feat: Override, Wochenend-Sperre und per-Screen-Override implementiert

docs/API-ENDPOINTS.md

@@ -587,6 +587,93 @@ Der Scheduler prüft jede Minute, ob die aktuelle Uhrzeit mit `power_on_time` od
 
 ---
 
+### Globaler Override
+
+| Methode | Pfad | Auth | Beschreibung |
+|---------|------|------|--------------|
+| GET | `/api/v1/global-override` | authUser | Aktiven Override abrufen (204 wenn keiner aktiv) |
+| POST | `/api/v1/global-override` | authUser | Override setzen + sofort MQTT an alle Screens |
+| DELETE | `/api/v1/global-override` | authUser | Override aufheben |
+
+**GET /api/v1/global-override**
+
+Ruft den aktuell aktiven globalen Override ab.
+
+**Response:** `200 OK` (wenn aktiv)
+```json
+{"type":"off","until":"2026-04-05T18:00:00+02:00","set_at":"2026-03-27T15:30:00+02:00"}
+```
+
+**Response:** `204 No Content` (wenn kein Override aktiv)
+
+---
+
+**POST /api/v1/global-override**
+
+Setzt einen globalen Override und sendet sofort MQTT-Befehle an alle Screens.
+
+**Request-Body:**
+```json
+{"type":"off","until":"2026-04-05T18:00:00+02:00"}
+```
+
+**Response:** `200 OK`
+```json
+{"type":"off","until":"2026-04-05T18:00:00+02:00","set_at":"2026-03-27T15:30:00+02:00"}
+```
+
+**Fehler:**
+- `400 Bad Request` — `type` nicht "on"/"off", oder ungültiges Zeitformat
+- `500 Internal Server Error` — DB-Fehler
+
+---
+
+**DELETE /api/v1/global-override**
+
+Hebt den aktuellen globalen Override auf.
+
+**Response:** `204 No Content`
+
+**Fehler:**
+- `500 Internal Server Error` — DB-Fehler
+
+---
+
+### Per-Screen Override
+
+| Methode | Pfad | Auth | Beschreibung |
+|---------|------|------|--------------|
+| POST | `/api/v1/screens/{screenSlug}/override` | authScreen | Per-Screen "Einschalten bis" setzen oder löschen |
+
+**POST /api/v1/screens/{screenSlug}/override**
+
+Setzt oder löscht den per-Screen "Einschalten bis"-Override. Mit diesem Override bleibt ein Monitor bis zu
+dem angegebenen Zeitpunkt eingeschaltet, selbst wenn der globale Schedule "aus" vorsieht.
+
+**Auth:** Erforderlich. Screen-Zugriff erforderlich.
+
+**Path-Parameter:**
+- `screenSlug` — Slug des Screens
+
+**Request-Body:**
+```json
+{"on_until":"2026-04-05T18:00:00+02:00"}
+```
+
+Um den Override zu löschen, `on_until` auf `null` setzen:
+```json
+{"on_until":null}
+```
+
+**Response:** `204 No Content`
+
+**Fehler:**
+- `400 Bad Request` — Ungültiges Zeitformat oder ungültiges JSON
+- `404 Not Found` — Screen nicht vorhanden
+- `500 Internal Server Error` — DB-Fehler
+
+---
+
 ## Message Wall
 
 ### POST /api/v1/tools/message-wall/resolve

docs/SCHEMA.md

@@ -523,6 +523,36 @@ Regeln:
 - `schedule_enabled = false` bedeutet: Zeitplan vorhanden, aber deaktiviert
 - Leere Zeitfelder bedeuten: kein Einschalt- bzw. kein Ausschaltbefehl
 
+Neue Spalte in `screen_schedules` (Migration `006`):
+- `override_on_until timestamptz` — Einschalten-Override: Monitor bleibt bis zu diesem Zeitpunkt eingeschaltet (null = kein Override)
+
+### `global_override` (Migration 006)
+
+Zweck:
+
+- Speichert den globalen Display-Override (maximal eine Zeile)
+
+Spalten:
+
+```sql
+id        INT         PRIMARY KEY DEFAULT 1
+type      TEXT        NOT NULL         -- "on" oder "off"
+until     TIMESTAMPTZ NOT NULL         -- Override aktiv bis zu diesem Zeitpunkt
+set_at    TIMESTAMPTZ NOT NULL DEFAULT now()  -- Wann der Override gesetzt wurde
+```
+
+Constraint:
+```sql
+CHECK (id = 1)
+```
+
+Regeln:
+
+- Die Tabelle enthaelt maximal eine Zeile (id = 1)
+- `type` bestimmt den globalen Zielzustand (alle Screens)
+- `until` gibt an, wann der Override automatisch aufgehoben wird
+- Der Scheduler prueft jede Minute, ob der Override noch aktiv ist (aktuell <= until)
+
 ### `screen_snapshots`
 
 Zweck:

server/backend/README.md

@@ -17,7 +17,7 @@ Dieses Verzeichnis enthaelt das zentrale Go-Backend fuer das Info-Board-System.
 - `internal/app/` — App-Initialisierung und Lifecycle
 - `internal/config/` — Konfiguration via Umgebungsvariablen
 - `internal/db/` — PostgreSQL-Anbindung und Migrations-Runner
-- `internal/store/` — Datenbankzugriff (TenantStore, ScreenStore, MediaStore, PlaylistStore, AuthStore)
+- `internal/store/` — Datenbankzugriff (TenantStore, ScreenStore, MediaStore, PlaylistStore, AuthStore, ScreenScheduleStore, GlobalOverrideStore)
 - `internal/fileutil/` — Upload-Hilfsfunktionen (SaveUploadedFile mit Tenant-Isolation)
 - `internal/httpapi/` — HTTP-Routing, Middleware und Handler
 - `internal/httpapi/csrf.go` — Double-Submit-Cookie CSRF-Schutz
@@ -42,6 +42,10 @@ Uhrzeit übereinstimmt — per MQTT den Befehl `display_on` bzw. `display_off` s
 Der Scheduler wird in `internal/app/app.go` als Goroutine gestartet und laeuft bis zum
 Kontext-Abbruch beim Server-Shutdown.
 
