优化考试排考

src/Jiaowu.Api/Infrastructure/Exams/ExamArrangementService.cs

@@ -7,8 +7,27 @@ namespace Jiaowu.Api.Infrastructure.Exams;
 
 public sealed class ExamArrangementService(AppDbContext db)
 {
-    private sealed record RoomOccupancy(Guid ClassroomId, DateTime StartsAt, DateTime EndsAt);
-    private sealed record InvigilatorOccupancy(Guid TeacherId, DateTime StartsAt, DateTime EndsAt);
+    private sealed record RoomGroupKey(
+        Guid CourseId,
+        DateOnly ExamDate,
+        int StartPeriod,
+        int PeriodCount,
+        Guid? RequiredBuildingId);
+
+    private sealed record RoomOccupancy(
+        Guid ClassroomId,
+        DateTime StartsAt,
+        DateTime EndsAt);
+
+    private sealed record InvigilatorOccupancy(
+        Guid TeacherId,
+        DateTime StartsAt,
+        DateTime EndsAt);
+
+    private sealed record CandidateSeat(
+        Guid ExamSessionId,
+        Guid StudentId,
+        string StudentNumber);
 
     public async Task<ExamArrangementResult> ArrangeAsync(
         Guid planId,
@@ -30,6 +49,12 @@ public sealed class ExamArrangementService(AppDbContext db)
             .Include(x => x.Sessions)
                 .ThenInclude(x => x.TeachingTask)
                     .ThenInclude(x => x!.Course)
+            .Include(x => x.Rooms)
+                .ThenInclude(x => x.SessionLinks)
+            .Include(x => x.Rooms)
+                .ThenInclude(x => x.Seats)
+            .Include(x => x.Rooms)
+                .ThenInclude(x => x.Invigilators)
             .FirstOrDefaultAsync(x => x.Id == planId, cancellationToken);
 
         if (plan is null)
@@ -46,206 +71,524 @@ public sealed class ExamArrangementService(AppDbContext db)
             plan.Sessions.Count(x => requestedIds.Contains(x.Id)) != requestedIds.Count)
             return ExamArrangementResult.Fail("所选场次不存在或不属于当前考试计划。");
 
-        var sessions = plan.Sessions
-            .Where(x => requestedIds.Count == 0 || requestedIds.Contains(x.Id))
-            .OrderBy(x => x.ExamDate)
-            .ThenBy(x => x.StartPeriod)
-            .ThenByDescending(x => x.RequiredInvigilatorCount)
-            .ToList();
-        if (sessions.Count == 0)
-            return ExamArrangementResult.Fail("没有可处理的考试场次。");
-
-        var termId = plan.AcademicTermId;
         var timeSlots = await db.ScheduleTimeSlots.AsNoTracking()
-            .Where(x => x.AcademicTermId == termId && x.IsEnabled)
+            .Where(x => x.AcademicTermId == plan.AcademicTermId && x.IsEnabled)
             .OrderBy(x => x.PeriodNumber)
             .ToListAsync(cancellationToken);
-
         if (timeSlots.Count == 0)
             return ExamArrangementResult.Fail("当前学期未配置上课时间表，无法计算考试时间段。");
 
         var timeSlotLookup = timeSlots.ToDictionary(x => x.PeriodNumber);
-        var rosterCounts = (await TeachingTaskRosterQuery.LoadForTasksAsync(
-                db,
-                sessions.Select(x => x.TeachingTaskId),
-                cancellationToken))
-            .GroupBy(x => x.TeachingTaskId)
-            .ToDictionary(x => x.Key, x => x.Count());
-
-        int assignedRooms = 0;
-        int assignedInvigilators = 0;
-        int unavailableRooms = 0;
-        int unavailableInvigilators = 0;
-        var messages = new List<string>();
-
-        // Track occupied time slots to avoid conflicts
-        var occupiedRooms = sessions
-            .Where(x => x.ClassroomId.HasValue)
-            .Select(x => new RoomOccupancy(x.ClassroomId!.Value, x.StartsAt, x.EndsAt))
-            .ToList();
-
-        var occupiedInvigilators = sessions
-            .SelectMany(x => x.Invigilators.Select(i =>
-                new InvigilatorOccupancy(i.TeacherId, x.StartsAt, x.EndsAt)))
-            .ToList();
-
-        foreach (var session in sessions)
-        {
-            // Compute StartsAt/EndsAt from time slots
+        foreach (var session in plan.Sessions)
             ComputeTimesFromSlots(session, timeSlotLookup);
-            var studentCount = rosterCounts.GetValueOrDefault(session.TeachingTaskId);
 
