feat(absences): Absence model + migration + admin registration

Per-worker dated records with 8 reason choices (Sick/Family/Annual/
Personal-Unpaid/IOD/Suspension/Absconded/Other), is_paid flag, optional
OneToOne to PayrollAdjustment for the auto-Bonus path, audit fields.
Unique-per-day at DB layer. 4 model tests.

core/admin.py

@@ -5,6 +5,7 @@ from .models import (
     ExpenseReceipt, ExpenseLineItem,
     WorkerCertificate, WorkerWarning,
     SiteReport,
+    Absence,
 )
 
 @admin.register(UserProfile)
@@ -85,6 +86,15 @@ class WorkerWarningAdmin(admin.ModelAdmin):
     search_fields = ('worker__name', 'reason', 'description')
     date_hierarchy = 'date'
 
+@admin.register(Absence)
+class AbsenceAdmin(admin.ModelAdmin):
+    list_display = ('worker', 'date', 'reason', 'is_paid', 'logged_by', 'created_at')
+    list_filter = ('reason', 'is_paid', 'date')
+    search_fields = ('worker__name', 'worker__id_number', 'notes')
+    raw_id_fields = ('worker', 'logged_by', 'payroll_adjustment')
+    readonly_fields = ('created_at', 'updated_at')
+    date_hierarchy = 'date'
+
 @admin.register(Team)
 class TeamAdmin(admin.ModelAdmin):
     list_display = ('name', 'supervisor', 'pay_frequency', 'pay_start_date', 'active')

core/migrations/0014_add_absence.py

@@ -0,0 +1,36 @@
+# Generated by Django 5.2.7 on 2026-05-14 17:19
+
+import django.db.models.deletion
+import django.utils.timezone
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0013_add_site_report'),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Absence',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('date', models.DateField(default=django.utils.timezone.now)),
+                ('reason', models.CharField(choices=[('sick', 'Sick'), ('family', 'Family Responsibility'), ('annual', 'Annual Leave'), ('unpaid', 'Personal / Unpaid Leave'), ('iod', 'Injury on Duty'), ('suspension', 'Suspension'), ('absconded', 'Absconded'), ('other', 'Other')], max_length=20)),
+                ('notes', models.TextField(blank=True, help_text='Free-form context (e.g. "flu, doctor\'s note", "bus broke down").')),
+                ('is_paid', models.BooleanField(default=False, help_text='Tick to pay the worker their daily rate for this day.')),
+                ('created_at', models.DateTimeField(auto_now_add=True)),
+                ('updated_at', models.DateTimeField(auto_now=True)),
+                ('logged_by', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='absences_logged', to=settings.AUTH_USER_MODEL)),
+                ('payroll_adjustment', models.OneToOneField(blank=True, help_text='Auto-created when is_paid=True. Cleared if is_paid is unchecked.', null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='absence', to='core.payrolladjustment')),
+                ('worker', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='absences', to='core.worker')),
+            ],
+            options={
+                'ordering': ['-date', '-created_at'],
+                'unique_together': {('worker', 'date')},
+            },
+        ),
+    ]

core/models.py

@@ -454,3 +454,70 @@ class WorkerWarning(models.Model):
 
