diff --git a/web/src/App.tsx b/web/src/App.tsx
index 2c31c06..b1a126b 100644
--- a/web/src/App.tsx
+++ b/web/src/App.tsx
@@ -24,6 +24,15 @@ const SettingsTab = lazy(() =>
 const ContactsTab = lazy(() =>
   import('./tabs/Contacts').then((m) => ({ default: m.ContactsTab })),
 );
+const CalendarTab = lazy(() =>
+  import('./tabs/Calendar').then((m) => ({ default: m.CalendarTab })),
+);
+const RemindersTab = lazy(() =>
+  import('./tabs/Reminders').then((m) => ({ default: m.RemindersTab })),
+);
+const NotesTab = lazy(() =>
+  import('./tabs/Notes').then((m) => ({ default: m.NotesTab })),
+);
 
 const queryClient = new QueryClient({
   defaultOptions: {
@@ -68,6 +77,9 @@ export function App(): ReactElement {
               <Route path="/messages" element={<MessagesTab />} />
               <Route path="/photos" element={<PhotosTab />} />
               <Route path="/mail" element={<MailTab />} />
+              <Route path="/calendar" element={<CalendarTab />} />
+              <Route path="/reminders" element={<RemindersTab />} />
+              <Route path="/notes" element={<NotesTab />} />
               <Route path="/contacts" element={<ContactsTab />} />
               <Route path="/settings" element={<SettingsTab />} />
               <Route path="*" element={<Navigate to="/dashboard" replace />} />
diff --git a/web/src/api/client.ts b/web/src/api/client.ts
index a85a1d9..6db1476 100644
--- a/web/src/api/client.ts
+++ b/web/src/api/client.ts
@@ -96,3 +96,23 @@ export async function apiPost<T>(path: string, body?: unknown): Promise<T> {
     throw new ApiError(0, path);
   }
 }
+
+export async function apiDelete<T>(path: string): Promise<T> {
+  try {
+    const base = getBaseUrl(path);
+    const headers: HeadersInit = {};
+    if (serviceToken && isUpstreamPath(path)) {
+      headers['Authorization'] = `Bearer ${serviceToken}`;
+    }
+    const res = await fetch(`${base}${path}`, {
+      method: 'DELETE',
+      credentials: 'include',
+      headers,
+    });
+    if (!res.ok) throw new ApiError(res.status, path);
+    return res.json() as Promise<T>;
+  } catch (err) {
+    if (err instanceof ApiError) throw err;
+    throw new ApiError(0, path);
+  }
+}
diff --git a/web/src/api/mail.ts b/web/src/api/mail.ts
index 1447114..b3f520a 100644
--- a/web/src/api/mail.ts
+++ b/web/src/api/mail.ts
@@ -1,4 +1,4 @@
-import { apiGet } from './client';
+import { apiGet, apiPost } from './client';
 import type { Conversation, Message } from '@/types';
 
 export async function fetchMailConversations(deviceId?: string): Promise<Conversation[]> {
@@ -19,3 +19,33 @@ export async function fetchMailThread(conversationId: string, limit = 100, since
     throw err instanceof Error ? err : new Error('fetchMailThread failed');
   }
 }
+
+export interface SendMailInput {
+  readonly to: string;
+  readonly cc?: readonly string[];
+  readonly bcc?: readonly string[];
+  readonly subject: string;
+  readonly body: string;
+  readonly isHtml?: boolean;
+}
+
+export interface SendMailResult {
+  readonly sendQueueId: string;
+}
+
+interface Envelope<T> {
+  readonly success: boolean;
+  readonly data: T;
+}
+
+export async function sendMail(input: SendMailInput, deviceId: string): Promise<SendMailResult> {
+  try {
+    const res = await apiPost<Envelope<SendMailResult>>(
+      `/my/mail/send?deviceId=${encodeURIComponent(deviceId)}`,
+      input,
+    );
+    return res.data;
+  } catch (err) {
+    throw err instanceof Error ? err : new Error('sendMail failed');
+  }
+}
diff --git a/web/src/layout/AppShell.tsx b/web/src/layout/AppShell.tsx
index 7ed0061..1c98f69 100644
--- a/web/src/layout/AppShell.tsx
+++ b/web/src/layout/AppShell.tsx
@@ -1,7 +1,17 @@
 import { type ReactElement, type ReactNode } from 'react';
 import { NavLink } from '@lilith/ui-router';
 import styled from '@lilith/ui-styled-components';
-import { BarChart3, MessageSquare, Image, Mail, Settings, Users } from 'lucide-react';
+import {
+  BarChart3,
+  Calendar,
+  CheckSquare,
+  FileText,
+  Image,
+  Mail,
+  MessageSquare,
+  Settings,
+  Users,
+} from 'lucide-react';
 import { GlobalSearch } from '@/components/GlobalSearch';
 