-            // ── Auto-assign classroom ──
-            if (assignClassrooms && !session.ClassroomId.HasValue)
+        var explicitlySelected = plan.Sessions
+            .Where(x => requestedIds.Count == 0 || requestedIds.Contains(x.Id))
+            .ToList();
+        if (explicitlySelected.Count == 0)
+            return ExamArrangementResult.Fail("没有可处理的考试场次。");
+
+        var selectedKeys = explicitlySelected
+            .Select(GroupKey)
+            .ToHashSet();
+        var sessions = plan.Sessions
+            .Where(x => selectedKeys.Contains(GroupKey(x)))
+            .OrderBy(x => x.ExamDate)
+            .ThenBy(x => x.StartPeriod)
+            .ThenBy(x => x.TeachingTask!.Course!.Code)
+            .ThenBy(x => x.TeachingTask!.TaskNumber)
+            .ToList();
+        var sessionIds = sessions.Select(x => x.Id).ToHashSet();
+
+        var roster = await TeachingTaskRosterQuery.LoadForTasksAsync(
+            db,
+            sessions.Select(x => x.TeachingTaskId),
+            cancellationToken);
+        var sessionByTaskId = sessions
+            .GroupBy(x => x.TeachingTaskId)
+            .ToDictionary(x => x.Key, x => x.First());
+
+        var replacedRooms = assignClassrooms
+            ? plan.Rooms
+                .Where(room => room.SessionLinks.Any(link =>
+                    sessionIds.Contains(link.ExamSessionId)))
+                .ToList()
+            : [];
+        var replacedRoomIds = replacedRooms.Select(x => x.Id).ToHashSet();
+        if (replacedRooms.Count > 0)
+            db.ExamRooms.RemoveRange(replacedRooms);
+
+        var occupiedRooms = await LoadOccupiedRoomsAsync(
+            plan,
+            sessionIds,
+            replacedRoomIds,
+            cancellationToken);
+        var rooms = await db.Classrooms.AsNoTracking()
+            .Include(x => x.Building)
+            .Where(x => x.IsEnabled)
+            .OrderBy(x => x.Building!.Name)
+            .ThenBy(x => x.Name)
+            .ToListAsync(cancellationToken);
+
+        var targetRooms = new List<ExamRoomAssignment>();
+        var messages = new List<string>();
+        var seatedStudents = 0;
+        var unavailableStudents = 0;
+
+        if (assignClassrooms)
+        {
+            foreach (var session in sessions)
             {
-                var room = await FindBestClassroomAsync(
-                    session, studentCount, occupiedRooms, cancellationToken);
-                if (room is not null)
+                session.ClassroomId = null;
+                if (session.Invigilators.Count > 0)
                 {
-                    session.ClassroomId = room.Id;
-                    occupiedRooms.Add(new RoomOccupancy(room.Id, session.StartsAt, session.EndsAt));
-                    assignedRooms++;
-                    messages.Add(
-                        $"“{session.TeachingTask!.Course!.Name}”→{room.Name}({room.Capacity}座)");
-                }
-                else
-                {
-                    unavailableRooms++;
-                    messages.Add(
-                        $"“{session.TeachingTask!.Course!.Name}”：无可用考场（需≥{studentCount}座）");
+                    db.ExamSessionInvigilators.RemoveRange(session.Invigilators);
+                    session.Invigilators.Clear();
                 }
             }
-            // ── Auto-assign invigilators ──
-            var currentInvigilatorCount = session.Invigilators.Count;
-            var needed = session.RequiredInvigilatorCount - currentInvigilatorCount;
-            if (assignInvigilators && needed > 0)
+
+            foreach (var group in sessions
+                         .GroupBy(GroupKey)
+                         .OrderBy(x => x.Key.ExamDate)
+                         .ThenBy(x => x.Key.StartPeriod)
+                         .ThenBy(x => x.First().TeachingTask!.Course!.Code))
             {
-                var courseTeacherIds = session.TeachingTask!.Teachers
-                    .Select(x => x.TeacherId).ToHashSet();
-                var newlyAssigned = await FindInvigilatorsAsync(
-                    session, needed, courseTeacherIds,
-                    occupiedInvigilators, cancellationToken);
-                foreach (var teacher in newlyAssigned)
+                var groupSessions = group.ToList();
+                var candidates = InterleaveCandidates(
+                    groupSessions,
+                    roster,
+                    sessionByTaskId);
+                if (candidates.Count == 0)
                 {
-                    session.Invigilators.Add(new ExamSessionInvigilator
+                    messages.Add(
+                        $"“{groupSessions[0].TeachingTask!.Course!.Name}”没有有效考生。");
+                    continue;
+                }
+
+                var availableRooms = rooms
+                    .Where(room =>
+                        (!group.Key.RequiredBuildingId.HasValue ||
+                         room.BuildingId == group.Key.RequiredBuildingId.Value) &&
+                        occupiedRooms.All(occupied =>
+                            occupied.ClassroomId != room.Id ||
+                            !ExamConflictRules.TimeOverlaps(
+                                occupied.StartsAt,
+                                occupied.EndsAt,
+                                groupSessions[0].StartsAt,
+                                groupSessions[0].EndsAt)))
+                    .ToList();
+                var selectedRooms = SelectRooms(
+                    availableRooms,
+                    candidates.Count);
+                if (selectedRooms.Sum(x => x.Capacity) < candidates.Count)
+                {
+                    unavailableStudents += candidates.Count;
+                    messages.Add(
+                        $"“{groupSessions[0].TeachingTask!.Course!.Name}”缺少足够考场容量，" +
+                        $"需 {candidates.Count} 座、可用 {selectedRooms.Sum(x => x.Capacity)} 座。");
+                    continue;
+                }
+
+                var offset = 0;
+                foreach (var classroom in selectedRooms)
+                {
+                    var roomCandidates = candidates
+                        .Skip(offset)
+                        .Take(classroom.Capacity)
+                        .ToList();
+                    if (roomCandidates.Count == 0) break;
+                    offset += roomCandidates.Count;
+
+                    var room = new ExamRoomAssignment
+                    {
+                        ExamPlanId = plan.Id,
+                        CourseId = group.Key.CourseId,
+                        ClassroomId = classroom.Id,
+                        ExamDate = group.Key.ExamDate,
+                        StartPeriod = group.Key.StartPeriod,
+                        PeriodCount = group.Key.PeriodCount,
+                        StartsAt = groupSessions[0].StartsAt,
+                        EndsAt = groupSessions[0].EndsAt,
+                        RequiredInvigilatorCount =
+                            groupSessions.Max(x => x.RequiredInvigilatorCount),
+                        SessionLinks = roomCandidates
+                            .Select(x => x.ExamSessionId)
+                            .Distinct()
+                            .Select(sessionId => new ExamRoomSession
+                            {
+                                ExamSessionId = sessionId
+                            })
+                            .ToList(),
+                        Seats = roomCandidates
+                            .Select((candidate, index) =>
+                                new ExamSeatAssignment
+                                {
+                                    ExamSessionId = candidate.ExamSessionId,
+                                    StudentId = candidate.StudentId,
+                                    SeatNumber = index + 1
+                                })
+                            .ToList()
+                    };
+                    db.ExamRooms.Add(room);
+                    targetRooms.Add(room);
+                    occupiedRooms.Add(new RoomOccupancy(
+                        classroom.Id,
+                        room.StartsAt,
+                        room.EndsAt));
+                    seatedStudents += roomCandidates.Count;
+                }
+
+                messages.Add(
+                    $"“{groupSessions[0].TeachingTask!.Course!.Name}”" +
+                    $"{groupSessions.Count}个教学班混排至{selectedRooms.Count}个考场。");
+            }
+        }
+        else
+        {
+            targetRooms.AddRange(plan.Rooms.Where(room =>
+                room.SessionLinks.Any(link =>
+                    sessionIds.Contains(link.ExamSessionId))));
+            var linkedSessionIds = targetRooms
+                .SelectMany(x => x.SessionLinks)
+                .Select(x => x.ExamSessionId)
+                .ToHashSet();
+            foreach (var session in sessions.Where(x =>
+                         !linkedSessionIds.Contains(x.Id) &&
+                         x.ClassroomId.HasValue))
+            {
+                var legacyRoom = CreateLegacyRoom(
+                    plan,
+                    session,
+                    roster.Where(x =>
+                        x.TeachingTaskId == session.TeachingTaskId));
+                db.ExamRooms.Add(legacyRoom);
+                targetRooms.Add(legacyRoom);
+                session.ClassroomId = null;
+                if (session.Invigilators.Count > 0)
+                {
+                    db.ExamSessionInvigilators.RemoveRange(session.Invigilators);
+                    session.Invigilators.Clear();
+                }
+            }
+            seatedStudents = targetRooms.Sum(x => x.Seats.Count);
+        }
+
+        var assignedInvigilators = 0;
+        var unavailableInvigilators = 0;
+        if (assignInvigilators)
+        {
+            if (targetRooms.Count == 0)
+                return ExamArrangementResult.Fail("尚未生成实际考场，请先分配考场。");
+
+            var occupiedInvigilators = plan.Rooms
+                .Where(x => !replacedRoomIds.Contains(x.Id) &&
+                            !targetRooms.Any(target => target.Id == x.Id))
+                .SelectMany(room => room.Invigilators.Select(item =>
+                    new InvigilatorOccupancy(
+                        item.TeacherId,
+                        room.StartsAt,
+                        room.EndsAt)))
+                .Concat(plan.Sessions
+                    .Where(x => !sessionIds.Contains(x.Id))
+                    .SelectMany(session => session.Invigilators.Select(item =>
+                        new InvigilatorOccupancy(
+                            item.TeacherId,
+                            session.StartsAt,
+                            session.EndsAt))))
+                .ToList();
+
+            foreach (var room in targetRooms
+                         .OrderBy(x => x.ExamDate)
+                         .ThenBy(x => x.StartPeriod)
+                         .ThenBy(x => x.ClassroomId))
+            {
+                var needed = room.RequiredInvigilatorCount -
+                             room.Invigilators.Count;
+                if (needed <= 0) continue;
+
+                var linkedSessionIds = room.SessionLinks
+                    .Select(x => x.ExamSessionId)
+                    .ToHashSet();
+                var excludedTeacherIds = sessions
+                    .Where(x => linkedSessionIds.Contains(x.Id))
+                    .SelectMany(x => x.TeachingTask!.Teachers)
+                    .Select(x => x.TeacherId)
+                    .ToHashSet();
+                var teachers = await FindInvigilatorsAsync(
+                    room,
+                    needed,
+                    excludedTeacherIds,
+                    occupiedInvigilators,
+                    cancellationToken);
+                foreach (var teacher in teachers)
+                {
+                    room.Invigilators.Add(new ExamRoomInvigilator
                     {
-                        ExamSessionId = session.Id,
                         TeacherId = teacher.Id
                     });
                     occupiedInvigilators.Add(new InvigilatorOccupancy(
-                        teacher.Id, session.StartsAt, session.EndsAt));
+                        teacher.Id,
+                        room.StartsAt,
+                        room.EndsAt));
                     assignedInvigilators++;
                 }
 
