diff --git a/ui/index.html b/ui/index.html
index d9601bce..fb628402 100644
--- a/ui/index.html
+++ b/ui/index.html
@@ -2,7 +2,7 @@
 <html lang="en">
   <head>
     <meta charset="UTF-8" />
-    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0, viewport-fit=cover" />
     <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
     <title>OpenResearch</title>
     <script>
diff --git a/ui/src/App.tsx b/ui/src/App.tsx
index 03cd3e72..f372b7e6 100644
--- a/ui/src/App.tsx
+++ b/ui/src/App.tsx
@@ -480,10 +480,13 @@ export default function App({ runtime, projectId, pane }: { runtime: RuntimeInfo
   const workspaceWide = windowWidth >= WORKSPACE_CARD_MIN_WIDTH;
   const workspaceCardVisible = mainView === "chat" && !panelOpen && workspaceWide;
   const [railOpen, setRailOpen] = useState(true);
+  const [mobileRailOpen, setMobileRailOpen] = useState(false);
+  const mobile = windowWidth < 768;
+  useEffect(() => { setMobileRailOpen(false); }, [mobile, location.href]);
   const [preferencesLoaded, setPreferencesLoaded] = useState(false);
   const railTemporarilyHidden = mainView === "chat" && panelOpen && !sidebarFitsWithPanel(windowWidth);
-  const railVisible = railOpen && !railTemporarilyHidden;
-  const stackPanel = mainView === "chat" && panelOpen && windowWidth < PANEL_MIN_WIDTH * 2;
+  const railVisible = mobile ? mobileRailOpen : railOpen && !railTemporarilyHidden;
+  const stackPanel = !mobile && mainView === "chat" && panelOpen && windowWidth < PANEL_MIN_WIDTH * 2;
   const visiblePanelWidth = Math.min(panelWidth, panelMaxWidth(windowWidth, railVisible));
   const bodyRef = useRef<HTMLDivElement>(null);
   const focusAfterRailChange = useRef<"rail" | "show" | Element | null>(null);
@@ -1651,6 +1654,12 @@ export default function App({ runtime, projectId, pane }: { runtime: RuntimeInfo
   const codeTab = requestedCodeTab
     ? (codeTabs.find((tab) => sameCodeTab(tab, requestedCodeTab)) ?? null)
     : null;
+  let activeWorkspaceView: "files" | "artifacts" | "experiments" | "terminal" | null = null;
+  if (panelOpen) {
+    if (expTab || codeTab) activeWorkspaceView = "experiments";
+    else if (fileTab) activeWorkspaceView = fileTab.source === "artifacts" ? "artifacts" : "files";
+    else if (rightTab === "files" || rightTab === "artifacts" || rightTab === "experiments" || rightTab === "terminal") activeWorkspaceView = rightTab;
+  }
   const contentTabByKey = new Map<string, ContentTab>();
   for (const tab of [...expTabs, ...fileTabs, ...planTabs, ...subagentTabs, ...sideTabs, ...codeTabs]) {
     contentTabByKey.set(rightTabKey(tab), tab);
@@ -1808,7 +1817,8 @@ export default function App({ runtime, projectId, pane }: { runtime: RuntimeInfo
     <RailHeader
       onCollapse={() => {
         focusAfterRailChange.current = "show";
-        setRailOpen(false);
+        if (mobile) setMobileRailOpen(false);
+        else setRailOpen(false);
       }}
     />
   );
@@ -1818,7 +1828,8 @@ export default function App({ runtime, projectId, pane }: { runtime: RuntimeInfo
       {projectId && <div className="absolute start-[calc(5.15rem/min(1,var(--desktop-page-zoom,1)))] top-[calc(-2px/min(1,var(--desktop-page-zoom,1)))] z-10 hidden h-[calc(44px/min(1,var(--desktop-page-zoom,1)))] items-center mac-titlebar:flex">
         <Tooltip interactive content={railVisible ? m.header_hide_sidebar() : m.chat_panel_show_sidebar()} className="rounded-md">
