diff --git a/frontend/src/components/ComposeDock.jsx b/frontend/src/components/ComposeDock.jsx
index c84c902..053c7d5 100644
--- a/frontend/src/components/ComposeDock.jsx
+++ b/frontend/src/components/ComposeDock.jsx
@@ -25,7 +25,7 @@ export default function ComposeDock({ account, onSent, agentOpen = true }) {
   const focusRef = useRef(null);
   const viewport = useViewport();
 
-  const agentReserve = agentOpen && viewport.width >= 960 ? AGENT_PANEL_WIDTH + MAIL_GAP : 0;
+  const agentReserve = agentOpen && viewport.width >= 1200 ? AGENT_PANEL_WIDTH + MAIL_GAP : 0;
   const dockRight = agentReserve + 16;
 
   const expandedWindows = useMemo(
diff --git a/frontend/src/components/DashboardPage.jsx b/frontend/src/components/DashboardPage.jsx
index 8d49a1d..45b4d81 100644
--- a/frontend/src/components/DashboardPage.jsx
+++ b/frontend/src/components/DashboardPage.jsx
@@ -28,6 +28,8 @@ import {
 import { useCallback, useEffect, useState } from "react";
 import { getCurrentAccount, getMyCompanyDomain } from "../api";
 import Brand from "./Brand";
+import MobileChrome from "./MobileChrome";
+import { ShellModeContext } from "../shellMode";
 import CompanyDnsSetup from "./CompanyDnsSetup";
 import CompanyDomains from "./CompanyDomains";
 import CompanyAdministrators from "./CompanyAdministrators";
@@ -110,6 +112,7 @@ export default function DashboardPage() {
   const [domainError, setDomainError] = useState("");
   const [active, setActive] = useState("Inbox");
   const [menuOpen, setMenuOpen] = useState(false);
+  const [sheet, setSheet] = useState(null);
   const [notice, setNotice] = useState("");
   const [loading, setLoading] = useState(true);
   const [mailRefreshKey, setMailRefreshKey] = useState(0);
@@ -174,6 +177,7 @@ export default function DashboardPage() {
     setCompanyActive(label);
     setAgentNav(null);
     setMenuOpen(false);
+    setSheet(null);
   }
 
   function selectMailItem(item) {
@@ -190,6 +194,7 @@ export default function DashboardPage() {
       setLens("all");
     }
     setMenuOpen(false);
+    setSheet(null);
   }
 
   function selectLabel(name) {
@@ -198,6 +203,7 @@ export default function DashboardPage() {
     setActive("Inbox");
     setLens(name);
     setMenuOpen(false);
+    setSheet(null);
   }
 
   function selectAgentItem(item, actionKey) {
@@ -206,6 +212,32 @@ export default function DashboardPage() {
     setLens("all");
     setAgentNav(actionKey);
     setMenuOpen(false);
+    const compact = window.matchMedia("(max-width: 1199px)").matches;
+    setSheet(actionKey === "handoff" || !compact ? null : "agent");
+  }
+
+  function openAgentDestination(actionKey) {
+    setCompanyActive(null);
+    setActive("Inbox");
+    setLens("all");
+    setAgentNav(actionKey);
+    setMenuOpen(false);
+    setSheet("agent");
+  }
+
+  function showMailboxForSheet() {
+    setCompanyActive(null);
+    setActive("Inbox");
+    setLens("all");
+    setMenuOpen(false);
+  }
+
+  function openSheet(next) {
+    if (next === "agent" || next === "calendar" || next === "notes") {
+      showMailboxForSheet();
+      setAgentNav(next === "agent" ? "ask" : null);
+    }
+    setSheet(next);
   }
 
   function openCompose(context = null) {
@@ -277,10 +309,15 @@ export default function DashboardPage() {
         : active;
 
   return (
-    <div className="dashboard">
+    <ShellModeContext.Provider value={{ sheet, setSheet }}>
+    <div
+      className="dashboard"
+      data-sheet={sheet || undefined}
+      data-onboarding={isOrgOnboarding ? "true" : undefined}
+    >
       <header className="dashboard-mobile-header">
