diff --git a/apps/web/src/components/ComposerPromptEditorTiptap.tsx b/apps/web/src/components/ComposerPromptEditorTiptap.tsx
index 4ba2418c5169b..58c5b107644fb 100644
--- a/apps/web/src/components/ComposerPromptEditorTiptap.tsx
+++ b/apps/web/src/components/ComposerPromptEditorTiptap.tsx
@@ -1101,7 +1101,7 @@ function ComposerPromptEditorTiptapInner(
 
   const editorAttributes = {
     class: cn(
-      "composer-tiptap -m-1 block max-h-52 min-h-12 overflow-y-auto p-1 whitespace-pre-wrap wrap-break-word bg-transparent leading-relaxed text-foreground focus:outline-none",
+      "composer-tiptap -m-1 block max-h-52 min-h-19.5 redesign:min-h-12 overflow-y-auto p-1 whitespace-pre-wrap wrap-break-word bg-transparent leading-relaxed text-foreground focus:outline-none",
       className,
     ),
     "data-testid": "composer-editor",
diff --git a/apps/web/src/components/GitActionsControl.tsx b/apps/web/src/components/GitActionsControl.tsx
index 479b6d7c7f491..5e7790e966510 100644
--- a/apps/web/src/components/GitActionsControl.tsx
+++ b/apps/web/src/components/GitActionsControl.tsx
@@ -120,6 +120,7 @@ import { getSourceControlPresentation, sourceControlIcon } from "~/sourceControl
 import { sourceControlClients } from "@t3tools/client-runtime/source-control-clients";
 import { formatDiffCount } from "@t3tools/client-runtime/diff-count";
 import { useOpenLink } from "~/browser/useOpenLink";
+import { useClientSettings } from "~/hooks/useSettings";
 
 interface GitActionsControlProps {
   presentation?: "toolbar" | "menu";
@@ -1151,8 +1152,10 @@ export default function GitActionsControl({
       ? (quickAction.hint ?? "This action is currently unavailable.")
       : null;
   const gitActionProgress = resolveGitActionProgressPresentation(vcsActionState);
+  const redesign = useClientSettings((s) => s.redesignEnabled);
   // A fresh draft with nothing to commit, push, or diff hides those rows until there is work.
   const quietEmptyDraft =
+    redesign &&
     isPanel &&
     draftId !== undefined &&
     gitActionProgress === null &&
diff --git a/apps/web/src/components/ThreadStatusIndicators.tsx b/apps/web/src/components/ThreadStatusIndicators.tsx
index 75cb84a318a2a..e28b0f8b08f77 100644
--- a/apps/web/src/components/ThreadStatusIndicators.tsx
+++ b/apps/web/src/components/ThreadStatusIndicators.tsx
@@ -292,7 +292,9 @@ function PullRequestBadge({
             aria-hidden
             className={cn("size-3 shrink-0", presentation.toneClassName)}
           />
-          <span className="text-secondary-label">{presentation.text}</span>
+          <span className={cn(presentation.toneClassName, "redesign:text-secondary-label")}>
+            {presentation.text}
+          </span>
         </span>
       </TooltipTrigger>
       <TooltipPopup
diff --git a/apps/web/src/components/chat/ComposerPrimaryActions.tsx b/apps/web/src/components/chat/ComposerPrimaryActions.tsx
index e2c2a95747c57..51c233807d154 100644
--- a/apps/web/src/components/chat/ComposerPrimaryActions.tsx
+++ b/apps/web/src/components/chat/ComposerPrimaryActions.tsx
@@ -2,7 +2,7 @@ import { memo, type MouseEventHandler, type PointerEventHandler } from "react";
 import { CheckIcon, ChevronDownIcon, ChevronLeftIcon, Minimize2Icon, PlayIcon } from "lucide-react";
 import { CornerUpRight, ListPlus } from "lucide";
 import { MorphIcon } from "~/components/MorphIcon";
-import { useEnvironmentIdentificationMode } from "~/hooks/useSettings";
+import { useClientSettings, useEnvironmentIdentificationMode } from "~/hooks/useSettings";
 import { formatContextWindowTokens } from "~/lib/contextWindow";
 import { cn } from "~/lib/utils";
