feat: server shutdown action with public cancel_task lifecycle method

Lets users choose what happens to LED targets when the server shuts
down. Default ("stop_targets") runs the existing per-device stop
sequence, so devices with auto-restore replay their prior state.
"Nothing" cancels the capture tasks without sending restore frames,
so the LEDs keep displaying their last frame on shutdown.

Backend:
- New setting ``shutdown_action`` persisted in db.settings
  (``stop_targets`` default | ``nothing``) with GET/PUT
  ``/api/v1/system/shutdown-action`` endpoints
- ``ProcessorManager.stop_all(restore_devices: bool = True)`` now
  picks the path based on the flag — ``proc.stop()`` for the normal
  branch, public ``proc.cancel_task()`` for the "nothing" branch.
- ``TargetProcessor.cancel_task()`` (new, on the abstract base) cancels
  the loop task and *awaits* its termination so no half-written frame
  is in flight when the process exits. Replaces an earlier draft that
  reached into the private ``_task`` attribute via ``getattr``.
- Lifespan in ``main.py`` reads the setting at shutdown and forwards
  the flag; falls back to ``stop_targets`` on any read error.
- ``/health`` exposes ``uptime_seconds`` (process-wide monotonic clock
  captured at first import of ``api.routes.system``) so the WebUI can
  show the *server's* uptime instead of the browser session's.

Browser launch:
- ``__main__._open_browser`` now polls ``/health`` for up to 30 s
  instead of sleeping a flat 2 s, so the tab opens once the server
  actually accepts requests.

Frontend:
- New "Shutdown action" picker in Settings → General, rendered via
  IconSelect with ICON_SQUARE / ICON_CIRCLE (added to ``core/icons.ts``
  + ``circle`` path to ``icon-paths.ts``).
- Transport-bar uptime ticker reads ``window.__serverUptime`` (typed
  in ``global.d.ts``); shows "—" until the first /health response
  lands so refresh doesn't briefly flash 00:00:00. After 99 h the
  format widens to "Dd HH:MM:SS".
- New i18n keys for the action picker (label, hint, opt.stop /
  opt.nothing + descriptions, saved / save_error toasts) in en/ru/zh.

No data migration needed — the setting is additive and defaults to
the existing behavior.

server/src/ledgrab/__main__.py

@@ -12,6 +12,8 @@ import threading
 import time
 import webbrowser
 from pathlib import Path
+from urllib.error import URLError
+from urllib.request import urlopen
 
 
 def _fix_embedded_tcl_paths() -> None:
@@ -54,9 +56,25 @@ def _run_server(server: uvicorn.Server) -> None:
     loop.run_until_complete(server.serve())
 
 
-def _open_browser(port: int, delay: float = 2.0) -> None:
+def _wait_for_server(port: int, timeout: float = 30.0, interval: float = 0.25) -> bool:
-    """Open the UI in the default browser after a short delay."""
+    """Poll /health until the server responds or *timeout* seconds elapse."""
-    time.sleep(delay)
+    url = f"http://localhost:{port}/health"
+    deadline = time.monotonic() + timeout
+    while time.monotonic() < deadline:
+        try:
+            with urlopen(url, timeout=1) as resp:  # noqa: S310 - localhost only
+                if 200 <= resp.status < 500:
+                    return True
+        except (URLError, ConnectionError, OSError, TimeoutError):
+            pass
+        time.sleep(interval)
+    return False
+
+
+def _open_browser(port: int) -> None:
+    """Open the UI in the default browser once the server is ready."""
+    if not _wait_for_server(port):
+        logger.warning("Server did not become ready in time; opening browser anyway")
     webbrowser.open(f"http://localhost:{port}")
 
 

server/src/ledgrab/api/routes/system.py

@@ -7,6 +7,7 @@ import asyncio
 import platform
 import subprocess
 import sys
+import time
 from datetime import datetime, timezone
 from typing import Optional
 
@@ -92,6 +93,13 @@ def _get_cpu_name() -> str | None:
 