-                if (newlyAssigned.Count < needed)
-                {
-                    unavailableInvigilators += needed - newlyAssigned.Count;
-                    messages.Add(
-                        $"“{session.TeachingTask!.Course!.Name}”：仅找到{newlyAssigned.Count}/{needed}名监考教师");
-                }
+                if (teachers.Count < needed)
+                    unavailableInvigilators += needed - teachers.Count;
             }
         }
 
         await db.SaveChangesAsync(cancellationToken);
 
+        var expandedCount = sessions.Count - explicitlySelected.Count;
+        var detail = messages.Count > 0
+            ? $" 详情：{string.Join("；", messages.Take(10))}"
+            : "";
         return new ExamArrangementResult(
             true,
-            $"{sessions.Count}个场次处理完成，分配{assignedRooms}个考场、{assignedInvigilators}名监考教师。" +
-            (unavailableRooms > 0 ? $" {unavailableRooms}个场次暂无可用考场。" : "") +
-            (unavailableInvigilators > 0 ? $" 仍缺{unavailableInvigilators}名监考教师。" : "") +
-            (messages.Count > 0 ? $" 详情：{string.Join("；", messages.Take(10))}" : ""));
+            $"{sessions.Count}个教学班场次处理完成，生成{targetRooms.Count}个实际考场，" +
+            $"安排{seatedStudents}名考生、{assignedInvigilators}名监考教师。" +
+            (expandedCount > 0
+                ? $" 为保持混排完整性，自动包含同组{expandedCount}个场次。"
+                : "") +
+            (unavailableStudents > 0
+                ? $" {unavailableStudents}名考生尚未安排考场。"
+                : "") +
+            (unavailableInvigilators > 0
+                ? $" 仍缺{unavailableInvigilators}名监考教师。"
+                : "") +
+            detail);
     }
 
