fix(desktop updates): pacman command downloads first, installs the local file

`sudo pacman -U <url>` also fetches `<url>.sig` and failed (404) on
CachyOS: remote packages fall under RemoteFileSigLevel (signature
required) and we don't sign the package. A downloaded file installs under
LocalFileSigLevel (optional): `curl -LO <url> && sudo pacman -U ./…`.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

package-lock.json

@@ -5026,9 +5026,9 @@
       "license": "MIT"
     },
     "node_modules/brace-expansion": {
-      "version": "1.1.18",
-      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.18.tgz",
-      "integrity": "sha512-Edep/X9fGqVNmzKBVsDYIOtD+z1tuezV70LBjdCst9Tqu76lsnvRiZ6oTic1n+/BIwX6QDGAO94PN4N2SADvtw==",
+      "version": "1.1.21",
+      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.21.tgz",
+      "integrity": "sha512-9zeA+KLZNNzglF2TPKRQEDyx6Yby7daAkuy8MiPzpXPsYDWi/DRM8jmwUDxokQjYqBpv5DgPiwD4h4ZZSy1Ujw==",
       "license": "MIT",
       "dependencies": {
         "balanced-match": "^1.0.0",

src/app/features/settings/general/General.tsx

@@ -112,7 +112,13 @@ import {
 import { chromeTranslationEngine } from '../../../utils/translation/chromeEngine';
 import { SequenceCardStyle } from '../styles.css';
 import { UpdateProgress, useTauriUpdater } from '../../../hooks/useTauriUpdater';
-import { describeUpdateError, manualDownloadUrl } from '../../../utils/updateErrors';
+import {
+  describeUpdateError,
+  isPackageManagedError,
+  manualDownloadUrl,
+  packageUpdateHelp,
+} from '../../../utils/updateErrors';
+import { copyToClipboard } from '../../../utils/dom';
 import { isTauri as isTauriEnv, invokeTauri, tauriInvoke } from '../../../hooks/useTauri';
 import { useKeychainMirrorStatus } from '../../../state/keychainMirror';
 import { isSafeGlobalToggleKey } from '../../../hooks/useCallHotkeys';
@@ -2794,12 +2800,76 @@ function updateProgressText(progress: UpdateProgress | undefined): string {
   return `Downloading update… ${pct}% (${formatMb(downloaded)} of ${formatMb(total)})${attempt}`;
 }
 
-function AppUpdates() {
-  const { isTauri, status, check, install } = useTauriUpdater();
-  if (!isTauri) return null;
+/**
+ * A Linux package install is updated with its package manager (the in-app
+ * updater can't write to /usr/bin): the command, Copy and a download link.
+ */
+function PackageUpdate({ help }: { help: NonNullable<ReturnType<typeof packageUpdateHelp>> }) {
+  const [copied, setCopied] = useState<'no' | 'yes' | 'failed'>('no');
+  const copy = () => {
+    const text = help.command ?? '';
+    if (!navigator.clipboard) {
+      copyToClipboard(text);
+      setCopied('yes');
+      return;
+    }
+    navigator.clipboard.writeText(text).then(
+      () => setCopied('yes'),
+      () => setCopied('failed'),
+    );
+  };
+  let copyLabel = 'Copy command';
+  if (copied === 'yes') copyLabel = 'Copied';
+  else if (copied === 'failed') copyLabel = 'Copy failed: select it above';
+  return (
+    <Box direction="Column" gap="200">
+      <Text size="T200">
+        Lotus Chat was installed as a system package, so update it the same way
+        {help.command ? ' (your chats and settings are kept):' : '.'}
+      </Text>
+      {help.command && (
+        <Text
+          size="T200"
+          style={{ fontFamily: 'monospace', wordBreak: 'break-all', userSelect: 'all' }}
+        >
+          {help.command}
+        </Text>
+      )}
+      <Box gap="200" wrap="Wrap">
+        {help.command && (
+          <Button size="300" radii="300" variant="Secondary" onClick={copy}>
+            <Text size="B300">{copyLabel}</Text>
+          </Button>
+        )}
+        <Button
+          size="300"
+          radii="300"
+          variant="Secondary"
+          fill="None"
+          outlined
+          onClick={() => window.open(help.url, '_blank')}
+        >
+          <Text size="B300">{help.download}</Text>
+        </Button>
+      </Box>
+    </Box>
+  );
+}
 
-  const description =
-    status.state === 'checking'
+function AppUpdates() {
+  const { isTauri, status, check, install, installKind } = useTauriUpdater();
+  if (!isTauri) return null;
+  const packageHelp = packageUpdateHelp(installKind);
+  const packageUpdate =
+    !!packageHelp &&
+    (status.state === 'available' ||
+      (status.state === 'error' && isPackageManagedError(status.message)));
+
+  const description = packageUpdate
+    ? status.state === 'available'
+      ? `Update available: v${status.version}`
+      : 'An update is available.'
+    : status.state === 'checking'
       ? 'Checking for updates...'
       : status.state === 'up-to-date'
         ? 'Lotus Chat is up to date.'
@@ -2816,8 +2886,7 @@ function AppUpdates() {
     else check();
   };
 