 _cpu_name: str | None = _get_cpu_name()
 
+# Captured at first import of this module. Process-wide elapsed time is
+# the closest the server has to "app start" without instrumenting main.py;
+# the system module is imported during router setup, before the server
+# accepts requests, so the drift is negligible. Used by /health to expose
+# uptime_seconds for the transport-bar ticker.
+_APP_START_MONOTONIC: float = time.monotonic()
+
 router = APIRouter()
 
 
@@ -122,6 +130,7 @@ async def health_check(request: Request):
         setup_required=setup_required,
         repo_url=REPO_URL,
         donate_url=DONATE_URL,
+        uptime_seconds=time.monotonic() - _APP_START_MONOTONIC,
     )
 
 

server/src/ledgrab/api/routes/system_settings.py

@@ -19,6 +19,9 @@ from ledgrab.api.schemas.system import (
     LogLevelResponse,
     MQTTSettingsRequest,
     MQTTSettingsResponse,
+    ShutdownAction,
+    ShutdownActionRequest,
+    ShutdownActionResponse,
 )
 from ledgrab.config import get_config
 from ledgrab.storage.database import Database
@@ -150,6 +153,55 @@ async def update_external_url(
     return ExternalUrlResponse(external_url=url)
 
 
+# ---------------------------------------------------------------------------
+# Shutdown action setting
+# ---------------------------------------------------------------------------
+
+_VALID_SHUTDOWN_ACTIONS: tuple[str, ...] = ("stop_targets", "nothing")
+_DEFAULT_SHUTDOWN_ACTION: ShutdownAction = "stop_targets"
+
+
+def load_shutdown_action(db: Database | None = None) -> ShutdownAction:
+    """Load the configured shutdown action. Returns the default if unset or corrupt."""
+    if db is None:
+        from ledgrab.api.dependencies import get_database
+
+        db = get_database()
+    data = db.get_setting("shutdown_action")
+    if not data:
+        return _DEFAULT_SHUTDOWN_ACTION
+    value = data.get("action")
+    if value in _VALID_SHUTDOWN_ACTIONS:
+        return value  # type: ignore[return-value]
+    return _DEFAULT_SHUTDOWN_ACTION
+
+
+@router.get(
+    "/api/v1/system/shutdown-action",
+    response_model=ShutdownActionResponse,
+    tags=["System"],
+)
+async def get_shutdown_action(_: AuthRequired, db: Database = Depends(get_database)):
+    """Get the configured server shutdown action."""
+    return ShutdownActionResponse(action=load_shutdown_action(db))
+
+
+@router.put(
+    "/api/v1/system/shutdown-action",
+    response_model=ShutdownActionResponse,
+    tags=["System"],
+)
+async def update_shutdown_action(
+    _: AuthRequired,
+    body: ShutdownActionRequest,
+    db: Database = Depends(get_database),
+):
+    """Set what happens to LED targets when the server shuts down."""
+    db.set_setting("shutdown_action", {"action": body.action})
+    logger.info("Shutdown action updated: %s", body.action)
+    return ShutdownActionResponse(action=body.action)
+
+
 # ---------------------------------------------------------------------------
 # Live log viewer WebSocket
 # ---------------------------------------------------------------------------

server/src/ledgrab/api/schemas/system.py

@@ -26,6 +26,10 @@ class HealthResponse(BaseModel):
     )
     repo_url: str = Field(default="", description="Source code repository URL")
     donate_url: str = Field(default="", description="Donation page URL")
+    uptime_seconds: float = Field(
+        default=0.0,
+        description="Process uptime in seconds since the server started.",
+    )
 
 
 class VersionResponse(BaseModel):
@@ -200,6 +204,32 @@ class ExternalUrlRequest(BaseModel):
     external_url: str = Field(default="", description="External base URL. Empty string to clear.")
 