+    private async Task<List<RoomOccupancy>> LoadOccupiedRoomsAsync(
+        ExamPlan plan,
+        IReadOnlySet<Guid> targetSessionIds,
+        IReadOnlySet<Guid> replacedRoomIds,
+        CancellationToken cancellationToken)
+    {
+        var occupied = plan.Rooms
+            .Where(x => !replacedRoomIds.Contains(x.Id))
+            .Select(x => new RoomOccupancy(
+                x.ClassroomId,
+                x.StartsAt,
+                x.EndsAt))
+            .ToList();
+        occupied.AddRange(plan.Sessions
+            .Where(x =>
+                !targetSessionIds.Contains(x.Id) &&
+                x.ClassroomId.HasValue)
+            .Select(x => new RoomOccupancy(
+                x.ClassroomId!.Value,
+                x.StartsAt,
+                x.EndsAt)));
+
+        var externalRooms = await db.ExamRooms.AsNoTracking()
+            .Where(x =>
+                x.ExamPlanId != plan.Id &&
+                x.ExamPlan!.Status != ExamPlanStatus.Archived)
+            .Select(x => new RoomOccupancy(
+                x.ClassroomId,
+                x.StartsAt,
+                x.EndsAt))
+            .ToListAsync(cancellationToken);
+        occupied.AddRange(externalRooms);
+
+        var externalLegacyRooms = await db.ExamSessions.AsNoTracking()
+            .Where(x =>
+                x.ExamPlanId != plan.Id &&
+                x.ExamPlan!.Status != ExamPlanStatus.Archived &&
+                x.ClassroomId != null)
+            .Select(x => new RoomOccupancy(
+                x.ClassroomId!.Value,
+                x.StartsAt,
+                x.EndsAt))
+            .ToListAsync(cancellationToken);
+        occupied.AddRange(externalLegacyRooms);
+        return occupied;
+    }
+
+    private async Task<List<Teacher>> FindInvigilatorsAsync(
+        ExamRoomAssignment room,
+        int needed,
+        HashSet<Guid> excludedTeacherIds,
+        List<InvigilatorOccupancy> occupied,
+        CancellationToken cancellationToken)
+    {
+        var busyTeacherIds = occupied
+            .Where(x => ExamConflictRules.TimeOverlaps(
+                x.StartsAt,
+                x.EndsAt,
+                room.StartsAt,
+                room.EndsAt))
+            .Select(x => x.TeacherId)
+            .ToHashSet();
+
+        var databaseBusyIds = await db.ExamRoomInvigilators.AsNoTracking()
+            .Where(x =>
+                x.ExamRoomId != room.Id &&
+                x.ExamRoom!.ExamPlan!.Status != ExamPlanStatus.Archived &&
+                x.ExamRoom.StartsAt < room.EndsAt &&
+                room.StartsAt < x.ExamRoom.EndsAt)
+            .Select(x => x.TeacherId)
+            .ToListAsync(cancellationToken);
+        foreach (var teacherId in databaseBusyIds)
+            busyTeacherIds.Add(teacherId);
+
+        var legacyBusyIds = await db.ExamSessionInvigilators.AsNoTracking()
+            .Where(x =>
+                x.ExamSession!.ExamPlan!.Status != ExamPlanStatus.Archived &&
+                x.ExamSession.StartsAt < room.EndsAt &&
+                room.StartsAt < x.ExamSession.EndsAt)
+            .Select(x => x.TeacherId)
+            .ToListAsync(cancellationToken);
+        foreach (var teacherId in legacyBusyIds)
+            busyTeacherIds.Add(teacherId);
+        foreach (var teacherId in excludedTeacherIds)
+            busyTeacherIds.Add(teacherId);
+
+        var candidates = await InvigilatorCandidateQuery
+            .Create(db, busyTeacherIds)
+            .ToListAsync(cancellationToken);
+        return candidates
+            .OrderBy(_ => Random.Shared.Next())
+            .Take(needed)
+            .ToList();
+    }
+
+    private static List<Classroom> SelectRooms(
+        IReadOnlyCollection<Classroom> availableRooms,
+        int candidateCount)
+    {
+        var remainingRooms = availableRooms.ToList();
+        var selected = new List<Classroom>();
+        var remainingSeats = candidateCount;
+        while (remainingSeats > 0 && remainingRooms.Count > 0)
+        {
+            var room = remainingRooms
+                           .Where(x => x.Capacity >= remainingSeats)
+                           .OrderBy(x => x.Capacity)
+                           .ThenBy(x => x.Name)
+                           .FirstOrDefault()
+                       ?? remainingRooms
+                           .OrderByDescending(x => x.Capacity)
+                           .ThenBy(x => x.Name)
+                           .First();
+            selected.Add(room);
+            remainingRooms.Remove(room);
+            remainingSeats -= room.Capacity;
+        }
+        return selected;
+    }
+
+    private static List<CandidateSeat> InterleaveCandidates(
+        IReadOnlyCollection<ExamSession> sessions,
+        IReadOnlyCollection<TeachingTaskRosterEntry> roster,
+        IReadOnlyDictionary<Guid, ExamSession> sessionByTaskId)
+    {
+        var sessionIds = sessions.Select(x => x.Id).ToHashSet();
+        var queues = roster
+            .Where(x =>
+                sessionByTaskId.TryGetValue(
+                    x.TeachingTaskId,
+                    out var session) &&
+                sessionIds.Contains(session.Id))
+            .GroupBy(x => x.TeachingTaskId)
+            .OrderBy(x => sessionByTaskId[x.Key].TeachingTask!.TaskNumber)
+            .Select(group => new Queue<CandidateSeat>(
+                group.OrderBy(x => x.StudentNumber)
+                    .Select(x => new CandidateSeat(
+                        sessionByTaskId[x.TeachingTaskId].Id,
+                        x.StudentId,
+                        x.StudentNumber))))
+            .ToList();
+
+        var result = new List<CandidateSeat>();
+        var assignedStudentIds = new HashSet<Guid>();
+        while (queues.Any(x => x.Count > 0))
+        {
+            foreach (var queue in queues)
+            {
+                while (queue.Count > 0)
+                {
+                    var candidate = queue.Dequeue();
+                    if (!assignedStudentIds.Add(candidate.StudentId))
+                        continue;
+                    result.Add(candidate);
+                    break;
+                }
+            }
+        }
+        return result;
+    }
+
+    private static ExamRoomAssignment CreateLegacyRoom(
+        ExamPlan plan,
+        ExamSession session,
+        IEnumerable<TeachingTaskRosterEntry> roster)
+    {
+        var students = roster
+            .OrderBy(x => x.StudentNumber)
+            .ToList();
+        return new ExamRoomAssignment
+        {
+            ExamPlanId = plan.Id,
+            CourseId = session.TeachingTask!.CourseId,
+            ClassroomId = session.ClassroomId!.Value,
+            ExamDate = session.ExamDate,
+            StartPeriod = session.StartPeriod,
+            PeriodCount = session.PeriodCount,
+            StartsAt = session.StartsAt,
+            EndsAt = session.EndsAt,
+            RequiredInvigilatorCount = session.RequiredInvigilatorCount,
+            SessionLinks =
+            [
+                new ExamRoomSession
+                {
+                    ExamSessionId = session.Id
+                }
+            ],
+            Seats = students.Select((student, index) =>
+                new ExamSeatAssignment
+                {
+                    ExamSessionId = session.Id,
+                    StudentId = student.StudentId,
+                    SeatNumber = index + 1
+                }).ToList(),
+            Invigilators = session.Invigilators.Select(x =>
+                new ExamRoomInvigilator
+                {
+                    TeacherId = x.TeacherId
+                }).ToList()
+        };
+    }
+
+    private static RoomGroupKey GroupKey(ExamSession session) => new(
+        session.TeachingTask!.CourseId,
+        session.ExamDate,
+        session.StartPeriod,
+        session.PeriodCount,
+        session.RequiredBuildingId);
+
     private static void ComputeTimesFromSlots(
         ExamSession session,
-        Dictionary<int, ScheduleTimeSlot> timeSlotLookup)
+        IReadOnlyDictionary<int, ScheduleTimeSlot> timeSlotLookup)
     {
         var startSlot = timeSlotLookup.GetValueOrDefault(session.StartPeriod);
         var endSlot = timeSlotLookup.GetValueOrDefault(
             session.StartPeriod + session.PeriodCount - 1);
         if (startSlot is null || endSlot is null) return;
 
-        var examDate = session.ExamDate;
-        session.StartsAt = examDate.ToDateTime(startSlot.StartsAt, DateTimeKind.Utc);
-        session.EndsAt = examDate.ToDateTime(endSlot.EndsAt, DateTimeKind.Utc);
-    }
-
-    private async Task<Classroom?> FindBestClassroomAsync(
-        ExamSession session,
-        int studentCount,
-        List<RoomOccupancy> occupied,
-        CancellationToken cancellationToken)
-    {
-        var query = db.Classrooms.AsNoTracking()
-            .Where(x => x.IsEnabled && x.Capacity >= studentCount);
-
-        if (session.RequiredBuildingId.HasValue)
-            query = query.Where(x => x.BuildingId == session.RequiredBuildingId.Value);
-
-        // Exclude classrooms already occupied in-memory
-        var occupiedRoomIds = occupied
-            .Where(x => ExamConflictRules.TimeOverlaps(
-                x.StartsAt, x.EndsAt, session.StartsAt, session.EndsAt))
-            .Select(x => x.ClassroomId)
-            .ToHashSet();
-
-        if (occupiedRoomIds.Count > 0)
-            query = query.WhereNotIn(occupiedRoomIds, x => x.Id);
-
-        // Exclude classrooms occupied by DB sessions not yet tracked in memory
-        var dbOccupiedRooms = await db.ExamSessions.AsNoTracking()
-            .Where(x => x.ExamPlanId == session.ExamPlanId &&
-                        x.Id != session.Id &&
-                        x.ClassroomId != null &&
-                        x.StartsAt < session.EndsAt &&
-                        session.StartsAt < x.EndsAt)
-            .Select(x => x.ClassroomId!.Value)
-            .ToListAsync(cancellationToken);
-
-        if (dbOccupiedRooms.Count > 0)
-            query = query.WhereNotIn(dbOccupiedRooms, x => x.Id);
-
-        return await query
-            .OrderBy(x => x.Capacity)
-            .FirstOrDefaultAsync(cancellationToken);
-    }
-
-    private async Task<List<Teacher>> FindInvigilatorsAsync(
-        ExamSession session,
-        int needed,
-        HashSet<Guid> excludeTeacherIds,
-        List<InvigilatorOccupancy> occupied,
-        CancellationToken cancellationToken)
-    {
-        var busyTeacherIds = occupied
-            .Where(x => ExamConflictRules.TimeOverlaps(
-                x.StartsAt, x.EndsAt, session.StartsAt, session.EndsAt))
-            .Select(x => x.TeacherId)
-            .ToHashSet();
-
-        var dbBusyIds = await db.ExamSessionInvigilators.AsNoTracking()
-            .Where(x => x.ExamSession!.ExamPlanId == session.ExamPlanId &&
-                        x.ExamSessionId != session.Id &&
-                        x.ExamSession!.StartsAt < session.EndsAt &&
-                        session.StartsAt < x.ExamSession.EndsAt)
-            .Select(x => x.TeacherId)
-            .ToListAsync(cancellationToken);
-
-        foreach (var id in dbBusyIds) busyTeacherIds.Add(id);
-        foreach (var id in excludeTeacherIds) busyTeacherIds.Add(id);
-
-        var candidates = await InvigilatorCandidateQuery
-            .Create(db, busyTeacherIds)
-            .ToListAsync(cancellationToken);
-
-        return candidates
-            .OrderBy(_ => Random.Shared.Next())
-            .Take(needed)
-            .ToList();
+        session.StartsAt = session.ExamDate.ToDateTime(
+            startSlot.StartsAt,
+            DateTimeKind.Utc);
+        session.EndsAt = session.ExamDate.ToDateTime(
+            endSlot.EndsAt,
+            DateTimeKind.Utc);
     }
 }
 