+**Wochenend-Sperre:** An Samstagen und Sonntagen werden Zeitplaene ignoriert — der Reconciler
+sendet dann keine automatischen Ein-/Ausschalt-Kommandos. Manuelle Overrides (global oder
+per-Screen) wirken jedoch auch am Wochenende.
+
 ## Datenbank-Stores
 
 ### AuthStore (`internal/store/auth.go`)
@@ -60,6 +64,16 @@ Kontext-Abbruch beim Server-Shutdown.
 - `EnsureAdminUser(ctx, tenantSlug, password)` — Admin-User beim Start anlegen
 - `VerifyPassword(ctx, userID, password)` — Passwort gegen bcrypt-Hash pruefen
 
+### GlobalOverrideStore (`internal/store/store.go`)
+
+Verwaltet einen systemweiten Display-Override (max. 1 Zeile in `global_override`):
+
+- `Get(ctx)` — aktuellen globalen Override laden (nil wenn keiner gesetzt)
+- `Upsert(ctx, type, until)` — Override setzen oder ueberschreiben (`type`: `"on"` | `"off"`)
+- `Delete(ctx)` — Override entfernen
+
+Der Reconciler im Scheduler wertet den globalen Override aus und wendet ihn auf alle Screens an.
+
 ### ScreenStore (`internal/store/screen.go`)
 
 **Screen-User Zugriffskontrolle:**
@@ -117,6 +131,10 @@ Kontext-Abbruch beim Server-Shutdown.
 | GET     | `/api/v1/screens/{screenId}/screenshot`   | Screenshot eines Screens abrufen      |
 | POST    | `/api/v1/screens/{screenSlug}/display`    | Display ein-/ausschalten (MQTT)       |
 | POST    | `/api/v1/screens/{screenSlug}/schedule`   | Display-Zeitplan speichern            |
+| GET     | `/api/v1/global-override`                 | Globalen Override abrufen (204 = kein aktiver Override) |
+| POST    | `/api/v1/global-override`                 | Globalen Override setzen (type + until); sendet sofort MQTT |
+| DELETE  | `/api/v1/global-override`                 | Globalen Override loeschen            |
+| POST    | `/api/v1/screens/{screenSlug}/override`   | Per-Screen-Override setzen oder loeschen (on_until: null = loeschen) |
 
 ### Nur Admins (`RequireAuth` + `RequireAdmin`)
 
@@ -182,8 +200,9 @@ Middleware zur rollenbasierten Zugriffskontrolle auf Screen-Ressourcen.
 
 ## Migrationen
 
-- `001_core.sql` — initiales Schema (Tenants, Screens, Playlists, Media, etc.)
+- `001_initial.sql` — initiales Schema (Tenants, Screens, Playlists, Media, etc.)
 - `002_auth.sql` — Auth-Tabellen (`users`, `sessions`)
 - `003_user_screen_permissions.sql` — Screen-User Management (`user_screen_permissions`)
 - `004_screen_status.sql` — Display-Zustand pro Screen (`screen_status`: screen_id, display_state, reported_at)
 - `005_screen_schedules.sql` — Zeitplan pro Screen (`screen_schedules`: screen_id, schedule_enabled, power_on_time, power_off_time)
+- `006_override.sql` — Spalte `override_on_until` in `screen_schedules` (per-Screen-Override) und Tabelle `global_override` (systemweiter Display-Override)

server/backend/internal/app/app.go

@@ -27,6 +27,7 @@ type App struct {
 	notifier      *mqttnotifier.Notifier
 	authStore     *store.AuthStore
 	scheduleStore       *store.ScreenScheduleStore
+	globalOverrideStore *store.GlobalOverrideStore
 	screenStore         *store.ScreenStore
 	dbPool        *db.Pool // V7: für db.Close() im Shutdown
 	logger        *log.Logger
@@ -62,6 +63,7 @@ func New() (*App, error) {
 	playlists := store.NewPlaylistStore(pool.Pool)
 	authStore := store.NewAuthStore(pool.Pool)
 	schedules := store.NewScreenScheduleStore(pool.Pool)
+	globalOverrides := store.NewGlobalOverrideStore(pool.Pool)
 
 	// Ensure admin user exists — generate a random password if none is configured.
 	adminPassword := cfg.AdminPassword
@@ -101,6 +103,7 @@ func New() (*App, error) {
 		Notifier:        notifier,
 		ScreenshotStore: ss,
 		ScheduleStore:       schedules,
+		GlobalOverrideStore: globalOverrides,
 		Config:              cfg,
 		UploadDir:       cfg.UploadDir,
 		Logger:          logger,
@@ -112,6 +115,7 @@ func New() (*App, error) {
 		notifier:      notifier,
 		authStore:     authStore,
 		scheduleStore:       schedules,
+		globalOverrideStore: globalOverrides,
 		screenStore:         screens,
 		dbPool:        pool, // V7: Referenz für Shutdown
 		logger:        logger,
@@ -145,8 +149,8 @@ func (a *App) Run() error {
 	}()
 
 	// Display-Zeitplan-Scheduler
-	go scheduler.Run(ctx, a.scheduleStore, a.screenStore, a.notifier)
+	go scheduler.Run(ctx, a.scheduleStore, a.screenStore, a.globalOverrideStore, a.notifier)
-	go scheduler.Reconcile(ctx, a.scheduleStore, a.screenStore, a.screenStore, a.notifier)
+	go scheduler.Reconcile(ctx, a.scheduleStore, a.screenStore, a.screenStore, a.globalOverrideStore, a.notifier)
 
 	// W2: Signal-Handler für Graceful Shutdown.
 	sigCh := make(chan os.Signal, 1)

server/backend/internal/db/migrations/006_override.sql

@@ -0,0 +1,14 @@
+-- Migration 006: Globaler Override + per-Screen Override-Zeitpunkt
+
+-- Globaler Override: immer maximal eine Zeile (id = 1 per CHECK-Constraint).
+create table if not exists global_override (
+    id      int         primary key default 1,
+    type    text        not null,           -- 'on' oder 'off'
+    until   timestamptz not null,
+    set_at  timestamptz not null default now(),
+    check (id = 1)
+);
+
+-- Per-Screen Override: Einschalten bis Zeitpunkt (null = kein Override).
+alter table screen_schedules
+    add column if not exists override_on_until timestamptz;

