Aufgabe: Ab-wann + Bis-wann mit gutem Picker; neue Klasse nur Weltkueche frei

- Modal: "Ab wann" (Sofort/Zeitpunkt) + "Bis wann" (Presets + date/time statt
  datetime-local), Live-Zusammenfassung; zukuenftiger Start => vorbereitet
- assignments.php: startsAt-Param (Default NOW()), T->Space
- modules.php: neue Klasse ohne Eintrag -> nur Weltkueche frei (_defaultMode),
  Rest gesperrt; Freigabe-Matrix bleibt (getrennt von der Aufgabe)
- schueler.html: Hinweis "Deine Lehrperson kann weitere Simulationen freischalten"

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

App/teacher.html

@@ -386,14 +386,26 @@ schueler01,Max M.,,,,,</pre>
       <option value="2">Stufe 2 — Fortgeschritten</option>
       <option value="3">Stufe 3 — Profi</option>
     </select>
-    <label>Fällig bis</label>
-    <div style="display:flex;gap:.3rem;flex-wrap:wrap;margin-bottom:.35rem">
+    <label>Ab wann?</label>
+    <div style="display:flex;gap:.3rem;margin-bottom:.4rem">
+      <button type="button" id="ss-start-now" class="btn" style="font-size:.7rem;padding:.3rem .7rem" onclick="ssStartMode('now')">▶ Sofort</button>
+      <button type="button" id="ss-start-at" class="btn btn-outline" style="font-size:.7rem;padding:.3rem .7rem" onclick="ssStartMode('at')">🕒 Zeitpunkt wählen</button>
+    </div>
+    <div id="ss-start-fields" style="display:none;gap:.4rem;margin-bottom:.5rem">
+      <input type="date" id="ss-start-date" onchange="ssUpdateSummary()" style="padding:.35rem .5rem;border:1.5px solid rgba(0,0,0,.12);border-radius:6px;font-size:.78rem;font-family:inherit">
+      <input type="time" id="ss-start-time" value="08:00" onchange="ssUpdateSummary()" style="padding:.35rem .5rem;border:1.5px solid rgba(0,0,0,.12);border-radius:6px;font-size:.78rem;font-family:inherit">
+    </div>
+    <label>Bis wann (Frist)</label>
+    <div style="display:flex;gap:.3rem;flex-wrap:wrap;margin-bottom:.4rem">
       <button type="button" class="btn btn-outline" style="font-size:.66rem;padding:.25rem .55rem" onclick="ssSetDue('heute')">Heute 13:00</button>
       <button type="button" class="btn btn-outline" style="font-size:.66rem;padding:.25rem .55rem" onclick="ssSetDue('morgen')">Morgen</button>
       <button type="button" class="btn btn-outline" style="font-size:.66rem;padding:.25rem .55rem" onclick="ssSetDue('woche')">+1 Woche</button>
       <button type="button" class="btn btn-outline" style="font-size:.66rem;padding:.25rem .55rem" onclick="ssSetDue('')">Kein Limit</button>
     </div>
-    <input type="datetime-local" id="ss-ends" onchange="ssUpdateSummary()">
+    <div style="display:flex;gap:.4rem;align-items:center">
+      <input type="date" id="ss-end-date" onchange="ssUpdateSummary()" style="padding:.35rem .5rem;border:1.5px solid rgba(0,0,0,.12);border-radius:6px;font-size:.78rem;font-family:inherit">
+      <input type="time" id="ss-end-time" value="13:00" onchange="ssUpdateSummary()" style="padding:.35rem .5rem;border:1.5px solid rgba(0,0,0,.12);border-radius:6px;font-size:.78rem;font-family:inherit">
+    </div>
     <label style="display:flex;align-items:flex-start;gap:.4rem;margin-top:.6rem;cursor:pointer">
       <input type="checkbox" id="ss-paused" onchange="ssUpdateSummary()" style="margin-top:.15rem"> <span style="font-size:.74rem">⏸ Vorbereiten — die Klasse startet erst, wenn du auf der Aufgaben-Card „▶ Start freigeben" drückst (gemeinsamer Start)</span>
     </label>
@@ -2895,7 +2907,9 @@ async function loadModuleMatrix() {