 
+# ─── Shutdown action schemas ───────────────────────────────────
+
+
+ShutdownAction = Literal["stop_targets", "nothing"]
+
+
+class ShutdownActionResponse(BaseModel):
+    """Current server shutdown action setting."""
+
+    action: ShutdownAction = Field(
+        description=(
+            "What happens to LED targets when the server shuts down. "
+            "`stop_targets` runs the normal stop sequence (per-device "
+            "auto_shutdown decides whether prior state is restored). "
+            "`nothing` skips device-touching teardown — lights freeze on "
+            "their last frame regardless of per-device auto_shutdown."
+        ),
+    )
+
+
+class ShutdownActionRequest(BaseModel):
+    """Update the server shutdown action setting."""
+
+    action: ShutdownAction = Field(description="New shutdown action.")
+
+
 # ─── Log level schemas ─────────────────────────────────────────
 
 

server/src/ledgrab/core/processing/processor_manager.py

@@ -770,8 +770,16 @@ class ProcessorManager(AutoRestartMixin, DeviceHealthMixin, DeviceTestModeMixin)
 
     # ===== LIFECYCLE =====
 
-    async def stop_all(self):
+    async def stop_all(self, restore_devices: bool = True):
-        """Stop processing and health monitoring for all targets and devices."""
+        """Stop processing and health monitoring for all targets and devices.
+
+        When ``restore_devices`` is False, processor tasks are cancelled
+        directly instead of going through ``proc.stop()`` (which sends
+        per-device auto_shutdown restore frames), and the global
+        idle-state restore loop is skipped. Used by the "Nothing"
+        shutdown action so lights freeze on their last frame regardless
+        of per-device auto_shutdown.
+        """
         await self._metrics_history.stop()
         await self.stop_health_monitoring()
 
@@ -781,7 +789,9 @@ class ProcessorManager(AutoRestartMixin, DeviceHealthMixin, DeviceTestModeMixin)
             if rs.restart_task and not rs.restart_task.done():
                 rs.restart_task.cancel()
 
-        # Stop all processors
+        if restore_devices:
+            # Stop all processors (per-device auto_shutdown decides whether
+            # the prior device state is restored).
             for target_id, proc in list(self._processors.items()):
                 if proc.is_running:
                     try:
@@ -793,6 +803,21 @@ class ProcessorManager(AutoRestartMixin, DeviceHealthMixin, DeviceTestModeMixin)
             # (serial devices already dark from processor close; WLED restored by snapshot)
             for device_id in self._devices:
                 await self._restore_device_idle_state(device_id)
+        else:
+            # "Nothing" mode: cancel processor capture tasks without sending
+            # restore frames so the LEDs keep displaying the last frame.
+            # ``cancel_task`` (defined on ``TargetProcessor``) awaits the
+            # cancellation so the loop's current iteration completes — no
+            # half-written frame on the wire when the process exits.
+            for target_id, proc in list(self._processors.items()):
+                try:
+                    await proc.cancel_task()
+                except Exception as e:
+                    logger.error(f"Error cancelling task for target {target_id}: {e}")
+            logger.info(
+                "Shutdown action 'nothing': skipped device restore for %d target(s)",
+                len(self._processors),
+            )
 
         # Close any cached idle LED clients (WLED only; serial has no cached clients)
         for did in list(self._idle_clients):

server/src/ledgrab/core/processing/target_processor.py

@@ -16,6 +16,10 @@ from dataclasses import dataclass
 from datetime import datetime
 from typing import TYPE_CHECKING, Any, Callable, Dict, Optional, Tuple
 
+from ledgrab.utils import get_logger
+
+logger = get_logger(__name__)
+
 if TYPE_CHECKING:
     from ledgrab.core.processing.color_strip_stream_manager import ColorStripStreamManager
     from ledgrab.core.processing.live_stream_manager import LiveStreamManager
@@ -145,6 +149,32 @@ class TargetProcessor(ABC):
         """
         ...
 