 public sealed record ExamArrangementResult(bool Success, string Message)
 {
-    public static ExamArrangementResult Fail(string message) => new(false, message);
+    public static ExamArrangementResult Fail(string message) =>
+        new(false, message);
 }

src/Jiaowu.Api/Infrastructure/Exams/ExamSignInWorkbookExporter.cs

@@ -163,11 +163,15 @@ public static class ExamSignInWorkbookExporter
         sheet.Row(7).Height = 27;
 
         var row = 8;
-        foreach (var student in session.Students.OrderBy(x => x.StudentNumber))
+        foreach (var student in session.Students
+                     .OrderBy(x => x.SeatNumber)
+                     .ThenBy(x => x.StudentNumber))
         {
             var index = row - 7;
             sheet.Cell(row, 1).Value = index;
-            sheet.Cell(row, 2).Value = index.ToString("D3");
+            sheet.Cell(row, 2).Value =
+                (student.SeatNumber > 0 ? student.SeatNumber : index)
+                .ToString("D3");
             sheet.Cell(row, 3).Value = student.StudentNumber;
             sheet.Cell(row, 4).Value = student.Name;
             sheet.Cell(row, 5).Value = student.ClassName;
@@ -297,4 +301,5 @@ public sealed record ExamSignInStudentData(
     Guid StudentId,
     string StudentNumber,
     string Name,
-    string ClassName);
+    string ClassName,
+    int SeatNumber = 0);

src/Jiaowu.Api/Infrastructure/Persistence/AppDbContext.cs

@@ -61,6 +61,11 @@ public sealed class AppDbContext(DbContextOptions<AppDbContext> options)
     public DbSet<ExamSession> ExamSessions => Set<ExamSession>();
     public DbSet<ExamSessionInvigilator> ExamSessionInvigilators =>
         Set<ExamSessionInvigilator>();
+    public DbSet<ExamRoomAssignment> ExamRooms => Set<ExamRoomAssignment>();
+    public DbSet<ExamRoomSession> ExamRoomSessions => Set<ExamRoomSession>();
+    public DbSet<ExamSeatAssignment> ExamSeats => Set<ExamSeatAssignment>();
+    public DbSet<ExamRoomInvigilator> ExamRoomInvigilators =>
+        Set<ExamRoomInvigilator>();
     public DbSet<MakeupExamPlan> MakeupExamPlans => Set<MakeupExamPlan>();
     public DbSet<MakeupExamSession> MakeupExamSessions => Set<MakeupExamSession>();
     public DbSet<MakeupExamSessionInvigilator> MakeupExamSessionInvigilators =>
@@ -719,6 +724,65 @@ public sealed class AppDbContext(DbContextOptions<AppDbContext> options)
             entity.HasOne(x => x.Teacher).WithMany()
                 .HasForeignKey(x => x.TeacherId).OnDelete(DeleteBehavior.Restrict);
         });
+        builder.Entity<ExamRoomAssignment>(entity =>
+        {
+            entity.ToTable("ExamRooms");
+            entity.HasIndex(x => new { x.ExamPlanId, x.StartsAt })
+                .HasDatabaseName("IX_ExamRooms_Plan_Time");
+            entity.HasIndex(x => new
+                {
+                    x.ExamPlanId,
+                    x.ClassroomId,
+                    x.StartsAt
+                })
+                .HasDatabaseName("IX_ExamRooms_Plan_Room_Time");
+            entity.HasIndex(x => x.CourseId)
+                .HasDatabaseName("IX_ExamRooms_CourseId");
+            entity.HasOne(x => x.ExamPlan).WithMany(x => x.Rooms)
+                .HasForeignKey(x => x.ExamPlanId).OnDelete(DeleteBehavior.Cascade);
+            entity.HasOne(x => x.Course).WithMany()
+                .HasForeignKey(x => x.CourseId).OnDelete(DeleteBehavior.Restrict);
+            entity.HasOne(x => x.Classroom).WithMany()
+                .HasForeignKey(x => x.ClassroomId).OnDelete(DeleteBehavior.Restrict);
+        });
+        builder.Entity<ExamRoomSession>(entity =>
+        {
+            entity.ToTable("ExamRoomSessions");
+            entity.HasKey(x => new { x.ExamRoomId, x.ExamSessionId });
+            entity.HasIndex(x => x.ExamSessionId)
+                .HasDatabaseName("IX_ExamRoomSessions_SessionId");
+            entity.HasOne(x => x.ExamRoom).WithMany(x => x.SessionLinks)
+                .HasForeignKey(x => x.ExamRoomId).OnDelete(DeleteBehavior.Cascade);
+            entity.HasOne(x => x.ExamSession).WithMany(x => x.RoomLinks)
+                .HasForeignKey(x => x.ExamSessionId).OnDelete(DeleteBehavior.Restrict);
+        });
+        builder.Entity<ExamSeatAssignment>(entity =>
+        {
+            entity.ToTable("ExamSeats");
+            entity.HasKey(x => new { x.ExamRoomId, x.StudentId });
+            entity.HasIndex(x => new { x.ExamSessionId, x.StudentId })
+                .IsUnique()
+                .HasDatabaseName("UX_ExamSeats_Session_Student");
+            entity.HasIndex(x => x.StudentId)
+                .HasDatabaseName("IX_ExamSeats_StudentId");
+            entity.HasOne(x => x.ExamRoom).WithMany(x => x.Seats)
+                .HasForeignKey(x => x.ExamRoomId).OnDelete(DeleteBehavior.Cascade);
+            entity.HasOne(x => x.ExamSession).WithMany(x => x.SeatAssignments)
+                .HasForeignKey(x => x.ExamSessionId).OnDelete(DeleteBehavior.Restrict);
+            entity.HasOne(x => x.Student).WithMany()
+                .HasForeignKey(x => x.StudentId).OnDelete(DeleteBehavior.Restrict);
+        });
+        builder.Entity<ExamRoomInvigilator>(entity =>
+        {
+            entity.ToTable("ExamRoomInvigilators");
+            entity.HasKey(x => new { x.ExamRoomId, x.TeacherId });
+            entity.HasIndex(x => x.TeacherId)
+                .HasDatabaseName("IX_ExamRoomInvigilators_TeacherId");
+            entity.HasOne(x => x.ExamRoom).WithMany(x => x.Invigilators)
+                .HasForeignKey(x => x.ExamRoomId).OnDelete(DeleteBehavior.Cascade);
+            entity.HasOne(x => x.Teacher).WithMany()
+                .HasForeignKey(x => x.TeacherId).OnDelete(DeleteBehavior.Restrict);
+        });
         builder.Entity<MakeupExamPlan>(entity =>
         {
             entity.Property(x => x.Name).HasMaxLength(120);