       var thumb = img
         ? '<img src="'+img+'" alt="" style="width:50px;height:50px;border-radius:9px;object-fit:cover;flex:none">'
         : '<span style="font-size:1.6rem;width:50px;text-align:center">'+(mod?mod.icon:'📋')+'</span>';
-      var end = a.ends_at ? 'fällig ' + new Date(a.ends_at).toLocaleDateString('de-AT',{weekday:'short',day:'2-digit',month:'2-digit',hour:'2-digit',minute:'2-digit'}) : 'ohne Zeitlimit';
+      var end = a.ends_at ? 'fällig ' + new Date(a.ends_at.replace(' ','T')).toLocaleDateString('de-AT',{weekday:'short',day:'2-digit',month:'2-digit',hour:'2-digit',minute:'2-digit'}) : 'ohne Zeitlimit';
+      var startMs = a.starts_at ? new Date(a.starts_at.replace(' ','T')).getTime() : 0;
+      if (startMs && startMs > Date.now()) end = 'ab ' + new Date(startMs).toLocaleDateString('de-AT',{weekday:'short',day:'2-digit',month:'2-digit',hour:'2-digit',minute:'2-digit'}) + ' · ' + end;
       var stateBadge = paused
         ? '<span style="background:#fdf1e6;color:#c25e1e;border:1px solid #e8c3a0;padding:.08rem .5rem;border-radius:99px;font-size:.62rem;font-weight:700">⏸ Vorbereitet</span>'
         : '<span style="background:#e5f2e7;color:#2a7a3a;border:1px solid #b9dcc0;padding:.08rem .5rem;border-radius:99px;font-size:.62rem;font-weight:700">▶ Läuft</span>';
@@ -3041,6 +3055,7 @@ async function loadAllMods() {
   if (Array.isArray(r)) ALL_MODS = r.filter(function(m){return m.status!=='archiv' && m.status!=='geplant';});
   return ALL_MODS;
 }
+var _ssStartMode = 'now';
 async function showStartSim(preselectedModuleId) {
   await loadAllMods();
   var sel = document.getElementById('ss-module');
@@ -3049,44 +3064,72 @@ async function showStartSim(preselectedModuleId) {
   if (preselectedModuleId) sel.value = preselectedModuleId;
   document.getElementById('ss-paused').checked = false;
   document.getElementById('ss-level').value = '1';
-  ssSetDue('woche');   // Default-Frist: +1 Woche (Hausübung); setzt Feld + Bestätigung
+  var now = new Date();
+  document.getElementById('ss-start-date').value = _ssDate(now);
+  document.getElementById('ss-start-time').value = '08:00';
+  ssStartMode('now');
+  ssSetDue('woche');   // Default-Frist: +1 Woche
   showModal('modal-startsim');
 }
 function _ssPad(n){ return String(n).padStart(2,'0'); }
-function _ssDtLocal(d){ return d.getFullYear()+'-'+_ssPad(d.getMonth()+1)+'-'+_ssPad(d.getDate())+'T'+_ssPad(d.getHours())+':'+_ssPad(d.getMinutes()); }
+function _ssDate(d){ return d.getFullYear()+'-'+_ssPad(d.getMonth()+1)+'-'+_ssPad(d.getDate()); }
+function ssStartMode(mode){
+  _ssStartMode = mode;
+  var now = document.getElementById('ss-start-now'), at = document.getElementById('ss-start-at');
+  var fields = document.getElementById('ss-start-fields');
+  now.className = mode==='now' ? 'btn' : 'btn btn-outline';
+  at.className  = mode==='at'  ? 'btn' : 'btn btn-outline';
+  fields.style.display = mode==='at' ? 'flex' : 'none';
+  ssUpdateSummary();
+}
 function ssSetDue(kind){
-  var el = document.getElementById('ss-ends');
-  if (kind === '') { el.value = ''; ssUpdateSummary(); return; }
+  var dd = document.getElementById('ss-end-date'), tt = document.getElementById('ss-end-time');
+  if (kind === '') { dd.value = ''; ssUpdateSummary(); return; }
   var d = new Date();
   if (kind === 'morgen') d.setDate(d.getDate()+1);
   else if (kind === 'woche') d.setDate(d.getDate()+7);
-  d.setHours(13, 0, 0, 0);
-  el.value = _ssDtLocal(d);
+  dd.value = _ssDate(d);
