refactor(webui): replace real-time polling with click-to-check version updates

- Remove background PyPI polling loop and WebSocket broadcast
- Remove UpdateBanner from ThreadHeader (keep main page clean)
- Add on-demand version check endpoint (GET /api/settings/version-check)
- Add 'About' section in Settings > Overview with check-for-updates button
- Design: no auto-fetch, user initiates check explicitly via button click

nanobot/webui/settings_api.py

@@ -34,9 +34,18 @@ from nanobot.webui.workspaces import (
     write_webui_default_access_mode,
 )
 
+from nanobot import __version__
+
 QueryParams = dict[str, list[str]]
 RuntimeSurface = Literal["browser", "native"]
 
+
+def _version_payload() -> dict[str, Any]:
+    """Return version info for the settings payload."""
+    return {
+        "current": __version__,
+    }
+
 _RUNTIME_CAPABILITIES = {
     "can_restart_engine": False,
     "can_pick_folder": False,
@@ -805,6 +814,7 @@ def settings_payload(
             "exec_path_append_set": bool(exec_config.path_append),
         },
         "requires_restart": requires_restart,
+        "version": _version_payload(),
     }
     return decorate_settings_payload(
         payload,

nanobot/webui/settings_routes.py

@@ -36,6 +36,7 @@ from nanobot.webui.settings_api import (
     update_transcription_settings,
     update_web_search_settings,
 )
+from nanobot.webui.version_check import check_for_update
 
 QueryParams = dict[str, list[str]]
 
@@ -117,6 +118,8 @@ class WebUISettingsRouter:
             return await self._handle_settings_cli_apps_action(request, "test")
         if path == "/api/settings/mcp-presets":
             return await self._handle_settings_mcp_presets(request)
+        if path == "/api/settings/version-check":
+            return await self._handle_settings_version_check(request)
         mcp_action = _MCP_PRESET_ACTIONS_BY_PATH.get(path)
         if mcp_action is not None:
             return await self._handle_settings_mcp_presets(request, mcp_action)
@@ -347,3 +350,15 @@ class WebUISettingsRouter:
         if action is None:
             return self._json_response(payload)
         return self._json_response(self._with_restart_state(payload, section="runtime"))
+
+    async def _handle_settings_version_check(self, request: WsRequest) -> Response:
+        if not self._authorized(request):
+            return self._unauthorized()
+        try:
+            update_info = await asyncio.to_thread(check_for_update)
+        except Exception:
+            self.logger.exception("version check failed")
+            return self._error_response(500, "version check failed")
+        return self._json_response({
+            "updateAvailable": update_info,
+        })

nanobot/webui/version_check.py

@@ -0,0 +1,51 @@
+"""On-demand version checker for nanobot-ai releases.
+
+Checks PyPI for newer versions when explicitly requested (no background polling).
+"""
+
+from __future__ import annotations
+
+import logging
+import time
+from typing import Any
+
+import httpx
+
+from nanobot import __version__
+
+logger = logging.getLogger(__name__)
+
+_PYPI_URL = "https://pypi.org/pypi/nanobot-ai/json"
+_CACHE_TTL_S = 300  # 5 minutes cache to avoid hammering PyPI
+
+_cache: tuple[float, str | None] = (0.0, None)
+
+
+def check_for_update() -> dict[str, Any] | None:
+    """Check PyPI for a newer version. Returns update info dict or None if up-to-date.
+
+    Uses a short cache to avoid repeated requests within the TTL window.
+    This is a blocking call — invoke from a thread or background task.
+    """
+    global _cache
+    now = time.monotonic()
+    cached_at, cached_val = _cache
+    if now - cached_at < _CACHE_TTL_S and cached_val is not None:
+        latest = cached_val
+    else:
+        try:
+            resp = httpx.get(_PYPI_URL, timeout=5.0, follow_redirects=True)
+            resp.raise_for_status()
+            latest = resp.json().get("info", {}).get("version")
+        except Exception:
+            logger.debug("PyPI version check failed", exc_info=True)
+            return None
+        _cache = (now, latest)
+
+    if not latest or latest == __version__:
+        return None
+    return {
+        "currentVersion": __version__,
+        "latestVersion": latest,
+        "pypiUrl": "https://pypi.org/project/nanobot-ai/",
+    }