 import { useShortcutModifierState } from "../../shortcutModifierState";
@@ -113,6 +113,7 @@ export const ComposerPrimaryActions = memo(function ComposerPrimaryActions({
     ? { onPointerDown: preventPointerFocus }
     : undefined;
   const environmentIdentificationMode = useEnvironmentIdentificationMode();
+  const redesign = useClientSettings((s) => s.redesignEnabled);
   const shortcutModifiers = useShortcutModifierState();
   const isQueuing =
     !isEditingQueuedMessage &&
@@ -368,7 +369,16 @@ export const ComposerPrimaryActions = memo(function ComposerPrimaryActions({
           render={
             <button
               type="button"
-              className="flex h-7 shrink-0 cursor-pointer items-center gap-1.5 rounded-(--control-radius) px-2 font-medium text-base text-foreground/80 tabular-nums outline-none hover:bg-accent hover:text-foreground focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-ring disabled:pointer-events-none disabled:opacity-64 sm:text-sm aria-pressed:bg-accent/60 aria-pressed:text-foreground [&_svg]:pointer-events-none [&_svg]:size-4 [&_svg]:text-muted-foreground"
+              className={
+                redesign
+                  ? "flex h-7 shrink-0 cursor-pointer items-center gap-1.5 rounded-(--control-radius) px-2 font-medium text-base text-foreground/80 tabular-nums outline-none hover:bg-accent hover:text-foreground focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-ring disabled:pointer-events-none disabled:opacity-64 sm:text-sm aria-pressed:bg-accent/60 aria-pressed:text-foreground [&_svg]:pointer-events-none [&_svg]:size-4 [&_svg]:text-muted-foreground"
+                  : cn(
+                      "flex h-9 shrink-0 cursor-pointer items-center gap-1.5 rounded-full border px-2.5 text-xs tabular-nums outline-none transition-colors focus-visible:ring-2 focus-visible:ring-inset focus-visible:ring-ring disabled:pointer-events-none disabled:opacity-64 sm:h-8 [&_svg]:pointer-events-none [&_svg]:size-3.5",
+                      keepFullHistory
+                        ? "border-border text-muted-foreground hover:text-foreground"
+                        : "border-warning/40 text-warning hover:bg-warning/8",
+                    )
+              }
               {...pointerFocusProps}
               aria-pressed={!keepFullHistory}
               aria-label={`Compact ${compactTokens} tokens of history before sending`}
@@ -378,8 +388,19 @@ export const ComposerPrimaryActions = memo(function ComposerPrimaryActions({
           }
         >
           <Minimize2Icon aria-hidden="true" />
-          {/* The token count lives in the tooltip so the permission label keeps its room. */}
-          {keepFullHistory ? "Keep full" : "Compact next"}
+          {/* The new design keeps the token count in the tooltip so the permission label keeps its room. */}
+          {redesign ? (
+            keepFullHistory ? (
+              "Keep full"
+            ) : (
+              "Compact next"
+            )
+          ) : (
+            <>
+              {keepFullHistory ? "Full" : "Compact"}
+              <span>{compactTokens}</span>
+            </>
+          )}
         </TooltipTrigger>
         <TooltipPopup>
           <div>
diff --git a/apps/web/src/components/chat/OpenInPicker.tsx b/apps/web/src/components/chat/OpenInPicker.tsx
index c86ad92038639..90fc9f1a4f332 100644
--- a/apps/web/src/components/chat/OpenInPicker.tsx
+++ b/apps/web/src/components/chat/OpenInPicker.tsx
@@ -412,11 +412,11 @@ export const OpenInPicker = memo(function OpenInPicker({
               getOpenInIconClass(primaryOption.kind),
               // Full-color app icons outshout the panel's line icons until the row is in use.