src/Jiaowu.Api/Infrastructure/Persistence/DevelopmentSqliteMigrator.cs

@@ -64,6 +64,8 @@ public sealed class DevelopmentSqliteMigrator(
         "20260727_34_course_adjustment_occurrences";
     private const string AcademicPlanningPrerequisitesMigration =
         "20260727_35_academic_planning_prerequisites";
+    private const string ExamRoomMixingMigration =
+        "20260727_36_exam_room_mixing";
 
     public async Task MigrateAsync(CancellationToken cancellationToken = default)
     {
@@ -468,6 +470,19 @@ public sealed class DevelopmentSqliteMigrator(
             AcademicPlanningPrerequisitesMigration,
             coursePrerequisitesExist ? [] : AcademicPlanningPrerequisiteStatements,
             cancellationToken);
+
+        var examRoomsExist = await db.Database
+            .SqlQueryRaw<int>(
+                """
+                SELECT COUNT(*) AS "Value"
+                FROM sqlite_master
+                WHERE type = 'table' AND name = 'ExamRooms'
+                """)
+            .AnyAsync(value => value > 0, cancellationToken);
+        await ApplyMigrationAsync(
+            ExamRoomMixingMigration,
+            examRoomsExist ? [] : ExamRoomMixingStatements,
+            cancellationToken);
     }
 
     private async Task ApplyMigrationAsync(
@@ -2132,4 +2147,112 @@ public sealed class DevelopmentSqliteMigrator(
         ON "CoursePrerequisites" ("PrerequisiteCourseId");
         """
     ];
+
+    private static readonly string[] ExamRoomMixingStatements =
+    [
+        """
+        CREATE TABLE "ExamRooms" (
+            "Id" TEXT NOT NULL CONSTRAINT "PK_ExamRooms" PRIMARY KEY,
+            "ExamPlanId" TEXT NOT NULL,
+            "CourseId" TEXT NOT NULL,
+            "ClassroomId" TEXT NOT NULL,
+            "ExamDate" TEXT NOT NULL,
+            "StartPeriod" INTEGER NOT NULL,
+            "PeriodCount" INTEGER NOT NULL,
+            "StartsAt" TEXT NOT NULL,
+            "EndsAt" TEXT NOT NULL,
+            "RequiredInvigilatorCount" INTEGER NOT NULL,
+            "CreatedAt" TEXT NOT NULL,
+            "UpdatedAt" TEXT NOT NULL,
+            CONSTRAINT "FK_ExamRooms_ExamPlans_ExamPlanId"
+                FOREIGN KEY ("ExamPlanId") REFERENCES "ExamPlans" ("Id")
+                ON DELETE CASCADE,
+            CONSTRAINT "FK_ExamRooms_Courses_CourseId"
+                FOREIGN KEY ("CourseId") REFERENCES "Courses" ("Id")
+                ON DELETE RESTRICT,
+            CONSTRAINT "FK_ExamRooms_Classrooms_ClassroomId"
+                FOREIGN KEY ("ClassroomId") REFERENCES "Classrooms" ("Id")
+                ON DELETE RESTRICT
+        );
+        """,
+        """
+        CREATE INDEX "IX_ExamRooms_Plan_Time"
+        ON "ExamRooms" ("ExamPlanId", "StartsAt");
+        """,
+        """
+        CREATE INDEX "IX_ExamRooms_Plan_Room_Time"
+        ON "ExamRooms" ("ExamPlanId", "ClassroomId", "StartsAt");
+        """,
+        """
+        CREATE INDEX "IX_ExamRooms_CourseId"
+        ON "ExamRooms" ("CourseId");
+        """,
+        """
+        CREATE INDEX "IX_ExamRooms_ClassroomId"
+        ON "ExamRooms" ("ClassroomId");
+        """,
+        """
+        CREATE TABLE "ExamRoomSessions" (
+            "ExamRoomId" TEXT NOT NULL,
+            "ExamSessionId" TEXT NOT NULL,
+            CONSTRAINT "PK_ExamRoomSessions"
+                PRIMARY KEY ("ExamRoomId", "ExamSessionId"),
+            CONSTRAINT "FK_ExamRoomSessions_ExamRooms_ExamRoomId"
+                FOREIGN KEY ("ExamRoomId") REFERENCES "ExamRooms" ("Id")
+                ON DELETE CASCADE,
+            CONSTRAINT "FK_ExamRoomSessions_ExamSessions_ExamSessionId"
+                FOREIGN KEY ("ExamSessionId") REFERENCES "ExamSessions" ("Id")
+                ON DELETE RESTRICT
+        );
+        """,
+        """
+        CREATE INDEX "IX_ExamRoomSessions_SessionId"
+        ON "ExamRoomSessions" ("ExamSessionId");
+        """,
+        """
+        CREATE TABLE "ExamSeats" (
+            "ExamRoomId" TEXT NOT NULL,
+            "ExamSessionId" TEXT NOT NULL,
+            "StudentId" TEXT NOT NULL,
+            "SeatNumber" INTEGER NOT NULL,
+            CONSTRAINT "PK_ExamSeats"
+                PRIMARY KEY ("ExamRoomId", "StudentId"),
+            CONSTRAINT "FK_ExamSeats_ExamRooms_ExamRoomId"
+                FOREIGN KEY ("ExamRoomId") REFERENCES "ExamRooms" ("Id")
+                ON DELETE CASCADE,
+            CONSTRAINT "FK_ExamSeats_ExamSessions_ExamSessionId"
+                FOREIGN KEY ("ExamSessionId") REFERENCES "ExamSessions" ("Id")
+                ON DELETE RESTRICT,
+            CONSTRAINT "FK_ExamSeats_Students_StudentId"
+                FOREIGN KEY ("StudentId") REFERENCES "Students" ("Id")
+                ON DELETE RESTRICT
+        );
+        """,
+        """
+        CREATE UNIQUE INDEX "UX_ExamSeats_Session_Student"
+        ON "ExamSeats" ("ExamSessionId", "StudentId");
+        """,
+        """
+        CREATE INDEX "IX_ExamSeats_StudentId"
+        ON "ExamSeats" ("StudentId");
+        """,
+        """
+        CREATE TABLE "ExamRoomInvigilators" (
+            "ExamRoomId" TEXT NOT NULL,
+            "TeacherId" TEXT NOT NULL,
+            CONSTRAINT "PK_ExamRoomInvigilators"
+                PRIMARY KEY ("ExamRoomId", "TeacherId"),
+            CONSTRAINT "FK_ExamRoomInvigilators_ExamRooms_ExamRoomId"
+                FOREIGN KEY ("ExamRoomId") REFERENCES "ExamRooms" ("Id")
+                ON DELETE CASCADE,
+            CONSTRAINT "FK_ExamRoomInvigilators_Teachers_TeacherId"
+                FOREIGN KEY ("TeacherId") REFERENCES "Teachers" ("Id")
+                ON DELETE RESTRICT
+        );
+        """,
+        """
+        CREATE INDEX "IX_ExamRoomInvigilators_TeacherId"
+        ON "ExamRoomInvigilators" ("TeacherId");
+        """
+    ];
 }

src/Jiaowu.Api/Infrastructure/Persistence/Migrations/MySql/20260727105716_ExamRoomMixing.cs

