diff --git a/apps/desktop/src/clientPersistence.test.ts b/apps/desktop/src/clientPersistence.test.ts
index df2178c0b0..88913ec0b5 100644
--- a/apps/desktop/src/clientPersistence.test.ts
+++ b/apps/desktop/src/clientPersistence.test.ts
@@ -53,6 +53,7 @@ const clientSettings: ClientSettings = {
   confirmThreadDelete: false,
   diffWordWrap: true,
   sidebarProjectSortOrder: "manual",
+  sidebarThreadPreviewCount: 6,
   sidebarThreadSortOrder: "created_at",
   timestampFormat: "24-hour",
 };
diff --git a/apps/web/src/components/Sidebar.tsx b/apps/web/src/components/Sidebar.tsx
index bb63db6fc0..dfdeca2c08 100644
--- a/apps/web/src/components/Sidebar.tsx
+++ b/apps/web/src/components/Sidebar.tsx
@@ -5,6 +5,7 @@ import {
   CloudIcon,
   FolderIcon,
   GitPullRequestIcon,
+  MinusIcon,
   PlusIcon,
   SettingsIcon,
   SquarePenIcon,
@@ -49,7 +50,10 @@ import {
 } from "@t3tools/client-runtime";
 import { Link, useLocation, useNavigate, useParams, useRouter } from "@tanstack/react-router";
 import {
+  MAX_SIDEBAR_THREAD_PREVIEW_COUNT,
+  MIN_SIDEBAR_THREAD_PREVIEW_COUNT,
   type SidebarProjectSortOrder,
+  type SidebarThreadPreviewCount,
   type SidebarThreadSortOrder,
 } from "@t3tools/contracts/settings";
 import { usePrimaryEnvironmentId } from "../environments/primary";
@@ -101,6 +105,7 @@ import {
 } from "./desktopUpdate.logic";
 import { Alert, AlertAction, AlertDescription, AlertTitle } from "./ui/alert";
 import { Button } from "./ui/button";
+import { Input } from "./ui/input";
 import { Menu, MenuGroup, MenuPopup, MenuRadioGroup, MenuRadioItem, MenuTrigger } from "./ui/menu";
 import { Tooltip, TooltipPopup, TooltipTrigger } from "./ui/tooltip";
 import {
@@ -145,7 +150,6 @@ import {
   useSavedEnvironmentRuntimeStore,
 } from "../environments/runtime";
 import type { Project, SidebarThreadSummary } from "../types";
-const THREAD_PREVIEW_LIMIT = 6;
 const SIDEBAR_SORT_LABELS: Record<SidebarProjectSortOrder, string> = {
   updated_at: "Last user message",
   created_at: "Created at",
@@ -161,6 +165,13 @@ const SIDEBAR_LIST_ANIMATION_OPTIONS = {
 } as const;
 const EMPTY_THREAD_JUMP_LABELS = new Map<string, string>();
 
+function clampSidebarThreadPreviewCount(value: number): SidebarThreadPreviewCount {
+  return Math.min(
+    MAX_SIDEBAR_THREAD_PREVIEW_COUNT,
+    Math.max(MIN_SIDEBAR_THREAD_PREVIEW_COUNT, value),
+  ) as SidebarThreadPreviewCount;
+}
+
 function threadJumpLabelMapsEqual(
   left: ReadonlyMap<string, string>,
   right: ReadonlyMap<string, string>,
@@ -977,6 +988,9 @@ const SidebarProjectItem = memo(function SidebarProjectItem(props: SidebarProjec
   const defaultThreadEnvMode = useSettings<ThreadEnvMode>(
     (settings) => settings.defaultThreadEnvMode,
   );
+  const sidebarThreadPreviewCount = useSettings<SidebarThreadPreviewCount>(
+    (settings) => settings.sidebarThreadPreviewCount,
+  );
   const router = useRouter();
   const markThreadUnread = useUiStateStore((state) => state.markThreadUnread);
   const toggleProject = useUiStateStore((state) => state.toggleProject);
@@ -1192,11 +1206,11 @@ const SidebarProjectItem = memo(function SidebarProjectItem(props: SidebarProjec
         },
       });
     };
-    const hasOverflowingThreads = visibleProjectThreads.length > THREAD_PREVIEW_LIMIT;
+    const hasOverflowingThreads = visibleProjectThreads.length > sidebarThreadPreviewCount;