-  const after =
-    status.state === 'available' ? (
+  const after = packageUpdate ? undefined : status.state === 'available' ? (
     <Button size="300" radii="300" onClick={() => install()}>
       <Text size="B300">Install &amp; Restart</Text>
     </Button>
@@ -2852,7 +2921,8 @@ function AppUpdates() {
       <Text size="L400">App Updates</Text>
       <SequenceCard className={SequenceCardStyle} variant="SurfaceVariant" direction="Column">
         <SettingTile title="Check for Updates" description={description} after={after} />
-        {status.state === 'error' && (
+        {packageUpdate && packageHelp && <PackageUpdate help={packageHelp} />}
+        {status.state === 'error' && !packageUpdate && (
           <Text size="T200" priority="300" style={{ wordBreak: 'break-word' }}>
             Details: {status.message}
           </Text>

src/app/hooks/useTauriUpdater.ts

@@ -1,7 +1,7 @@
-import { useCallback } from 'react';
+import { useCallback, useEffect } from 'react';
 import { atom, useAtom, useSetAtom } from 'jotai';
 import { useTauriEvent } from './useTauri';
-import { UpdatePhase, parseUpdateError } from '../utils/updateErrors';
+import { InstallKind, UpdatePhase, parseUpdateError, toInstallKind } from '../utils/updateErrors';
 
 type TauriInternals = { invoke: (cmd: string, args?: Record<string, unknown>) => Promise<unknown> };
 const tauriInvoke = (): TauriInternals['invoke'] | undefined =>
@@ -36,6 +36,11 @@ export type UpdateFailure = { phase: UpdatePhase; message: string };
 // mid-request by the resolve/reject below, so nothing gets stuck.
 const updateStatusAtom = atom<UpdateStatus>({ state: 'idle' });
 
+// How this install gets updated; asked once. A desktop build without the
+// command (older than it) rejects the call: keep the old in-app behaviour.
+const installKindAtom = atom<InstallKind | undefined>(undefined);
+let installKindRequested = false;
+
 /**
  * Mirror native download progress into the status. Mounted once (in
  * TauriUpdateFeature) so the listener isn't duplicated per consumer.
@@ -50,6 +55,16 @@ export function useTauriUpdateProgress(): void {
 export function useTauriUpdater() {
   const isTauri = !!tauriInvoke();
   const [status, setStatus] = useAtom(updateStatusAtom);
+  const [installKind, setInstallKind] = useAtom(installKindAtom);
+
+  useEffect(() => {
+    const invoke = tauriInvoke();
+    if (!invoke || installKindRequested) return;
+    installKindRequested = true;
+    invoke('update_install_kind')
+      .then((kind) => setInstallKind(toInstallKind(kind)))
+      .catch(() => setInstallKind('in-app'));
+  }, [setInstallKind]);
 
   const check = useCallback(async () => {
     const invoke = tauriInvoke();
@@ -89,5 +104,5 @@ export function useTauriUpdater() {
     }
   }, [setStatus]);
 
-  return { isTauri, status, check, install };
+  return { isTauri, status, check, install, installKind: installKind ?? 'in-app' };
 }

src/app/pages/client/ClientNonUIFeatures.tsx

@@ -69,6 +69,7 @@ import { dismissToastAtom, toastQueueAtom } from '../../state/toast';
 import { useReminders } from '../../hooks/useReminders';
 import { getRoomRetentionMs, isExpired } from '../../utils/retention';
 import { useTauriUpdateProgress, useTauriUpdater } from '../../hooks/useTauriUpdater';
+import { settingsRequestAtom } from '../../state/settingsRequest';
 import { isNetworkUpdateError } from '../../utils/updateErrors';
 import { invokeTauri, isTauri as isTauriApp, useTauriEvent } from '../../hooks/useTauri';
 import { CloseBehaviorPrompt } from '../../components/CloseBehaviorPrompt';
@@ -913,7 +914,8 @@ const UPDATE_PROGRESS_TOAST = 'tauri-update-progress';
 const UPDATE_FAILED_TOAST = 'tauri-update-failed';
 
 function TauriUpdateFeature() {
-  const { isTauri, status, check, install } = useTauriUpdater();
+  const { isTauri, status, check, install, installKind } = useTauriUpdater();
+  const requestSettings = useSetAtom(settingsRequestAtom);
   useTauriUpdateProgress();
   const setToast = useSetAtom(toastQueueAtom);
   const dismissToast = useSetAtom(dismissToastAtom);
@@ -972,18 +974,24 @@ function TauriUpdateFeature() {
     if (status.state !== 'available') return;
     if (firedRef.current === status.version) return;
     firedRef.current = status.version;
+    // A Linux package install can't be updated in place: point at the
+    // package-manager command in Settings instead of an install that fails.
+    const viaPackage = installKind !== 'in-app';
     setToast({
       id: `tauri-update-${status.version}`,
       displayName: '⬆ Update Available',
-      body: `Lotus Chat ${status.version} is ready. Click to install and restart.`,
+      body: viaPackage
+        ? `Lotus Chat ${status.version} is available. Click for the command to update it with your package manager.`
+        : `Lotus Chat ${status.version} is ready. Click to install and restart.`,
       roomName: 'System',
       roomId: '',
       onClick: () => {
-        installFromToast();
+        if (viaPackage) requestSettings('general');
+        else installFromToast();
       },
       sticky: true,
     });
-  }, [status, setToast, installFromToast]);
+  }, [status, setToast, installFromToast, installKind, requestSettings]);
 
