Feature Specification: Attendance Management

1. Overview & Vision

The Attendance module provides real-time check-in/out tracking, automated late detection, overtime calculation, and an organization-wide attendance summary for HR managers — replacing manual timesheets.

2. Personas & Stakeholders

Persona	Goal
Employee	Check in/out daily and view their own monthly timesheet.
Manager	See which team members are present, late, or absent today.
HR Admin	Review org-wide attendance trends and export timesheets.

3. User Stories

• As an employee, I want to check in from the app so my attendance is recorded without a physical scanner.
• As a manager, I want to see who on my team is late today so I can plan accordingly.
• As HR, I want a monthly summary of late arrivals per department.

4. Functional Requirements (FR)

• REQ-AT-001: Self-service check-in and check-out from the HRM UI.
• REQ-AT-002: Automated late detection — flag if check-in is after the configured shift start time.
• REQ-AT-003: Overtime calculation — hours beyond the standard shift are flagged and summed.
• REQ-AT-004: Monthly timesheet view per employee with daily status (Present / Late / Absent / Leave).
• REQ-AT-005: Org-wide attendance summary — HR can see all employees' status for any given day.

5. Non-Functional Requirements (NFR)

• Accuracy: Check-in timestamp recorded server-side to prevent client clock manipulation.
• Idempotency: Multiple check-in attempts on the same day are rejected after the first.

6. Business Logic & Rules

• Status Rules: An employee can only check out after checking in on the same day.
• Late Threshold: Configurable per shift (default: check-in > 5 minutes after shift start = late).
• Overtime: Any check-out more than 30 minutes after shift end is counted as overtime (configurable).
• Leave Sync: Days with an approved leave request are automatically marked as Leave, not Absent.

7. User Interface (UI/UX)

• Check-in card: Prominent button on the employee dashboard; changes to "Check Out" after check-in.
• Timesheet: Monthly calendar grid — each cell shows status badge + check-in/out times.
• Org Summary: Table view for HR — employee rows × day columns, color-coded status cells.

8. Information Architecture

• "Attendance" section in HRM sidebar, accessible to all employees.
• HR-only "Summary" tab within Attendance.

9. Data Model & Persistence

• Table: attendance_records (employee_id, date, check_in_at, check_out_at, status, overtime_minutes).

10. API & Service Layer

• POST /attendance/check-in
• POST /attendance/check-out
• GET /attendance/me?month=YYYY-MM
• GET /attendance/summary?date=YYYY-MM-DD (HR only)

11. Integration Patterns

• Leave sync: Queries leave_requests to auto-fill leave days in the timesheet.
• Notifications: Late arrival triggers an in-app notification to the employee's manager.

12. Security & Permissions

• RBAC: All employees can check in/out and view their own records. attendance:read_all for HR.
• Isolation: Org-scoped — employees only see their own org's data.

13. Error Handling & Resilience

• Double check-in returns 409 Conflict with a descriptive message.
• Check-out without check-in returns 400 Bad Request.

14. Performance & Scalability

• Daily summaries are pre-aggregated at midnight via a background job.

15. Globalization & i18n

• Shift times respect the organization's configured timezone.

16. Accessibility (a11y)

• Check-in button has ARIA label; status badges have text alternatives.

17. Observability & Analytics

• Late arrival rate per department (feeds into the Analytics module).
• Overtime hours trending over past 30 days.

18. Testing & Quality

• Unit tests for check-in/out status rules and overtime calculation.
• Integration tests for leave-sync auto-fill logic.

19. Constraints & Assumptions

• Single shift per day per employee (multiple shifts planned for v2).

20. Future Enhancements

• Geo-fenced check-in (require employee to be on-site).
• QR-code based check-in for physical terminals.
• Multi-shift support.