     const previewThreads =
       isThreadListExpanded || !hasOverflowingThreads
         ? visibleProjectThreads
-        : visibleProjectThreads.slice(0, THREAD_PREVIEW_LIMIT);
+        : visibleProjectThreads.slice(0, sidebarThreadPreviewCount);
     const visibleThreadKeys = new Set(
       [...previewThreads, ...(pinnedCollapsedThread ? [pinnedCollapsedThread] : [])].map((thread) =>
         scopedThreadKey(scopeThreadRef(thread.environmentId, thread.id)),
@@ -1225,6 +1239,7 @@ const SidebarProjectItem = memo(function SidebarProjectItem(props: SidebarProjec
     pinnedCollapsedThread,
     projectExpanded,
     projectThreads,
+    sidebarThreadPreviewCount,
     threadLastVisitedAts,
     visibleProjectThreads,
   ]);
@@ -1836,14 +1851,41 @@ type SortableProjectHandleProps = Pick<
 function ProjectSortMenu({
   projectSortOrder,
   threadSortOrder,
+  threadPreviewCount,
   onProjectSortOrderChange,
   onThreadSortOrderChange,
+  onThreadPreviewCountChange,
 }: {
   projectSortOrder: SidebarProjectSortOrder;
   threadSortOrder: SidebarThreadSortOrder;
+  threadPreviewCount: SidebarThreadPreviewCount;
   onProjectSortOrderChange: (sortOrder: SidebarProjectSortOrder) => void;
   onThreadSortOrderChange: (sortOrder: SidebarThreadSortOrder) => void;
+  onThreadPreviewCountChange: (count: SidebarThreadPreviewCount) => void;
 }) {
+  const [threadPreviewInput, setThreadPreviewInput] = useState(() => String(threadPreviewCount));
+
+  useEffect(() => {
+    setThreadPreviewInput(String(threadPreviewCount));
+  }, [threadPreviewCount]);
+
+  const commitThreadPreviewCount = useCallback(
+    (nextValue: string) => {
+      const parsedValue = Number.parseInt(nextValue, 10);
+      if (!Number.isInteger(parsedValue)) {
+        setThreadPreviewInput(String(threadPreviewCount));
+        return;
+      }
+
+      const clampedValue = clampSidebarThreadPreviewCount(parsedValue);
+      setThreadPreviewInput(String(clampedValue));
+      if (clampedValue !== threadPreviewCount) {
+        onThreadPreviewCountChange(clampedValue);
+      }
+    },
+    [onThreadPreviewCountChange, threadPreviewCount],
+  );
+
   return (
     <Menu>
       <Tooltip>
@@ -1854,9 +1896,9 @@ function ProjectSortMenu({
         >
           <ArrowUpDownIcon className="size-3.5" />
         </TooltipTrigger>
-        <TooltipPopup side="right">Sort projects</TooltipPopup>
+        <TooltipPopup side="right">Sidebar options</TooltipPopup>
       </Tooltip>
-      <MenuPopup align="end" side="bottom" className="min-w-44">
+      <MenuPopup align="end" side="bottom" className="min-w-52">
         <MenuGroup>
           <div className="px-2 py-1 sm:text-xs font-medium text-muted-foreground">
             Sort projects
@@ -1895,6 +1937,63 @@ function ProjectSortMenu({
             ))}
           </MenuRadioGroup>
         </MenuGroup>
+        <MenuGroup>
+          <div className="px-2 pt-2 pb-1 text-muted-foreground sm:text-xs font-medium">
+            Visible threads
+          </div>
+          <div className="flex items-center gap-2 px-2 py-1">
+            <Button
+              size="icon-xs"
+              variant="outline"
+              className="size-7 shrink-0"
+              aria-label="Decrease visible thread count"