server/backend/internal/httpapi/manage/override.go

@@ -0,0 +1,138 @@
+// server/backend/internal/httpapi/manage/override.go
+package manage
+
+import (
+	"context"
+	"encoding/json"
+	"log/slog"
+	"net/http"
+	"time"
+
+	"git.az-it.net/az/morz-infoboard/server/backend/internal/mqttnotifier"
+	"git.az-it.net/az/morz-infoboard/server/backend/internal/reqcontext"
+	"git.az-it.net/az/morz-infoboard/server/backend/internal/store"
+)
+
+// globalOverrideStore ist das Interface für Handler-Tests.
+type globalOverrideStore interface {
+	Get(ctx context.Context) (*store.GlobalOverride, error)
+	Upsert(ctx context.Context, overrideType string, until time.Time) error
+	Delete(ctx context.Context) error
+}
+
+// HandleGetGlobalOverride gibt den aktuellen globalen Override zurück (204 wenn keiner aktiv).
+func HandleGetGlobalOverride(overrides globalOverrideStore) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		o, err := overrides.Get(r.Context())
+		if err != nil {
+			http.Error(w, "internal error", http.StatusInternalServerError)
+			return
+		}
+		if o == nil || time.Now().After(o.Until) {
+			w.WriteHeader(http.StatusNoContent)
+			return
+		}
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(o) //nolint:errcheck
+	}
+}
+
+// HandleSetGlobalOverride setzt den globalen Override und schickt sofort MQTT an alle Screens.
+// Hinweis: Der Override wird global gespeichert und vom Reconciler auf alle Screens angewendet.
+// Über authOnly haben alle eingeloggten Nutzer Zugriff; die sofortigen MQTT-Kommandos gehen
+// jedoch nur an ihre zugänglichen Screens. Soll der Zugriff auf Admins beschränkt werden,
+// authOnly durch authAdmin ersetzen.
+func HandleSetGlobalOverride(overrides globalOverrideStore, screens *store.ScreenStore, notifier *mqttnotifier.Notifier) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		var body struct {
+			Type  string    `json:"type"`
+			Until time.Time `json:"until"`
+		}
+		if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+			http.Error(w, "invalid JSON", http.StatusBadRequest)
+			return
+		}
+		if body.Type != "on" && body.Type != "off" {
+			http.Error(w, `type must be "on" or "off"`, http.StatusBadRequest)
+			return
+		}
+		if body.Until.IsZero() || !time.Now().Before(body.Until) {
+			http.Error(w, "until must be in the future", http.StatusBadRequest)
+			return
+		}
+
+		if err := overrides.Upsert(r.Context(), body.Type, body.Until); err != nil {
+			slog.Error("set global override: upsert failed", "err", err)
+			http.Error(w, "internal error", http.StatusInternalServerError)
+			return
+		}
+
+		// Sofort MQTT an alle zugänglichen Screens schicken (falls screens/notifier vorhanden)
+		if screens != nil && notifier != nil {
+			u := reqcontext.UserFromContext(r.Context())
+			var allScreens []*store.Screen
+			if u != nil {
+				switch u.Role {
+				case "admin":
+					allScreens, _ = screens.ListAll(r.Context())
+				default:
+					allScreens, _ = screens.GetAccessibleScreens(r.Context(), u.ID)
+				}
+			}
+			action := "display_" + body.Type
+			for _, sc := range allScreens {
+				if err := notifier.SendDisplayCommand(sc.Slug, action); err != nil {
+					slog.Warn("set global override: send command failed", "slug", sc.Slug, "err", err)
+				}
+			}
+		}
+
+		w.WriteHeader(http.StatusNoContent)
+	}
+}
+
+// HandleDeleteGlobalOverride entfernt den globalen Override.
+func HandleDeleteGlobalOverride(overrides globalOverrideStore) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if err := overrides.Delete(r.Context()); err != nil {
+			slog.Error("delete global override: failed", "err", err)
+			http.Error(w, "internal error", http.StatusInternalServerError)
+			return
+		}
+		w.WriteHeader(http.StatusNoContent)
+	}
+}
+
+// HandleSetScreenOverride setzt oder löscht den per-Screen-Override (on_until: null → löschen).
+func HandleSetScreenOverride(screens *store.ScreenStore, schedules *store.ScreenScheduleStore) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		screenSlug := r.PathValue("screenSlug")
+		screen, err := screens.GetBySlug(r.Context(), screenSlug)
+		if err != nil {
+			http.Error(w, "screen not found", http.StatusNotFound)
+			return
+		}
+		if !requireScreenAccess(w, r, screen) {
+			return
+		}
+
+		var body struct {
+			OnUntil *time.Time `json:"on_until"`
+		}
+		if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
+			http.Error(w, "invalid JSON", http.StatusBadRequest)
+			return
+		}
+		if body.OnUntil != nil && !time.Now().Before(*body.OnUntil) {
+			http.Error(w, "on_until must be in the future", http.StatusBadRequest)
+			return
+		}
+
+		if err := schedules.SetOverrideOnUntil(r.Context(), screen.ID, body.OnUntil); err != nil {
+			slog.Error("set screen override: db error", "screen_id", screen.ID, "err", err)
+			http.Error(w, "internal error", http.StatusInternalServerError)
+			return
+		}
+		w.WriteHeader(http.StatusNoContent)
+	}
+}

server/backend/internal/httpapi/manage/override_test.go

@@ -0,0 +1,98 @@
+// server/backend/internal/httpapi/manage/override_test.go
+package manage_test
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"git.az-it.net/az/morz-infoboard/server/backend/internal/httpapi/manage"
+	"git.az-it.net/az/morz-infoboard/server/backend/internal/store"
+)
+
+// --- Mocks ---
+
+type mockGlobalOverrideStore struct {
+	current      *store.GlobalOverride
+	upsertCalled bool
+	deleteCalled bool
+}
+
+func (m *mockGlobalOverrideStore) Get(_ context.Context) (*store.GlobalOverride, error) {
+	return m.current, nil
+}
+func (m *mockGlobalOverrideStore) Upsert(_ context.Context, t string, u time.Time) error {
+	m.current = &store.GlobalOverride{Type: t, Until: u}
+	m.upsertCalled = true
+	return nil
+}
+func (m *mockGlobalOverrideStore) Delete(_ context.Context) error {
+	m.current = nil
+	m.deleteCalled = true
+	return nil
+}
+
+// --- Tests ---
+
+func TestHandleGetGlobalOverride_None(t *testing.T) {
+	h := manage.HandleGetGlobalOverride(&mockGlobalOverrideStore{})
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/global-override", nil)
+	w := httptest.NewRecorder()
+	h.ServeHTTP(w, req)
+	if w.Code != http.StatusNoContent {
+		t.Fatalf("want 204, got %d", w.Code)
+	}
+}
+
+func TestHandleGetGlobalOverride_Active(t *testing.T) {
+	until := time.Now().Add(time.Hour)
+	m := &mockGlobalOverrideStore{
+		current: &store.GlobalOverride{Type: "off", Until: until},
+	}
+	h := manage.HandleGetGlobalOverride(m)
+	req := httptest.NewRequest(http.MethodGet, "/api/v1/global-override", nil)
+	w := httptest.NewRecorder()
+	h.ServeHTTP(w, req)
+	if w.Code != http.StatusOK {
+		t.Fatalf("want 200, got %d", w.Code)
+	}
+	var resp store.GlobalOverride
+	if err := json.NewDecoder(w.Body).Decode(&resp); err != nil {
+		t.Fatal("decode response:", err)
+	}
+	if resp.Type != "off" {
+		t.Errorf("want type=off, got %q", resp.Type)
+	}
+}
+
+func TestHandleSetGlobalOverride_InvalidType(t *testing.T) {
+	h := manage.HandleSetGlobalOverride(&mockGlobalOverrideStore{}, nil, nil)
+	body := `{"type":"maybe","until":"` + time.Now().Add(time.Hour).Format(time.RFC3339) + `"}`
+	req := httptest.NewRequest(http.MethodPost, "/api/v1/global-override", bytes.NewBufferString(body))
+	req.Header.Set("Content-Type", "application/json")
+	w := httptest.NewRecorder()
+	h.ServeHTTP(w, req)
+	if w.Code != http.StatusBadRequest {
+		t.Fatalf("want 400, got %d", w.Code)
+	}
+}
+
+func TestHandleDeleteGlobalOverride(t *testing.T) {
+	m := &mockGlobalOverrideStore{
+		current: &store.GlobalOverride{Type: "off", Until: time.Now().Add(time.Hour)},
+	}
+	h := manage.HandleDeleteGlobalOverride(m)
+	req := httptest.NewRequest(http.MethodDelete, "/api/v1/global-override", nil)
+	w := httptest.NewRecorder()
+	h.ServeHTTP(w, req)
+	if w.Code != http.StatusNoContent {
+		t.Fatalf("want 204, got %d", w.Code)
+	}
+	if !m.deleteCalled {
+		t.Error("Delete() was not called")
+	}
+}