webui/src/components/settings/SettingsView.tsx

@@ -10,6 +10,7 @@ import {
 } from "react";
 import {
   Activity,
+  ArrowUpCircle,
   Bot,
   Brain,
   Check,
@@ -22,6 +23,7 @@ import {
   Database,
   Eye,
   EyeOff,
+  ExternalLink,
   Gem,
   Globe2,
   Grid3X3,
@@ -75,6 +77,7 @@ import {
 import { Input } from "@/components/ui/input";
 import { Textarea } from "@/components/ui/textarea";
 import {
+  checkVersion,
   createModelConfiguration,
   fetchSettings,
   fetchSettingsUsage,
@@ -1852,6 +1855,104 @@ function OverviewSettings({
           />
         </SettingsGroup>
       </section>
+
+      <section>
+        <SettingsSectionTitle>{tx("settings.sections.about", "About")}</SettingsSectionTitle>
+        <SettingsGroup>
+          <VersionCheckRow currentVersion={settings.version?.current} />
+        </SettingsGroup>
+      </section>
+    </div>
+  );
+}
+
+function VersionCheckRow({ currentVersion }: { currentVersion?: string }) {
+  const { t } = useTranslation();
+  const tx = (key: string, fallback: string) => t(key, { defaultValue: fallback });
+  const { token } = useClient();
+  const [checking, setChecking] = useState(false);
+  const [result, setResult] = useState<
+    | { type: "up-to-date" }
+    | { type: "update"; latestVersion: string; pypiUrl?: string }
+    | { type: "error"; message: string }
+    | null
+  >(null);
+
+  const handleCheck = async () => {
+    setChecking(true);
+    setResult(null);
+    try {
+      const res = await checkVersion(token);
+      if (res.updateAvailable) {
+        setResult({
+          type: "update",
+          latestVersion: res.updateAvailable.latestVersion,
+          pypiUrl: res.updateAvailable.pypiUrl,
+        });
+      } else {
+        setResult({ type: "up-to-date" });
+      }
+    } catch (err) {
+      setResult({ type: "error", message: (err as Error).message });
+    } finally {
+      setChecking(false);
+    }
+  };
+
+  return (
+    <div className="flex min-h-[62px] flex-col gap-3 px-4 py-3.5 sm:flex-row sm:items-center sm:justify-between sm:px-5">
+      <div className="min-w-0">
+        <div className="text-[14px] font-medium leading-5 text-foreground">
+          {tx("settings.about.version", "Version")}
+        </div>
+        <div className="mt-0.5 text-[12px] leading-5 text-muted-foreground">
+          {currentVersion ? `v${currentVersion}` : "nanobot"}
+        </div>
+      </div>
+      <div className="flex shrink-0 flex-col items-end gap-2">
+        <Button
+          size="sm"
+          variant="outline"
+          onClick={() => void handleCheck()}
+          disabled={checking}
+          className="rounded-full"
+        >
+          {checking ? (
+            <Loader2 className="mr-1.5 h-3.5 w-3.5 animate-spin" aria-hidden />
+          ) : (
+            <ArrowUpCircle className="mr-1.5 h-3.5 w-3.5" aria-hidden />
+          )}
+          {checking
+            ? tx("settings.about.checking", "Checking...")
+            : tx("settings.about.checkForUpdates", "Check for updates")}
+        </Button>
+        {result?.type === "up-to-date" ? (
+          <span className="inline-flex items-center gap-1.5 text-[12px] text-emerald-600 dark:text-emerald-300">
+            <Check className="h-3 w-3" aria-hidden />
+            {tx("settings.about.upToDate", "You're up to date")}
+          </span>
+        ) : null}
+        {result?.type === "update" ? (
+          <span className="inline-flex items-center gap-1.5 text-[12px] text-blue-600 dark:text-blue-300">
+            <ArrowUpCircle className="h-3 w-3" aria-hidden />
+            {tx("settings.about.updateAvailable", "Update available")}{result.latestVersion && ` v${result.latestVersion}`}
+            {result.pypiUrl ? (
+              <a
+                href={result.pypiUrl}
+                target="_blank"
+                rel="noopener noreferrer"
+                className="inline-flex items-center gap-0.5 underline-offset-2 hover:underline"
+              >
+                PyPI
+                <ExternalLink className="h-2.5 w-2.5" aria-hidden />
+              </a>
+            ) : null}
+          </span>
+        ) : null}
+        {result?.type === "error" ? (
+          <span className="text-[12px] text-destructive">{result.message}</span>
+        ) : null}
+      </div>
     </div>
   );
 }

webui/src/lib/api.ts

@@ -229,6 +229,26 @@ export async function fetchSettingsUsage(
   );
 }
 
+export interface VersionCheckResult {
+  updateAvailable: {
+    currentVersion: string;
+    latestVersion: string;
+    pypiUrl?: string;
+  } | null;
+}
+
+export async function checkVersion(
+  token: string,
+  base: string = "",
+): Promise<VersionCheckResult> {
+  return request<VersionCheckResult>(
+    `${base}/api/settings/version-check`,
+    token,
+    undefined,
+    10_000,
+  );
+}
+
 export async function fetchWorkspaces(
   token: string,
   base: string = "",

webui/src/lib/types.ts

@@ -485,6 +485,9 @@ export interface SettingsPayload {
   };
   requires_restart: boolean;
   restart_required_sections?: Array<"runtime" | "browser" | "image">;
+  version?: {
+    current: string;
+  };
 }
 
 export interface AppPackageRef {