+    async def cancel_task(self) -> None:
+        """Cancel the processing task without restoring device state.
+
+        Used by ``ProcessorManager.stop_all(restore_devices=False)`` at
+        server shutdown when the user has chosen "Nothing" — LEDs should
+        keep displaying their last frame, so we skip the per-device
+        ``stop()`` path that sends restore frames. We still flip
+        ``_is_running`` and await the cancellation so the loop's current
+        iteration completes (no half-written frame on the wire).
+
+        Subclasses with extra non-device cleanup (e.g. live-stream
+        release) may override this; the default just stops the task.
+        """
+        self._is_running = False
+        task = self._task
+        if task is not None and not task.done():
+            task.cancel()
+            try:
+                await task
+            except asyncio.CancelledError:
+                pass
+            except Exception:
+                # Log but don't propagate — caller is shutting down.
+                logger.debug("Task raised during cancel_task", exc_info=True)
+        self._task = None
+
     # ----- Settings -----
 
     @abstractmethod

server/src/ledgrab/main.py

@@ -412,9 +412,22 @@ async def lifespan(app: FastAPI):
     except Exception as e:
         logger.error(f"Error stopping OS notification listener: {e}")
 
-    # Stop all processing
+    # Stop all processing.
+    # The shutdown action setting controls whether per-device restore
+    # frames are sent: "stop_targets" (default) runs the normal stop
+    # sequence; "nothing" cancels capture tasks so the LEDs freeze on
+    # their last frame.
     try:
-        await processor_manager.stop_all()
+        from ledgrab.api.routes.system_settings import load_shutdown_action
+
+        action = load_shutdown_action(db)
+    except Exception as e:
+        logger.error(f"Error reading shutdown action setting, defaulting to stop_targets: {e}")
+        action = "stop_targets"
+
+    logger.info("Shutdown action: %s", action)
+    try:
+        await processor_manager.stop_all(restore_devices=action != "nothing")
         logger.info("Stopped all processors")
     except Exception as e:
         logger.error(f"Error stopping processors: {e}")

server/src/ledgrab/static/js/app.ts

@@ -219,6 +219,7 @@ import {
     connectLogViewer, disconnectLogViewer, clearLogViewer, applyLogFilter,
     openLogOverlay, closeLogOverlay,
     loadLogLevel, setLogLevel,
+    loadShutdownAction, setShutdownAction,
     saveExternalUrl, getBaseOrigin, loadExternalUrl,
 } from './features/settings.ts';
 import {
@@ -615,6 +616,8 @@ Object.assign(window, {
     closeLogOverlay,
     loadLogLevel,
     setLogLevel,
+    loadShutdownAction,
+    setShutdownAction,
     saveExternalUrl,
     getBaseOrigin,
 

server/src/ledgrab/static/js/core/api.ts

@@ -305,6 +305,19 @@ export async function loadServerInfo() {
         if (data.repo_url) serverRepoUrl = data.repo_url;
         if (data.donate_url) serverDonateUrl = data.donate_url;
 
+        // Seed the transport-bar uptime ticker with the server's actual
+        // uptime. Survives page reloads and tracks the *server* process,
+        // not this browser session. The inline ticker reads this from
+        // ``window.__serverUptime`` and falls back to "—" if absent.
+        // ``recordedAtPerf`` uses ``performance.now()`` so wall-clock
+        // changes (NTP step, DST) don't make the counter jump.
+        if (typeof data.uptime_seconds === 'number') {
+            window.__serverUptime = {
+                uptimeSec: data.uptime_seconds,
+                recordedAtPerf: performance.now(),
+            };
+        }
+
         // Demo mode detection
         if (data.demo_mode && !demoMode) {
             demoMode = true;