+              disabled={threadPreviewCount <= MIN_SIDEBAR_THREAD_PREVIEW_COUNT}
+              onClick={() =>
+                onThreadPreviewCountChange(clampSidebarThreadPreviewCount(threadPreviewCount - 1))
+              }
+            >
+              <MinusIcon className="size-3.5" />
+            </Button>
+            <Input
+              nativeInput
+              type="text"
+              inputMode="numeric"
+              min={MIN_SIDEBAR_THREAD_PREVIEW_COUNT}
+              max={MAX_SIDEBAR_THREAD_PREVIEW_COUNT}
+              pattern="[0-9]*"
+              size="sm"
+              className="w-14"
+              aria-label="Visible thread count"
+              value={threadPreviewInput}
+              onKeyDownCapture={(event) => {
+                event.stopPropagation();
+              }}
+              onChange={(event) => {
+                setThreadPreviewInput(event.currentTarget.value.replace(/[^0-9]/g, ""));
+              }}
+              onBlur={(event) => {
+                commitThreadPreviewCount(event.currentTarget.value);
+              }}
+              onKeyDown={(event) => {
+                if (event.key === "Enter") {
+                  commitThreadPreviewCount(event.currentTarget.value);
+                }
+              }}
+            />
+            <Button
+              size="icon-xs"
+              variant="outline"
+              className="size-7 shrink-0"
+              aria-label="Increase visible thread count"
+              disabled={threadPreviewCount >= MAX_SIDEBAR_THREAD_PREVIEW_COUNT}
+              onClick={() =>
+                onThreadPreviewCountChange(clampSidebarThreadPreviewCount(threadPreviewCount + 1))
+              }
+            >
+              <PlusIcon className="size-3.5" />
+            </Button>
+          </div>
+        </MenuGroup>
       </MenuPopup>
     </Menu>
   );
@@ -2012,6 +2111,7 @@ interface SidebarProjectsContentProps {
   handleDesktopUpdateButtonClick: () => void;
   projectSortOrder: SidebarProjectSortOrder;
   threadSortOrder: SidebarThreadSortOrder;
+  threadPreviewCount: SidebarThreadPreviewCount;
   updateSettings: ReturnType<typeof useUpdateSettings>["updateSettings"];
   shouldShowProjectPathEntry: boolean;
   handleStartAddProject: () => void;
@@ -2063,6 +2163,7 @@ const SidebarProjectsContent = memo(function SidebarProjectsContent(
     handleDesktopUpdateButtonClick,
     projectSortOrder,
     threadSortOrder,
+    threadPreviewCount,
     updateSettings,
     shouldShowProjectPathEntry,
     handleStartAddProject,
@@ -2115,6 +2216,12 @@ const SidebarProjectsContent = memo(function SidebarProjectsContent(
     },
     [updateSettings],
   );
+  const handleThreadPreviewCountChange = useCallback(
+    (count: SidebarThreadPreviewCount) => {
+      updateSettings({ sidebarThreadPreviewCount: count });
+    },
+    [updateSettings],
+  );
   const handleAddProjectInputChange = useCallback(
     (event: React.ChangeEvent<HTMLInputElement>) => {
       setNewCwd(event.target.value);
@@ -2170,8 +2277,10 @@ const SidebarProjectsContent = memo(function SidebarProjectsContent(
             <ProjectSortMenu
               projectSortOrder={projectSortOrder}
               threadSortOrder={threadSortOrder}
+              threadPreviewCount={threadPreviewCount}
               onProjectSortOrderChange={handleProjectSortOrderChange}