         <Brand />
-        <button aria-label="Open navigation" type="button" onClick={() => setMenuOpen(true)}>
+        <button aria-label="Open navigation" type="button" onClick={() => { setSheet(null); setMenuOpen(true); }}>
           <Menu size={21} />
         </button>
       </header>
@@ -525,7 +562,31 @@ export default function DashboardPage() {
           }}
         />
       )}
+      {sheet && sheet !== "more" && (
+        <button className="shell-drawer-scrim" type="button" aria-label="Close panel" onClick={() => setSheet(null)} />
+      )}
+      {!isOrgOnboarding && (
+        <MobileChrome
+          sheet={sheet}
+          mailActive={!sheet && !companyActive && agentNav !== "handoff"}
+          account={account}
+          onMail={() => selectMailItem("Inbox")}
+          onAgent={() => openSheet("agent")}
+          onCompose={() => openCompose()}
+          onCalendar={() => openSheet("calendar")}
+          onMore={() => setSheet((current) => (current === "more" ? null : "more"))}
+          onClose={() => setSheet(null)}
+          onSettings={() => selectMailItem("Settings")}
+          onNotes={() => openSheet("notes")}
+          onHandoff={() => selectAgentItem("Human Handoff", "handoff")}
+          onActionItems={() => openAgentDestination("actions")}
+          onSummaries={() => openAgentDestination("summaries")}
+          onIntegrations={() => openAgentDestination("integrations")}
+          onLogout={logout}
+        />
+      )}
       <ComposeDock account={account} onSent={emailSent} agentOpen={!companyActive} />
     </div>
+    </ShellModeContext.Provider>
   );
 }
diff --git a/frontend/src/components/MailboxView.jsx b/frontend/src/components/MailboxView.jsx
index 18ac6c1..a3e082f 100644
--- a/frontend/src/components/MailboxView.jsx
+++ b/frontend/src/components/MailboxView.jsx
@@ -11,6 +11,7 @@ import {
   RefreshCw,
   Search,
   Settings,
+  Sparkles,
   Sun,
   Tag,
   Users,
@@ -37,6 +38,8 @@ import MailRow from "./MailRow";
 import MailboxEmptyState from "./MailboxEmptyState";
 import MailboxSelectionBar from "./MailboxSelectionBar";
 import StickyNotesPanel from "./StickyNotesPanel";
+import { useShellMode } from "../shellMode";
+import { shellTitle } from "./MobileChrome";
 import {
   categoryCounts,
   emailCategory,
@@ -118,6 +121,7 @@ export default function MailboxView({
   onStats,
 }) {
   const token = sessionStorage.getItem("agmail_access_token");
+  const { sheet, setSheet } = useShellMode();
   const [emails, setEmails] = useState([]);
   const [nextCursor, setNextCursor] = useState(null);
   const [total, setTotal] = useState(0);
@@ -679,6 +683,14 @@ export default function MailboxView({
           <button className="workspace-ask agent-action" type="button" onClick={() => runQuickAction("summarize")}>
             <AgentSpark /> Ask Agent
           </button>
+          <button
+            className="shell-agent-toggle"
+            type="button"
+            aria-label="Open AG Agent"
+            onClick={() => setSheet(sheet === "agent" ? null : "agent")}
+          >
+            <Sparkles size={16} />
+          </button>
         </div>
         <div className="workspace-zone workspace-zone-account">
           <button type="button" className="workspace-icon" aria-label="Refresh" onClick={load}><RefreshCw size={16} /></button>
@@ -840,7 +852,7 @@ export default function MailboxView({
                 </div>
               )}
 
-              <div className={`mailbox-rows${isEmpty ? " is-empty" : ""}`} aria-busy={status.loading}>