server/src/ledgrab/static/js/core/icon-paths.ts

@@ -23,6 +23,7 @@ export const flaskConical = '<path d="M14 2v6a2 2 0 0 0 .245.96l5.51 10.08A2 2 0
 export const pencil       = '<path d="M21.174 6.812a1 1 0 0 0-3.986-3.987L3.842 16.174a2 2 0 0 0-.5.83l-1.321 4.352a.5.5 0 0 0 .623.622l4.353-1.32a2 2 0 0 0 .83-.497z"/><path d="m15 5 4 4"/>';
 export const play         = '<path d="M5 5a2 2 0 0 1 3.008-1.728l11.997 6.998a2 2 0 0 1 .003 3.458l-12 7A2 2 0 0 1 5 19z"/>';
 export const square       = '<rect width="18" height="18" x="3" y="3" rx="2"/>';
+export const circle       = '<circle cx="12" cy="12" r="9"/>';
 export const pause        = '<rect x="14" y="3" width="5" height="18" rx="1"/><rect x="5" y="3" width="5" height="18" rx="1"/>';
 export const settings     = '<path d="M9.671 4.136a2.34 2.34 0 0 1 4.659 0 2.34 2.34 0 0 0 3.319 1.915 2.34 2.34 0 0 1 2.33 4.033 2.34 2.34 0 0 0 0 3.831 2.34 2.34 0 0 1-2.33 4.033 2.34 2.34 0 0 0-3.319 1.915 2.34 2.34 0 0 1-4.659 0 2.34 2.34 0 0 0-3.32-1.915 2.34 2.34 0 0 1-2.33-4.033 2.34 2.34 0 0 0 0-3.831A2.34 2.34 0 0 1 6.35 6.051a2.34 2.34 0 0 0 3.319-1.915"/><circle cx="12" cy="12" r="3"/>';
 export const ruler        = '<path d="M21.3 15.3a2.4 2.4 0 0 1 0 3.4l-2.6 2.6a2.4 2.4 0 0 1-3.4 0L2.7 8.7a2.41 2.41 0 0 1 0-3.4l2.6-2.6a2.41 2.41 0 0 1 3.4 0Z"/><path d="m14.5 12.5 2-2"/><path d="m11.5 9.5 2-2"/><path d="m8.5 6.5 2-2"/><path d="m17.5 15.5 2-2"/>';

server/src/ledgrab/static/js/core/icons.ts

@@ -342,6 +342,8 @@ export const ICON_GITHUB         = _svg(P.github);
 export const ICON_CHEVRON_UP     = _svg(P.chevronUp);
 export const ICON_CHEVRON_DOWN   = _svg(P.chevronDown);
 export const ICON_PLUS           = _svg(P.plus);
+export const ICON_SQUARE         = _svg(P.square);
+export const ICON_CIRCLE         = _svg(P.circle);
 export const ICON_GIT_MERGE      = _svg(P.gitMerge);
 export const ICON_COPY           = _svg(P.copy);
 

server/src/ledgrab/static/js/features/settings.ts

@@ -7,7 +7,7 @@ import { API_BASE, fetchWithAuth } from '../core/api.ts';
 import { Modal } from '../core/modal.ts';
 import { showToast, showConfirm } from '../core/ui.ts';
 import { t } from '../core/i18n.ts';
-import { ICON_UNDO, ICON_DOWNLOAD } from '../core/icons.ts';
+import { ICON_UNDO, ICON_DOWNLOAD, ICON_SQUARE, ICON_CIRCLE } from '../core/icons.ts';
 import { IconSelect } from '../core/icon-select.ts';
 import { openAuthedWs } from '../core/ws-auth.ts';
 
@@ -260,6 +260,13 @@ const settingsModal = new Modal('settings-modal');
 
 let _logLevelIconSelect: IconSelect | null = null;
 let _autoBackupIntervalIconSelect: IconSelect | null = null;
+let _shutdownActionIconSelect: IconSelect | null = null;
+
+type ShutdownAction = 'stop_targets' | 'nothing';
+const _SHUTDOWN_ACTIONS: readonly ShutdownAction[] = ['stop_targets', 'nothing'] as const;
+function _isShutdownAction(v: string): v is ShutdownAction {
+    return (_SHUTDOWN_ACTIONS as readonly string[]).includes(v);
+}
 