+  tt.value = '13:00';
   ssUpdateSummary();
 }
+// Kombiniert date+time zu 'YYYY-MM-DDTHH:MM' (oder null, wenn kein Datum)
+function _ssCombine(dateId, timeId){
+  var d = document.getElementById(dateId).value;
+  if (!d) return null;
+  var t = document.getElementById(timeId).value || '00:00';
+  return d + 'T' + t;
+}
+function ssStartValue(){ return _ssStartMode === 'now' ? null : _ssCombine('ss-start-date','ss-start-time'); }
+function ssEndValue(){ return _ssCombine('ss-end-date','ss-end-time'); }
+function _ssFmt(v){ return new Date(v).toLocaleDateString('de-AT',{weekday:'short',day:'2-digit',month:'2-digit',hour:'2-digit',minute:'2-digit'}); }
 function ssUpdateSummary(){
   var el = document.getElementById('ss-summary'); if (!el) return;
   var modSel = document.getElementById('ss-module');
   var modTxt = (modSel && modSel.options[modSel.selectedIndex]) ? modSel.options[modSel.selectedIndex].text : '—';
   var lvl = document.getElementById('ss-level').value;
-  var ends = document.getElementById('ss-ends').value;
-  var paused = document.getElementById('ss-paused').checked;
-  var endTxt = ends ? new Date(ends).toLocaleDateString('de-AT',{weekday:'short',day:'2-digit',month:'2-digit',hour:'2-digit',minute:'2-digit'}) : 'ohne Zeitlimit';
-  var startTxt = paused ? '⏸ startet auf dein Signal' : '▶ startet sofort';
-  el.innerHTML = '<b>'+esc(modTxt)+'</b> · Stufe '+lvl+' · fällig <b>'+esc(endTxt)+'</b> · '+startTxt;
+  var startsAt = ssStartValue();
+  var endsAt   = ssEndValue();
+  var paused   = document.getElementById('ss-paused').checked;
+  var future   = startsAt && new Date(startsAt) > new Date();
+  var startTxt = startsAt ? ('ab <b>'+esc(_ssFmt(startsAt))+'</b>') : (paused ? '⏸ auf dein Signal' : '▶ sofort');
+  var endTxt   = endsAt ? ('fällig <b>'+esc(_ssFmt(endsAt))+'</b>') : 'ohne Frist';
+  var note = (paused || future) ? ' <span style="color:#c25e1e">· Klasse wartet auf „Start freigeben"</span>' : '';
+  el.innerHTML = '<b>'+esc(modTxt)+'</b> · Stufe '+lvl+' · '+startTxt+' · '+endTxt+note;
 }
 async function startSimulation() {
   var moduleId = document.getElementById('ss-module').value;
   var level    = parseInt(document.getElementById('ss-level').value);
-  var endsAt   = document.getElementById('ss-ends').value || null;
-  var paused   = document.getElementById('ss-paused').checked;
+  var startsAt = ssStartValue();
+  var endsAt   = ssEndValue();
+  var future   = startsAt && new Date(startsAt) > new Date();
+  // Zukünftiger Start ⇒ automatisch „vorbereitet" (Klasse wartet), sonst Checkbox.
+  var paused   = document.getElementById('ss-paused').checked || !!future;
 
   // Sowohl class_modules (Modus + Level + Pause) als auch class_assignments
-  // (Auftragshistorie) setzen, damit Schüler-Cockpit + saves.php-Filter +
-  // Live-View den gleichen Auftragszustand sehen.
+  // (Auftragshistorie inkl. Zeitfenster) setzen.
   var rm = await api('modules', {action:'set_mode', classId:currentClassId, moduleId:moduleId, mode:'teacher_started', currentLevel:level, dueDate:endsAt, paused:paused});
   if (rm && rm.error) { alert(rm.error); return; }
-  var r = await api('assignments', {action:'create', classId:currentClassId, moduleId:moduleId, level:level, endsAt:endsAt});
+  var r = await api('assignments', {action:'create', classId:currentClassId, moduleId:moduleId, level:level, startsAt:startsAt, endsAt:endsAt});
   if (r.error) { alert(r.error); return; }
   hideModal('modal-startsim');
   loadModuleMatrix();