+              <div className={`mailbox-rows${isEmpty ? " is-empty" : ""}${selectedCount > 0 ? " selecting" : ""}`} aria-busy={status.loading}>
                 {status.loading && <div className="mailbox-state loading">Loading messages…</div>}
                 {status.error && (
                   <div className="mailbox-state error" role="alert">
@@ -916,7 +928,15 @@ export default function MailboxView({
           </div>
         </div>
 
-        <aside className="mailbox-rail">
+        <aside className={`mailbox-rail${sheet ? ` shell-${sheet}` : ""}`}>
+          {(sheet === "agent" || sheet === "calendar" || sheet === "notes") && (
+            <div className="shell-sheet-bar">
+              <button type="button" aria-label="Back" onClick={() => setSheet(null)}>
+                <ChevronLeft size={18} strokeWidth={1.75} />
+              </button>
+              <strong>{shellTitle(sheet)}</strong>
+            </div>
+          )}
           <AgAgentPanel
             account={account}
             emails={listedEmails}
diff --git a/frontend/src/components/MobileChrome.jsx b/frontend/src/components/MobileChrome.jsx
new file mode 100644
index 0000000..214b08e
--- /dev/null
+++ b/frontend/src/components/MobileChrome.jsx
@@ -0,0 +1,101 @@
+import {
+  CalendarDays,
+  CircleHelp,
+  HandHelping,
+  Inbox,
+  ListChecks,
+  LogOut,
+  MoreHorizontal,
+  Plug,
+  Plus,
+  Settings,
+  Sparkles,
+  StickyNote,
+  Sun,
+} from "lucide-react";
+
+const SHEET_LABEL = {
+  agent: "AG Agent",
+  calendar: "Calendar",
+  notes: "Notes",
+};
+
+export function shellTitle(sheet) {
+  return SHEET_LABEL[sheet] || "";
+}
+
+export default function MobileChrome({
+  sheet,
+  mailActive,
+  account,
+  onMail,
+  onAgent,
+  onCompose,
+  onCalendar,
+  onMore,
+  onClose,
+  onSettings,
+  onNotes,
+  onHandoff,
+  onActionItems,
+  onSummaries,
+  onIntegrations,
+  onLogout,
+}) {
+  return (
+    <>
+      <nav className="mobile-bottom-nav" aria-label="App">
+        <button type="button" className={mailActive ? "active" : ""} onClick={onMail}>
+          <Inbox size={18} strokeWidth={1.75} />
+          <span>Mail</span>
+        </button>
+        <button type="button" className={sheet === "agent" ? "active" : ""} onClick={onAgent}>
+          <Sparkles size={18} strokeWidth={1.75} />
+          <span>Agent</span>
+        </button>
+        <button type="button" className="mobile-bottom-compose" onClick={onCompose}>
+          <span className="mobile-bottom-plus" aria-hidden="true"><Plus size={20} strokeWidth={2} /></span>
+          <span>Compose</span>
+        </button>
+        <button type="button" className={sheet === "calendar" ? "active" : ""} onClick={onCalendar}>
+          <CalendarDays size={18} strokeWidth={1.75} />
+          <span>Calendar</span>
+        </button>
+        <button type="button" className={sheet === "more" || sheet === "notes" ? "active" : ""} onClick={onMore}>
+          <MoreHorizontal size={18} strokeWidth={1.75} />
+          <span>More</span>
+        </button>
+      </nav>
+
+      {sheet === "more" && (
+        <div className="mobile-more-layer">
+          <button type="button" className="mobile-more-scrim" aria-label="Close more" onClick={onClose} />
+          <section className="mobile-more-sheet" role="dialog" aria-label="More">
+            <header className="mobile-more-head">
+              <strong>More</strong>
+              <button type="button" onClick={onClose} aria-label="Close">Close</button>
+            </header>
+            <div className="mobile-more-account">
