diff --git a/apps/frontend/src/renderer/components/Sidebar.tsx b/apps/frontend/src/renderer/components/Sidebar.tsx
index 5114b549..b7a55588 100644
--- a/apps/frontend/src/renderer/components/Sidebar.tsx
+++ b/apps/frontend/src/renderer/components/Sidebar.tsx
@@ -50,6 +50,7 @@ import { AddProjectModal } from './AddProjectModal';
 import { GitSetupModal } from './GitSetupModal';
 import { RateLimitIndicator } from './RateLimitIndicator';
 import { ClaudeCodeStatusBadge } from './ClaudeCodeStatusBadge';
+import { UpdateBanner } from './UpdateBanner';
 import type { Project, AutoBuildVersionInfo, GitStatus, ProjectEnvConfig } from '../../shared/types';
 
 export type SidebarView = 'kanban' | 'terminals' | 'roadmap' | 'context' | 'ideation' | 'github-issues' | 'gitlab-issues' | 'github-prs' | 'gitlab-merge-requests' | 'changelog' | 'insights' | 'worktrees' | 'agent-tools';
@@ -328,6 +329,9 @@ export function Sidebar({
         {/* Rate Limit Indicator - shows when Claude is rate limited */}
         <RateLimitIndicator />
 
+        {/* Update Banner - shows when app update is available */}
+        <UpdateBanner />
+
         {/* Bottom section with Settings, Help, and New Task */}
         <div className="p-4 space-y-3">
           {/* Claude Code Status Badge */}
diff --git a/apps/frontend/src/renderer/components/UpdateBanner.tsx b/apps/frontend/src/renderer/components/UpdateBanner.tsx
new file mode 100644
index 00000000..c7b2ad23
--- /dev/null
+++ b/apps/frontend/src/renderer/components/UpdateBanner.tsx
@@ -0,0 +1,261 @@
+import { useState, useEffect, useCallback, useRef } from "react";
+import { useTranslation } from "react-i18next";
+import { Download, X, RefreshCw } from "lucide-react";
+import { Button } from "./ui/button";
+import { cn } from "../lib/utils";
+import type { AppUpdateAvailableEvent, AppUpdateProgress } from "../../shared/types";
+
+// Poll for updates every 5 minutes
+const UPDATE_CHECK_INTERVAL_MS = 5 * 60 * 1000;
+
+interface UpdateBannerProps {
+  className?: string;
+}
+
+/**
+ * Inline update notification banner for the sidebar.
+ * Shows when a new application update is available and provides
+ * quick access to download/install or dismiss.
+ */
+export function UpdateBanner({ className }: UpdateBannerProps) {
+  const { t } = useTranslation(["navigation", "common"]);
+  const [updateInfo, setUpdateInfo] = useState<AppUpdateAvailableEvent | null>(null);
+  const [isDismissed, setIsDismissed] = useState(false);
+  const [isDownloading, setIsDownloading] = useState(false);
+  const [downloadProgress, setDownloadProgress] = useState<AppUpdateProgress | null>(null);
+  const [isDownloaded, setIsDownloaded] = useState(false);
+  const [downloadError, setDownloadError] = useState<string | null>(null);
+
+  // Ref to track current version for stable callbacks
+  const currentVersionRef = useRef<string | null>(null);
+
+  // Check for updates
+  const checkForUpdate = useCallback(async () => {
+    try {
+      if (!window.electronAPI?.checkAppUpdate) {
+        return;
+      }
+
+      const result = await window.electronAPI.checkAppUpdate();
+      if (result.success && result.data) {
+        const newVersion = result.data.version;
+        // New update available - show banner (unless same version already dismissed)
+        if (currentVersionRef.current !== newVersion) {
+          setIsDismissed(false);
+          // Reset downloaded state when a newer version is found
+          setIsDownloaded(false);
+          currentVersionRef.current = newVersion;
+        }
+        setUpdateInfo({
+          version: newVersion,
+          releaseNotes: result.data.releaseNotes,
+          releaseDate: result.data.releaseDate,
+        });
+      }
+    } catch (err) {
+      // Silent failure - update check is non-critical
