-foreground transition-colors"
+                >
+                  {m}m
+                </button>
+              ))}
+            </div>
+            <button
+              onClick={() => onDismiss(alert.id)}
+              className="p-1 rounded hover:bg-accent/10 hover:text-accent text-muted-foreground transition-colors shrink-0"
+            >
+              <X className="h-3.5 w-3.5" />
+            </button>
+          </div>
+        ))}
+      </div>
+    </div>
+  );
+}
+
+function getRelativeTime(dateStr: string): string {
+  const date = new Date(dateStr);
+  const now = new Date();
+  const diffMs = now.getTime() - date.getTime();
+  const diffMins = Math.floor(diffMs / 60000);
+
+  if (diffMins < 1) return 'Just now';
+  if (diffMins < 60) return `${diffMins}m ago`;
+  const diffHours = Math.floor(diffMins / 60);
+  if (diffHours < 24) return `${diffHours}h ago`;
+  const diffDays = Math.floor(diffHours / 24);
+  return `${diffDays}d ago`;
+}

frontend/src/components/dashboard/DashboardPage.tsx

@@ -5,6 +5,7 @@ import { Bell, Plus, Calendar as CalIcon, ListTodo } from 'lucide-react';
 import api from '@/lib/api';
 import type { DashboardData, UpcomingResponse, WeatherData } from '@/types';
 import { useSettings } from '@/hooks/useSettings';
+import { useAlerts } from '@/hooks/useAlerts';
 import StatsWidget from './StatsWidget';
 import TodoWidget from './TodoWidget';
 import CalendarWidget from './CalendarWidget';
@@ -13,6 +14,7 @@ import WeekTimeline from './WeekTimeline';
 import DayBriefing from './DayBriefing';
 import CountdownWidget from './CountdownWidget';
 import TrackedProjectsWidget from './TrackedProjectsWidget';
+import AlertBanner from './AlertBanner';
 import EventForm from '../calendar/EventForm';
 import TodoForm from '../todos/TodoForm';
 import ReminderForm from '../reminders/ReminderForm';
@@ -32,6 +34,7 @@ function getGreeting(name?: string): string {
 
 export default function DashboardPage() {
   const { settings } = useSettings();
+  const { alerts, dismiss: dismissAlert, snooze: snoozeAlert } = useAlerts();
   const [quickAddType, setQuickAddType] = useState<'event' | 'todo' | 'reminder' | null>(null);
   const [dropdownOpen, setDropdownOpen] = useState(false);
   const dropdownRef = useRef<HTMLDivElement>(null);
@@ -178,6 +181,9 @@ export default function DashboardPage() {
             />
           </div>
 
+          {/* Alert Banner */}
+          <AlertBanner alerts={alerts} onDismiss={dismissAlert} onSnooze={snoozeAlert} />
+
           {/* Main Content — 2 columns */}
           <div className="grid gap-5 lg:grid-cols-5 animate-slide-up" style={{ animationDelay: '100ms', animationFillMode: 'backwards' }}>
             {/* Left: Upcoming feed (wider) */}
@@ -208,8 +214,12 @@ export default function DashboardPage() {
             </div>
           </div>
 
-          {/* Active Reminders */}
+          {/* Active Reminders — exclude those already shown in alert banner */}
-          {data.active_reminders.length > 0 && (
+          {(() => {
+            const alertIds = new Set(alerts.map((a) => a.id));
+            const futureReminders = data.active_reminders.filter((r) => !alertIds.has(r.id));
+            if (futureReminders.length === 0) return null;
+            return (
               <Card className="animate-slide-up" style={{ animationDelay: '150ms', animationFillMode: 'backwards' }}>
                 <CardHeader>
                   <CardTitle className="flex items-center gap-2">
@@ -221,7 +231,7 @@ export default function DashboardPage() {
                 </CardHeader>
                 <CardContent>
                   <div className="space-y-0.5">
-                  {data.active_reminders.map((reminder) => (
+                    {futureReminders.map((reminder) => (
                       <div
                         key={reminder.id}
                         className="flex items-center gap-2 py-1.5 px-2 rounded-md hover:bg-card-elevated transition-colors duration-150"
@@ -236,7 +246,8 @@ export default function DashboardPage() {
                   </div>
                 </CardContent>
               </Card>
-          )}
+            );
+          })()}
 
