diff --git a/apps/web/src/components/ServerUpdateAction.browser.test.tsx b/apps/web/src/components/ServerUpdateAction.browser.test.tsx
index ed3a723652a56..ace7f45976eff 100644
--- a/apps/web/src/components/ServerUpdateAction.browser.test.tsx
+++ b/apps/web/src/components/ServerUpdateAction.browser.test.tsx
@@ -171,6 +171,17 @@ describe("ServerUpdateAction", () => {
     },
   );
 
+  it("does not update a desktop app when no confirmation dialog can be shown", async () => {
+    using _state = setup();
+    testState.updateServer.mockResolvedValue(success("desktop-app"));
+    await using screen = await renderAction({
+      selfUpdate: "desktop-managed",
+      desktopAppUpdate: true,
+    });
+    await click(screen, "Update");
+    expect(testState.updateServer).not.toHaveBeenCalled();
+  });
+
   it("disables the action once maintenance access is removed", async () => {
     using _state = setup();
     await using screen = await renderAction();
@@ -237,4 +248,24 @@ describe("ServerUpdatesAction", () => {
       expect.objectContaining({ type: "success", title: "Office updated" }),
     );
   });
+
+  const withDesktop: ReadonlyArray<ServerUpdateTarget> = [
+    targets[0]!,
+    {
+      environmentId: "batch-desktop" as EnvironmentId,
+      serverLabel: "Studio",
+      selfUpdate: "desktop-managed",
+      desktopAppUpdate: true,
+      targetVersion: "0.0.31",
+    },
+  ];
+
+  it("does not update any machine when a desktop app needs a confirmation that cannot be shown", async () => {
+    using _state = setup();
+    testState.updateServer.mockResolvedValue(success());
+    await using screen = await mount(withDesktop);
+    await click(screen, "Update all");
+    expect(testState.updateServer).not.toHaveBeenCalled();
+    expect(button(screen, "Update all")!.disabled).toBe(false);
+  });
 });
diff --git a/apps/web/src/components/ServerUpdateAction.tsx b/apps/web/src/components/ServerUpdateAction.tsx
index 32a2811aca189..9eddb99cee13e 100644
--- a/apps/web/src/components/ServerUpdateAction.tsx
+++ b/apps/web/src/components/ServerUpdateAction.tsx
@@ -43,6 +43,7 @@ const UPDATE_STAGE_LABELS: Record<ServerUpdateStage, string> = {
   resuming: "Restarting…",
 };
 const pendingUpdateEnvironmentIds = new Set<EnvironmentId>();
+const DESKTOP_UPDATE_INTERRUPTION_WARNING = "Updates interrupt tasks and tool calls.";
 
 export function serverUpdateStageLabel(stage: ServerUpdateStage): string {
   return UPDATE_STAGE_LABELS[stage];
@@ -199,10 +200,9 @@ export function ServerUpdatesAction({
       );
       const desktopTargets = available.filter((target) => target.selfUpdate === "desktop-managed");
       if (desktopTargets.length > 0) {
-        const confirmed =
-          (await requestConfirmDialog(
-            `Update the T3 Code desktop apps on ${desktopTargets.map((target) => target.serverLabel).join(", ")}? They will close and relaunch on those machines.`,
-          )) ?? true;
+        const confirmed = await requestConfirmDialog(
+          `Update the T3 Code desktop apps on ${desktopTargets.map((target) => target.serverLabel).join(", ")}?\n\n${DESKTOP_UPDATE_INTERRUPTION_WARNING}`,
+        );
         if (!confirmed) return;
       }
       await Promise.all(available.map((target) => update(target)));
@@ -305,10 +305,9 @@ export function ServerUpdateAction({
       return;
     }
     if (isDesktopAppUpdate) {
-      const confirmed =
-        (await requestConfirmDialog(
-          `Update the T3 Code desktop app that runs the ${serverLabel}? It will close and relaunch on that machine.`,
-        )) ?? true;
+      const confirmed = await requestConfirmDialog(
+        `Update the T3 Code desktop app that runs the ${serverLabel}?\n\n${DESKTOP_UPDATE_INTERRUPTION_WARNING}`,
+      );
       if (!confirmed) {
         return;
       }
diff --git a/apps/web/src/components/sidebar/SidebarUpdatePill.browser.test.tsx b/apps/web/src/components/sidebar/SidebarUpdatePill.browser.test.tsx
index 03bb2c72849e2..93a6f38c4de3c 100644
--- a/apps/web/src/components/sidebar/SidebarUpdatePill.browser.test.tsx
+++ b/apps/web/src/components/sidebar/SidebarUpdatePill.browser.test.tsx
@@ -1,10 +1,11 @@
-import type { DesktopUpdateState } from "@t3tools/contracts";
+import type { DesktopUpdateState, EnvironmentId } from "@t3tools/contracts";
 import { describe, expect, it, vi } from "vite-plus/test";
 import { page, userEvent } from "vite-plus/test/browser";
 