   // [cinny-desktop #6] Mirror a pending update into the tray ("Restart to
   // update" + tooltip) so a dismissed toast isn't the only reminder. Kept while

src/app/utils/updateErrors.test.ts

@@ -55,3 +55,36 @@ test('manual download link: Windows gets the installer, others the release page'
   );
   assert.equal(manualDownloadUrl('Mozilla/5.0 (X11; Linux x86_64)'), MANUAL_DOWNLOAD_URL.other);
 });
+
+test('install kinds: anything unknown keeps the in-app updater', async () => {
+  const { toInstallKind } = await import('./updateErrors');
+  assert.equal(toInstallKind('pacman'), 'pacman');
+  assert.equal(toInstallKind('deb'), 'deb');
+  assert.equal(toInstallKind('manual'), 'manual');
+  assert.equal(toInstallKind('in-app'), 'in-app');
+  assert.equal(toInstallKind(undefined), 'in-app', 'older desktop build without the command');
+  assert.equal(toInstallKind('rpm'), 'in-app');
+});
+
+test('package installs get their package manager’s command, not an Install button', async () => {
+  const { packageUpdateHelp, isPackageManagedError } = await import('./updateErrors');
+  const pacman = packageUpdateHelp('pacman')!;
+  // Not `pacman -U <url>`: that also wants `<url>.sig`, which we don't publish.
+  assert.equal(
+    pacman.command,
+    'curl -LO https://code.lotusguild.org/LotusGuild/cinny-desktop/releases/download/latest/LotusChat-x86_64.pkg.tar.zst && sudo pacman -U ./LotusChat-x86_64.pkg.tar.zst',
+  );
+  assert.match(pacman.url, /LotusChat-x86_64\.pkg\.tar\.zst$/);
+  const deb = packageUpdateHelp('deb')!;
+  assert.match(deb.command!, /sudo apt install \.\/LotusChat-x86_64\.deb$/);
+  assert.equal(packageUpdateHelp('manual')?.command, undefined);
+  assert.equal(packageUpdateHelp('in-app'), undefined);
+  assert.equal(
+    isPackageManagedError('package-managed (pacman): update Lotus Chat with your package manager'),
+    true,
+  );
+  assert.equal(
+    isPackageManagedError('Permission denied (os error 13) at path "/usr/bin/tauri_current_app"'),
+    false,
+  );
+});

src/app/utils/updateErrors.ts

@@ -47,3 +47,46 @@ export const describeUpdateError = (phase: UpdatePhase, message: string): string
   }
   return 'The update downloaded but couldn’t be installed. Download the installer yourself and run it; your chats and settings are kept.';
 };
+
+/**
+ * How this desktop install gets updated (cinny-desktop `update_install_kind`).
+ * Linux package installs can't be replaced in place by the in-app updater
+ * (it tried to write into /usr/bin: "Permission denied (os error 13)"), so
+ * they get their package manager's command instead of an Install button.
+ */
+export type InstallKind = 'in-app' | 'pacman' | 'deb' | 'manual';
+
+const RELEASE_DOWNLOAD =
+  'https://code.lotusguild.org/LotusGuild/cinny-desktop/releases/download/latest';
+
+export const toInstallKind = (value: unknown): InstallKind =>
+  value === 'pacman' || value === 'deb' || value === 'manual' ? value : 'in-app';
+
+export type PackageUpdateHelp = { command?: string; url: string; download: string };
+
+export const packageUpdateHelp = (kind: InstallKind): PackageUpdateHelp | undefined => {
+  if (kind === 'pacman') {
+    const url = `${RELEASE_DOWNLOAD}/LotusChat-x86_64.pkg.tar.zst`;
+    // Download first, then install the local file: `pacman -U <url>` also
+    // fetches `<url>.sig` and fails without it (we don't sign packages),
+    // while a local file falls under LocalFileSigLevel (signature optional).
+    return {
+      command: `curl -LO ${url} && sudo pacman -U ./LotusChat-x86_64.pkg.tar.zst`,
+      url,
+      download: 'Download package',
+    };
+  }
+  if (kind === 'deb') {
+    const url = `${RELEASE_DOWNLOAD}/LotusChat-x86_64.deb`;
+    return {
+      command: `curl -LO ${url} && sudo apt install ./LotusChat-x86_64.deb`,
+      url,
+      download: 'Download package',
+    };
+  }
+  if (kind === 'manual') return { url: MANUAL_DOWNLOAD_URL.other, download: 'Open downloads' };
+  return undefined;
+};
+
+/** The native side refuses an in-app install on a package install. */
+export const isPackageManagedError = (message: string): boolean => /package-managed/.test(message);