+              <span>{account.first_name[0]}{account.last_name[0]}</span>
+              <div>
+                <strong>{account.first_name} {account.last_name}</strong>
+                <small>{account.email}</small>
+              </div>
+              <button type="button" aria-label="Log out" onClick={onLogout}><LogOut size={16} /></button>
+            </div>
+            <p>Workspace</p>
+            <button type="button" onClick={onSettings}><Settings size={16} /> Settings</button>
+            <button type="button" onClick={onNotes}><StickyNote size={16} /> Notes</button>
+            <button type="button" onClick={onClose}><CircleHelp size={16} /> Help</button>
+            <button type="button" onClick={onIntegrations}><Plug size={16} /> Integrations</button>
+            <button type="button" onClick={onClose}><Sun size={16} /> Appearance</button>
+            <p>Agent</p>
+            <button type="button" onClick={onHandoff}><HandHelping size={16} /> Human Handoff</button>
+            <button type="button" onClick={onActionItems}><ListChecks size={16} /> Action Items</button>
+            <button type="button" onClick={onSummaries}><Sparkles size={16} /> Summaries</button>
+          </section>
+        </div>
+      )}
+    </>
+  );
+}
diff --git a/frontend/src/main.jsx b/frontend/src/main.jsx
index 1202ac7..c26d223 100644
--- a/frontend/src/main.jsx
+++ b/frontend/src/main.jsx
@@ -2,6 +2,7 @@ import React from "react";
 import ReactDOM from "react-dom/client";
 import App from "./App";
 import "./styles.css";
+import "./responsive.css";
 
 ReactDOM.createRoot(document.getElementById("root")).render(
   <React.StrictMode>
diff --git a/frontend/src/responsive.css b/frontend/src/responsive.css
new file mode 100644
index 0000000..9397be9
--- /dev/null
+++ b/frontend/src/responsive.css
@@ -0,0 +1,473 @@
+/* Responsive presentation only. Desktop rules at min-width 1200px stay in styles.css. */
+
+.mobile-bottom-nav,
+.shell-agent-toggle,
+.shell-drawer-scrim,
+.shell-sheet-bar,
+.mobile-more-layer { display:none; }
+
+@media (min-width:768px) and (max-width:1199px) {
+  html,body { overflow-x:clip; }
+  .dashboard { display:grid; grid-template-columns:72px minmax(0,1fr); overflow-x:clip; }
+  .dashboard-mobile-header { display:none; }
+  .dashboard-sidebar {
+    width:72px;
+    position:sticky;
+    top:0;
+    left:auto;
+    transform:none;
+    padding:16px 8px 12px;
+    z-index:12;
+  }
+  .dashboard-brand-row { justify-content:center; padding:0; }
+  .dashboard-brand-row .brand > span:not(.brand-mark),
+  .dashboard-compose span,
+  .dashboard-sidebar-section h2,
+  .dashboard-nav-item em,
+  .dashboard-profile > div { position:absolute; width:1px; height:1px; padding:0; margin:-1px; overflow:hidden; clip:rect(0,0,0,0); white-space:nowrap; border:0; }
+  .dashboard-brand-row > button,
+  .dashboard-profile > button { display:none; }
+  .dashboard-compose { width:44px; min-height:40px; margin:16px auto 0; padding:0; }
+  .dashboard-nav-item { justify-content:center; padding:0; gap:0; }
+  .dashboard-nav-item span { position:absolute; width:1px; height:1px; overflow:hidden; clip:rect(0,0,0,0); }
+  .dashboard-profile { grid-template-columns:34px; justify-content:center; padding-left:0; padding-right:0; }
+  .dashboard-content { min-width:0; padding:12px 12px 16px; }
+  .workspace-header { display:flex; flex-wrap:wrap; height:auto; min-height:56px; }
+  .workspace-zone-command { flex:1 1 220px; }
+  .workspace-zone-command .workspace-search { width:100%; max-width:none; }
+  .workspace-account div,