@@ -0,0 +1,196 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Jiaowu.Api.Infrastructure.Persistence.Migrations.MySql
+{
+    /// <inheritdoc />
+    public partial class ExamRoomMixing : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "ExamRooms",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "char(36)", nullable: false),
+                    ExamPlanId = table.Column<Guid>(type: "char(36)", nullable: false),
+                    CourseId = table.Column<Guid>(type: "char(36)", nullable: false),
+                    ClassroomId = table.Column<Guid>(type: "char(36)", nullable: false),
+                    ExamDate = table.Column<DateTime>(type: "date", nullable: false),
+                    StartPeriod = table.Column<int>(type: "int", nullable: false),
+                    PeriodCount = table.Column<int>(type: "int", nullable: false),
+                    StartsAt = table.Column<DateTime>(type: "datetime(6)", nullable: false),
+                    EndsAt = table.Column<DateTime>(type: "datetime(6)", nullable: false),
+                    RequiredInvigilatorCount = table.Column<int>(type: "int", nullable: false),
+                    CreatedAt = table.Column<DateTime>(type: "datetime(6)", nullable: false),
+                    UpdatedAt = table.Column<DateTime>(type: "datetime(6)", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_ExamRooms", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_ExamRooms_Classrooms_ClassroomId",
+                        column: x => x.ClassroomId,
+                        principalTable: "Classrooms",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Restrict);
+                    table.ForeignKey(
+                        name: "FK_ExamRooms_Courses_CourseId",
+                        column: x => x.CourseId,
+                        principalTable: "Courses",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Restrict);
+                    table.ForeignKey(
+                        name: "FK_ExamRooms_ExamPlans_ExamPlanId",
+                        column: x => x.ExamPlanId,
+                        principalTable: "ExamPlans",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                })
+                .Annotation("MySQL:Charset", "utf8mb4");
+
+            migrationBuilder.CreateTable(
+                name: "ExamRoomInvigilators",
+                columns: table => new
+                {
+                    ExamRoomId = table.Column<Guid>(type: "char(36)", nullable: false),
+                    TeacherId = table.Column<Guid>(type: "char(36)", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_ExamRoomInvigilators", x => new { x.ExamRoomId, x.TeacherId });
+                    table.ForeignKey(
+                        name: "FK_ExamRoomInvigilators_ExamRooms_ExamRoomId",
+                        column: x => x.ExamRoomId,
+                        principalTable: "ExamRooms",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                    table.ForeignKey(
+                        name: "FK_ExamRoomInvigilators_Teachers_TeacherId",
+                        column: x => x.TeacherId,
+                        principalTable: "Teachers",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Restrict);
+                })
+                .Annotation("MySQL:Charset", "utf8mb4");
+
+            migrationBuilder.CreateTable(
+                name: "ExamRoomSessions",
+                columns: table => new
+                {
+                    ExamRoomId = table.Column<Guid>(type: "char(36)", nullable: false),
+                    ExamSessionId = table.Column<Guid>(type: "char(36)", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_ExamRoomSessions", x => new { x.ExamRoomId, x.ExamSessionId });
+                    table.ForeignKey(
+                        name: "FK_ExamRoomSessions_ExamRooms_ExamRoomId",
+                        column: x => x.ExamRoomId,
+                        principalTable: "ExamRooms",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                    table.ForeignKey(
+                        name: "FK_ExamRoomSessions_ExamSessions_ExamSessionId",
+                        column: x => x.ExamSessionId,
+                        principalTable: "ExamSessions",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Restrict);
+                })
+                .Annotation("MySQL:Charset", "utf8mb4");
+
+            migrationBuilder.CreateTable(
+                name: "ExamSeats",
+                columns: table => new
+                {
+                    ExamRoomId = table.Column<Guid>(type: "char(36)", nullable: false),
+                    StudentId = table.Column<Guid>(type: "char(36)", nullable: false),
+                    ExamSessionId = table.Column<Guid>(type: "char(36)", nullable: false),
+                    SeatNumber = table.Column<int>(type: "int", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_ExamSeats", x => new { x.ExamRoomId, x.StudentId });
+                    table.ForeignKey(
+                        name: "FK_ExamSeats_ExamRooms_ExamRoomId",
+                        column: x => x.ExamRoomId,
+                        principalTable: "ExamRooms",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                    table.ForeignKey(
+                        name: "FK_ExamSeats_ExamSessions_ExamSessionId",
+                        column: x => x.ExamSessionId,
+                        principalTable: "ExamSessions",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Restrict);
+                    table.ForeignKey(
+                        name: "FK_ExamSeats_Students_StudentId",
+                        column: x => x.StudentId,
+                        principalTable: "Students",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Restrict);
+                })
+                .Annotation("MySQL:Charset", "utf8mb4");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_ExamRoomInvigilators_TeacherId",
+                table: "ExamRoomInvigilators",
+                column: "TeacherId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_ExamRooms_ClassroomId",
+                table: "ExamRooms",
+                column: "ClassroomId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_ExamRooms_CourseId",
+                table: "ExamRooms",
+                column: "CourseId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_ExamRooms_Plan_Room_Time",
+                table: "ExamRooms",
+                columns: new[] { "ExamPlanId", "ClassroomId", "StartsAt" });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_ExamRooms_Plan_Time",
+                table: "ExamRooms",
+                columns: new[] { "ExamPlanId", "StartsAt" });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_ExamRoomSessions_SessionId",
+                table: "ExamRoomSessions",
+                column: "ExamSessionId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_ExamSeats_StudentId",
+                table: "ExamSeats",
+                column: "StudentId");
+
+            migrationBuilder.CreateIndex(
+                name: "UX_ExamSeats_Session_Student",
+                table: "ExamSeats",
+                columns: new[] { "ExamSessionId", "StudentId" },
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "ExamRoomInvigilators");
+
+            migrationBuilder.DropTable(
+                name: "ExamRoomSessions");
+
+            migrationBuilder.DropTable(
+                name: "ExamSeats");
+
+            migrationBuilder.DropTable(
+                name: "ExamRooms");
+        }
+    }
+}

src/Jiaowu.Api/Infrastructure/Persistence/Migrations/MySql/AppDbContextModelSnapshot.cs

@@ -1558,6 +1558,119 @@ namespace Jiaowu.Api.Infrastructure.Persistence.Migrations.MySql
                     b.ToTable("ExamPlans");
                 });
 