           {/* Tracked Projects */}
           <div className="animate-slide-up" style={{ animationDelay: '200ms', animationFillMode: 'backwards' }}>

frontend/src/components/layout/AppLayout.tsx

@@ -2,11 +2,13 @@ import { useState } from 'react';
 import { Outlet } from 'react-router-dom';
 import { Menu } from 'lucide-react';
 import { useTheme } from '@/hooks/useTheme';
+import { useAlerts } from '@/hooks/useAlerts';
 import { Button } from '@/components/ui/button';
 import Sidebar from './Sidebar';
 
 export default function AppLayout() {
   useTheme();
+  useAlerts();
   const [collapsed, setCollapsed] = useState(false);
   const [mobileOpen, setMobileOpen] = useState(false);
 

frontend/src/hooks/useAlerts.tsx

@@ -0,0 +1,188 @@
+import { useRef, useEffect, useCallback } from 'react';
+import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query';
+import { useLocation } from 'react-router-dom';
+import { toast } from 'sonner';
+import api from '@/lib/api';
+import type { Reminder } from '@/types';
+
+const MAX_TOASTS = 3;
+
+export function useAlerts() {
+  const queryClient = useQueryClient();
+  const location = useLocation();
+  const firedRef = useRef<Set<number>>(new Set());
+  const prevPathnameRef = useRef(location.pathname);
+  const isDashboard = location.pathname === '/' || location.pathname === '/dashboard';
+
+  const { data: alerts = [] } = useQuery<Reminder[]>({
+    queryKey: ['reminders', 'due'],
+    queryFn: async () => {
+      const { data } = await api.get<Reminder[]>('/reminders/due');
+      return data;
+    },
+    refetchInterval: 30_000,
+    staleTime: 0,
+    refetchIntervalInBackground: false,
+    refetchOnWindowFocus: true,
+  });
+
+  // Prune firedRef — remove IDs no longer in the response
+  useEffect(() => {
+    const currentIds = new Set(alerts.map((a) => a.id));
+    firedRef.current.forEach((id) => {
+      if (!currentIds.has(id)) {
+        firedRef.current.delete(id);
+        toast.dismiss(`reminder-${id}`);
+      }
+    });
+  }, [alerts]);
+
+  // Handle route changes
+  useEffect(() => {
+    const wasOnDashboard = prevPathnameRef.current === '/' || prevPathnameRef.current === '/dashboard';
+    const nowOnDashboard = isDashboard;
+    prevPathnameRef.current = location.pathname;
+
+    if (nowOnDashboard) {
+      // Moving TO dashboard — dismiss all toasts, banner takes over
+      alerts.forEach((a) => toast.dismiss(`reminder-${a.id}`));
+      toast.dismiss('reminder-summary');
+      firedRef.current.clear();
+    } else if (wasOnDashboard && !nowOnDashboard) {
+      // Moving AWAY from dashboard — fire toasts for current alerts
+      firedRef.current.clear();
+      fireToasts(alerts);
+    }
+  }, [location.pathname]); // eslint-disable-line react-hooks/exhaustive-deps
+
+  // Fire toasts for new alerts on non-dashboard pages
+  useEffect(() => {
+    if (isDashboard) return;
+    fireToasts(alerts);
+  }, [alerts, isDashboard]); // eslint-disable-line react-hooks/exhaustive-deps
+
+  function fireToasts(reminders: Reminder[]) {
+    const newAlerts = reminders.filter((a) => !firedRef.current.has(a.id));
+    if (newAlerts.length === 0) return;
+
+    const toShow = newAlerts.slice(0, MAX_TOASTS);
+    const overflow = newAlerts.length - MAX_TOASTS;
+
+    toShow.forEach((reminder) => {
+      firedRef.current.add(reminder.id);
+      toast.custom(
+        (t) => renderToast(t, reminder),
+        { id: `reminder-${reminder.id}`, duration: Infinity }
+      );
+    });
+
+    // Mark remaining as fired to prevent re-firing
+    newAlerts.slice(MAX_TOASTS).forEach((a) => firedRef.current.add(a.id));
+
+    if (overflow > 0) {
+      toast.custom(
+        (t) => renderSummaryToast(t, overflow),
+        { id: 'reminder-summary', duration: Infinity }
+      );
+    }
+  }
+
+  function renderToast(_t: string | number, reminder: Reminder) {
+    const timeAgo = reminder.remind_at ? getRelativeTime(reminder.remind_at) : '';
+    return (
+      <div className="flex items-start gap-3 bg-card border border-border rounded-lg p-3 shadow-lg w-[356px]">
+        <div className="p-1.5 rounded-md bg-orange-500/10 shrink-0 mt-0.5">