 const TOKENS = {
@@ -21,6 +31,9 @@ const NAV_ITEMS: { to: string; label: string; end: boolean; icon: ReactNode }[]
   { to: '/contacts', label: 'Contacts', end: false, icon: <Users size={16} /> },
   { to: '/photos', label: 'Photos', end: false, icon: <Image size={16} /> },
   { to: '/mail', label: 'Mail', end: false, icon: <Mail size={16} /> },
+  { to: '/calendar', label: 'Calendar', end: false, icon: <Calendar size={16} /> },
+  { to: '/reminders', label: 'Reminders', end: false, icon: <CheckSquare size={16} /> },
+  { to: '/notes', label: 'Notes', end: false, icon: <FileText size={16} /> },
   { to: '/settings', label: 'Settings', end: false, icon: <Settings size={16} /> },
 ];
 
diff --git a/web/src/tabs/Mail/index.tsx b/web/src/tabs/Mail/index.tsx
index baded02..45d85a1 100644
--- a/web/src/tabs/Mail/index.tsx
+++ b/web/src/tabs/Mail/index.tsx
@@ -1,13 +1,19 @@
-import { useEffect, useState, type ReactElement } from 'react';
+import { useEffect, useState, type FormEvent, type ReactElement } from 'react';
 import styled from '@lilith/ui-styled-components';
-import { Mail } from 'lucide-react';
+import { Mail, Plus } from 'lucide-react';
+import { useMutation, useQueryClient } from '@tanstack/react-query';
 import { useSearchParams } from '@lilith/ui-router';
 import { useMailConversations } from '@/hooks/useMail';
+import { sendMail, type SendMailInput } from '@/api/mail';
 import { MailList } from './MailList';
 import { MailThread } from './MailThread';
 import { EmptyState } from '@/components/EmptyState';
 import { PageError } from '@/components/PageError';
 
+// Server-side `/my/mail/send` requires a deviceId. Once SSO-driven device
+// resolution lands on the web side this will source from the session.
+const DEVICE_ID: string | undefined = undefined;
+
 const Root = styled.div`
   display: flex;
   flex-direction: column;
@@ -22,6 +28,30 @@ const PageHeading = styled.h1`
   color: #e0e0f0;
   border-bottom: 1px solid #2a2a38;
   background: #0a0a0f;
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+`;
+
+const Toolbar = styled.div`
+  padding: 8px 20px;
+  border-bottom: 1px solid #2a2a38;
+  background: #0a0a0f;
+`;
+
+const PrimaryButton = styled.button`
+  background: #4a4af0;
+  border: none;
+  color: white;
+  font-size: 12px;
+  font-weight: 600;
+  padding: 6px 12px;
+  border-radius: 6px;
+  cursor: pointer;
+  display: inline-flex;
+  align-items: center;
+  gap: 4px;
+  &:disabled { opacity: 0.5; cursor: not-allowed; }
 `;
 
 const Body = styled.div`
@@ -65,34 +95,190 @@ const SpinnerWrap = styled.div`
   text-align: center;
 `;
 
+const FormCard = styled.form`
+  display: flex;
+  flex-direction: column;
+  gap: 10px;
+  padding: 16px 20px;
+  border-bottom: 1px solid #2a2a38;
+  background: #0d0d14;
+`;
+
+const Field = styled.label`
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+  font-size: 11px;
+  color: #a0a0b0;
+`;
+
+const TextInput = styled.input`
+  background: #18182a;
+  border: 1px solid #2a2a38;
+  color: #e0e0f0;
+  border-radius: 6px;
+  padding: 6px 8px;
+  font-size: 13px;
+`;
+
+const TextArea = styled.textarea`
+  background: #18182a;
+  border: 1px solid #2a2a38;
+  color: #e0e0f0;
+  border-radius: 6px;
+  padding: 8px;
+  font-size: 13px;
+  font-family: inherit;
+  min-height: 120px;
+  resize: vertical;
+`;
+
+const ButtonRow = styled.div`
+  display: flex;
+  gap: 8px;
+  align-items: center;
+`;
+
+const Ghost = styled.button`
+  background: transparent;
+  color: #a0a0b0;
+  border: 1px solid #2a2a38;
+  font-size: 12px;
+  padding: 6px 12px;
+  border-radius: 6px;
+  cursor: pointer;
+`;
+
+const StatusLine = styled.span<{ $variant: 'info' | 'error' | 'success' }>`
+  font-size: 11px;
+  color: ${(p) =>
+    p.$variant === 'success' ? '#7ad97a' : p.$variant === 'error' ? '#e07a7a' : '#8a8a9a'};
+`;
+
+interface ComposeState {
+  to: string;
+  subject: string;
+  body: string;
+}
+
+const blankForm = (): ComposeState => ({ to: '', subject: '', body: '' });
+
 export function MailTab(): ReactElement {
   const [searchParams] = useSearchParams();
   const convParam = searchParams.get('conv');
-
   const [selectedId, setSelectedId] = useState<string | null>(convParam);
-  const { data, isLoading, error } = useMailConversations();
+  const [composing, setComposing] = useState(false);
+  const [form, setForm] = useState<ComposeState>(blankForm);
 
   useEffect(() => {
     if (convParam) setSelectedId(convParam);
   }, [convParam]);
+  const { data, isLoading, error } = useMailConversations();
+  const qc = useQueryClient();
 