+    }
+  }, []);
+
+  // Check if there's already a downloaded update on mount
+  useEffect(() => {
+    const checkDownloaded = async () => {
+      try {
+        if (!window.electronAPI?.getDownloadedAppUpdate) {
+          return;
+        }
+        const result = await window.electronAPI.getDownloadedAppUpdate();
+        if (result.success && result.data) {
+          currentVersionRef.current = result.data.version;
+          setUpdateInfo({
+            version: result.data.version,
+            releaseNotes: result.data.releaseNotes,
+            releaseDate: result.data.releaseDate,
+          });
+          setIsDownloaded(true);
+        }
+      } catch {
+        // Silent failure
+      }
+    };
+    checkDownloaded();
+  }, []);
+
+  // Initial check and periodic polling
+  useEffect(() => {
+    checkForUpdate();
+
+    const interval = setInterval(() => {
+      checkForUpdate();
+    }, UPDATE_CHECK_INTERVAL_MS);
+
+    return () => clearInterval(interval);
+  }, [checkForUpdate]);
+
+  // Listen for push notifications about updates
+  useEffect(() => {
+    if (!window.electronAPI?.onAppUpdateAvailable) {
+      return;
+    }
+
+    const cleanup = window.electronAPI.onAppUpdateAvailable((info) => {
+      // New update notification - reset dismiss state if new version
+      if (currentVersionRef.current !== info.version) {
+        setIsDismissed(false);
+        currentVersionRef.current = info.version;
+      }
+      setUpdateInfo(info);
+      setIsDownloading(false);
+      setIsDownloaded(false);
+      setDownloadProgress(null);
+      setDownloadError(null);
+    });
+
+    return cleanup;
+  }, []);
+
+  // Listen for download progress
+  useEffect(() => {
+    if (!window.electronAPI?.onAppUpdateProgress) {
+      return;
+    }
+
+    const cleanup = window.electronAPI.onAppUpdateProgress((progress) => {
+      setDownloadProgress(progress);
+    });
+
+    return cleanup;
+  }, []);
+
+  // Listen for download completed
+  useEffect(() => {
+    if (!window.electronAPI?.onAppUpdateDownloaded) {
+      return;
+    }
+
+    const cleanup = window.electronAPI.onAppUpdateDownloaded(() => {
+      setIsDownloading(false);
+      setIsDownloaded(true);
+      setDownloadProgress(null);
+    });
+
+    return cleanup;
+  }, []);
+
+  // Handle update and restart
+  const handleUpdate = async () => {
+    if (isDownloaded) {
+      // Already downloaded - just install
+      window.electronAPI?.installAppUpdate?.();
+      return;
+    }
+
+    // Start download
+    setIsDownloading(true);
+    setDownloadError(null);
+
+    try {
+      if (!window.electronAPI?.downloadAppUpdate) {
+        setDownloadError(t("navigation:updateBanner.downloadError"));
+        setIsDownloading(false);
+        return;
+      }
+      const result = await window.electronAPI.downloadAppUpdate();
+      if (!result.success) {
+        setDownloadError(result.error || t("navigation:updateBanner.downloadError"));
+        setIsDownloading(false);
+      }
+    } catch (error) {
+      setDownloadError(t("navigation:updateBanner.downloadError"));
+      setIsDownloading(false);
+    }
+  };
+
+  // Handle dismiss
+  const handleDismiss = () => {
+    setIsDismissed(true);
+  };
+
+  // Don't render if no update or dismissed
+  if (!updateInfo || isDismissed) {
+    return null;
+  }
+
+  return (
+    <div
+      className={cn(
+        "mx-3 mb-3 rounded-lg border border-info/30 bg-info/10 p-3",
+        className
+      )}
+    >
+      {/* Header with version and dismiss */}
+      <div className="flex items-start justify-between gap-2 mb-2">
+        <div className="flex items-center gap-2">
+          <Download className="h-4 w-4 text-info shrink-0" />
+          <span className="text-xs font-medium text-foreground">