           <IconButton aria-label={railVisible ? m.header_hide_sidebar() : m.chat_panel_show_sidebar()} aria-expanded={railVisible} onClick={() => {
-            if (railVisible) setRailOpen(false);
+            if (mobile) setMobileRailOpen(!mobileRailOpen);
+            else if (railVisible) setRailOpen(false);
             else {
               focusAfterRailChange.current = "rail";
               setRailOpen(true);
@@ -1833,7 +1844,7 @@ export default function App({ runtime, projectId, pane }: { runtime: RuntimeInfo
       {runtime.kind === "local" && <UpdateBanner status={updateStatus} hasSidebar={Boolean(projectId)} />}
       <DesktopAppBanner />
       {workspaceError && <div role="alert" className="flex items-center gap-2 px-4 mac-titlebar:ps-titlebar-sidebar-controls mac-titlebar:min-h-titlebar win-titlebar:pe-win-controls py-2 text-subtext"><span>{workspaceError}</span><Button onClick={retryWorkspace}>{m.app_retry()}</Button></div>}
-      <div ref={bodyRef} className={`app-body workspace-body relative flex flex-1 min-h-0 ${stackPanel ? "flex-col [&>.chat-pane]:overflow-y-auto [&_.chat-empty]:min-h-0 [&_.chat-empty]:overflow-y-auto [&_.chat-empty]:justify-start [&_.chat-empty]:p-0" : ""} ${workspaceCardVisible ? "workspace-card-visible" : ""}`}>
+      <div ref={bodyRef} className={`app-body workspace-body relative flex flex-1 min-h-0 ${stackPanel ? "flex-col [&>.chat-pane]:overflow-y-auto [&_.chat-empty]:min-h-0 [&_.chat-empty]:overflow-y-auto [&_.chat-empty]:justify-start [&_.chat-empty]:p-0" : ""} ${workspaceCardVisible ? "workspace-card-visible" : ""} ${mainView === "chat" && workspaceReady && !conversationError ? "has-workspace-tools" : ""}`}>
         {projectId && (
           <ChatPanel
             projectId={projectId}
@@ -1843,14 +1854,20 @@ export default function App({ runtime, projectId, pane }: { runtime: RuntimeInfo
             onRetryContent={retryConversation}
             railHeader={railHeader}
             railOpen={railVisible}
+            mobileRail={mobile}
+            onCloseMobileRail={() => setMobileRailOpen(false)}
+            contentInert={mobile && panelOpen && mainView === "chat"}
             onShowRail={() => {
-              focusAfterRailChange.current = "rail";
-              setRailOpen(true);
-              if (railTemporarilyHidden) closePanel();
+              if (mobile) setMobileRailOpen(true);
+              else {
+                focusAfterRailChange.current = "rail";
+                setRailOpen(true);
+                if (railTemporarilyHidden) closePanel();
+              }
             }}
-            onNewProject={() => setNewProjectOpen(true)}
+            onNewProject={() => { setMobileRailOpen(false); setNewProjectOpen(true); }}
             mainView={mainView}
-            onSelectMainView={selectMainView}
+            onSelectMainView={(view) => { setMobileRailOpen(false); selectMainView(view); }}
             onOpenFile={openChatFile}
             onOpenRun={openRunLogs}
             runExperimentName={runExperimentName}
@@ -1863,7 +1880,7 @@ export default function App({ runtime, projectId, pane }: { runtime: RuntimeInfo
             composerFocusNonce={composerFocusNonce}
             runtime={runtime}
             activeSessionId={activeSessionId}
-            onActiveSessionChange={onActiveSessionChange}
+            onActiveSessionChange={(...args) => { setMobileRailOpen(false); onActiveSessionChange(...args); }}
