diff --git a/ui/src/components/AppShell.tsx b/ui/src/components/AppShell.tsx
index d7b1634f..a8fc0f4b 100644
--- a/ui/src/components/AppShell.tsx
+++ b/ui/src/components/AppShell.tsx
@@ -18,7 +18,7 @@ export function AppShell({ user, title, description, backTo, children }: AppShel
     <div className="flex h-svh overflow-hidden bg-background text-foreground">
       <AppSidebar user={user} />
       <main className="flex-1 overflow-y-auto">
-        <div className="mx-auto max-w-3xl px-8 py-10">
+        <div className="mx-auto max-w-3xl px-4 pt-14 pb-6 sm:px-8 sm:py-10">
           {backTo && (
             <Link
               to={backTo.to}
@@ -83,7 +83,7 @@ export function SettingsRow({
   comingSoon,
 }: SettingsRowProps) {
   return (
-    <div className="flex items-center justify-between gap-6 border-b border-border px-4 py-3 last:border-b-0">
+    <div className="flex flex-col gap-2 border-b border-border px-4 py-3 last:border-b-0 sm:flex-row sm:items-center sm:justify-between sm:gap-6">
       <label className="flex flex-col gap-0.5" htmlFor={htmlFor}>
         <span className="flex items-center gap-2">
           <span
@@ -103,7 +103,7 @@ export function SettingsRow({
           <span className="text-xs text-muted-foreground">{description}</span>
         )}
       </label>
-      <div className={`shrink-0 ${comingSoon ? "opacity-50" : ""}`}>{control}</div>
+      <div className={`sm:shrink-0 ${comingSoon ? "opacity-50" : ""}`}>{control}</div>
     </div>
   );
 }
diff --git a/ui/src/components/AppSidebar.tsx b/ui/src/components/AppSidebar.tsx
index a4752133..84684b18 100644
--- a/ui/src/components/AppSidebar.tsx
+++ b/ui/src/components/AppSidebar.tsx
@@ -51,6 +51,7 @@ export function AppSidebar({ user }: { user: SessionUser }) {
       <nav className="flex flex-1 flex-col gap-0.5 px-2">
         <Link
           to="/agents"
+          onClick={layout.closeOnMobile}
           className={cn(
             "flex items-center gap-2.5 rounded-md px-2.5 py-1.5 text-xs/relaxed text-muted-foreground transition-colors",
             "hover:bg-sidebar-accent hover:text-sidebar-accent-foreground",
@@ -65,6 +66,7 @@ export function AppSidebar({ user }: { user: SessionUser }) {
             <Link
               key={item.to}
               to={item.to}
+              onClick={layout.closeOnMobile}
               className={cn(
                 "flex items-center gap-2.5 rounded-md px-2.5 py-1.5 text-xs/relaxed text-muted-foreground transition-colors",
                 "hover:bg-sidebar-accent hover:text-sidebar-accent-foreground",
diff --git a/ui/src/components/agents/AgentRunCard.tsx b/ui/src/components/agents/AgentRunCard.tsx
index c4387c90..e86d242d 100644
--- a/ui/src/components/agents/AgentRunCard.tsx
+++ b/ui/src/components/agents/AgentRunCard.tsx
@@ -69,25 +69,29 @@ export function AgentRunCard({ thread }: AgentRunCardProps) {
 
       <div className="min-w-0 flex-1">
         <div className="truncate text-sm font-medium text-[var(--ui-text)]">{thread.title}</div>
-        <div className="mt-1 flex items-center gap-2 text-xs text-[var(--ui-text-dim)]">
+        <div className="mt-1 flex min-w-0 items-center gap-2 text-xs text-[var(--ui-text-dim)]">
           {source && SourceIcon && (
             <>
-              <span className="flex items-center gap-1" title={source.label}>
+              <span className="flex shrink-0 items-center gap-1" title={source.label}>
                 <SourceIcon className="size-3.5" aria-label={source.label} />
                 {source.label}
               </span>
-              <span>·</span>
+              <span className="shrink-0">·</span>
             </>
           )}
-          <span>{thread.model}</span>
+          <span className="min-w-0 truncate" title={thread.model}>
+            {thread.model}
+          </span>
           {thread.repo && (
             <>
-              <span>·</span>
-              <span>{thread.repo}</span>
+              <span className="shrink-0">·</span>
+              <span className="min-w-0 truncate" title={thread.repo}>
+                {thread.repo}
+              </span>
             </>
           )}
-          <span>·</span>
-          <span>{formatRelativeTime(thread.updatedAt)}</span>
+          <span className="shrink-0">·</span>
+          <span className="shrink-0 whitespace-nowrap">{formatRelativeTime(thread.updatedAt)}</span>
         </div>
       </div>
 