+            modelBuilder.Entity("Jiaowu.Api.Domain.Academic.ExamRoomAssignment", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("char(36)");
+
+                    b.Property<Guid>("ClassroomId")
+                        .HasColumnType("char(36)");
+
+                    b.Property<Guid>("CourseId")
+                        .HasColumnType("char(36)");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<DateTime>("EndsAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<DateTime>("ExamDate")
+                        .HasColumnType("date");
+
+                    b.Property<Guid>("ExamPlanId")
+                        .HasColumnType("char(36)");
+
+                    b.Property<int>("PeriodCount")
+                        .HasColumnType("int");
+
+                    b.Property<int>("RequiredInvigilatorCount")
+                        .HasColumnType("int");
+
+                    b.Property<int>("StartPeriod")
+                        .HasColumnType("int");
+
+                    b.Property<DateTime>("StartsAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("ClassroomId");
+
+                    b.HasIndex("CourseId")
+                        .HasDatabaseName("IX_ExamRooms_CourseId");
+
+                    b.HasIndex("ExamPlanId", "StartsAt")
+                        .HasDatabaseName("IX_ExamRooms_Plan_Time");
+
+                    b.HasIndex("ExamPlanId", "ClassroomId", "StartsAt")
+                        .HasDatabaseName("IX_ExamRooms_Plan_Room_Time");
+
+                    b.ToTable("ExamRooms", (string)null);
+                });
+
+            modelBuilder.Entity("Jiaowu.Api.Domain.Academic.ExamRoomInvigilator", b =>
+                {
+                    b.Property<Guid>("ExamRoomId")
+                        .HasColumnType("char(36)");
+
+                    b.Property<Guid>("TeacherId")
+                        .HasColumnType("char(36)");
+
+                    b.HasKey("ExamRoomId", "TeacherId");
+
+                    b.HasIndex("TeacherId")
+                        .HasDatabaseName("IX_ExamRoomInvigilators_TeacherId");
+
+                    b.ToTable("ExamRoomInvigilators", (string)null);
+                });
+
+            modelBuilder.Entity("Jiaowu.Api.Domain.Academic.ExamRoomSession", b =>
+                {
+                    b.Property<Guid>("ExamRoomId")
+                        .HasColumnType("char(36)");
+
+                    b.Property<Guid>("ExamSessionId")
+                        .HasColumnType("char(36)");
+
+                    b.HasKey("ExamRoomId", "ExamSessionId");
+
+                    b.HasIndex("ExamSessionId")
+                        .HasDatabaseName("IX_ExamRoomSessions_SessionId");
+
+                    b.ToTable("ExamRoomSessions", (string)null);
+                });
+
+            modelBuilder.Entity("Jiaowu.Api.Domain.Academic.ExamSeatAssignment", b =>
+                {
+                    b.Property<Guid>("ExamRoomId")
+                        .HasColumnType("char(36)");
+
+                    b.Property<Guid>("StudentId")
+                        .HasColumnType("char(36)");
+
+                    b.Property<Guid>("ExamSessionId")
+                        .HasColumnType("char(36)");
+
+                    b.Property<int>("SeatNumber")
+                        .HasColumnType("int");
+
+                    b.HasKey("ExamRoomId", "StudentId");
+
+                    b.HasIndex("StudentId")
+                        .HasDatabaseName("IX_ExamSeats_StudentId");
+
+                    b.HasIndex("ExamSessionId", "StudentId")
+                        .IsUnique()
+                        .HasDatabaseName("UX_ExamSeats_Session_Student");
+
+                    b.ToTable("ExamSeats", (string)null);
+                });
+
             modelBuilder.Entity("Jiaowu.Api.Domain.Academic.ExamSession", b =>
                 {
                     b.Property<Guid>("Id")
@@ -4097,6 +4210,98 @@ namespace Jiaowu.Api.Infrastructure.Persistence.Migrations.MySql
                     b.Navigation("AcademicTerm");
                 });
 
+            modelBuilder.Entity("Jiaowu.Api.Domain.Academic.ExamRoomAssignment", b =>
+                {
+                    b.HasOne("Jiaowu.Api.Domain.Academic.Classroom", "Classroom")
+                        .WithMany()
+                        .HasForeignKey("ClassroomId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.HasOne("Jiaowu.Api.Domain.Academic.Course", "Course")
+                        .WithMany()
+                        .HasForeignKey("CourseId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.HasOne("Jiaowu.Api.Domain.Academic.ExamPlan", "ExamPlan")
+                        .WithMany("Rooms")
+                        .HasForeignKey("ExamPlanId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Classroom");
+
+                    b.Navigation("Course");
+
+                    b.Navigation("ExamPlan");
+                });
+
+            modelBuilder.Entity("Jiaowu.Api.Domain.Academic.ExamRoomInvigilator", b =>
+                {
+                    b.HasOne("Jiaowu.Api.Domain.Academic.ExamRoomAssignment", "ExamRoom")
+                        .WithMany("Invigilators")
+                        .HasForeignKey("ExamRoomId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("Jiaowu.Api.Domain.Academic.Teacher", "Teacher")
+                        .WithMany()
+                        .HasForeignKey("TeacherId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.Navigation("ExamRoom");
+
+                    b.Navigation("Teacher");
+                });
+
+            modelBuilder.Entity("Jiaowu.Api.Domain.Academic.ExamRoomSession", b =>
+                {
+                    b.HasOne("Jiaowu.Api.Domain.Academic.ExamRoomAssignment", "ExamRoom")
+                        .WithMany("SessionLinks")
+                        .HasForeignKey("ExamRoomId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("Jiaowu.Api.Domain.Academic.ExamSession", "ExamSession")
+                        .WithMany("RoomLinks")
+                        .HasForeignKey("ExamSessionId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.Navigation("ExamRoom");
+
+                    b.Navigation("ExamSession");
+                });
+
+            modelBuilder.Entity("Jiaowu.Api.Domain.Academic.ExamSeatAssignment", b =>
+                {
+                    b.HasOne("Jiaowu.Api.Domain.Academic.ExamRoomAssignment", "ExamRoom")
+                        .WithMany("Seats")
+                        .HasForeignKey("ExamRoomId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("Jiaowu.Api.Domain.Academic.ExamSession", "ExamSession")
+                        .WithMany("SeatAssignments")
+                        .HasForeignKey("ExamSessionId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.HasOne("Jiaowu.Api.Domain.Academic.Student", "Student")
+                        .WithMany()
+                        .HasForeignKey("StudentId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.Navigation("ExamRoom");
+
+                    b.Navigation("ExamSession");
+
+                    b.Navigation("Student");
+                });
+
             modelBuilder.Entity("Jiaowu.Api.Domain.Academic.ExamSession", b =>
                 {
                     b.HasOne("Jiaowu.Api.Domain.Academic.Classroom", "Classroom")
@@ -4832,12 +5037,27 @@ namespace Jiaowu.Api.Infrastructure.Persistence.Migrations.MySql
 
             modelBuilder.Entity("Jiaowu.Api.Domain.Academic.ExamPlan", b =>
                 {
+                    b.Navigation("Rooms");
+
                     b.Navigation("Sessions");
                 });
 
+            modelBuilder.Entity("Jiaowu.Api.Domain.Academic.ExamRoomAssignment", b =>
+                {
+                    b.Navigation("Invigilators");
+
+                    b.Navigation("Seats");
+
+                    b.Navigation("SessionLinks");
+                });
+
             modelBuilder.Entity("Jiaowu.Api.Domain.Academic.ExamSession", b =>
                 {
                     b.Navigation("Invigilators");
+
+                    b.Navigation("RoomLinks");
+
+                    b.Navigation("SeatAssignments");
                 });
 
             modelBuilder.Entity("Jiaowu.Api.Domain.Academic.GradeItem", b =>