               isPanel &&
-                "grayscale dark:opacity-70 group-hover/details-split:opacity-100 group-hover/details-split:grayscale-0 group-has-[[data-popup-open]]/details-split:opacity-100 group-has-[[data-popup-open]]/details-split:grayscale-0",
+                "redesign:grayscale redesign:dark:opacity-70 redesign:group-hover/details-split:opacity-100 redesign:group-hover/details-split:grayscale-0 redesign:group-has-[[data-popup-open]]/details-split:opacity-100 redesign:group-has-[[data-popup-open]]/details-split:grayscale-0",
               // A hairline keeps pale app icons from dissolving into the card.
               isPanel &&
                 primaryOption.kind === "brand" &&
-                "rounded-sm ring-1 ring-black/10 dark:ring-white/15",
+                "redesign:rounded-sm redesign:ring-1 redesign:ring-black/10 redesign:dark:ring-white/15",
             )}
           />
         ) : isPanel ? (
diff --git a/apps/web/src/components/chat/TraitsPicker.tsx b/apps/web/src/components/chat/TraitsPicker.tsx
index 68580c39a1e3e..f6d099dfbb059 100644
--- a/apps/web/src/components/chat/TraitsPicker.tsx
+++ b/apps/web/src/components/chat/TraitsPicker.tsx
@@ -24,7 +24,7 @@ import {
   normalizeModelSlug,
 } from "@t3tools/shared/model";
 import { memo } from "react";
-import { GaugeIcon } from "lucide-react";
+import { BrainIcon, GaugeIcon } from "lucide-react";
 import {
   Menu,
   MenuGroup,
@@ -600,7 +600,8 @@ export const TraitsPicker = memo(function TraitsPicker({
                 size === "xs" ? "gap-1" : "gap-1.5",
               )}
             >
-              <ComposerControlIcon icon={GaugeIcon} size={size} />
+              <ComposerControlIcon icon={BrainIcon} size={size} className="redesign:hidden" />
+              <ComposerControlIcon icon={GaugeIcon} size={size} className="hidden redesign:block" />
               <span data-composer-control-label className="min-w-0 truncate">
                 {triggerLabel}
               </span>
@@ -608,7 +609,8 @@ export const TraitsPicker = memo(function TraitsPicker({
             </span>
           ) : (
             <>
-              <ComposerControlIcon icon={GaugeIcon} size={size} />
+              <ComposerControlIcon icon={BrainIcon} size={size} className="redesign:hidden" />
+              <ComposerControlIcon icon={GaugeIcon} size={size} className="hidden redesign:block" />
               <span data-composer-control-label>{triggerLabel}</span>
               <ComposerControlChevron size={size} />
             </>
diff --git a/apps/web/src/components/settings/AppearanceSettingsPanel.tsx b/apps/web/src/components/settings/AppearanceSettingsPanel.tsx
index a7b0756f64464..437061ccfdd10 100644
--- a/apps/web/src/components/settings/AppearanceSettingsPanel.tsx
+++ b/apps/web/src/components/settings/AppearanceSettingsPanel.tsx
@@ -351,32 +351,35 @@ export function AppearanceSettingsPanel() {
             </div>
           }
         />
-        <SettingsRow
-          {...searchableSetting("sidebar-project-icon-colors")}
-          description="Show project icons in the sidebar in full color instead of gray."
-          resetAction={
-            settings.sidebarProjectIconColors !==
-            DEFAULT_UNIFIED_SETTINGS.sidebarProjectIconColors ? (
-              <SettingResetButton
-                label="colored project icons"
-                onClick={() =>
-                  updateSettings({
-                    sidebarProjectIconColors: DEFAULT_UNIFIED_SETTINGS.sidebarProjectIconColors,
-                  })
+        {/* Only the new design grays project icons, so the option only exists there. */}
+        {settings.redesignEnabled ? (
+          <SettingsRow
+            {...searchableSetting("sidebar-project-icon-colors")}
+            description="Show project icons in the sidebar in full color instead of gray."