diff --git a/ui/src/components/agents/AgentThreadView.tsx b/ui/src/components/agents/AgentThreadView.tsx
index 7479f732..fa398a3e 100644
--- a/ui/src/components/agents/AgentThreadView.tsx
+++ b/ui/src/components/agents/AgentThreadView.tsx
@@ -1,5 +1,4 @@
 import { useEffect, useMemo, useState } from "react";
-import { FolderIcon } from "@phosphor-icons/react";
 
 import type { SessionUser } from "@/lib/api";
 import type { PendingPrompt } from "@/lib/agents/pendingPrompts";
@@ -83,17 +82,6 @@ export function AgentThreadView({ user, thread }: AgentThreadViewProps) {
   return (
     <AgentsShell user={user} activeThreadId={thread.id}>
       <div className="flex min-w-0 flex-1 flex-col">
-        <div className="flex shrink-0 items-center gap-2 border-b border-[var(--ui-border)] px-4 py-3">
-          <span className="truncate text-sm font-medium text-[color:var(--ui-text)]">
-            {thread.title}
-          </span>
-          {thread.repo && (
-            <span className="flex min-w-0 items-center gap-1 text-xs text-[color:var(--ui-text-dim)]">
-              <FolderIcon className="size-3.5 shrink-0" />
-              <span className="truncate">{thread.repoFullName}</span>
-            </span>
-          )}
-        </div>
         <div className="flex min-h-0 flex-1 flex-col">
           {hasMessages ? (
             <div className="relative flex min-h-0 flex-1 flex-col overflow-hidden">
diff --git a/ui/src/components/agents/AgentsSidebar.tsx b/ui/src/components/agents/AgentsSidebar.tsx
index 5a25c08d..75933533 100644
--- a/ui/src/components/agents/AgentsSidebar.tsx
+++ b/ui/src/components/agents/AgentsSidebar.tsx
@@ -59,6 +59,7 @@ export function AgentsSidebar({ user, activeThreadId }: AgentsSidebarProps) {
       <div className="px-2 pb-1">
         <Link
           to="/agents"
+          onClick={layout.closeOnMobile}
           className="flex w-full items-center gap-2.5 rounded-md px-2.5 py-1.5 text-xs font-medium text-[var(--ui-text)] transition-colors hover:bg-[var(--ui-sidebar-hover)]"
         >
           <PlusIcon className="size-4" />
@@ -73,6 +74,7 @@ export function AgentsSidebar({ user, activeThreadId }: AgentsSidebarProps) {
             <Link
               key={item.to}
               to={item.to}
+              onClick={layout.closeOnMobile}
               className="flex items-center gap-2.5 rounded-md px-2.5 py-1.5 text-xs text-[var(--ui-text-muted)] transition-colors hover:bg-[var(--ui-sidebar-hover)] hover:text-[var(--ui-text)]"
             >
               <Icon className="size-4" />
@@ -83,9 +85,24 @@ export function AgentsSidebar({ user, activeThreadId }: AgentsSidebarProps) {
       </nav>
 