             preferredAgent={uiState.preferredAgent}
             onPreferredAgentChange={persistPreferredAgent}
             preferredAutonomy={uiState.preferredAutonomy ?? DEFAULT_AUTONOMY}
@@ -1891,7 +1908,7 @@ export default function App({ runtime, projectId, pane }: { runtime: RuntimeInfo
             runs={runs}
             onOpenExperiment={(id, runId) => openExperimentTab(id, "overview", "preview", runId)}
             rightOffset={panelOpen && !stackPanel ? visiblePanelWidth + 14 : undefined}
-            activeView={panelOpen && (rightTab === "files" || rightTab === "artifacts" || rightTab === "experiments" || rightTab === "terminal") ? rightTab : null}
+            activeView={activeWorkspaceView}
             projectId={activeProject.id}
             onCompute={() => selectMainView("compute")}
             sessionId={activeSessionId}
@@ -1909,7 +1926,7 @@ export default function App({ runtime, projectId, pane }: { runtime: RuntimeInfo
         {mainView === "chat" && panelOpen && (
           <aside
             className={`right-pane relative shrink-0 min-w-0 flex flex-col bg-background [&.max]:fixed [&.max]:inset-0 [&.max]:z-60 [&.max]:border-s-0 overflow-hidden ${stackPanel ? "border-t border-t-border" : "border-s border-s-border"} ${panelMax ? "max" : ""}`}
-            style={panelMax ? undefined : stackPanel ? { width: "100%", height: "50%" } : { width: visiblePanelWidth }}
+            style={mobile || panelMax ? undefined : stackPanel ? { width: "100%", height: "50%" } : { width: visiblePanelWidth }}
             data-onboarding="experiments"
           >
             {!stackPanel && <div
diff --git a/ui/src/app.css b/ui/src/app.css
index 8e1cfd08..e3d4f13f 100644
--- a/ui/src/app.css
+++ b/ui/src/app.css
@@ -449,3 +449,58 @@
   font-size: inherit;
 }
 }
+
+@media (max-width: 767px) {
+  html, body, #root { height: 100dvh; }
+  .app { padding-top: env(safe-area-inset-top); }
+  .workspace-body.has-workspace-tools { padding-bottom: calc(64px + env(safe-area-inset-bottom)); }
+  .workspace-body > .chat-pane .chat-header { padding-inline: 8px; }
+  .chat-heading-row { grid-template-columns: 44px minmax(0, 1fr) 0; }
+  .chat-heading-row > span > .icon-btn, .mac-titlebar-spacer > span > .icon-btn { width: 44px; height: 44px; }
+  .workspace-tools { display: none; }
+  .workspace-mobile-nav {
+    display: flex;
+    position: fixed;
+    inset-inline: 0;
+    bottom: 0;
+    z-index: 65;
+    min-height: 64px;
+    padding: 4px 8px calc(4px + env(safe-area-inset-bottom));
+    border-top: 1px solid var(--border);
+    background: var(--base);
+  }
+  .workspace-mobile-nav > * { flex: 1 1 0; min-width: 0; }
+  .workspace-mobile-nav > button, .workspace-mobile-nav > div > button {
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    justify-content: center;
+    gap: 4px;
+    min-height: 56px;
+    border-radius: var(--radius-md);
+    color: var(--subtext);
+    font-size: 11px;
+    white-space: nowrap;
+  }
+  .workspace-mobile-nav button span { max-width: 100%; overflow: hidden; text-overflow: ellipsis; }
+  .workspace-mobile-nav button:focus-visible { outline: 2px solid var(--focus); outline-offset: -2px; }
+  .workspace-mobile-nav button[aria-pressed="true"] { background: var(--surface); color: var(--text); }
+  .mobile-rail-dialog { width: min(320px, calc(100vw - 40px)); padding-top: env(safe-area-inset-top); padding-bottom: env(safe-area-inset-bottom); background: var(--base); }