 /** Build interval items (hour-tiles) for auto-backup and update check pickers.
  *  Labels match the existing native-<option> text verbatim so no new i18n keys are needed.
@@ -275,6 +282,24 @@ export function _getHourIntervalItems(): { value: string; icon: string; label: s
     ];
 }
 
+/** Build shutdown-action items lazily so t() has locale data loaded. */
+function _getShutdownActionItems(): { value: string; icon: string; label: string; desc: string }[] {
+    return [
+        {
+            value: 'stop_targets',
+            icon: ICON_SQUARE,
+            label: t('settings.shutdown_action.opt.stop'),
+            desc: t('settings.shutdown_action.opt.stop_desc'),
+        },
+        {
+            value: 'nothing',
+            icon: ICON_CIRCLE,
+            label: t('settings.shutdown_action.opt.nothing'),
+            desc: t('settings.shutdown_action.opt.nothing_desc'),
+        },
+    ];
+}
+
 /** Build log-level items lazily so t() has locale data loaded. */
 function _getLogLevelItems(): { value: string; icon: string; label: string; desc: string }[] {
     return [
@@ -325,11 +350,25 @@ export function openSettingsModal(): void {
         }
     }
 
+    // Initialize shutdown-action icon select
+    if (!_shutdownActionIconSelect) {
+        const sel = document.getElementById('settings-shutdown-action') as HTMLSelectElement | null;
+        if (sel) {
+            _shutdownActionIconSelect = new IconSelect({
+                target: sel,
+                items: _getShutdownActionItems(),
+                columns: 2,
+                onChange: () => setShutdownAction(),
+            });
+        }
+    }
+
     loadApiKeysList();
     loadExternalUrl();
     loadAutoBackupSettings();
     loadBackupList();
     loadLogLevel();
+    loadShutdownAction();
 }
 
 export function closeSettingsModal(): void {
@@ -669,3 +708,43 @@ export async function setLogLevel(): Promise<void> {
     }
 }
 
+// ─── Shutdown action ──────────────────────────────────────────
+
+export async function loadShutdownAction(): Promise<void> {
+    try {
+        const resp = await fetchWithAuth('/system/shutdown-action');
+        if (!resp.ok) return;
+        const data = await resp.json();
+        const action: ShutdownAction = _isShutdownAction(data.action) ? data.action : 'stop_targets';
+        if (_shutdownActionIconSelect) {
+            _shutdownActionIconSelect.setValue(action);
+        } else {
+            const select = document.getElementById('settings-shutdown-action') as HTMLSelectElement | null;
+            if (select) select.value = action;
+        }
+    } catch (err) {
+        console.error('Failed to load shutdown action:', err);
+    }
+}
+
+export async function setShutdownAction(): Promise<void> {
+    const select = document.getElementById('settings-shutdown-action') as HTMLSelectElement | null;
+    if (!select) return;
+    const value = select.value;
+    if (!_isShutdownAction(value)) return;
+    try {
+        const resp = await fetchWithAuth('/system/shutdown-action', {
+            method: 'PUT',
+            body: JSON.stringify({ action: value }),
+        });
+        if (!resp.ok) {
+            const err = await resp.json().catch(() => ({}));
+            throw new Error(err.detail || `HTTP ${resp.status}`);
+        }
+        showToast(t('settings.shutdown_action.saved'), 'success');
+    } catch (err) {
+        console.error('Failed to set shutdown action:', err);
+        showToast(t('settings.shutdown_action.save_error') + ': ' + err.message, 'error');
+    }
+}
+

server/src/ledgrab/static/js/global.d.ts

@@ -22,6 +22,14 @@ interface Window {
     setApiKey: (key: string | null) => void;
     _authRequired: boolean | undefined;
 
