feat: group-based day management in schedule editor

- Auto-detect class groups (same trainer + type + time across days)
- Edit modal shows all group days pre-selected (e.g., ВТ/ПТ both lit)
- Toggle days to add/remove class from specific days
- Delete removes class from all days in the group
- New class modal lets you pick multiple days at once
- Visual hints: green +day / red −day for pending changes

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/app/admin/schedule/page.tsx

@@ -238,6 +238,11 @@ function ClassBlock({
 }
 
 // ---------- Edit Modal ----------
+/** Check if two classes are the same "group" (same trainer + type + time) */
+function isSameGroup(a: ScheduleClass, b: ScheduleClass): boolean {
+  return a.trainer === b.trainer && a.type === b.type && a.time === b.time;
+}
+
 function ClassModal({
   cls,
   trainers,
@@ -245,17 +250,56 @@ function ClassModal({
   onSave,
   onDelete,
   onClose,
+  allDays,
+  currentDay,
 }: {
   cls: ScheduleClass;
   trainers: string[];
   classTypes: string[];
-  onSave: (cls: ScheduleClass) => void;
+  /** For edit: saves to current day + manages group days. For new: creates on selected days. */
+  onSave: (cls: ScheduleClass, days: string[]) => void;
   onDelete?: () => void;
   onClose: () => void;
+  /** All schedule days (sorted) */
+  allDays: ScheduleDay[];
+  /** Current day name */
+  currentDay: string;
 }) {
   const [draft, setDraft] = useState<ScheduleClass>(cls);
   const trainerOptions = trainers.map((t) => ({ value: t, label: t }));
   const typeOptions = classTypes.map((t) => ({ value: t, label: t }));
+  const isNew = !onDelete;
+
+  // Find which days already have this exact group (for edit mode)
+  const groupDays = useMemo(() => {
+    if (isNew) return new Set<string>();
+    const days = new Set<string>();
+    for (const day of allDays) {
+      if (day.classes.some((c) => isSameGroup(c, cls))) {
+        days.add(day.day);
+      }
+    }
+    return days;
+  }, [allDays, cls, isNew]);
+
+  const [selectedDays, setSelectedDays] = useState<Set<string>>(
+    () => isNew ? new Set([currentDay]) : new Set(groupDays)
+  );
+
+  function toggleDay(day: string) {
+    setSelectedDays((prev) => {
+      const next = new Set(prev);
+      // Must have at least one day selected
+      if (next.has(day) && next.size <= 1) return next;
+      if (next.has(day)) next.delete(day);
+      else next.add(day);
+      return next;
+    });
+  }
+
+  // Compute what changed for the hint
+  const addedDays = [...selectedDays].filter((d) => !groupDays.has(d));
+  const removedDays = [...groupDays].filter((d) => !selectedDays.has(d));
 
   return (
     <div className="fixed inset-0 z-50 flex items-center justify-center bg-black/60" onClick={onClose}>
@@ -265,7 +309,7 @@ function ClassModal({
       >
         <div className="flex items-center justify-between mb-4">
           <h3 className="text-lg font-bold text-white">
-            {onDelete ? "Редактировать занятие" : "Новое занятие"}
+            {isNew ? "Новое занятие" : "Редактировать занятие"}
           </h3>
           <button type="button" onClick={onClose} className="text-neutral-400 hover:text-white">
             <X size={20} />
@@ -273,6 +317,46 @@ function ClassModal({
         </div>
 