+            resetAction={
+              settings.sidebarProjectIconColors !==
+              DEFAULT_UNIFIED_SETTINGS.sidebarProjectIconColors ? (
+                <SettingResetButton
+                  label="colored project icons"
+                  onClick={() =>
+                    updateSettings({
+                      sidebarProjectIconColors: DEFAULT_UNIFIED_SETTINGS.sidebarProjectIconColors,
+                    })
+                  }
+                />
+              ) : null
+            }
+            control={
+              <Switch
+                checked={settings.sidebarProjectIconColors}
+                onCheckedChange={(checked) =>
+                  updateSettings({ sidebarProjectIconColors: Boolean(checked) })
                 }
+                aria-label="Colored project icons"
               />
-            ) : null
-          }
-          control={
-            <Switch
-              checked={settings.sidebarProjectIconColors}
-              onCheckedChange={(checked) =>
-                updateSettings({ sidebarProjectIconColors: Boolean(checked) })
-              }
-              aria-label="Colored project icons"
-            />
-          }
-        />
+            }
+          />
+        ) : null}
         <SettingsRow
           {...searchableSetting("math-rendering")}
           description="Typeset LaTeX math, such as $x^2$ or \[x^2\], in messages and Markdown previews. The composer keeps TeX source editable."
diff --git a/apps/web/src/components/settings/BetaSettingsPanel.tsx b/apps/web/src/components/settings/BetaSettingsPanel.tsx
index 00a9e5825d72a..a92ce9d695639 100644
--- a/apps/web/src/components/settings/BetaSettingsPanel.tsx
+++ b/apps/web/src/components/settings/BetaSettingsPanel.tsx
@@ -23,6 +23,27 @@ export function BetaSettingsPanel() {
   return (
     <SettingsPageContainer>
       <SettingsSection id="beta" title="Beta">
+        <SettingsRow
+          {...searchableSetting("new-design")}
+          description="Try the quieter design: gray sidebar icons, dimmer read threads, and simpler composer controls."
+          resetAction={
+            settings.redesignEnabled !== DEFAULT_UNIFIED_SETTINGS.redesignEnabled ? (
+              <SettingResetButton
+                label="new design"
+                onClick={() =>
+                  updateSettings({ redesignEnabled: DEFAULT_UNIFIED_SETTINGS.redesignEnabled })
+                }
+              />
+            ) : null
+          }
+          control={
+            <Switch
+              checked={settings.redesignEnabled}
+              onCheckedChange={(checked) => updateSettings({ redesignEnabled: Boolean(checked) })}
+              aria-label="New design"
+            />
+          }
+        />
         <SettingsRow
           {...searchableSetting("working-shelf")}
           description="Fold working and monitoring threads into a Working section. They return to the top of the inbox when they need you."