server/backend/internal/httpapi/manage/templates.go

@@ -982,6 +982,27 @@ const manageTmpl = `<!DOCTYPE html>
           </div>
           <p id="schedule-save-ok" class="save-ok mt-2" style="font-size:.8rem">✓ Gespeichert</p>
         </div>
+<!-- Per-Screen Override (Einschalten bis) -->
+<div class="box mb-3">
+  <h3 class="title is-6 mb-2">Einschalten bis (Override)</h3>
+  {{if not_expired .Schedule.OverrideOnUntil}}
+  <p style="font-size:.875rem;color:#059669;margin-bottom:.5rem">
+    &#x23F0; Aktiv bis {{.Schedule.OverrideOnUntil.Format "02.01.2006 15:04"}}
+  </p>
+  <button class="button is-small is-light" type="button"
+          onclick="clearScreenOverridePage()">Override aufheben</button>
+  {{else}}
+  <p style="font-size:.8rem;color:#6b7280;margin-bottom:.5rem">
+    &#220;berschreibt Zeitplan und Wochenend-Sperre &#x2014; Monitor bleibt bis zum angegebenen Zeitpunkt eingeschaltet.
+  </p>
+  <div style="display:flex;gap:.5rem;align-items:center;flex-wrap:wrap">
+    <input type="datetime-local" id="screen-override-until" class="input is-small" style="width:16rem">
+    <button class="button is-small is-success" type="button"
+            onclick="setScreenOverridePage()">Setzen</button>
+  </div>
+  {{end}}
+  <p id="screen-override-ok" class="save-ok mt-2" style="font-size:.8rem">&#x2713; Gespeichert</p>
+</div>
         <!-- Upload (collapsed) -->
         <div class="box mb-3">
           <details id="upload-details">
@@ -1189,6 +1210,33 @@ function saveSchedule() {
   }).catch(function() { showToast('Netzwerkfehler', 'is-danger'); });
 }
 
+function setScreenOverridePage() {
+  var val = document.getElementById('screen-override-until').value;
+  if (!val) { showToast('Bitte Datum und Uhrzeit angeben', 'is-warning'); return; }
+  var dt = new Date(val);
+  fetch('/api/v1/screens/' + SCREEN_SLUG + '/override', {
+    method: 'POST',
+    headers: {'Content-Type': 'application/json', 'X-CSRF-Token': getCsrf(), 'X-Requested-With': 'fetch'},
+    body: JSON.stringify({on_until: dt.toISOString()})
+  }).then(function(r) {
+    if (r.ok) {
+      var ok = document.getElementById('screen-override-ok');
+      if (ok) { ok.classList.add('show'); setTimeout(function() { ok.classList.remove('show'); }, 2000); }
+    } else { showToast('Fehler beim Setzen des Overrides', 'is-danger'); }
+  }).catch(function() { showToast('Netzwerkfehler', 'is-danger'); });
+}
+
+function clearScreenOverridePage() {
+  fetch('/api/v1/screens/' + SCREEN_SLUG + '/override', {
+    method: 'POST',
+    headers: {'Content-Type': 'application/json', 'X-CSRF-Token': getCsrf(), 'X-Requested-With': 'fetch'},
+    body: JSON.stringify({on_until: null})
+  }).then(function(r) {
+    if (r.ok) { location.reload(); }
+    else { showToast('Fehler beim Aufheben des Overrides', 'is-danger'); }
+  }).catch(function() { showToast('Netzwerkfehler', 'is-danger'); });
+}
+
 // ─── ?msg= toast ─────────────────────────────────────────────────
 (function() {
   var msg = new URLSearchParams(window.location.search).get('msg');
@@ -1392,6 +1440,29 @@ const screenOverviewTmpl = `<!DOCTYPE html>
 <section class="section">
   <div class="container">
     <h1 class="title is-4 mb-5">Meine Bildschirme</h1>
+    <!-- Globaler Override-Banner -->
+<div id="global-override-section" style="margin-bottom:1rem">
+  {{if .GlobalOverride}}
+  <div class="notification {{if eq .GlobalOverride.Type "off"}}is-warning{{else}}is-info{{end}} is-light py-2 px-3" style="display:flex;align-items:center;gap:1rem;flex-wrap:wrap">
+    <span>
+      Alle Monitore <strong>{{if eq .GlobalOverride.Type "off"}}ausgeschaltet{{else}}eingeschaltet{{end}}</strong>
+      bis {{.GlobalOverride.Until.Format "02.01.2006 15:04"}}
+    </span>
+    <button class="button is-small" type="button" onclick="deleteGlobalOverride()">Override aufheben</button>
+  </div>
+  {{else}}
+  <div style="display:flex;gap:.5rem;flex-wrap:wrap;align-items:center">
+    <button class="button is-small is-danger is-light" type="button" onclick="showGlobalOverrideForm('off')">Alle ausschalten bis&#x2026;</button>
+    <button class="button is-small is-success is-light" type="button" onclick="showGlobalOverrideForm('on')">Alle einschalten bis&#x2026;</button>
+    <span id="override-result" style="font-size:.8rem;color:#6b7280"></span>
+  </div>
+  <div id="global-override-form" style="display:none;margin-top:.5rem;gap:.5rem;align-items:center;flex-wrap:wrap">
+    <input type="datetime-local" id="global-override-until" class="input is-small" style="width:16rem">
+    <button class="button is-small is-primary" type="button" onclick="setGlobalOverride()">Setzen</button>
+    <button class="button is-small is-light" type="button" onclick="hideGlobalOverrideForm()">Abbrechen</button>
+  </div>
+  {{end}}
+</div>
     {{if gt (len .Cards) 1}}
     <div class="bulk-bar">
       <span style="font-size:.875rem;font-weight:600;color:#374151">Alle Displays:</span>
@@ -1424,6 +1495,24 @@ const screenOverviewTmpl = `<!DOCTYPE html>
               <button class="button is-small is-danger is-light" type="button"
                       onclick="sendDisplayCmd('{{.Screen.Slug}}','off')">Aus</button>
             </div>
+        <!-- Per-Screen Override -->
+        <div style="margin-top:.5rem;font-size:.8rem">
+          {{if .OverrideOnUntil}}
+          <span style="color:#059669">&#x23F0; Ein bis {{.OverrideOnUntil.Format "02.01. 15:04"}}</span>
+          <button class="button is-small is-light" style="padding:0 .4rem;height:1.4rem" type="button"
+                  onclick="clearScreenOverride('{{.Screen.Slug}}')">&#x2715;</button>
+          {{else}}
+          <details style="display:inline">
+            <summary style="cursor:pointer;color:#6b7280">Einschalten bis&#x2026;</summary>
+            <div style="display:flex;gap:.3rem;align-items:center;margin-top:.3rem;flex-wrap:wrap">
+              <input type="datetime-local" id="override-until-{{.Screen.Slug}}"
+                     class="input is-small" style="width:13rem;font-size:.75rem">
+              <button class="button is-small is-success is-light" type="button"
+                      onclick="setScreenOverride('{{.Screen.Slug}}')">Setzen</button>
+            </div>
+          </details>
+          {{end}}
+        </div>
           </div>
         </div>
       </div>
@@ -1513,6 +1602,68 @@ function bulkDisplay(state) {
     }).catch(function(){});
   });
 }
+
+var _globalOverrideType = '';
+
+function showGlobalOverrideForm(type) {
+  _globalOverrideType = type;
+  var form = document.getElementById('global-override-form');
+  if (form) form.style.display = 'flex';
+}
+
+function hideGlobalOverrideForm() {
+  var form = document.getElementById('global-override-form');
+  if (form) form.style.display = 'none';
+}
+
+function setGlobalOverride() {
+  var val = document.getElementById('global-override-until').value;
+  if (!val) {
+    document.getElementById('override-result').textContent = 'Bitte Datum und Uhrzeit angeben';
+    return;
+  }
+  var dt = new Date(val);
+  fetch('/api/v1/global-override', {
+    method: 'POST',
+    headers: {'Content-Type': 'application/json', 'X-CSRF-Token': getCsrf(), 'X-Requested-With': 'fetch'},
+    body: JSON.stringify({type: _globalOverrideType, until: dt.toISOString()})
+  }).then(function(r) {
+    if (r.ok) { location.reload(); }
+    else { document.getElementById('override-result').textContent = 'Fehler beim Setzen'; }
+  }).catch(function() { document.getElementById('override-result').textContent = 'Netzwerkfehler'; });
+}
+
+function deleteGlobalOverride() {
+  fetch('/api/v1/global-override', {
+    method: 'DELETE',
+    headers: {'X-CSRF-Token': getCsrf(), 'X-Requested-With': 'fetch'}
+  }).then(function(r) {
+    if (r.ok) { location.reload(); }
+  }).catch(function(){});
+}
+
+function setScreenOverride(slug) {
+  var val = document.getElementById('override-until-' + slug).value;
+  if (!val) return;
+  var dt = new Date(val);
+  fetch('/api/v1/screens/' + slug + '/override', {
+    method: 'POST',
+    headers: {'Content-Type': 'application/json', 'X-CSRF-Token': getCsrf(), 'X-Requested-With': 'fetch'},
+    body: JSON.stringify({on_until: dt.toISOString()})
+  }).then(function(r) {
+    if (r.ok) { location.reload(); }
+  }).catch(function(){});
+}
+
+function clearScreenOverride(slug) {
+  fetch('/api/v1/screens/' + slug + '/override', {
+    method: 'POST',
+    headers: {'Content-Type': 'application/json', 'X-CSRF-Token': getCsrf(), 'X-Requested-With': 'fetch'},
+    body: JSON.stringify({on_until: null})
+  }).then(function(r) {
+    if (r.ok) { location.reload(); }
+  }).catch(function(){});
+}
 </script>
 </body>
 </html>`