               onThreadSortOrderChange={handleThreadSortOrderChange}
+              onThreadPreviewCountChange={handleThreadPreviewCountChange}
             />
             <Tooltip>
               <TooltipTrigger
@@ -2336,6 +2445,7 @@ export default function Sidebar() {
   const isOnSettings = pathname.startsWith("/settings");
   const sidebarThreadSortOrder = useSettings((s) => s.sidebarThreadSortOrder);
   const sidebarProjectSortOrder = useSettings((s) => s.sidebarProjectSortOrder);
+  const sidebarThreadPreviewCount = useSettings((s) => s.sidebarThreadPreviewCount);
   const defaultThreadEnvMode = useSettings((s) => s.defaultThreadEnvMode);
   const { updateSettings } = useUpdateSettings();
   const { handleNewThread } = useNewThreadHandler();
@@ -2790,11 +2900,11 @@ export default function Sidebar() {
           return [];
         }
         const isThreadListExpanded = expandedThreadListsByProject.has(project.projectKey);
-        const hasOverflowingThreads = projectThreads.length > THREAD_PREVIEW_LIMIT;
+        const hasOverflowingThreads = projectThreads.length > sidebarThreadPreviewCount;
         const previewThreads =
           isThreadListExpanded || !hasOverflowingThreads
             ? projectThreads
-            : projectThreads.slice(0, THREAD_PREVIEW_LIMIT);
+            : projectThreads.slice(0, sidebarThreadPreviewCount);
         const renderedThreads = pinnedCollapsedThread ? [pinnedCollapsedThread] : previewThreads;
         return renderedThreads.map((thread) =>
           scopedThreadKey(scopeThreadRef(thread.environmentId, thread.id)),
@@ -2802,6 +2912,7 @@ export default function Sidebar() {
       }),
     [
       sidebarThreadSortOrder,
+      sidebarThreadPreviewCount,
       expandedThreadListsByProject,
       projectExpandedById,
       routeThreadKey,
@@ -3136,6 +3247,7 @@ export default function Sidebar() {
             handleDesktopUpdateButtonClick={handleDesktopUpdateButtonClick}
             projectSortOrder={sidebarProjectSortOrder}
             threadSortOrder={sidebarThreadSortOrder}
+            threadPreviewCount={sidebarThreadPreviewCount}
             updateSettings={updateSettings}
             shouldShowProjectPathEntry={shouldShowProjectPathEntry}
             handleStartAddProject={handleStartAddProject}
diff --git a/apps/web/src/components/settings/SettingsPanels.tsx b/apps/web/src/components/settings/SettingsPanels.tsx
index c8766f2643..b7eccbcc22 100644
--- a/apps/web/src/components/settings/SettingsPanels.tsx
+++ b/apps/web/src/components/settings/SettingsPanels.tsx
@@ -368,6 +368,9 @@ export function useSettingsRestore(onRestored?: () => void) {
       ...(settings.timestampFormat !== DEFAULT_UNIFIED_SETTINGS.timestampFormat
         ? ["Time format"]
         : []),
+      ...(settings.sidebarThreadPreviewCount !== DEFAULT_UNIFIED_SETTINGS.sidebarThreadPreviewCount
+        ? ["Visible threads"]
+        : []),
       ...(settings.diffWordWrap !== DEFAULT_UNIFIED_SETTINGS.diffWordWrap
         ? ["Diff line wrapping"]
         : []),
@@ -394,6 +397,7 @@ export function useSettingsRestore(onRestored?: () => void) {
       settings.defaultThreadEnvMode,
       settings.diffWordWrap,
       settings.enableAssistantStreaming,
+      settings.sidebarThreadPreviewCount,
       settings.timestampFormat,