diff --git a/apps/web/src/components/settings/settingsSearch.ts b/apps/web/src/components/settings/settingsSearch.ts
index 769dc7a447cb0..3bf179631a920 100644
--- a/apps/web/src/components/settings/settingsSearch.ts
+++ b/apps/web/src/components/settings/settingsSearch.ts
@@ -353,6 +353,12 @@ export const SETTINGS_SEARCH_ITEMS = [
     to: "/settings/general",
     searchTerms: ["usage quota rate limit reset recover continue"],
   },
+  {
+    id: "new-design",
+    title: "New design",
+    to: "/settings/beta",
+    searchTerms: ["beta redesign look style sidebar composer gray quieter classic"],
+  },
   {
     id: "working-shelf",
     title: "Working section",
diff --git a/apps/web/src/components/sidebar/SidebarListMarkers.tsx b/apps/web/src/components/sidebar/SidebarListMarkers.tsx
index f70f8b92f942a..611219b16e63e 100644
--- a/apps/web/src/components/sidebar/SidebarListMarkers.tsx
+++ b/apps/web/src/components/sidebar/SidebarListMarkers.tsx
@@ -3,6 +3,7 @@ import { useSortable } from "@dnd-kit/sortable";
 import { CSS } from "@dnd-kit/utilities";
 import { type ReactNode } from "react";
 import { cn } from "~/lib/utils";
+import { useClientSettings } from "../../hooks/useSettings";
 import {
   animateSidebarLayoutChanges,
   sidebarMarkerId,
@@ -115,6 +116,8 @@ export function SidebarSectionHeader(props: {
       : props.marker === "snoozed-header"
         ? "snoozed"
         : "settled";
+  const redesign = useClientSettings((s) => s.redesignEnabled);
+  const collapsedCount = props.toggle.expanded ? null : props.count;
   return (
     <SortableSidebarMarker
       marker={props.marker}
@@ -127,12 +130,13 @@ export function SidebarSectionHeader(props: {
         tone={props.isDropTarget ? "accent" : props.dragging ? "emphasized" : "muted"}
         data-testid={`sidebar-${shelf}-shelf-toggle`}
         accessory={
-          props.toggle.expanded ? null : (
-            <span className="font-normal tabular-nums">{props.count}</span>
-          )
+          redesign && collapsedCount !== null ? (
+            <span className="font-normal tabular-nums">{collapsedCount}</span>
+          ) : null
         }
       >
         {props.label}
+        {!redesign && collapsedCount !== null ? ` (${collapsedCount})` : null}
       </CollapsibleSectionHeader>
     </SortableSidebarMarker>
   );
diff --git a/apps/web/src/components/sidebar/SidebarThreadRow.tsx b/apps/web/src/components/sidebar/SidebarThreadRow.tsx
index f5ad695d975bc..c2393f3fe9b7b 100644
--- a/apps/web/src/components/sidebar/SidebarThreadRow.tsx
+++ b/apps/web/src/components/sidebar/SidebarThreadRow.tsx
@@ -198,7 +198,7 @@ function SidebarProviderStack(props: {
       acpRegistryIconUrl={currentEntry.acpRegistryIconUrl}
       showBadge={showInstanceBadge}
       size="compact"
-      iconClassName="opacity-50 grayscale"
+      iconClassName="opacity-60 redesign:opacity-50 redesign:grayscale"
     />
   );
   if (stack.length === 1) {
@@ -978,12 +978,12 @@ const SidebarThreadRow = memo(function SidebarThreadRow(props: SidebarThreadRowP
             ? cn(
                 "truncate",
                 shouldRecede
-                  ? "text-foreground/75 group-hover/sidebar-row:text-foreground group-focus-visible/sidebar-row:text-foreground"
+                  ? "text-secondary-label redesign:text-foreground/75 redesign:group-hover/sidebar-row:text-foreground redesign:group-focus-visible/sidebar-row:text-foreground"
                   : isUnread || isWoke || status === "input" || status === "request"
                     ? "text-foreground"
                     : status === "failed"
                       ? "text-foreground/95"
-                      : "text-foreground",
+                      : "text-foreground/90 redesign:text-foreground",
               )
             : cn(
                 "truncate group-focus-within/sidebar-row:text-foreground group-hover/sidebar-row:text-foreground",
@@ -1284,7 +1284,7 @@ const SidebarThreadRow = memo(function SidebarThreadRow(props: SidebarThreadRowP
                     // Repeated brand colors outshout titles; color returns on the row in focus.