server/backend/internal/httpapi/manage/ui.go

@@ -137,6 +137,9 @@ var tmplFuncs = template.FuncMap{
 		}
 		return t.Format("02.01.2006 15:04")
 	},
+	"not_expired": func(t *time.Time) bool {
+		return t != nil && time.Now().Before(*t)
+	},
 }
 
 // HandleAdminUI renders the admin overview page (screens + users tabs).
@@ -283,10 +286,11 @@ func HandleRemoveUserFromScreen(screens *store.ScreenStore) http.HandlerFunc {
 type screenCard struct {
 	Screen          *store.Screen
 	DisplayState    string
+	OverrideOnUntil *time.Time
 }
 
 // HandleScreenOverview renders a card-based overview of all accessible screens for a screen_user.
-func HandleScreenOverview(screens *store.ScreenStore, notifier *mqttnotifier.Notifier, cfg config.Config) http.HandlerFunc {
+func HandleScreenOverview(screens *store.ScreenStore, schedules *store.ScreenScheduleStore, overrides *store.GlobalOverrideStore, notifier *mqttnotifier.Notifier, cfg config.Config) http.HandlerFunc {
 	t := template.Must(template.New("screenOverview").Funcs(tmplFuncs).Parse(screenOverviewTmpl))
 	return func(w http.ResponseWriter, r *http.Request) {
 		u := reqcontext.UserFromContext(r.Context())
@@ -310,11 +314,23 @@ func HandleScreenOverview(screens *store.ScreenStore, notifier *mqttnotifier.Not
 		cards := make([]screenCard, 0, len(accessible))
 		for _, sc := range accessible {
 			ds, _ := screens.GetDisplayState(r.Context(), sc.ID)
-			cards = append(cards, screenCard{Screen: sc, DisplayState: ds})
+			sched, _ := schedules.Get(r.Context(), sc.ID)
+			var overrideOnUntil *time.Time
+			if sched != nil && sched.OverrideOnUntil != nil && time.Now().Before(*sched.OverrideOnUntil) {
+				overrideOnUntil = sched.OverrideOnUntil
 			}
+			cards = append(cards, screenCard{Screen: sc, DisplayState: ds, OverrideOnUntil: overrideOnUntil})
+		}
+
+		var activeOverride *store.GlobalOverride
+		if o, err := overrides.Get(r.Context()); err == nil && o != nil && time.Now().Before(o.Until) {
+			activeOverride = o
+		}
+
 		renderTemplate(w, t, map[string]any{
 			"Cards":          cards,
 			"CSRFToken":      csrfToken,
+			"GlobalOverride": activeOverride,
 		})
 	}
 }

server/backend/internal/httpapi/router.go

@@ -22,6 +22,7 @@ type RouterDeps struct {
 	Notifier        *mqttnotifier.Notifier
 	ScreenshotStore *ScreenshotStore
 	ScheduleStore       *store.ScreenScheduleStore
+	GlobalOverrideStore *store.GlobalOverrideStore
 	Config              config.Config
 	UploadDir       string
 	Logger          *log.Logger
@@ -164,7 +165,7 @@ func registerManageRoutes(mux *http.ServeMux, d RouterDeps) {
 	// ── Playlist management UI ────────────────────────────────────────────
 	// authScreen enforces that screen_user only accesses their permitted screens.
 	mux.Handle("GET /manage",
-		authOnly(http.HandlerFunc(manage.HandleScreenOverview(d.ScreenStore, notifier, d.Config))))
+		authOnly(http.HandlerFunc(manage.HandleScreenOverview(d.ScreenStore, d.ScheduleStore, d.GlobalOverrideStore, notifier, d.Config))))
 	mux.Handle("GET /manage/{screenSlug}",
 		authScreen(http.HandlerFunc(manage.HandleManageUI(d.TenantStore, d.ScreenStore, d.ScheduleStore, d.MediaStore, d.PlaylistStore, d.Config, notifier))))
 	mux.Handle("POST /manage/{screenSlug}/upload",
@@ -192,6 +193,18 @@ func registerManageRoutes(mux *http.ServeMux, d RouterDeps) {
 	mux.Handle("POST /api/v1/screens/{screenSlug}/schedule",
 		authScreen(http.HandlerFunc(manage.HandleUpdateSchedule(d.ScreenStore, d.ScheduleStore))))
 