-  const threads = Array.isArray(data) ? data : [];
-  const selected = threads.find((c) => c.id === selectedId) ?? null;
+  const selected = data?.find((c) => c.id === selectedId) ?? null;
+
+  const sendMut = useMutation({
+    mutationFn: (input: SendMailInput) => sendMail(input, DEVICE_ID ?? ''),
+    onSuccess: () => {
+      setForm(blankForm());
+      setComposing(false);
+      qc.invalidateQueries({ queryKey: ['mail-conversations'] });
+    },
+  });
+
+  const onSubmit = (e: FormEvent<HTMLFormElement>): void => {
+    e.preventDefault();
+    if (!form.to || !form.subject || !form.body) return;
+    sendMut.mutate({ to: form.to, subject: form.subject, body: form.body });
+  };
+
+  const cancel = (): void => {
+    setForm(blankForm());
+    setComposing(false);
+    sendMut.reset();
+  };
 
   return (
     <Root>
-      <PageHeading>Mail</PageHeading>
+      <PageHeading>
+        <span>Mail</span>
+      </PageHeading>
+      <Toolbar>
+        <PrimaryButton
+          type="button"
+          onClick={() => setComposing(true)}
+          disabled={composing || sendMut.isPending}
+        >
+          <Plus size={13} /> Compose
+        </PrimaryButton>
+      </Toolbar>
+
+      {composing && (
+        <FormCard onSubmit={onSubmit}>
+          <Field>
+            <span>To</span>
+            <TextInput
+              type="email"
+              required
+              value={form.to}
+              onChange={(e) => setForm({ ...form, to: e.target.value })}
+              placeholder="alice@example.com"
+              disabled={sendMut.isPending}
+            />
+          </Field>
+          <Field>
+            <span>Subject</span>
+            <TextInput
+              type="text"
+              required
+              value={form.subject}
+              onChange={(e) => setForm({ ...form, subject: e.target.value })}
+              disabled={sendMut.isPending}
+            />
+          </Field>
+          <Field>
+            <span>Body</span>
+            <TextArea
+              required
+              value={form.body}
+              onChange={(e) => setForm({ ...form, body: e.target.value })}
+              disabled={sendMut.isPending}
+            />
+          </Field>
+          <ButtonRow>
+            <PrimaryButton type="submit" disabled={sendMut.isPending || !DEVICE_ID}>
+              {sendMut.isPending ? 'Queuing…' : 'Send'}
+            </PrimaryButton>
+            <Ghost type="button" onClick={cancel} disabled={sendMut.isPending}>
+              Cancel
+            </Ghost>
+            {!DEVICE_ID && (
+              <StatusLine $variant="info">
+                Set DEVICE_ID before sending (no SSO device resolution yet).
+              </StatusLine>
+            )}
+            {sendMut.isError && (
+              <StatusLine $variant="error">
+                {sendMut.error instanceof Error ? sendMut.error.message : 'Send failed'}
+              </StatusLine>
+            )}
+            {sendMut.isSuccess && <StatusLine $variant="success">Queued for delivery.</StatusLine>}
+          </ButtonRow>
+        </FormCard>
+      )}
+
       <Body>
         <SidePanel aria-label="Email thread list">
           {isLoading && <SpinnerWrap aria-live="polite">Loading…</SpinnerWrap>}
           {error && <PageError message="Failed to load email threads" />}
-          {!isLoading && !error && threads.length === 0 && (
+          {!isLoading && !error && data?.length === 0 && (
             <EmptyState icon={<Mail size={28} />} heading="No emails" sub="Email threads will appear here once sync runs." />
           )}
-          {!isLoading && !error && threads.length > 0 && (
+          {!isLoading && !error && data && data.length > 0 && (
             <>
-              <ThreadCount>{threads.length} thread{threads.length !== 1 ? 's' : ''}</ThreadCount>
-              <MailList conversations={threads} selectedId={selectedId} onSelect={setSelectedId} />
+              <ThreadCount>{data.length} thread{data.length !== 1 ? 's' : ''}</ThreadCount>
+              <MailList conversations={data} selectedId={selectedId} onSelect={setSelectedId} />
             </>
           )}
         </SidePanel>