+  .workspace-account > svg { display:none; }
+  .mailbox-stage { grid-template-columns:minmax(0,1fr); }
+  .mailbox-rail {
+    display:flex;
+    position:fixed;
+    top:0;
+    right:0;
+    bottom:0;
+    width:min(320px,86vw);
+    min-width:0;
+    max-width:320px;
+    z-index:45;
+    transform:translateX(105%);
+    transition:transform .25s ease;
+    overflow:auto;
+    background:var(--canvas);
+    padding:12px;
+    box-shadow:-12px 0 40px rgba(8,8,33,.16);
+  }
+  .dashboard[data-sheet="agent"] .mailbox-rail,
+  .dashboard[data-sheet="calendar"] .mailbox-rail,
+  .dashboard[data-sheet="notes"] .mailbox-rail { transform:none; }
+  .mailbox-notes-pane { display:none; }
+  .mailbox-rail.shell-notes .mailbox-notes-pane { display:flex; min-height:0; max-height:none; }
+  .shell-agent-toggle {
+    width:36px;
+    height:36px;
+    display:grid;
+    place-items:center;
+    border:1px solid var(--agent-border);
+    border-radius:var(--radius-sm);
+    background:var(--agent-soft);
+    color:var(--agent);
+  }
+  .dashboard[data-sheet="agent"] .shell-drawer-scrim,
+  .dashboard[data-sheet="calendar"] .shell-drawer-scrim,
+  .dashboard[data-sheet="notes"] .shell-drawer-scrim {
+    display:block;
+    position:fixed;
+    inset:0;
+    z-index:44;
+    border:0;
+    background:#08082155;
+  }
+  .shell-sheet-bar {
+    display:flex;
+    align-items:center;
+    gap:8px;
+    min-height:44px;
+    margin-bottom:8px;
+  }
+  .shell-sheet-bar button {
+    width:32px;
+    height:32px;
+    display:grid;
+    place-items:center;
+    border:0;
+    border-radius:8px;
+    background:transparent;
+    color:#4a4652;
+  }
+  .shell-sheet-bar strong { font-size:14px; color:#171424; }
+  .compose-dock { right:12px !important; }
+  .compose-window {
+    width:min(640px,calc(100vw - 96px));
+    min-width:0;
+    max-width:calc(100vw - 96px);
+    height:min(640px,calc(100vh - 32px));
+  }
+  .compose-window.expanded {
+    width:min(900px,calc(100vw - 48px));
+    min-width:0;
+    max-width:calc(100vw - 48px);
+    height:min(78vh,calc(100vh - 32px));
+  }
+}
+
+@media (max-width:767px) {
+  html,body { overflow-x:clip; }
+  .dashboard { display:block; min-height:100vh; overflow-x:clip; }
+  .dashboard-mobile-header {
+    height:56px;
+    padding:0 16px;
+    display:flex;
+    align-items:center;
+    justify-content:space-between;
+    position:sticky;
+    top:0;
+    z-index:40;
+    border-bottom:1px solid var(--line);
+    background:#fffefd;
+  }
+  .dashboard-mobile-header .brand { font-size:18px; gap:8px; }
+  .dashboard-mobile-header .brand-mark { width:30px; height:28px; }
+  .dashboard-mobile-header > button { width:32px; height:32px; }
+  .dashboard-sidebar {
+    width:min(320px,86vw);
+    height:100vh;
+    max-height:100vh;
+    position:fixed;
+    top:0;
+    left:0;
+    z-index:70;
+    transform:translateX(-105%);
+    transition:transform .25s ease;
+  }
+  .dashboard-sidebar.open { transform:translateX(0); }
+  .dashboard-brand-row > button { display:grid; }
+  .dashboard-scrim { display:block; position:fixed; inset:0; z-index:65; border:0; background:#08082155; }
+  .dashboard-content {
+    min-width:0;
+    padding:0 0 calc(76px + env(safe-area-inset-bottom));
+  }
+  .dashboard-content > *:not(.mailbox-workspace) { padding:16px 16px 0; }
+  .dashboard-content h1 { font-size:28px; letter-spacing:-0.03em; overflow-wrap:anywhere; }
+  .human-handoff-page { max-width:none; margin:0; padding:0; }
+  .handoff-page-title,
+  .human-handoff-head h1.handoff-page-title { white-space:normal; font-size:22px; }