 import "~/index.css";
 import { act, render } from "../../../test/render";
 import { SidebarUpdatePill } from "./SidebarUpdatePill";
+import { UpdateEverythingDialog } from "./UpdateEverythingDialog";
 
 const mocks = vi.hoisted(() => {
   const listeners = new Set<() => void>();
@@ -140,4 +141,31 @@ describe("SidebarUpdatePill update everything", () => {
     await userEvent.keyboard("{Escape}");
     await vi.waitFor(() => expect(document.activeElement).toBe(button.element()));
   });
+
+  it("warns that an app restart interrupts work before any threads have loaded", async () => {
+    setup(null);
+    const studio = "studio" as EnvironmentId;
+    await using _screen = await render(
+      <UpdateEverythingDialog
+        open
+        onOpenChange={() => {}}
+        version={null}
+        providerCount={0}
+        rows={[
+          {
+            environmentId: studio,
+            label: "Studio",
+            app: "desktop-app",
+            skipped: null,
+            providers: [],
+          },
+        ]}
+        restarts={[{ environmentId: studio, continuesThreads: true }]}
+        onConfirm={() => {}}
+      />,
+    );
+    const dialog = page.getByRole("alertdialog");
+    await expect.element(dialog.getByText(/interrupt/i)).toBeVisible();
+    await expect.element(dialog).toHaveAccessibleDescription(/interrupt/i);
+  });
 });
diff --git a/apps/web/src/components/sidebar/UpdateEverythingDialog.tsx b/apps/web/src/components/sidebar/UpdateEverythingDialog.tsx
index 9bf101b6fa4e7..56edd9010dceb 100644
--- a/apps/web/src/components/sidebar/UpdateEverythingDialog.tsx
+++ b/apps/web/src/components/sidebar/UpdateEverythingDialog.tsx
@@ -2,7 +2,7 @@ import { useAtomValue } from "@effect/atom-react";
 import { EnvironmentId } from "@t3tools/contracts";
 import { Atom } from "effect/reactivity";
 import { ChevronRightIcon } from "lucide-react";
-import { Fragment, type RefObject, useRef } from "react";
+import { Fragment, type RefObject, useId, useRef } from "react";
 
 import { environmentThreadShells } from "~/state/threads";
 import {
@@ -51,7 +51,7 @@ interface UpdateEverythingDialogProps {
   readonly title?: string;
   readonly confirmLabel?: string;
   readonly notes?: ReadonlyArray<string>;
-  /** Shown in place of running-thread counts; disables the confirm button. */
+  /** Shown in place of the interruption warning; disables the confirm button. */
   readonly disabledReason?: string | null;
   /** The confirmed work is starting; it cannot be cancelled from here. */
   readonly busy?: boolean;
@@ -62,6 +62,7 @@ type UpdateEverythingDialogContentProps = Omit<
   "open" | "onOpenChange"
 > & {
   readonly cancelRef: RefObject<HTMLButtonElement | null>;
+  readonly descriptionId: string;
 };
 