+          <svg className="h-4 w-4 text-orange-400" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round">
+            <path d="M6 8a6 6 0 0 1 12 0c0 7 3 9 3 9H3s3-2 3-9" /><path d="M10.3 21a1.94 1.94 0 0 0 3.4 0" />
+          </svg>
+        </div>
+        <div className="flex-1 min-w-0">
+          <p className="text-sm font-medium text-foreground truncate">{reminder.title}</p>
+          <p className="text-xs text-muted-foreground mt-0.5">{timeAgo}</p>
+          <div className="flex items-center gap-1.5 mt-2">
+            <div className="flex items-center gap-0.5 text-[11px]">
+              {[5, 10, 15].map((m) => (
+                <button
+                  key={m}
+                  onClick={() => handleSnooze(reminder.id, m as 5 | 10 | 15)}
+                  className="px-1.5 py-0.5 rounded bg-secondary hover:bg-card-elevated text-muted-foreground hover:text-foreground transition-colors"
+                >
+                  {m}m
+                </button>
+              ))}
+            </div>
+            <button
+              onClick={() => handleDismiss(reminder.id)}
+              className="ml-auto px-2 py-0.5 rounded text-[11px] bg-secondary hover:bg-card-elevated text-muted-foreground hover:text-foreground transition-colors"
+            >
+              Dismiss
+            </button>
+          </div>
+        </div>
+      </div>
+    );
+  }
+
+  function renderSummaryToast(_t: string | number, count: number) {
+    return (
+      <div className="flex items-center gap-3 bg-card border border-border rounded-lg p-3 shadow-lg w-[356px]">
+        <div className="p-1.5 rounded-md bg-orange-500/10 shrink-0">
+          <svg className="h-4 w-4 text-orange-400" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round">
+            <path d="M6 8a6 6 0 0 1 12 0c0 7 3 9 3 9H3s3-2 3-9" /><path d="M10.3 21a1.94 1.94 0 0 0 3.4 0" />
+          </svg>
+        </div>
+        <p className="text-sm text-muted-foreground">
+          +{count} more reminder{count > 1 ? 's' : ''} due
+        </p>
+      </div>
+    );
+  }
+
+  const dismissMutation = useMutation({
+    mutationFn: (id: number) => api.patch(`/reminders/${id}/dismiss`),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ['reminders'] });
+      queryClient.invalidateQueries({ queryKey: ['dashboard'] });
+    },
+  });
+
+  const snoozeMutation = useMutation({
+    mutationFn: ({ id, minutes }: { id: number; minutes: 5 | 10 | 15 }) =>
+      api.patch(`/reminders/${id}/snooze`, { minutes }),
+    onSuccess: () => {
+      queryClient.invalidateQueries({ queryKey: ['reminders'] });
+      queryClient.invalidateQueries({ queryKey: ['dashboard'] });
+    },
+  });
+
+  const handleDismiss = useCallback((id: number) => {
+    toast.dismiss(`reminder-${id}`);
+    firedRef.current.delete(id);
+    dismissMutation.mutate(id);
+    // If summary toast exists and we're reducing count, dismiss it too — next poll will re-evaluate
+    toast.dismiss('reminder-summary');
+  }, [dismissMutation]);
+
+  const handleSnooze = useCallback((id: number, minutes: 5 | 10 | 15) => {
+    toast.dismiss(`reminder-${id}`);
+    firedRef.current.delete(id);
+    snoozeMutation.mutate({ id, minutes });
+    toast.dismiss('reminder-summary');
+  }, [snoozeMutation]);
+
+  return { alerts, dismiss: handleDismiss, snooze: handleSnooze };
+}
+
+function getRelativeTime(dateStr: string): string {
+  const date = new Date(dateStr);
+  const now = new Date();
+  const diffMs = now.getTime() - date.getTime();
+  const diffMins = Math.floor(diffMs / 60000);
+
+  if (diffMins < 1) return 'Just now';
+  if (diffMins < 60) return `${diffMins}m ago`;
+  const diffHours = Math.floor(diffMins / 60);
+  if (diffHours < 24) return `${diffHours}h ago`;
+  const diffDays = Math.floor(diffHours / 24);
+  return `${diffDays}d ago`;
+}

frontend/src/types/index.ts

@@ -85,6 +85,7 @@ export interface Reminder {
   remind_at?: string;
   is_active: boolean;
   is_dismissed: boolean;
+  snoozed_until?: string | null;
   recurrence_rule?: string;
   created_at: string;
   updated_at: string;