       theme,
     ],
diff --git a/apps/web/src/localApi.test.ts b/apps/web/src/localApi.test.ts
index 68047f4495..f4260920cb 100644
--- a/apps/web/src/localApi.test.ts
+++ b/apps/web/src/localApi.test.ts
@@ -503,6 +503,7 @@ describe("wsApi", () => {
       diffWordWrap: true,
       sidebarProjectSortOrder: "manual",
       sidebarThreadSortOrder: "created_at",
+      sidebarThreadPreviewCount: 6,
       timestampFormat: "24-hour",
     });
     const setClientSettings = vi.fn().mockResolvedValue(undefined);
@@ -531,6 +532,7 @@ describe("wsApi", () => {
       diffWordWrap: true,
       sidebarProjectSortOrder: "manual",
       sidebarThreadSortOrder: "created_at",
+      sidebarThreadPreviewCount: 6,
       timestampFormat: "24-hour",
     });
     await api.persistence.getSavedEnvironmentRegistry();
@@ -549,6 +551,7 @@ describe("wsApi", () => {
       diffWordWrap: true,
       sidebarProjectSortOrder: "manual",
       sidebarThreadSortOrder: "created_at",
+      sidebarThreadPreviewCount: 6,
       timestampFormat: "24-hour",
     });
     expect(getSavedEnvironmentRegistry).toHaveBeenCalledWith();
@@ -568,6 +571,7 @@ describe("wsApi", () => {
       diffWordWrap: true,
       sidebarProjectSortOrder: "manual",
       sidebarThreadSortOrder: "created_at",
+      sidebarThreadPreviewCount: 6,
       timestampFormat: "24-hour",
     });
     await api.persistence.setSavedEnvironmentRegistry([
@@ -591,6 +595,7 @@ describe("wsApi", () => {
       diffWordWrap: true,
       sidebarProjectSortOrder: "manual",
       sidebarThreadSortOrder: "created_at",
+      sidebarThreadPreviewCount: 6,
       timestampFormat: "24-hour",
     });
     await expect(api.persistence.getSavedEnvironmentRegistry()).resolves.toEqual([
diff --git a/packages/contracts/src/settings.ts b/packages/contracts/src/settings.ts
index 426f8bee56..e2f6982dc8 100644
--- a/packages/contracts/src/settings.ts
+++ b/packages/contracts/src/settings.ts
@@ -23,6 +23,17 @@ export const SidebarThreadSortOrder = Schema.Literals(["updated_at", "created_at
 export type SidebarThreadSortOrder = typeof SidebarThreadSortOrder.Type;
 export const DEFAULT_SIDEBAR_THREAD_SORT_ORDER: SidebarThreadSortOrder = "updated_at";
 
+export const MIN_SIDEBAR_THREAD_PREVIEW_COUNT = 2;
+export const MAX_SIDEBAR_THREAD_PREVIEW_COUNT = 10;
+export const SidebarThreadPreviewCount = Schema.Int.check(
+  Schema.isBetween({
+    minimum: MIN_SIDEBAR_THREAD_PREVIEW_COUNT,
+    maximum: MAX_SIDEBAR_THREAD_PREVIEW_COUNT,
+  }),
+);
+export type SidebarThreadPreviewCount = typeof SidebarThreadPreviewCount.Type;
+export const DEFAULT_SIDEBAR_THREAD_PREVIEW_COUNT: SidebarThreadPreviewCount = 6;
+
 export const ClientSettingsSchema = Schema.Struct({
   confirmThreadArchive: Schema.Boolean.pipe(Schema.withDecodingDefault(Effect.succeed(false))),
   confirmThreadDelete: Schema.Boolean.pipe(Schema.withDecodingDefault(Effect.succeed(true))),
@@ -36,6 +47,9 @@ export const ClientSettingsSchema = Schema.Struct({
   timestampFormat: TimestampFormat.pipe(
     Schema.withDecodingDefault(Effect.succeed(DEFAULT_TIMESTAMP_FORMAT)),
   ),
+  sidebarThreadPreviewCount: SidebarThreadPreviewCount.pipe(
+    Schema.withDecodingDefault(Effect.succeed(DEFAULT_SIDEBAR_THREAD_PREVIEW_COUNT)),
+  ),
 });
 export type ClientSettings = typeof ClientSettingsSchema.Type;