+    // ─── Transport bar ───
+    /** Server-process uptime seed for the transport-bar ticker. Set by
+     *  api.ts on every /health response; read by the inline ticker in
+     *  index.html. ``recordedAtPerf`` is a ``performance.now()`` reading,
+     *  not Date.now(), so the extrapolation is immune to wall-clock jumps
+     *  (NTP step, DST). */
+    __serverUptime: { uptimeSec: number; recordedAtPerf: number } | undefined;
+
     // ─── Visual effects (called from inline <script>) ───
     _updateBgAnimAccent: (accent: string) => void;
     _updateBgAnimTheme: (dark: boolean) => void;
@@ -397,6 +405,8 @@ startTargetOverlay: (...args: any[]) => any;
     closeLogOverlay: (...args: any[]) => any;
     loadLogLevel: (...args: any[]) => any;
     setLogLevel: (...args: any[]) => any;
+    loadShutdownAction: (...args: any[]) => any;
+    setShutdownAction: (...args: any[]) => any;
     saveExternalUrl: (...args: any[]) => any;
     getBaseOrigin: (...args: any[]) => any;
 

server/src/ledgrab/static/locales/en.json

@@ -1788,6 +1788,14 @@
   "settings.log_level.desc.warning": "Potential problems",
   "settings.log_level.desc.error": "Failures only",
   "settings.log_level.desc.critical": "Fatal errors only",
+  "settings.shutdown_action.label": "Shutdown action",
+  "settings.shutdown_action.hint": "What happens to LED targets when the server shuts down. \"Stop targets\" runs the normal stop sequence so devices with auto-restore restore their prior state. \"Nothing\" leaves the lights showing the last frame.",
+  "settings.shutdown_action.saved": "Shutdown action saved",
+  "settings.shutdown_action.save_error": "Failed to save shutdown action",
+  "settings.shutdown_action.opt.stop": "Stop targets",
+  "settings.shutdown_action.opt.stop_desc": "Run the normal stop sequence (per-device auto-restore applies)",
+  "settings.shutdown_action.opt.nothing": "Nothing",
+  "settings.shutdown_action.opt.nothing_desc": "Leave lights showing the last frame",
   "settings.auto_backup.label": "Auto-Backup",
   "settings.auto_backup.hint": "Automatically create periodic backups of all configuration. Old backups are pruned when the maximum count is reached.",
   "settings.auto_backup.enable": "Enable auto-backup",

server/src/ledgrab/static/locales/ru.json

@@ -1604,6 +1604,14 @@
   "settings.log_level.desc.warning": "Возможные проблемы",
   "settings.log_level.desc.error": "Только ошибки",
   "settings.log_level.desc.critical": "Только критические ошибки",
+  "settings.shutdown_action.label": "Действие при выключении",
+  "settings.shutdown_action.hint": "Что происходит с LED-целями при остановке сервера. «Остановить цели» — обычная последовательность остановки, устройства с авто-восстановлением восстановят прежнее состояние. «Ничего» — оставить свет таким, каким он был на последнем кадре.",
+  "settings.shutdown_action.saved": "Действие при выключении сохранено",
+  "settings.shutdown_action.save_error": "Не удалось сохранить действие при выключении",
+  "settings.shutdown_action.opt.stop": "Остановить цели",
+  "settings.shutdown_action.opt.stop_desc": "Обычная остановка (учитывается авто-восстановление устройств)",
+  "settings.shutdown_action.opt.nothing": "Ничего",
+  "settings.shutdown_action.opt.nothing_desc": "Оставить свет на последнем кадре",
   "settings.auto_backup.label": "Авто-бэкап",
   "settings.auto_backup.hint": "Автоматическое создание периодических резервных копий конфигурации. Старые копии удаляются при превышении максимального количества.",
   "settings.auto_backup.enable": "Включить авто-бэкап",