       <div className="min-h-0 flex-1 overflow-y-auto px-2 pb-2">
-        <ThreadGroup label="Today" threads={groups.today} activeThreadId={activeThreadId} />
-        <ThreadGroup label="Last 30 days" threads={groups.last30} activeThreadId={activeThreadId} />
-        <ThreadGroup label="Older" threads={groups.older} activeThreadId={activeThreadId} />
+        <ThreadGroup
+          label="Today"
+          threads={groups.today}
+          activeThreadId={activeThreadId}
+          onNavigate={layout.closeOnMobile}
+        />
+        <ThreadGroup
+          label="Last 30 days"
+          threads={groups.last30}
+          activeThreadId={activeThreadId}
+          onNavigate={layout.closeOnMobile}
+        />
+        <ThreadGroup
+          label="Older"
+          threads={groups.older}
+          activeThreadId={activeThreadId}
+          onNavigate={layout.closeOnMobile}
+        />
       </div>
 
       <div className="p-2">
@@ -99,10 +116,12 @@ function ThreadGroup({
   label,
   threads,
   activeThreadId,
+  onNavigate,
 }: {
   label: string;
   threads: Array<AgentThread>;
   activeThreadId?: string;
+  onNavigate?: () => void;
 }) {
   if (threads.length === 0) return null;
 
@@ -112,13 +131,26 @@ function ThreadGroup({
         {label}
       </div>
       {threads.map((thread) => (
-        <ThreadRow key={thread.id} thread={thread} isActive={thread.id === activeThreadId} />
+        <ThreadRow
+          key={thread.id}
+          thread={thread}
+          isActive={thread.id === activeThreadId}
+          onNavigate={onNavigate}
+        />
       ))}
     </div>
   );
 }
 
-function ThreadRow({ thread, isActive }: { thread: AgentThread; isActive: boolean }) {
+function ThreadRow({
+  thread,
+  isActive,
+  onNavigate,
+}: {
+  thread: AgentThread;
+  isActive: boolean;
+  onNavigate?: () => void;
+}) {
   const deleteThread = useDeleteAgentThread();
   const badge =
     thread.diffStats && thread.diffStats.additions > 0
@@ -141,6 +173,7 @@ function ThreadRow({ thread, isActive }: { thread: AgentThread; isActive: boolea
     <Link
       to="/agents/$threadId"
       params={{ threadId: thread.id }}
+      onClick={onNavigate}
       className={cn(
         "group mb-0.5 flex items-center gap-2 rounded-lg px-2.5 py-1.5 transition-colors",
         isActive
diff --git a/ui/src/components/sidebar-layout.tsx b/ui/src/components/sidebar-layout.tsx
index 2c9b4b8f..7ea9e5e4 100644
--- a/ui/src/components/sidebar-layout.tsx
+++ b/ui/src/components/sidebar-layout.tsx
@@ -20,6 +20,9 @@ function readStoredWidth(): number {
 
 function readStoredCollapsed(): boolean {
   if (typeof window === "undefined") return false;
+  // On mobile the sidebar is a full-screen overlay, so start collapsed to keep
+  // the chat visible regardless of the stored desktop preference.
+  if (window.matchMedia("(max-width: 767px)").matches) return true;
   return window.localStorage.getItem(STORAGE_COLLAPSED) === "1";
 }
 
@@ -40,7 +43,13 @@ export function useSidebarLayout() {
 
   const toggle = useCallback(() => setCollapsed(!collapsed), [collapsed, setCollapsed]);
 
-  return { width, collapsed, setWidth, setCollapsed, toggle };
+  const closeOnMobile = useCallback(() => {
+    if (typeof window === "undefined") return;
+    // State-only: don't persist, so the desktop collapsed preference is preserved.
+    if (window.matchMedia("(max-width: 767px)").matches) setCollapsedState(true);
+  }, []);
+
+  return { width, collapsed, setWidth, setCollapsed, toggle, closeOnMobile };
 }
 
 interface SidebarFrameProps {
@@ -76,10 +85,16 @@ export function SidebarFrame({
   return (
     <aside
       style={{ width }}
-      className={cn("relative flex h-svh shrink-0 flex-col", className)}
+      className={cn(
+        "relative flex h-svh shrink-0 flex-col",
+        "max-md:fixed max-md:inset-0 max-md:z-40 max-md:!w-full",
+        className,
+      )}
     >
       {children}
-      <ResizeHandle width={width} onResize={setWidth} />
+      <div className="max-md:hidden">
+        <ResizeHandle width={width} onResize={setWidth} />
+      </div>
     </aside>
   );
 }