+  .mobile-rail-dialog .session-rail { width: 100%; height: 100%; }
+  .session-rail .rail-nav-item { min-height: 44px; }
+  .workspace-body .right-pane, .workspace-body .right-pane.max {
+    position: fixed;
+    inset: env(safe-area-inset-top) 0 calc(64px + env(safe-area-inset-bottom));
+    width: 100%;
+    border: 0;
+    z-index: 60;
+  }
+  .right-pane .panel-resizer, .right-pane .panel-controls > :first-child { display: none; }
+  .right-pane > .tabs { min-height: 52px; }
+  .right-pane .panel-controls > span > button { width: 44px; height: 44px; }
+  .chat-empty { padding: 20px 16px; overflow-y: auto; }
+  .chat-empty h2 { font-size: 28px; line-height: 1.2; }
+  .chat-thread, .settings-view-scroll, .home { scrollbar-gutter: auto; }
+  .composer-actions { flex-wrap: wrap; }
+  input, textarea, select { font-size: 16px; }
+}
diff --git a/ui/src/components/ChatPanel.tsx b/ui/src/components/ChatPanel.tsx
index c1529e6d..6033f6e1 100644
--- a/ui/src/components/ChatPanel.tsx
+++ b/ui/src/components/ChatPanel.tsx
@@ -1,3 +1,4 @@
+import { Dialog } from "@base-ui/react/dialog";
 import { ComposerProjectPicker } from "./ComposerProjectPicker";
 import { ProjectInfoCard } from "./ProjectInfoCard";
 import { SessionHoverCard } from "./SessionHoverCard";
@@ -4419,6 +4420,7 @@ function SessionRow({
           anchor={anchor}
           cardId={cardId}
           cardRef={cardRef}
+          container={ref.current?.closest(".mobile-rail-dialog") ?? document.body}
           onEnter={() => { pointerInside.current = true; window.clearTimeout(closeTimer.current); }}
           onLeave={() => { cardWarmUntil.current = Date.now() + 500; pointerInside.current = false; scheduleClose(); }}
           onOpenExperiment={(projectId, experimentId) => { closeCard(); onOpenExperiment(projectId, experimentId); }}
@@ -4534,6 +4536,9 @@ export function ChatPanel({
   onRetryContent,
   railHeader,
   railOpen,
+  mobileRail = false,
+  onCloseMobileRail,
+  contentInert = false,
   onShowRail,
   onNewProject,
   mainView,
@@ -4569,6 +4574,9 @@ export function ChatPanel({
   railHeader?: React.ReactNode;
   /** Whether the agents rail is showing (collapsed via its own header icon). */
   railOpen: boolean;
+  mobileRail?: boolean;
+  onCloseMobileRail?: () => void;
+  contentInert?: boolean;
   /** Reopen the rail (from the chat header's sidebar icon). */
   onShowRail: () => void;
   onNewProject?: () => void;
@@ -4671,15 +4679,15 @@ export function ChatPanel({
   const [focusedSidebarRow, setFocusedSidebarRow] = useState<string | null>(null);
   const [chatLimits, setChatLimits] = useState<Record<string, number>>({});
   const sidebarExpanded = sidebarExpandedAll || Object.keys(chatLimits).length > 0;
-  useLayoutEffect(() => {
-    const body = railBodyRef.current;
+  const setRailBody = useCallback((body: HTMLDivElement | null) => {
+    railBodyRef.current = body;
     if (!body || embedded) return;
     const resize = () => setRailHeight(body.clientHeight);
     const observer = new ResizeObserver(resize);
     observer.observe(body);
     resize();
-    return () => observer.disconnect();
-  }, [railOpen, embedded, mainView]);
+    return () => { observer.disconnect(); railBodyRef.current = null; };
+  }, [embedded]);
   const recentActivity = new Map(projectActivity.map((activity) => [activity.projectId, activity.lastActivityAt]));