+  .human-handoff-card-body {
+    grid-template-areas:"avatar name status" "avatar email email" "actions actions actions";
+    grid-template-columns:36px minmax(0,1fr) auto;
+  }
+  .human-handoff-card-actions { margin-top:8px; flex-wrap:wrap; justify-content:flex-end; }
+  .human-handoff-card-chips { padding-left:0; }
+  .handoff-drawer,.handoff-test-modal,.people-drawer { width:100%; max-width:100%; }
+
+  .mailbox-workspace { gap:0; }
+  .workspace-header {
+    display:flex;
+    flex-direction:column;
+    align-items:stretch;
+    gap:8px;
+    min-height:0;
+    margin:12px 16px 8px;
+    padding:0;
+    background:transparent;
+    border-radius:0;
+  }
+  .workspace-zone-command { padding:0; }
+  .workspace-zone-command .workspace-search { width:100%; max-width:none; height:42px; }
+  .workspace-search-kbd,.workspace-search kbd { display:none; }
+  .workspace-zone-account { display:none; }
+  .workspace-zone-actions { width:100%; padding:0; justify-content:space-between; }
+  .mailbox-shell { margin-top:0; border-radius:0; }
+  .mailbox-stage { display:block; }
+  .mailbox-main-column { min-width:0; }
+  .mailbox-list-bar { min-height:40px; padding:0 8px; }
+  .mailbox-pagination-range { font-size:11px; }
+  .mailbox-categories {
+    display:flex;
+    flex-wrap:nowrap;
+    overflow-x:auto;
+    white-space:nowrap;
+    scrollbar-width:none;
+  }
+  .mailbox-categories::-webkit-scrollbar { display:none; }
+  .mailbox-categories button { flex:0 0 auto; }
+  .mailbox-filters { grid-template-columns:1fr; }
+  .mailbox-selection-bar { display:flex; flex-wrap:wrap; }
+  .mailbox-selection-actions { overflow-x:auto; flex-wrap:nowrap; max-width:100%; }
+  .mailbox-rows { max-height:none; }
+  .mailbox-row {
+    height:auto;
+    min-height:66px;
+    max-height:none;
+    padding:9px 12px;
+    grid-template-columns:30px minmax(0,1fr) auto;
+    grid-template-rows:auto auto auto;
+    column-gap:10px;
+    row-gap:1px;
+    align-items:center;
+    overflow:hidden;
+  }
+  .mailbox-check { position:absolute; width:1px; height:1px; margin:0; overflow:hidden; opacity:0; }
+  .mailbox-rows.selecting .mailbox-row { grid-template-columns:16px 30px minmax(0,1fr) auto; }
+  .mailbox-rows.selecting .mailbox-check {
+    position:static;
+    width:16px;
+    height:16px;
+    opacity:1;
+    grid-column:1;
+    grid-row:1 / span 3;
+  }
+  .mailbox-avatar { grid-column:1; grid-row:1 / span 3; align-self:center; width:30px; height:30px; }
+  .mailbox-rows.selecting .mailbox-avatar { grid-column:2; }
+  .mailbox-sender-wrap { grid-column:2; grid-row:1; align-self:end; }
+  .mailbox-rows.selecting .mailbox-sender-wrap { grid-column:3; }
+  .mailbox-sender { font-size:12px; font-weight:600; }
+  .mailbox-subject-line {
+    grid-column:2;
+    grid-row:2;
+    display:flex;
+    flex-direction:column;
+    align-items:flex-start;
+    white-space:normal;
+    overflow:hidden;
+  }
+  .mailbox-rows.selecting .mailbox-subject-line { grid-column:3; }
+  .mailbox-subject { font-size:11.5px; font-weight:550; }
+  .mailbox-preview { display:block; max-width:100%; font-size:10.5px; white-space:nowrap; }
+  .mailbox-preview-sep { display:none; }
+  .mailbox-row-labels {
+    grid-column:2;
+    grid-row:3;
+    min-width:0;
+    justify-content:flex-start;
+    overflow:hidden;
+  }
+  .mailbox-rows.selecting .mailbox-row-labels { grid-column:3; }
+  .mailbox-row-labels:empty { display:none; }
+  .mailbox-attachment-icon.empty { display:none; }
+  .mailbox-attachment-icon { grid-column:3; grid-row:2; width:16px; height:16px; }