+            {t("navigation:updateBanner.title")}
+          </span>
+        </div>
+        <button
+          type="button"
+          onClick={handleDismiss}
+          className="text-muted-foreground hover:text-foreground transition-colors"
+          aria-label={t("navigation:updateBanner.dismiss")}
+        >
+          <X className="h-3.5 w-3.5" />
+        </button>
+      </div>
+
+      {/* Version info */}
+      <p className="text-xs text-muted-foreground mb-3">
+        {t("navigation:updateBanner.version", { version: updateInfo.version })}
+      </p>
+
+      {/* Download progress */}
+      {isDownloading && downloadProgress && (
+        <div className="mb-3">
+          <div className="flex items-center justify-between text-[10px] text-muted-foreground mb-1">
+            <span>{t("navigation:updateBanner.downloading")}</span>
+            <span>{Math.round(downloadProgress.percent)}%</span>
+          </div>
+          <div className="h-1 w-full bg-muted rounded-full overflow-hidden">
+            <div
+              className="h-full bg-info transition-all duration-300"
+              style={{ width: `${downloadProgress.percent}%` }}
+            />
+          </div>
+        </div>
+      )}
+
+      {/* Error message */}
+      {downloadError && (
+        <p className="text-[10px] text-destructive mb-2">{downloadError}</p>
+      )}
+
+      {/* Action button */}
+      <Button
+        size="sm"
+        className="w-full h-7 text-xs gap-1.5"
+        onClick={handleUpdate}
+        disabled={isDownloading}
+      >
+        {isDownloading ? (
+          <>
+            <RefreshCw className="h-3 w-3 animate-spin" />
+            {t("navigation:updateBanner.downloading")}
+          </>
+        ) : isDownloaded ? (
+          <>
+            <RefreshCw className="h-3 w-3" />
+            {t("navigation:updateBanner.installAndRestart")}
+          </>
+        ) : (
+          <>
+            <Download className="h-3 w-3" />
+            {t("navigation:updateBanner.updateAndRestart")}
+          </>
+        )}
+      </Button>
+    </div>
+  );
+}
diff --git a/apps/frontend/src/shared/i18n/locales/en/navigation.json b/apps/frontend/src/shared/i18n/locales/en/navigation.json
index 37323518..c5409543 100644
--- a/apps/frontend/src/shared/i18n/locales/en/navigation.json
+++ b/apps/frontend/src/shared/i18n/locales/en/navigation.json
@@ -30,6 +30,15 @@
   "messages": {
     "initializeToCreateTasks": "Initialize Auto Claude to create tasks"
   },
+  "updateBanner": {
+    "title": "Update Available",
+    "version": "Version {{version}} is ready",
+    "updateAndRestart": "Update and Restart",
+    "installAndRestart": "Install and Restart",
+    "downloading": "Downloading...",
+    "dismiss": "Dismiss",
+    "downloadError": "Failed to download update"
+  },
   "claudeCode": {
     "checking": "Checking Claude Code...",
     "upToDate": "Claude Code is up to date",
diff --git a/apps/frontend/src/shared/i18n/locales/fr/navigation.json b/apps/frontend/src/shared/i18n/locales/fr/navigation.json
index 1a9327f8..19646a2f 100644
--- a/apps/frontend/src/shared/i18n/locales/fr/navigation.json
+++ b/apps/frontend/src/shared/i18n/locales/fr/navigation.json
@@ -30,6 +30,15 @@
   "messages": {
     "initializeToCreateTasks": "Initialisez Auto Claude pour créer des tâches"
   },
+  "updateBanner": {
+    "title": "Mise à jour disponible",
+    "version": "Version {{version}} est prête",
+    "updateAndRestart": "Mettre à jour et redémarrer",
+    "installAndRestart": "Installer et redémarrer",
+    "downloading": "Téléchargement...",
+    "dismiss": "Ignorer",
+    "downloadError": "Échec du téléchargement de la mise à jour"
+  },
   "claudeCode": {
     "checking": "Vérification de Claude Code...",
     "upToDate": "Claude Code est à jour",