         <div className="space-y-4">
+          {/* Day selector — always visible */}
+          {allDays.length > 1 && (
+            <div>
+              <label className="block text-sm text-neutral-400 mb-2">Дни</label>
+              <div className="flex flex-wrap gap-1.5">
+                {allDays.map((d) => {
+                  const active = selectedDays.has(d.day);
+                  return (
+                    <button
+                      key={d.day}
+                      type="button"
+                      onClick={() => toggleDay(d.day)}
+                      className={`rounded-lg px-3 py-1.5 text-xs font-medium transition-all ${
+                        active
+                          ? "bg-gold/20 text-gold border border-gold/40"
+                          : "border border-white/10 text-neutral-500 hover:text-white hover:border-white/20"
+                      }`}
+                    >
+                      {d.dayShort}
+                    </button>
+                  );
+                })}
+              </div>
+              {!isNew && (addedDays.length > 0 || removedDays.length > 0) && (
+                <div className="mt-1.5 flex flex-wrap gap-x-3 text-[11px]">
+                  {addedDays.length > 0 && (
+                    <span className="text-emerald-400">
+                      + {addedDays.map((d) => allDays.find((ad) => ad.day === d)?.dayShort).join(", ")}
+                    </span>
+                  )}
+                  {removedDays.length > 0 && (
+                    <span className="text-red-400">
+                      − {removedDays.map((d) => allDays.find((ad) => ad.day === d)?.dayShort).join(", ")}
+                    </span>
+                  )}
+                </div>
+              )}
+            </div>
+          )}
+
           <TimeRangeField
             label="Время"
             value={draft.time}
@@ -316,7 +400,7 @@ function ClassModal({
           <button
             type="button"
             onClick={() => {
-              onSave(draft);
+              onSave(draft, [...selectedDays]);
               onClose();
             }}
             className="flex-1 rounded-lg bg-gold px-4 py-2.5 text-sm font-medium text-black hover:opacity-90 transition-opacity"
@@ -829,16 +913,32 @@ function CalendarGrid({
           cls={editingData.cls}
           trainers={trainers}
           classTypes={classTypes}
-          onSave={(updated) => {
+          allDays={sortedDays}
-            const day = sortedDays[editingClass.dayIndex];
+          currentDay={sortedDays[editingClass.dayIndex]?.day}
-            const classes = [...day.classes];
+          onSave={(updated, days) => {
-            classes[editingClass.classIndex] = updated;
+            const original = editingData.cls;
-            updateDay(editingClass.dayIndex, { ...day, classes });
+            const selectedSet = new Set(days);
+
+            const updatedDays = location.days.map((d) => {
+              const inSelected = selectedSet.has(d.day);
+              // Remove old matching group entries
+              let classes = d.classes.filter((c) => !isSameGroup(c, original));
+              // Add updated class to selected days
+              if (inSelected) {
+                classes = [...classes, updated];
+              }
+              return { ...d, classes };
+            });
+            onChange({ ...location, days: updatedDays });
           }}
           onDelete={() => {
-            const day = sortedDays[editingClass.dayIndex];
+            // Delete from ALL days that have this group
-            const classes = day.classes.filter((_, i) => i !== editingClass.classIndex);
+            const original = editingData.cls;
-            updateDay(editingClass.dayIndex, { ...day, classes });
+            const updatedDays = location.days.map((d) => ({
+              ...d,
+              classes: d.classes.filter((c) => !isSameGroup(c, original)),
+            }));
+            onChange({ ...location, days: updatedDays });
           }}
           onClose={() => setEditingClass(null)}
         />
@@ -850,10 +950,17 @@ function CalendarGrid({
           cls={newClass.cls}
           trainers={trainers}
           classTypes={classTypes}
-          onSave={(created) => {
+          allDays={sortedDays}
-            const day = sortedDays[newClass.dayIndex];
+          currentDay={sortedDays[newClass.dayIndex]?.day}
-            const classes = [...day.classes, created];
+          onSave={(created, days) => {
-            updateDay(newClass.dayIndex, { ...day, classes });
+            const targetDayNames = new Set(days);
+            const updatedDays = location.days.map((d) => {
+              if (targetDayNames.has(d.day)) {
+                return { ...d, classes: [...d.classes, created] };
+              }
+              return d;
+            });
+            onChange({ ...location, days: updatedDays });
           }}
           onClose={() => setNewClass(null)}
         />