 export function UpdateEverythingDialog({
@@ -70,15 +71,25 @@ export function UpdateEverythingDialog({
   ...content
 }: UpdateEverythingDialogProps) {
   const cancelRef = useRef<HTMLButtonElement>(null);
+  const descriptionId = useId();
   return (
     <AlertDialog open={open} onOpenChange={onOpenChange}>
       {/* Refocusing the trigger after a pointer close shows its focus ring and opens its tooltip. */}
       <AlertDialogPopup
         className="sm:max-w-xl"
+        aria-describedby={
+          (content.disabledReason ?? null) === null && content.rows.some((row) => row.app !== null)
+            ? `${descriptionId} ${descriptionId}-interruption`
+            : descriptionId
+        }
         initialFocus={cancelRef}
         finalFocus={(closeType) => closeType === "keyboard"}
       >
-        <UpdateEverythingDialogContent {...content} cancelRef={cancelRef} />
+        <UpdateEverythingDialogContent
+          {...content}
+          cancelRef={cancelRef}
+          descriptionId={descriptionId}
+        />
       </AlertDialogPopup>
     </AlertDialog>
   );
@@ -102,25 +113,8 @@ function UpdateEverythingDialogContent({
   notes = [],
   disabledReason = null,
   busy = false,
+  descriptionId,
 }: UpdateEverythingDialogContentProps) {
-  const stopped = useAtomValue(
-    runningThreadCountAtom(
-      restarts
-        .filter((machine) => !machine.continuesThreads)
-        .map((machine) => machine.environmentId)
-        .join("\n"),
-    ),
-  );
-  const continuing = useAtomValue(
-    runningThreadCountAtom(
-      restarts
-        .filter((machine) => machine.continuesThreads)
-        .map((machine) => machine.environmentId)
-        .join("\n"),
-    ),
-  );
-  const running = stopped + continuing;
-  const threads = `${running} running ${running === 1 ? "thread" : "threads"}`;
   const restarting = new Set(restarts.map((machine) => machine.environmentId));
   const updating = rows.filter((row) => row.app !== null || row.providers.length > 0);
   const skipped = rows.filter((row) => row.skipped !== null);
@@ -131,7 +125,7 @@ function UpdateEverythingDialogContent({
         <AlertDialogTitle>
           {title ?? `Update ${updating.length} ${updating.length === 1 ? "machine" : "machines"}?`}
         </AlertDialogTitle>
-        <AlertDialogDescription>
+        <AlertDialogDescription id={descriptionId}>
           {version !== null ? (
             <>
               T3 Code <span className="font-mono text-xs">{version}</span>
@@ -214,17 +208,18 @@ function UpdateEverythingDialogContent({
         </div>
       </ScrollArea>
       <AlertDialogFooter>
+        {/* Thread counts come from client snapshots that can still be loading, so the warning
+            cannot depend on them. */}
         {disabledReason !== null ? (
           <p className="self-center text-sm max-sm:order-1 max-sm:text-center sm:mr-auto">
             {disabledReason}
           </p>
-        ) : running > 0 ? (
-          <p className="self-center text-muted-foreground text-sm max-sm:order-1 max-sm:text-center sm:mr-auto">
-            {stopped === 0
-              ? `${threads} will be interrupted and can resume after the restart.`
-              : continuing === 0
-                ? `${threads} will be interrupted.`
-                : `${threads} will be interrupted. ${continuing} can resume after the restart.`}
+        ) : updating.some((row) => row.app !== null) ? (
+          <p
+            id={`${descriptionId}-interruption`}
+            className="self-center text-muted-foreground text-sm max-sm:order-1 max-sm:text-center sm:mr-auto"
+          >
+            Updates interrupt tasks and tool calls.
           </p>
         ) : null}
         <AlertDialogClose ref={cancelRef} render={<Button variant="outline" disabled={busy} />}>