+  .mailbox-rows.selecting .mailbox-attachment-icon { grid-column:4; }
+  .mailbox-row-rail { grid-column:3; grid-row:1; height:auto; align-self:start; }
+  .mailbox-rows.selecting .mailbox-row-rail { grid-column:4; }
+  .mailbox-time { font-size:9.5px; opacity:1; }
+  .mailbox-row:hover .mailbox-time,
+  .mailbox-row:focus-within .mailbox-time,
+  .mailbox-row.selected .mailbox-time { opacity:1; }
+  .mailbox-hover-actions { display:none; }
+  .mailbox-star { grid-column:3; grid-row:3; width:28px; height:28px; align-self:end; }
+  .mailbox-rows.selecting .mailbox-star { grid-column:4; }
+
+  .mailbox-rail { display:none; }
+  .dashboard[data-sheet="agent"] .mailbox-rail,
+  .dashboard[data-sheet="calendar"] .mailbox-rail,
+  .dashboard[data-sheet="notes"] .mailbox-rail {
+    display:flex;
+    position:fixed;
+    top:56px;
+    left:0;
+    right:0;
+    bottom:calc(64px + env(safe-area-inset-bottom));
+    width:auto;
+    min-width:0;
+    max-width:none;
+    z-index:35;
+    transform:none;
+    overflow:auto;
+    background:var(--canvas);
+    padding:12px 16px 16px;
+  }
+  .dashboard[data-sheet="agent"] .mailbox-main-column,
+  .dashboard[data-sheet="agent"] .workspace-header,
+  .dashboard[data-sheet="calendar"] .mailbox-main-column,
+  .dashboard[data-sheet="calendar"] .workspace-header,
+  .dashboard[data-sheet="notes"] .mailbox-main-column,
+  .dashboard[data-sheet="notes"] .workspace-header { display:none; }
+  .mailbox-notes-pane { display:none; min-height:0; max-height:none; }
+  .mailbox-rail.shell-notes .agent-panel { display:none; }
+  .mailbox-rail.shell-notes .mailbox-notes-pane { display:flex; width:100%; }
+  .shell-sheet-bar {
+    display:flex;
+    align-items:center;
+    gap:8px;
+    min-height:40px;
+    margin:0 0 8px;
+  }
+  .shell-sheet-bar button {
+    width:32px;
+    height:32px;
+    display:grid;
+    place-items:center;
+    border:0;
+    border-radius:8px;
+    background:transparent;
+    color:#4a4652;
+  }
+  .shell-sheet-bar strong { font:650 16px/1.2 "DM Sans"; color:#171424; }
+  .agent-panel { overflow:visible; }
+  .mail-detail-toolbar { overflow-x:auto; }
+
+  .mobile-bottom-nav {
+    position:fixed;
+    left:0;
+    right:0;
+    bottom:0;
+    z-index:50;
+    height:calc(64px + env(safe-area-inset-bottom));
+    padding:4px 6px env(safe-area-inset-bottom);
+    display:grid;
+    grid-template-columns:repeat(5,minmax(0,1fr));
+    align-items:center;
+    background:#fff;
+    border-top:1px solid var(--line);
+  }
+  .mobile-bottom-nav button {
+    min-width:0;
+    min-height:44px;
+    padding:0;
+    display:flex;
+    flex-direction:column;
+    align-items:center;
+    justify-content:center;
+    gap:2px;
+    border:0;
+    background:transparent;
+    color:#6f6b76;
+    font-size:10px;
+    font-weight:600;
+  }
+  .mobile-bottom-nav button.active { color:var(--coral); }
+  .mobile-bottom-plus {
+    width:36px;
+    height:28px;
+    display:grid;
+    place-items:center;
+    border-radius:10px;
+    color:#fff;
+    background:linear-gradient(180deg,#ff806d 0%,#ff5c55 100%);
+    box-shadow:0 4px 14px rgba(255,88,72,.24);
+  }
+  .mobile-bottom-compose { color:#c95945; }
+  body.compose-open .mobile-bottom-nav { display:none; }
+
+  .mobile-more-layer {
+    position:fixed;
+    inset:0;
+    z-index:60;
+    display:flex;
+    align-items:flex-end;
+  }
+  .mobile-more-scrim { position:absolute; inset:0; border:0; background:#08082155; }
+  .mobile-more-sheet {
+    position:relative;
+    width:100%;
+    max-height:min(78vh,640px);
+    overflow:auto;