   const sortedProjects = [...sidebarProjects].sort((a, b) => Number(pinnedProjects.includes(b.id)) - Number(pinnedProjects.includes(a.id)) || Math.max(recentActivity.get(b.id) ?? 0, b.updatedAt) - Math.max(recentActivity.get(a.id) ?? 0, a.updatedAt));
   const candidateLimit = sidebarGrouping === "list" || sidebarExpanded ? sortedProjects.length : Math.max(1, Math.ceil(railHeight / 36));
@@ -6765,7 +6773,7 @@ export function ChatPanel({
         </div>
       </div>
       <div className="relative flex-1 min-h-0">
-      <div ref={railBodyRef} tabIndex={-1} className={`rail-body h-full overflow-x-hidden ${sidebarScrollable ? "overflow-y-auto" : "overflow-y-hidden"}`}>
+      <div ref={setRailBody} tabIndex={-1} className={`rail-body h-full overflow-x-hidden ${sidebarScrollable ? "overflow-y-auto" : "overflow-y-hidden"}`}>
         <div className="relative" style={{ height: (sidebarScrollable ? sidebarVirtualizer.getTotalSize() : defaultRowsHeight) + (showProjectMore ? 38 : 0) + (sidebarExpandedAll ? 46 : 0) }}>
           {(sidebarScrollable
             ? sidebarVirtualItems.map((item) => ({ row: sidebarRows[item.index], top: item.start, index: item.index }))
@@ -6902,10 +6910,19 @@ export function ChatPanel({
   );
 
   const headerClass = `chat-header flex items-center gap-2 py-0 px-4 bg-background shrink-0 h-12 mac-titlebar:h-titlebar relative z-4 w-full max-w-readable my-0 mx-auto [&::after]:content-[''] [&::after]:absolute [&::after]:top-full [&::after]:start-0 [&::after]:end-0 [&::after]:h-6 [&::after]:bg-[linear-gradient(to_bottom,_var(--base),_transparent)] [&::after]:pointer-events-none`;
-  const railReopen = !railOpen && !embedded && (
+  const displayedRail = mobileRail ? (
+    <Dialog.Root open={railOpen} onOpenChange={(open) => { if (!open) onCloseMobileRail?.(); }}>
+      <Dialog.Portal>
+        <Dialog.Backdrop className="fixed inset-0 z-70 bg-modal-backdrop" />
+        <Dialog.Popup aria-modal="true" aria-label={m.chat_panel_show_sidebar()} className="mobile-rail-dialog fixed inset-y-0 start-0 z-80 outline-none">{rail}</Dialog.Popup>
+      </Dialog.Portal>
+    </Dialog.Root>
+  ) : railOpen ? rail : null;
+  const railReopen = (!railOpen || mobileRail) && !embedded && (
     <Tooltip interactive content={m.chat_panel_show_sidebar()} className="rounded-md mac-titlebar:invisible">
       <IconButton
         aria-label={m.chat_panel_show_sidebar()}
+        aria-expanded={railOpen}
         onClick={onShowRail}
         className="mac-titlebar:ms-titlebar-inset"
       >
@@ -6917,9 +6934,9 @@ export function ChatPanel({
   if (mainView !== "chat") {
     return (
       <>
-        {railOpen && rail}
-        <section className="chat-pane flex-1 min-w-0 flex flex-col bg-background min-h-0">
-          {!railOpen && <div className="mac-titlebar-spacer flex h-12 mac-titlebar:h-titlebar shrink-0 items-center">{railReopen}</div>}
+        {displayedRail}
+        <section inert={contentInert} className="chat-pane flex-1 min-w-0 flex flex-col bg-background min-h-0">
+          {(!railOpen || mobileRail) && <div className="mac-titlebar-spacer flex h-12 mac-titlebar:h-titlebar shrink-0 items-center">{railReopen}</div>}
           {/* Keyed per view so no tab inherits the chat thread's or another tab's scroll offset. */}
           <div key={mainView} className="settings-view-scroll flex-1 min-h-0 overflow-y-auto [scrollbar-gutter:stable_both-edges]">