                     !props.isActive &&
                       !projectIconColors &&
-                      "opacity-60 grayscale group-focus-visible/sidebar-row:opacity-100 group-focus-visible/sidebar-row:grayscale-0 group-any-hover/sidebar-row:opacity-100 group-any-hover/sidebar-row:grayscale-0",
+                      "redesign:opacity-60 redesign:grayscale redesign:group-focus-visible/sidebar-row:opacity-100 redesign:group-focus-visible/sidebar-row:grayscale-0 redesign:group-any-hover/sidebar-row:opacity-100 redesign:group-any-hover/sidebar-row:grayscale-0",
                   )}
                 />
               ) : null}
@@ -1292,7 +1292,12 @@ const SidebarThreadRow = memo(function SidebarThreadRow(props: SidebarThreadRowP
                 label for the wider row controls. */}
               {pinIndicator}
               {props.projectDisplayName ? (
-                <span className="min-w-0 flex-1 truncate text-secondary-label text-xs">
+                <span
+                  className={cn(
+                    "min-w-0 flex-1 truncate text-secondary-label text-xs",
+                    shouldRecede ? "font-normal" : "font-medium redesign:font-normal",
+                  )}
+                >
                   {props.projectDisplayName}
                 </span>
               ) : (
@@ -1449,7 +1454,7 @@ const SidebarThreadRow = memo(function SidebarThreadRow(props: SidebarThreadRowP
               {thread.branch ? (
                 <>
                   <ThreadWorktreeIndicator thread={thread} />
-                  <span className="flex min-w-0 flex-1">
+                  <span className="flex min-w-0 flex-1 text-muted-foreground/40 redesign:text-inherit">
                     <MiddleTruncate value={thread.branch} showTitle={false} />
                   </span>
                 </>
@@ -1458,9 +1463,11 @@ const SidebarThreadRow = memo(function SidebarThreadRow(props: SidebarThreadRowP
                   <EnvironmentMachineIcon
                     aria-hidden
                     kind={props.environmentMachine}
-                    className="size-3 shrink-0"
+                    className="size-3 shrink-0 text-muted-foreground/40 redesign:text-inherit"
                   />
-                  <span className="min-w-0 flex-1 truncate">{props.scratchMachineLabel}</span>
+                  <span className="min-w-0 flex-1 truncate text-muted-foreground/40 redesign:text-inherit">
+                    {props.scratchMachineLabel}
+                  </span>
                 </>
               ) : (
                 <span className="flex-1" />
diff --git a/apps/web/src/components/ui/button.tsx b/apps/web/src/components/ui/button.tsx
index 803a6fa04b7ec..5637baf28abbc 100644
--- a/apps/web/src/components/ui/button.tsx
+++ b/apps/web/src/components/ui/button.tsx
@@ -106,7 +106,7 @@ const inlineButtonVariants = cva(
         muted: "text-muted-foreground hover:text-foreground",
         destructive: "text-destructive/80 hover:text-destructive",
         picker:
-          "gap-1 text-foreground decoration-from-font underline-offset-4 hover:underline data-popup-open:underline",
+          "gap-1 text-foreground underline decoration-foreground/30 decoration-dotted decoration-from-font underline-offset-4 hover:decoration-foreground hover:decoration-solid data-popup-open:decoration-foreground data-popup-open:decoration-solid redesign:no-underline redesign:hover:underline redesign:data-popup-open:underline",
       },
     },
   },
diff --git a/apps/web/src/components/ui/collapsible-section-header.tsx b/apps/web/src/components/ui/collapsible-section-header.tsx
index 14b0ad4465bc6..4dd632c469d70 100644
--- a/apps/web/src/components/ui/collapsible-section-header.tsx