server/src/ledgrab/static/locales/zh.json

@@ -1604,6 +1604,14 @@
   "settings.log_level.desc.warning": "潜在问题",
   "settings.log_level.desc.error": "仅显示错误",
   "settings.log_level.desc.critical": "仅显示致命错误",
+  "settings.shutdown_action.label": "关机时执行",
+  "settings.shutdown_action.hint": "服务器关闭时对 LED 目标的处理方式。「停止目标」执行正常的停止流程，启用自动恢复的设备会恢复先前状态。「无」会让灯保持显示最后一帧。",
+  "settings.shutdown_action.saved": "已保存关机动作",
+  "settings.shutdown_action.save_error": "保存关机动作失败",
+  "settings.shutdown_action.opt.stop": "停止目标",
+  "settings.shutdown_action.opt.stop_desc": "执行正常停止流程（按设备应用自动恢复）",
+  "settings.shutdown_action.opt.nothing": "无",
+  "settings.shutdown_action.opt.nothing_desc": "让灯保持最后一帧",
   "settings.auto_backup.label": "自动备份",
   "settings.auto_backup.hint": "自动定期创建所有配置的备份。当达到最大数量时，旧备份会被自动清理。",
   "settings.auto_backup.enable": "启用自动备份",

server/src/ledgrab/templates/index.html

@@ -544,18 +544,31 @@
         // Initialize on load
         updateAuthUI();
 
-        // Transport-bar session uptime ticker — time since page load.
+        // Transport-bar uptime ticker — shows the SERVER's process uptime,
+        // not the browser session. api.ts populates window.__serverUptime
+        // from /health on initial load and on every connection re-check;
+        // until that lands we fall back to "—" so a refresh doesn't briefly
+        // flash 00:00:00. After 99h the format widens to D HH:MM:SS so the
+        // counter stays meaningful for long-running services.
+        // The drift between fetch and now is computed against
+        // performance.now() (monotonic) so an NTP step / DST change /
+        // user clock-set on the host doesn't visibly jump the counter.
         (function() {
-            const pageLoadedAt = Date.now();
             const el = document.getElementById('transport-uptime');
             if (!el) return;
             function pad(n) { return n < 10 ? '0' + n : String(n); }
             function render() {
-                const secs = Math.floor((Date.now() - pageLoadedAt) / 1000);
+                const ref = window.__serverUptime;
-                const h = Math.floor(secs / 3600);
+                if (!ref) { el.textContent = '—'; return; }
+                const elapsedSinceFetch = (performance.now() - ref.recordedAtPerf) / 1000;
+                const secs = Math.max(0, Math.floor(ref.uptimeSec + elapsedSinceFetch));
+                const d = Math.floor(secs / 86400);
+                const h = Math.floor((secs % 86400) / 3600);
                 const m = Math.floor((secs % 3600) / 60);
                 const s = secs % 60;
-                el.textContent = `${pad(h)}:${pad(m)}:${pad(s)}`;
+                el.textContent = d > 0
+                    ? `${d}d ${pad(h)}:${pad(m)}:${pad(s)}`
+                    : `${pad(h)}:${pad(m)}:${pad(s)}`;
             }
             render();
             setInterval(render, 1000);

server/src/ledgrab/templates/modals/settings.html

@@ -57,6 +57,19 @@
                     </select>
                 </div>
 
+                <!-- Shutdown action section -->
+                <div class="form-group">
+                    <div class="label-row">
+                        <label data-i18n="settings.shutdown_action.label">Shutdown action</label>
+                        <button type="button" class="hint-toggle" onclick="toggleHint(this)" title="?">?</button>
+                    </div>
+                    <small class="input-hint" style="display:none" data-i18n="settings.shutdown_action.hint">What happens to LED targets when the server shuts down. "Stop targets" runs the normal stop sequence so devices with auto-restore restore their prior state. "Nothing" leaves the lights showing the last frame.</small>
+                    <select id="settings-shutdown-action">
+                        <option value="stop_targets">Stop targets</option>
+                        <option value="nothing">Nothing</option>
+                    </select>
+                </div>
+
                 <!-- Server Logs button (opens overlay) -->
                 <div class="form-group">
                     <div class="label-row">