```
@startuml
class UserAccount {
  - Long id
  - String name
  - String email
  - Role role
  - UserStatus status
  - Integer gridX
  - Integer gridY
  + isAccountLocked(): boolean
  + hasSkill(String skill): boolean
}

enum Role { ADMIN, SUPERVISOR, GRID_WORKER }
enum UserStatus { ACTIVE, INACTIVE, SUSPENDED }
UserAccount *-- Role
UserAccount *-- UserStatus
@enduml

```
@startuml
class Feedback {
  - Long id
  - String eventId
  - String title
  - PollutionType pollutionType
  - SeverityLevel severityLevel
  - FeedbackStatus status
  - Long submitterId
  + updateStatus(newStatus)
  + isHighPriority(): boolean
}

class Attachment {
 + id: Long
 + fileName: String
 + fileType: String
 + storedFileName: String
}

enum FeedbackStatus { PENDING_REVIEW, PROCESSED, AI_REJECTED, TASK_CREATED, CLOSED }
Feedback "1" -- "*" Attachment : has
Feedback *-- FeedbackStatus
UserAccount "1" -- "*" Feedback : submits
@enduml

@startuml
class Task {
  - Long id
  - Long feedbackId
  - Long assigneeId
  - Long creatorId
  - TaskStatus status
  - SeverityLevel priority
  + assignTo(userId)
  + markAsCompleted()
}

        class Assignment {
  - Long id
  - Long taskId
  - Long assigneeId
  - AssignmentStatus status
  + accept()
}

class TaskHistory {
  - Long id
  - Task task
  - TaskStatus oldStatus
  - TaskStatus newStatus
  - UserAccount changedBy
}

enum TaskStatus { CREATED, ASSIGNED, IN_PROGRESS, SUBMITTED, APPROVED, REJECTED, CANCELED }
Task "1" -- "1" Feedback : created_from
Task "1" -- "*" Assignment
Task "1" -- "*" TaskHistory
UserAccount "1" -- "*" Task : assigned_to
Task *-- TaskStatus
@enduml

@startuml
class Grid {
  - Long id
  - Integer gridX
  - Integer gridY
  - String cityName
  - boolean isObstacle
}

class MapGrid {
  - Long id
  - int x
  - int y
  - boolean isObstacle
  - String terrainType
}
@enduml
```

@startuml
class AqiData {
  - Long id
  - Grid grid
  - Long reporterId
  - Integer aqiValue
  - String primaryPollutant
}

class AqiRecord {
  - Long id
  - String cityName
  - Integer aqiValue
  - LocalDateTime recordTime
}

class PollutantThreshold {
  - Long id
  - String pollutantName
  - Double threshold
  - String unit
}
@enduml
```

@startuml
class OperationLog {
  - Long id
  - UserAccount user
  - OperationType operationType
  - String description
  - LocalDateTime createdAt
}

class PasswordResetToken {
  - Long id
  - String token
  - UserAccount user
  - LocalDateTime expiryDate
  + isExpired(): boolean
}

class TaskSubmission {
    - Long id
    - Task task
    - String notes
    - LocalDateTime submittedAt
}

class AssignmentRecord {
    - Long id
    - Feedback feedback
    - UserAccount gridWorker
    - UserAccount admin
    - AssignmentMethod assignmentMethod
}
@enduml