+	// ── Globaler Override ────────────────────────────────────────────────
+	mux.Handle("GET /api/v1/global-override",
+		authOnly(http.HandlerFunc(manage.HandleGetGlobalOverride(d.GlobalOverrideStore))))
+	mux.Handle("POST /api/v1/global-override",
+		authOnly(http.HandlerFunc(manage.HandleSetGlobalOverride(d.GlobalOverrideStore, d.ScreenStore, notifier))))
+	mux.Handle("DELETE /api/v1/global-override",
+		authOnly(http.HandlerFunc(manage.HandleDeleteGlobalOverride(d.GlobalOverrideStore))))
+
+	// ── Per-Screen Override ───────────────────────────────────────────────
+	mux.Handle("POST /api/v1/screens/{screenSlug}/override",
+		authScreen(http.HandlerFunc(manage.HandleSetScreenOverride(d.ScreenStore, d.ScheduleStore))))
+
 	// ── JSON API — screens ────────────────────────────────────────────────
 	// Self-registration: no auth (player calls this on startup).
 	mux.HandleFunc("POST /api/v1/screens/register",

server/backend/internal/scheduler/scheduler.go

@@ -25,15 +25,20 @@ type DisplayStateGetter interface {
 	GetDisplayState(ctx context.Context, screenID string) (string, error)
 }
 
+// AllScreensLister lädt alle bekannten Screens.
+type AllScreensLister interface {
+	ListAll(ctx context.Context) ([]*store.Screen, error)
+}
+
 // Run startet den Scheduler-Loop. Blockiert bis ctx abgebrochen wird.
-func Run(ctx context.Context, schedules *store.ScreenScheduleStore, screens ScreenSlugGetter, notifier DisplayCommander) {
+func Run(ctx context.Context, schedules *store.ScreenScheduleStore, screens ScreenSlugGetter, globalOverrides *store.GlobalOverrideStore, notifier DisplayCommander) {
 	ticker := time.NewTicker(1 * time.Minute)
 	defer ticker.Stop()
 
 	for {
 		select {
 		case <-ticker.C:
-			check(ctx, schedules, screens, notifier)
+			check(ctx, schedules, screens, globalOverrides, notifier)
 		case <-ctx.Done():
 			return
 		}
@@ -41,39 +46,50 @@ func Run(ctx context.Context, schedules *store.ScreenScheduleStore, screens Scre
 }
 
 // Reconcile läuft alle 5 Minuten und gleicht Ist- und Soll-Zustand ab.
-func Reconcile(ctx context.Context, schedules *store.ScreenScheduleStore, screens ScreenSlugGetter, states DisplayStateGetter, notifier DisplayCommander) {
+func Reconcile(ctx context.Context, schedules *store.ScreenScheduleStore, screens AllScreensLister, states DisplayStateGetter, globalOverrides *store.GlobalOverrideStore, notifier DisplayCommander) {
 	ticker := time.NewTicker(5 * time.Minute)
 	defer ticker.Stop()
 
 	for {
 		select {
 		case <-ticker.C:
-			reconcile(ctx, schedules, screens, states, notifier)
+			reconcile(ctx, schedules, screens, states, globalOverrides, notifier)
 		case <-ctx.Done():
 			return
 		}
 	}
 }
 
-func reconcile(ctx context.Context, schedules *store.ScreenScheduleStore, screens ScreenSlugGetter, states DisplayStateGetter, notifier DisplayCommander) {
+func reconcile(ctx context.Context, schedules *store.ScreenScheduleStore, allScreens AllScreensLister, states DisplayStateGetter, globalOverrides *store.GlobalOverrideStore, notifier DisplayCommander) {
-	now := time.Now().Format("15:04")
+	now := time.Now()
 
-	enabled, err := schedules.ListEnabled(ctx)
+	screenList, err := allScreens.ListAll(ctx)
 	if err != nil {
-		slog.Error("reconciler: list enabled schedules failed", "err", err)
+		slog.Error("reconciler: list all screens failed", "err", err)
 		return
 	}
 
-	for _, sc := range enabled {
+	globalOverride, err := globalOverrides.Get(ctx)
-		if sc.PowerOnTime == "" || sc.PowerOffTime == "" {
+	if err != nil {
+		slog.Warn("reconciler: get global override failed", "err", err)
+		// nicht fatal — ohne Override fortfahren
+	}
+
+	for _, screen := range screenList {
+		sc, err := schedules.Get(ctx, screen.ID)
+		if err != nil {
+			slog.Warn("reconciler: get schedule failed", "screen_id", screen.ID, "err", err)
 			continue
 		}
 
-		want := desiredState(sc.PowerOnTime, sc.PowerOffTime, now)
+		want, shouldControl := resolveDesiredState(*sc, globalOverride, now)
+		if !shouldControl {
+			continue
+		}
 
-		got, err := states.GetDisplayState(ctx, sc.ScreenID)
+		got, err := states.GetDisplayState(ctx, screen.ID)
 		if err != nil {
-			slog.Warn("reconciler: get display state failed", "screen_id", sc.ScreenID, "err", err)
+			slog.Warn("reconciler: get display state failed", "screen_id", screen.ID, "err", err)
 			continue
 		}
 
@@ -81,17 +97,11 @@ func reconcile(ctx context.Context, schedules *store.ScreenScheduleStore, screen
 			continue
 		}
 
-		screen, err := screens.GetByID(ctx, sc.ScreenID)
-		if err != nil {
-			slog.Warn("reconciler: screen not found", "screen_id", sc.ScreenID, "err", err)
-			continue
-		}
-
 		action := "display_" + want
 		if err := notifier.SendDisplayCommand(screen.Slug, action); err != nil {
-			slog.Error("reconciler: send command failed", "screen_id", sc.ScreenID, "action", action, "err", err)
+			slog.Error("reconciler: send command failed", "screen_id", screen.ID, "action", action, "err", err)
 		} else {
-			slog.Info("reconciler: corrected display state", "screen_id", sc.ScreenID, "slug", screen.Slug, "was", got, "want", want)
+			slog.Info("reconciler: corrected display state", "screen_id", screen.ID, "slug", screen.Slug, "was", got, "want", want)
 		}
 	}
 }
@@ -113,10 +123,49 @@ func desiredState(onTime, offTime, now string) string {
 	return "off"
 }
 