             {contentError ? <div role="alert" className="p-6 text-subtext">{contentError}<Button onClick={onRetryContent}>{m.app_retry()}</Button></div>
@@ -6932,11 +6949,11 @@ export function ChatPanel({
 
   return (
     <>
-      {railOpen && rail}
-      <section data-side-chat={embedded || undefined} className="chat-pane flex-1 min-w-0 flex flex-col bg-background min-h-0">
+      {displayedRail}
+      <section inert={contentInert} data-side-chat={embedded || undefined} className="chat-pane flex-1 min-w-0 flex flex-col bg-background min-h-0">
         {/* Header — session title on the left, end-pane view switchers on the
           right, fading into the chat below (sessions live in the rail). */}
-        <div className={railOpen || embedded ? "contents" : "grid shrink-0 grid-cols-[2rem_minmax(0,1fr)_2rem] mac-titlebar:grid-cols-titlebar-chat items-center"}>
+        <div className={railOpen && !mobileRail || embedded ? "contents" : "chat-heading-row grid shrink-0 grid-cols-[2rem_minmax(0,1fr)_2rem] mac-titlebar:grid-cols-titlebar-chat items-center"}>
           {railReopen}
           <div className={headerClass}>
           <div className="flex min-w-0 flex-1 items-center gap-2">
diff --git a/ui/src/components/SessionHoverCard.tsx b/ui/src/components/SessionHoverCard.tsx
index 820fd9f7..78daceaa 100644
--- a/ui/src/components/SessionHoverCard.tsx
+++ b/ui/src/components/SessionHoverCard.tsx
@@ -70,7 +70,7 @@ function ExperimentRow({ row, sessionProjectId, tabbable, onFocus, onOpen }: {
   );
 }
 
-export function SessionHoverCard({ session, modelName, projectName, harnessLogo, anchor, cardId, cardRef, onEnter, onLeave, onOpenExperiment, onReturnToRow, onContinue }: {
+export function SessionHoverCard({ session, modelName, projectName, harnessLogo, anchor, cardId, cardRef, container, onEnter, onLeave, onOpenExperiment, onReturnToRow, onContinue }: {
   session: ChatSession;
   modelName: string | null;
   projectName?: string;
@@ -78,6 +78,7 @@ export function SessionHoverCard({ session, modelName, projectName, harnessLogo,
   anchor: DOMRect;
   cardId: string;
   cardRef: React.RefObject<HTMLDivElement | null>;
+  container: Element;
   onEnter: () => void;
   onLeave: () => void;
   onOpenExperiment: (projectId: string, experimentId: string) => void;
@@ -190,6 +191,6 @@ export function SessionHoverCard({ session, modelName, projectName, harnessLogo,
         </div>
       </div>}
     </div>,
-    document.body,
+    container,
   );
 }
diff --git a/ui/src/components/WorkspaceTools.tsx b/ui/src/components/WorkspaceTools.tsx
index df0afd42..c34ebefe 100644
--- a/ui/src/components/WorkspaceTools.tsx
+++ b/ui/src/components/WorkspaceTools.tsx
@@ -45,6 +45,16 @@ export function WorkspaceTools({ expanded, experiments, runs, onOpenExperiment,
     { id: "terminal", label: m.workspace_terminal(), Icon: Terminal, onClick: onTerminal },
   ];
   return (
+    <>
+    <nav aria-label={m.workspace_tools_heading()} className="workspace-mobile-nav hidden">
+      {items.map(({ id, label, Icon, onClick }) => (
+        <button key={id} type="button" aria-pressed={activeView === id} onClick={onClick}>
+          <Icon size={20} aria-hidden="true" />
+          <span>{label}</span>
+        </button>
+      ))}
+      {onSideChat && sessionId && <SideChatPicker parentId={sessionId} sessions={sessions} onSelect={onSelectSideChat} onCreate={onSideChat} mobile />}
