feat: add initial Django domain models

backend/checkins/admin.py

@@ -0,0 +1,17 @@
+from django.contrib import admin
+
+from .models import CheckIn
+
+
+@admin.register(CheckIn)
+class CheckInAdmin(admin.ModelAdmin):
+    list_display = ("reservation", "checked_in_at", "checked_in_by", "source", "created_at")
+    list_filter = ("source", "checked_in_at", "created_at")
+    search_fields = (
+        "reservation__name",
+        "reservation__email",
+        "reservation__performance__show__title",
+        "checked_in_by__username",
+        "checked_in_by__email",
+    )
+    readonly_fields = ("created_at", "updated_at")

backend/checkins/migrations/0001_initial.py

@@ -0,0 +1,54 @@
+# Generated by Django 5.2.3 on 2026-04-28
+
+import django.db.models.deletion
+import django.utils.timezone
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    initial = True
+
+    dependencies = [
+        ("bookings", "0001_initial"),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="CheckIn",
+            fields=[
+                ("id", models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name="ID")),
+                ("checked_in_at", models.DateTimeField(default=django.utils.timezone.now)),
+                (
+                    "source",
+                    models.CharField(choices=[("qr_scan", "QR scan"), ("manual", "Manual")], default="qr_scan", max_length=20),
+                ),
+                ("created_at", models.DateTimeField(auto_now_add=True)),
+                ("updated_at", models.DateTimeField(auto_now=True)),
+                (
+                    "checked_in_by",
+                    models.ForeignKey(
+                        on_delete=django.db.models.deletion.PROTECT,
+                        related_name="checkins",
+                        to=settings.AUTH_USER_MODEL,
+                    ),
+                ),
+                (
+                    "reservation",
+                    models.OneToOneField(
+                        on_delete=django.db.models.deletion.PROTECT,
+                        related_name="check_in",
+                        to="bookings.reservation",
+                    ),
+                ),
+            ],
+            options={
+                "ordering": ["-checked_in_at"],
+                "indexes": [
+                    models.Index(fields=["checked_in_at"], name="checkins_ch_checked_761e33_idx"),
+                    models.Index(fields=["checked_in_by"], name="checkins_ch_checked_becaae_idx"),
+                ],
+            },
+        ),
+    ]

backend/checkins/migrations/__init__.py

@@ -0,0 +1 @@
+

backend/checkins/models.py

@@ -1 +1,46 @@
-# Domain models will be added when check-in behavior is implemented.
+from django.conf import settings
+from django.core.exceptions import ValidationError
+from django.db import models
+from django.utils import timezone
+
+from bookings.models import Reservation
+
+
+class CheckIn(models.Model):
+    class Source(models.TextChoices):
+        QR_SCAN = "qr_scan", "QR scan"
+        MANUAL = "manual", "Manual"
+
+    reservation = models.OneToOneField(
+        Reservation,
+        on_delete=models.PROTECT,
+        related_name="check_in",
+    )
+    checked_in_at = models.DateTimeField(default=timezone.now)
+    checked_in_by = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        on_delete=models.PROTECT,
+        related_name="checkins",
+    )
+    source = models.CharField(max_length=20, choices=Source.choices, default=Source.QR_SCAN)
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+
+    class Meta:
+        ordering = ["-checked_in_at"]
+        indexes = [
+            models.Index(fields=["checked_in_at"]),
+            models.Index(fields=["checked_in_by"]),
+        ]
+
+    def __str__(self):
+        return f"Check-in for reservation {self.reservation_id}"
+
+    def clean(self):
+        super().clean()
+        if self.reservation_id and not self.reservation.is_confirmed:
+            raise ValidationError({"reservation": "Only confirmed reservations can be checked in."})
+
+    def save(self, *args, **kwargs):
+        self.full_clean()
+        return super().save(*args, **kwargs)