+++ b/apps/web/src/components/ui/collapsible-section-header.tsx
@@ -62,7 +62,7 @@ export function CollapsibleSectionHeader({
         className={cn(
           "shrink-0 transition-transform",
           variant === "row" ? "size-4 text-muted-foreground" : "size-3",
-          !expanded && "-rotate-90",
+          !expanded && "rotate-180 redesign:-rotate-90",
         )}
       />
     </button>
diff --git a/apps/web/src/index.css b/apps/web/src/index.css
index 7142f65cc763c..649c63efc2f68 100644
--- a/apps/web/src/index.css
+++ b/apps/web/src/index.css
@@ -4,6 +4,8 @@
 @custom-variant light (&:not(.dark, .dark *));
 /* Window Controls Overlay: active when Electron exposes native titlebar control geometry. */
 @custom-variant wco (&:is(.wco, .wco *));
+/* Beta "New design" (Settings -> Beta) sets data-redesign on <html>. */
+@custom-variant redesign (&:where([data-redesign] *));
 
 /* Secondary hovering pointers reveal sidebar actions on touch-primary devices. */
 @custom-variant any-hover {
@@ -1243,8 +1245,6 @@ html[data-mobile-composer-route-transition="true"]::view-transition-old(t3-mobil
     --accent-foreground: #f7f9ff;
     --muted: #0a0a0a;
     --muted-foreground: #a3a3a3;
-    /* Row metadata sits a step below read titles (75% white). */
-    --secondary-label: #8f8f8f;
     --border: rgb(255 255 255 / 8%);
     --input: rgb(255 255 255 / 18%);
     --sidebar: var(--card);
@@ -1663,6 +1663,11 @@ body {
   padding: 0;
 }
 
+/* New design: sidebar row metadata sits a step below read titles (75% white). */
+.dark[data-redesign] [data-app-sidebar] {
+  --secondary-label: #8f8f8f;
+}
+
 /* Lighter default icon stroke. Zero specificity, so stroke-* classes still win
    over it while it still beats lucide's stroke-width="2" attribute. */
 :where(svg.lucide[stroke-width="2"]) {
diff --git a/apps/web/src/routes/__root.tsx b/apps/web/src/routes/__root.tsx
index 2152b2c86bd75..d18e89d161a04 100644
--- a/apps/web/src/routes/__root.tsx
+++ b/apps/web/src/routes/__root.tsx
@@ -294,6 +294,10 @@ function ContrastAppearanceSync() {
   }, [diffColorScheme]);
 
   const chatWidth = useClientSettings((settings) => settings.chatWidth);
+  const redesignEnabled = useClientSettings((settings) => settings.redesignEnabled);
+  useEffect(() => {
+    document.documentElement.toggleAttribute("data-redesign", redesignEnabled);
+  }, [redesignEnabled]);
   useEffect(() => {
     document.documentElement.dataset.chatWidth = chatWidth;
   }, [chatWidth]);
diff --git a/packages/contracts/src/settings.ts b/packages/contracts/src/settings.ts
index 7ebdf72310c35..045e71a5eae9f 100644
--- a/packages/contracts/src/settings.ts
+++ b/packages/contracts/src/settings.ts
@@ -477,6 +477,8 @@ export const ClientSettingsSchema = Schema.Struct({
   mathRenderingEnabled: Schema.Boolean.pipe(Schema.withDecodingDefault(Effect.succeed(false))),
   // Sidebar project icons rest in grayscale so titles lead; this keeps their colors.
   sidebarProjectIconColors: Schema.Boolean.pipe(Schema.withDecodingDefault(Effect.succeed(false))),
+  // Beta: the quieter sidebar, composer and panel design. Off keeps the current look.
+  redesignEnabled: Schema.Boolean.pipe(Schema.withDecodingDefault(Effect.succeed(false))),
 });
 export type ClientSettings = typeof ClientSettingsSchema.Type;
 
@@ -1683,5 +1685,6 @@ export const ClientSettingsPatch = Schema.Struct({
   wordWrap: Schema.optionalKey(Schema.Boolean),
   mathRenderingEnabled: Schema.optionalKey(Schema.Boolean),
   sidebarProjectIconColors: Schema.optionalKey(Schema.Boolean),
+  redesignEnabled: Schema.optionalKey(Schema.Boolean),
 });
 export type ClientSettingsPatch = typeof ClientSettingsPatch.Type;