+    padding:8px 16px calc(16px + env(safe-area-inset-bottom));
+    border-radius:16px 16px 0 0;
+    background:#fff;
+    box-shadow:0 -12px 40px rgba(8,8,33,.16);
+  }
+  .mobile-more-head,.mobile-more-account,.mobile-more-sheet > button {
+    display:flex;
+    align-items:center;
+  }
+  .mobile-more-head { justify-content:space-between; min-height:44px; }
+  .mobile-more-head strong { font-size:16px; color:#171424; }
+  .mobile-more-head button,.mobile-more-account button {
+    border:0;
+    background:transparent;
+    color:#6f6b76;
+    font-size:12px;
+    font-weight:600;
+  }
+  .mobile-more-account {
+    gap:10px;
+    margin-bottom:8px;
+    padding-bottom:10px;
+    border-bottom:1px solid var(--line);
+  }
+  .mobile-more-account > span {
+    width:34px;
+    height:34px;
+    display:grid;
+    place-items:center;
+    border-radius:11px;
+    background:linear-gradient(180deg,#ff9a82,#ff6f57);
+    color:#2a2038;
+    font-size:11px;
+    font-weight:700;
+  }
+  .mobile-more-account div { min-width:0; flex:1; display:grid; }
+  .mobile-more-account strong,.mobile-more-account small { overflow:hidden; text-overflow:ellipsis; white-space:nowrap; }
+  .mobile-more-account strong { font-size:13px; color:#171424; }
+  .mobile-more-account small { color:#8d8792; font-size:11px; }
+  .mobile-more-sheet > p {
+    margin:12px 0 4px;
+    color:#97929a;
+    font-size:10px;
+    font-weight:700;
+    letter-spacing:.08em;
+    text-transform:uppercase;
+  }
+  .mobile-more-sheet > button {
+    width:100%;
+    min-height:42px;
+    gap:10px;
+    border:0;
+    border-radius:10px;
+    background:transparent;
+    color:#3d3948;
+    font-size:14px;
+    font-weight:600;
+    text-align:left;
+  }
+  .mobile-more-sheet > button:hover { background:#faf5f2; }
+
+  .compose-dock {
+    position:fixed;
+    inset:0;
+    right:0 !important;
+    bottom:0;
+    width:100%;
+    z-index:80;
+    align-items:stretch;
+  }
+  .compose-dock-expanded { width:100%; height:100%; }
+  .compose-window,
+  .compose-window.docked,
+  .compose-window.expanded {
+    position:fixed;
+    inset:0;
+    left:0;
+    top:0;
+    right:0;
+    bottom:0;
+    transform:none;
+    width:100%;
+    min-width:0;
+    max-width:none;
+    height:100dvh;
+    border-radius:0;
+    z-index:80;
+  }
+  .dashboard-notice { left:16px; right:16px; bottom:calc(76px + env(safe-area-inset-bottom)); }
+}
+
+@media (max-width:1199px) {
+  .mailbox-rail.shell-calendar .agent-panel-hello,
+  .mailbox-rail.shell-calendar .agent-stat-grid,
+  .mailbox-rail.shell-calendar .agent-quick,
+  .mailbox-rail.shell-calendar .agent-attention-block,
+  .mailbox-rail.shell-calendar .agent-deadlines,
+  .mailbox-rail.shell-calendar .agent-panel-note,
+  .mailbox-rail.shell-calendar .agent-loading-block,
+  .mailbox-rail.shell-calendar .agent-caught-up,
+  .mailbox-rail.shell-calendar .agent-ready-card,
+  .mailbox-rail.shell-calendar .agent-email-context,
+  .mailbox-rail.shell-calendar .agent-insight,
+  .mailbox-rail.shell-calendar .mailbox-notes-pane,
+  .mailbox-rail.shell-agent .mailbox-notes-pane { display:none; }
+  .mailbox-rail.shell-notes .agent-panel { display:none; }
+}
diff --git a/frontend/src/shellMode.js b/frontend/src/shellMode.js
new file mode 100644
index 0000000..c34eeb6
--- /dev/null
+++ b/frontend/src/shellMode.js
@@ -0,0 +1,10 @@
+import { createContext, useContext } from "react";
+
+export const ShellModeContext = createContext({
+  sheet: null,
+  setSheet: () => {},
+});
+
+export function useShellMode() {
+  return useContext(ShellModeContext);
+}