     def __str__(self):
         return f'{self.worker.name} — {self.get_severity_display()} ({self.date})'
+
+
+class Absence(models.Model):
+    """Per-worker, dated record of a day NOT worked. The supervisor or
+    admin captured WHY (sick, annual leave, absconded, etc.) and
+    optionally whether the day is to be paid at the worker's daily rate.
+
+    When `is_paid` is True the save flow (in views) creates a Bonus
+    PayrollAdjustment for that worker on that date, linked via the
+    OneToOneField below. Edit/delete of the Absence propagates the
+    adjustment (mirrors the Advance Payment -> Loan -> Repayment
+    cascade pattern in payroll).
+    """
+
+    # === ABSENCE REASONS ===
+    # SA labour-relations terminology. The DB stores the snake_case key;
+    # users see the human label via get_reason_display().
+    REASON_CHOICES = [
+        ('sick',         'Sick'),
+        ('family',       'Family Responsibility'),
+        ('annual',       'Annual Leave'),
+        ('unpaid',       'Personal / Unpaid Leave'),
+        ('iod',          'Injury on Duty'),
+        ('suspension',   'Suspension'),
+        ('absconded',    'Absconded'),
+        ('other',        'Other'),
+    ]
+
+    worker = models.ForeignKey(
+        Worker, related_name='absences', on_delete=models.CASCADE,
+    )
+    date = models.DateField(default=timezone.now)
+    reason = models.CharField(max_length=20, choices=REASON_CHOICES)
+    notes = models.TextField(
+        blank=True,
+        help_text='Free-form context (e.g. "flu, doctor\'s note", "bus broke down").',
+    )
+
+    # === PAYROLL LINK ===
+    is_paid = models.BooleanField(
+        default=False,
+        help_text='Tick to pay the worker their daily rate for this day.',
+    )
+    payroll_adjustment = models.OneToOneField(
+        'PayrollAdjustment',
+        on_delete=models.SET_NULL,
+        null=True, blank=True,
+        related_name='absence',
+        help_text='Auto-created when is_paid=True. Cleared if is_paid is unchecked.',
+    )
+
+    # === AUDIT ===
+    logged_by = models.ForeignKey(
+        User, on_delete=models.SET_NULL, null=True, blank=True,
+        related_name='absences_logged',
+    )
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        # One absence per worker per day — enforced at the DB layer.
+        unique_together = [('worker', 'date')]
+        # Newest first on lists.
+        ordering = ['-date', '-created_at']
+
+    def __str__(self):
+        return f'{self.worker.name} — {self.get_reason_display()} — {self.date:%d %b %Y}'

core/tests.py

@@ -10,7 +10,7 @@ from django.contrib.auth.models import User
 from django.test import TestCase
 from django.urls import reverse
 
-from core.models import Project, Team, Worker, WorkLog, PayrollRecord, PayrollAdjustment, Loan
+from core.models import Project, Team, Worker, WorkLog, PayrollRecord, PayrollAdjustment, Loan, Absence
 from core.views import _build_work_log_payroll_context, _build_report_context
 
 
@@ -1684,3 +1684,53 @@ class AttendanceLogRedirectsToSiteReportTests(TestCase):
                         msg=f"Expected redirect to .../edit/, got {response.url}")
         # And exactly one work log was created
         self.assertEqual(WorkLog.objects.count(), 1)
+
+
+# ====================================================================
+# === Worker Absence — Phase 1: Model layer ==========================
+# ====================================================================
+
+from datetime import date as _date
+from django.db import IntegrityError
+
+
+class AbsenceModelTests(TestCase):
+    """Per-worker dated absence records. Mirrors WorkerWarning shape."""
+
+    @classmethod
+    def setUpTestData(cls):
+        cls.worker = Worker.objects.create(
+            name='Joe Mokoena', id_number='8001015800086',
+            monthly_salary=Decimal('6000.00'),
+        )
+
+    def test_defaults(self):
+        """is_paid defaults to False; payroll_adjustment is null; date defaults to today."""
+        a = Absence.objects.create(worker=self.worker, reason='sick')
+        # Re-fetch from DB so the DateField default (timezone.now) is coerced
+        # from datetime → date by the DB layer (mirrors WorkerWarning pattern).
+        a.refresh_from_db()
+        self.assertFalse(a.is_paid)
+        self.assertIsNone(a.payroll_adjustment)
+        self.assertEqual(a.date, _date.today())
+
+    def test_unique_per_worker_per_day(self):
+        """Cannot have two absences for the same worker on the same day."""
+        d = _date(2026, 5, 14)
+        Absence.objects.create(worker=self.worker, date=d, reason='sick')
+        with self.assertRaises(IntegrityError):
+            Absence.objects.create(worker=self.worker, date=d, reason='family')
+
+    def test_ordering_newest_first(self):
+        """Default queryset order is -date."""
+        Absence.objects.create(worker=self.worker, date=_date(2026, 5, 10), reason='sick')
+        Absence.objects.create(worker=self.worker, date=_date(2026, 5, 15), reason='annual')
+        Absence.objects.create(worker=self.worker, date=_date(2026, 5, 12), reason='other')
+        dates = list(Absence.objects.values_list('date', flat=True))
+        self.assertEqual(dates, [_date(2026, 5, 15), _date(2026, 5, 12), _date(2026, 5, 10)])
+
+    def test_reverse_accessor_on_worker(self):
+        """worker.absences.all() works (related_name='absences')."""
+        Absence.objects.create(worker=self.worker, date=_date(2026, 5, 1), reason='sick')
+        Absence.objects.create(worker=self.worker, date=_date(2026, 5, 2), reason='family')
+        self.assertEqual(self.worker.absences.count(), 2)