+// resolveDesiredState ermittelt den Soll-Zustand eines Screens unter Berücksichtigung
+// aller Prioritätsstufen:
+//  1. per-Screen override_on_until (höchste Priorität)
+//  2. globaler Override
+//  3. Wochenende (Sa/So)
+//  4. normaler Zeitplan
+//
+// Gibt ("", false) zurück wenn keine Automatisierung aktiv ist.
+func resolveDesiredState(sc store.ScreenSchedule, globalOverride *store.GlobalOverride, now time.Time) (desired string, shouldControl bool) {
+	// 1. Per-Screen-Override: überschreibt alles
+	if sc.OverrideOnUntil != nil && now.Before(*sc.OverrideOnUntil) {
+		return "on", true
+	}
+	// 2. Globaler Override
+	if globalOverride != nil && now.Before(globalOverride.Until) {
+		return globalOverride.Type, true
+	}
+	// 3. Wochenende: Zeitpläne werden ignoriert, Monitore bleiben aus
+	wd := now.Weekday()
+	if wd == time.Saturday || wd == time.Sunday {
+		return "off", true
+	}
+	// 4. Normaler Zeitplan
+	if !sc.ScheduleEnabled || (sc.PowerOnTime == "" && sc.PowerOffTime == "") {
+		return "", false
+	}
+	return desiredState(sc.PowerOnTime, sc.PowerOffTime, now.Format("15:04")), true
+}
+
 // check prüft alle aktiven Zeitpläne und sendet ggf. Befehle.
-func check(ctx context.Context, schedules *store.ScreenScheduleStore, screens ScreenSlugGetter, notifier DisplayCommander) {
+func check(ctx context.Context, schedules *store.ScreenScheduleStore, screens ScreenSlugGetter, globalOverrides *store.GlobalOverrideStore, notifier DisplayCommander) {
 	// Uses process-local timezone — ensure TZ env var is set in the container (e.g. Europe/Berlin).
-	now := time.Now().Format("15:04")
+	now := time.Now()
+	nowStr := now.Format("15:04")
+
+	// Wochenende: keine Einschalte-Kommandos senden
+	isWeekend := now.Weekday() == time.Saturday || now.Weekday() == time.Sunday
+
+	// Globaler Override "off" aktiv?
+	globalOverrideOff := false
+	if o, err := globalOverrides.Get(ctx); err == nil && o != nil && now.Before(o.Until) && o.Type == "off" {
+		globalOverrideOff = true
+	}
 
 	enabled, err := schedules.ListEnabled(ctx)
 	if err != nil {
@@ -132,9 +181,9 @@ func check(ctx context.Context, schedules *store.ScreenScheduleStore, screens Sc
 		}
 
 		var action string
-		if sc.PowerOnTime != "" && sc.PowerOnTime == now {
+		if sc.PowerOnTime != "" && sc.PowerOnTime == nowStr {
 			action = "display_on"
-		} else if sc.PowerOffTime != "" && sc.PowerOffTime == now {
+		} else if sc.PowerOffTime != "" && sc.PowerOffTime == nowStr {
 			action = "display_off"
 		}
 
@@ -142,6 +191,19 @@ func check(ctx context.Context, schedules *store.ScreenScheduleStore, screens Sc
 			continue
 		}
 
+		// display_on unterdrücken wenn per-Screen-Override, Wochenende oder globaler Override "off"
+		if action == "display_on" {
+			if sc.OverrideOnUntil != nil && now.Before(*sc.OverrideOnUntil) {
+				// per-Screen Override aktiv → Kommando trotzdem senden (Override = on)
+			} else if isWeekend {
+				slog.Info("scheduler: display_on unterdrückt (Wochenende)", "screen_id", sc.ScreenID)
+				continue
+			} else if globalOverrideOff {
+				slog.Info("scheduler: display_on unterdrückt (globaler Override off)", "screen_id", sc.ScreenID)
+				continue
+			}
+		}
+
 		if err := notifier.SendDisplayCommand(screen.Slug, action); err != nil {
 			slog.Error("scheduler: send command failed", "screen_id", sc.ScreenID, "action", action, "err", err)
 		} else {

server/backend/internal/scheduler/scheduler_test.go

@@ -0,0 +1,129 @@
+package scheduler
+
+import (
+	"testing"
+	"time"
+
+	"git.az-it.net/az/morz-infoboard/server/backend/internal/store"
+)
+
+func ptrTime(t time.Time) *time.Time { return &t }
+
+func TestResolveDesiredState(t *testing.T) {
+	// Donnerstag 10:00 UTC
+	thu := time.Date(2026, 3, 26, 10, 0, 0, 0, time.UTC)
+	// Samstag 10:00 UTC
+	sat := time.Date(2026, 3, 28, 10, 0, 0, 0, time.UTC)
+
+	tests := []struct {
+		name        string
+		sc          store.ScreenSchedule
+		override    *store.GlobalOverride
+		now         time.Time
+		wantDesired string
+		wantControl bool
+	}{
+		{
+			name:        "per-screen override aktiv → on",
+			sc:          store.ScreenSchedule{OverrideOnUntil: ptrTime(thu.Add(time.Hour))},
+			now:         thu,
+			wantDesired: "on", wantControl: true,
+		},
+		{
+			name: "per-screen override abgelaufen → fällt durch zu Zeitplan",
+			sc: store.ScreenSchedule{
+				ScheduleEnabled: true,
+				PowerOnTime:     "09:00", PowerOffTime: "17:00",
+				OverrideOnUntil: ptrTime(thu.Add(-time.Hour)), // abgelaufen
+			},
+			now:         thu,
+			wantDesired: "on", wantControl: true, // Zeitplan: 09:00–17:00, jetzt 10:00
+		},
+		{
+			name: "per-screen override schlägt globalen Override off",
+			sc:   store.ScreenSchedule{OverrideOnUntil: ptrTime(thu.Add(time.Hour))},
+			override: &store.GlobalOverride{
+				Type:  "off",
+				Until: thu.Add(time.Hour),
+			},
+			now:         thu,
+			wantDesired: "on", wantControl: true,
+		},
+		{
+			name: "globaler Override off aktiv → off",
+			sc:   store.ScreenSchedule{ScheduleEnabled: true, PowerOnTime: "09:00", PowerOffTime: "17:00"},
+			override: &store.GlobalOverride{
+				Type:  "off",
+				Until: thu.Add(time.Hour),
+			},
+			now:         thu,
+			wantDesired: "off", wantControl: true,
+		},
+		{
+			name: "globaler Override on aktiv → on",
+			sc:   store.ScreenSchedule{},
+			override: &store.GlobalOverride{
+				Type:  "on",
+				Until: thu.Add(time.Hour),
+			},
+			now:         thu,
+			wantDesired: "on", wantControl: true,
+		},
+		{
+			name: "globaler Override abgelaufen → fällt durch",
+			sc:   store.ScreenSchedule{ScheduleEnabled: true, PowerOnTime: "09:00", PowerOffTime: "17:00"},
+			override: &store.GlobalOverride{
+				Type:  "off",
+				Until: thu.Add(-time.Hour), // abgelaufen
+			},
+			now:         thu,
+			wantDesired: "on", wantControl: true,
+		},
+		{
+			name:        "Wochenende → off",
+			sc:          store.ScreenSchedule{ScheduleEnabled: true, PowerOnTime: "09:00", PowerOffTime: "17:00"},
+			now:         sat,
+			wantDesired: "off", wantControl: true,
+		},
+		{
+			name:        "Wochenende + per-screen override → on",
+			sc:          store.ScreenSchedule{OverrideOnUntil: ptrTime(sat.Add(time.Hour))},
+			now:         sat,
+			wantDesired: "on", wantControl: true,
+		},
+		{
+			name:        "normaler Zeitplan: innerhalb → on",
+			sc:          store.ScreenSchedule{ScheduleEnabled: true, PowerOnTime: "09:00", PowerOffTime: "17:00"},
+			now:         thu, // 10:00
+			wantDesired: "on", wantControl: true,
+		},
+		{
+			name:        "normaler Zeitplan: außerhalb → off",
+			sc:          store.ScreenSchedule{ScheduleEnabled: true, PowerOnTime: "09:00", PowerOffTime: "17:00"},
+			now:         time.Date(2026, 3, 26, 8, 0, 0, 0, time.UTC), // 08:00
+			wantDesired: "off", wantControl: true,
+		},
+		{
+			name:        "kein Zeitplan, kein Override → keine Steuerung",
+			sc:          store.ScreenSchedule{},
+			now:         thu,
+			wantDesired: "", wantControl: false,
+		},
+		{
+			name:        "Zeitplan deaktiviert → keine Steuerung",
+			sc:          store.ScreenSchedule{ScheduleEnabled: false, PowerOnTime: "09:00", PowerOffTime: "17:00"},
+			now:         thu,
+			wantDesired: "", wantControl: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			gotDesired, gotControl := resolveDesiredState(tt.sc, tt.override, tt.now)
+			if gotDesired != tt.wantDesired || gotControl != tt.wantControl {
+				t.Errorf("resolveDesiredState() = (%q, %v), want (%q, %v)",
+					gotDesired, gotControl, tt.wantDesired, tt.wantControl)
+			}
+		})
+	}
+}