+    </nav>
     <div className="workspace-tools absolute end-3.5 top-2 mac-titlebar:top-1.5 z-30" style={{ insetInlineEnd: rightOffset }}>
       {!expanded ? (
         <nav aria-label={m.workspace_tools_heading()} className="flex items-center justify-end gap-1">
@@ -103,11 +113,13 @@ export function WorkspaceTools({ expanded, experiments, runs, onOpenExperiment,
         </nav>
       )}
     </div>
+    </>
   );
 }
 
-function SideChatPicker({ parentId, sessions, onSelect, onCreate, expanded = false }: {
+function SideChatPicker({ parentId, sessions, onSelect, onCreate, expanded = false, mobile = false }: {
   expanded?: boolean;
+  mobile?: boolean;
   parentId: string;
   sessions: ChatSession[];
   onSelect: (sessionId: string) => void;
@@ -127,7 +139,11 @@ function SideChatPicker({ parentId, sessions, onSelect, onCreate, expanded = fal
   useLayoutEffect(() => {
     if (!open) return;
     const position = () => {
-      if (panelRef.current) panelRef.current.style.maxHeight = `${Math.max(0, Math.min(384, window.innerHeight - panelRef.current.getBoundingClientRect().top - 8))}px`;
+      if (!panelRef.current) return;
+      const available = mobile
+        ? (triggerRef.current?.getBoundingClientRect().top ?? 0) - 12
+        : window.innerHeight - panelRef.current.getBoundingClientRect().top - 8;
+      panelRef.current.style.maxHeight = `${Math.max(0, Math.min(384, available))}px`;
     };
     position();
     window.addEventListener("resize", position);
@@ -136,7 +152,7 @@ function SideChatPicker({ parentId, sessions, onSelect, onCreate, expanded = fal
       window.removeEventListener("resize", position);
       window.removeEventListener("scroll", position, true);
     };
-  }, [open]);
+  }, [open, mobile]);
 
   const openPicker = () => {
     clearTimeout(closeTimer.current);
@@ -183,7 +199,12 @@ function SideChatPicker({ parentId, sessions, onSelect, onCreate, expanded = fal
       onBlur={(event) => {
         if (!event.currentTarget.contains(event.relatedTarget)) setOpen(false);
       }}>
-      {expanded ? (
+      {mobile ? (
+        <button {...triggerProps} className="w-full">
+          <MessagesSquare size={20} aria-hidden="true" />
+          <span>{m.side_chat_open()}</span>
+        </button>
+      ) : expanded ? (
         <MenuItem {...triggerProps} active={open} className="min-h-7 py-1 text-text">
           <span className="flex items-center gap-4"><MessagesSquare size={16} />{m.side_chat_open()}</span>
         </MenuItem>
@@ -194,7 +215,7 @@ function SideChatPicker({ parentId, sessions, onSelect, onCreate, expanded = fal
       )}
       {open && (
         <div ref={panelRef} role="dialog" aria-label={m.side_chat_list({ count: children.length })}
-          className="absolute end-0 top-[calc(100%_+_4px)] z-50 flex w-80 max-w-[calc(100vw-1rem)] flex-col overflow-hidden rounded-lg border border-border bg-background p-1.5 shadow-menu">
+          className={`absolute end-0 ${mobile ? "bottom-[calc(100%_+_4px)]" : "top-[calc(100%_+_4px)]"} z-50 flex w-80 max-w-[calc(100vw-1rem)] flex-col overflow-hidden rounded-lg border border-border bg-background p-1.5 shadow-menu`}>
           <div className="flex shrink-0 items-center justify-between gap-2 px-2">
             <span className="text-sm font-medium text-text">{m.side_chat_list({ count: children.length })}</span>
             {children.length > 0 && (