server/backend/internal/store/store.go

@@ -46,6 +46,7 @@ type ScreenSchedule struct {
 	ScheduleEnabled bool       `json:"schedule_enabled"`
 	PowerOnTime     string     `json:"power_on_time"`
 	PowerOffTime    string     `json:"power_off_time"`
+	OverrideOnUntil *time.Time `json:"override_on_until,omitempty"`
 }
 
 type MediaAsset struct {
@@ -653,9 +654,9 @@ func scanPlaylistItem(row interface {
 func (s *ScreenScheduleStore) Get(ctx context.Context, screenID string) (*ScreenSchedule, error) {
 	var sc ScreenSchedule
 	err := s.pool.QueryRow(ctx,
-		`select screen_id, schedule_enabled, power_on_time, power_off_time
+		`select screen_id, schedule_enabled, power_on_time, power_off_time, override_on_until
 		   from screen_schedules where screen_id = $1`, screenID).
-		Scan(&sc.ScreenID, &sc.ScheduleEnabled, &sc.PowerOnTime, &sc.PowerOffTime)
+		Scan(&sc.ScreenID, &sc.ScheduleEnabled, &sc.PowerOnTime, &sc.PowerOffTime, &sc.OverrideOnUntil)
 	if errors.Is(err, pgx.ErrNoRows) {
 		return &ScreenSchedule{ScreenID: screenID}, nil
 	}
@@ -666,6 +667,8 @@ func (s *ScreenScheduleStore) Get(ctx context.Context, screenID string) (*Screen
 }
 
 // Upsert speichert oder aktualisiert den Zeitplan eines Screens.
+// Hinweis: override_on_until wird hier bewusst nicht angefasst – das ist
+// ausschließlich Aufgabe von SetOverrideOnUntil (saubere Trennung, kein Datenverlust).
 func (s *ScreenScheduleStore) Upsert(ctx context.Context, sc *ScreenSchedule) error {
 	_, err := s.pool.Exec(ctx,
 		`insert into screen_schedules (screen_id, schedule_enabled, power_on_time, power_off_time)
@@ -681,7 +684,7 @@ func (s *ScreenScheduleStore) Upsert(ctx context.Context, sc *ScreenSchedule) er
 // ListEnabled gibt alle Screens mit aktivem Zeitplan zurück.
 func (s *ScreenScheduleStore) ListEnabled(ctx context.Context) ([]*ScreenSchedule, error) {
 	rows, err := s.pool.Query(ctx,
-		`select screen_id, schedule_enabled, power_on_time, power_off_time
+		`select screen_id, schedule_enabled, power_on_time, power_off_time, override_on_until
 		   from screen_schedules
 		  where schedule_enabled = true
 		    and (power_on_time != '' or power_off_time != '')`)
@@ -692,10 +695,73 @@ func (s *ScreenScheduleStore) ListEnabled(ctx context.Context) ([]*ScreenSchedul
 	var out []*ScreenSchedule
 	for rows.Next() {
 		var sc ScreenSchedule
-		if err := rows.Scan(&sc.ScreenID, &sc.ScheduleEnabled, &sc.PowerOnTime, &sc.PowerOffTime); err != nil {
+		if err := rows.Scan(&sc.ScreenID, &sc.ScheduleEnabled, &sc.PowerOnTime, &sc.PowerOffTime, &sc.OverrideOnUntil); err != nil {
 			return nil, err
 		}
 		out = append(out, &sc)
 	}
 	return out, rows.Err()
 }
+
+// SetOverrideOnUntil setzt oder löscht den per-Screen-Override (null = löschen).
+func (s *ScreenScheduleStore) SetOverrideOnUntil(ctx context.Context, screenID string, until *time.Time) error {
+	_, err := s.pool.Exec(ctx,
+		`insert into screen_schedules (screen_id, override_on_until)
+		 values ($1, $2)
+		 on conflict (screen_id) do update
+		   set override_on_until = excluded.override_on_until`,
+		screenID, until)
+	return err
+}
+
+// ------------------------------------------------------------------
+// GlobalOverrideStore
+// ------------------------------------------------------------------
+
+// GlobalOverride beschreibt einen aktiven globalen Display-Override.
+type GlobalOverride struct {
+	Type  string    `json:"type"`   // "on" oder "off"
+	Until time.Time `json:"until"`
+	SetAt time.Time `json:"set_at"`
+}
+
+// GlobalOverrideStore verwaltet den globalen Display-Override (max. 1 Zeile).
+type GlobalOverrideStore struct{ pool *pgxpool.Pool }
+
+func NewGlobalOverrideStore(pool *pgxpool.Pool) *GlobalOverrideStore {
+	return &GlobalOverrideStore{pool: pool}
+}
+
+// Get lädt den aktuellen globalen Override. Gibt nil zurück wenn keiner gesetzt ist.
+func (s *GlobalOverrideStore) Get(ctx context.Context) (*GlobalOverride, error) {
+	var o GlobalOverride
+	err := s.pool.QueryRow(ctx,
+		`select type, until, set_at from global_override where id = 1`).
+		Scan(&o.Type, &o.Until, &o.SetAt)
+	if errors.Is(err, pgx.ErrNoRows) {
+		return nil, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	return &o, nil
+}
+
+// Upsert setzt oder überschreibt den globalen Override.
+func (s *GlobalOverrideStore) Upsert(ctx context.Context, overrideType string, until time.Time) error {
+	_, err := s.pool.Exec(ctx,
+		`insert into global_override (id, type, until, set_at)
+		 values (1, $1, $2, now())
+		 on conflict (id) do update
+		   set type   = excluded.type,
+		       until  = excluded.until,
+		       set_at = excluded.set_at`,
+		overrideType, until)
+	return err
+}
+
+// Delete entfernt den globalen Override.
+func (s *GlobalOverrideStore) Delete(ctx context.Context) error {
+	_, err := s.pool.Exec(ctx, `delete from global_override where id = 1`)
+	return err
+}