zilencer: Add RemotePushDevice model.

This commit adds a `RemotePushDevice` model where each row
corresponds to an account on an install of the app registered
to receive mobile push notifications.

zilencer/migrations/0065_remotepushdevice.py

@@ -0,0 +1,47 @@
+# Generated by Django 5.2.3 on 2025-06-24 07:49
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("zerver", "0725_realmuserdefault_web_left_sidebar_unreads_count_summary_and_more"),
+        ("zilencer", "0001_squashed_0064_remotezulipserver_last_merge_base"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="RemotePushDevice",
+            fields=[
+                ("device_id", models.BigAutoField(primary_key=True, serialize=False)),
+                ("token", models.CharField(max_length=4096)),
+                ("token_kind", models.PositiveSmallIntegerField(choices=[(1, "APNs"), (2, "FCM")])),
+                ("push_account_id", models.BigIntegerField()),
+                ("expired_time", models.DateTimeField(null=True)),
+                ("ios_app_id", models.TextField(null=True)),
+                (
+                    "realm",
+                    models.ForeignKey(
+                        null=True, on_delete=django.db.models.deletion.CASCADE, to="zerver.realm"
+                    ),
+                ),
+                (
+                    "remote_realm",
+                    models.ForeignKey(
+                        null=True,
+                        on_delete=django.db.models.deletion.CASCADE,
+                        to="zilencer.remoterealm",
+                    ),
+                ),
+            ],
+            options={
+                "constraints": [
+                    models.UniqueConstraint(
+                        fields=("push_account_id", "token"),
+                        name="unique_remote_push_device_push_account_id_token",
+                    )
+                ],
+            },
+        ),
+    ]

zilencer/models.py

@@ -587,3 +587,48 @@ def has_stale_audit_log(server: RemoteZulipServer) -> bool:
         return True
 
     return False
+
+
+class RemotePushDevice(models.Model):
+    """Each row corresponds to an account on an install of the app
+    registered to receive mobile push notifications.
+    """
+
+    device_id = models.BigAutoField(primary_key=True)
+
+    # Set to null for self-hosters. `remote_realm` is set instead.
+    realm = models.ForeignKey(Realm, on_delete=models.CASCADE, null=True)
+
+    # Set to null for zulip cloud. `realm` is set instead.
+    remote_realm = models.ForeignKey(RemoteRealm, on_delete=models.CASCADE, null=True)
+
+    # A token that uniquely identifies the app instance.
+    #
+    # FCM and APNs don't specify a maximum token length, so we only enforce
+    # that they're at most the maximum FCM / APNs payload size of 4096 bytes.
+    token = models.CharField(max_length=4096)
+
+    class TokenKind(models.IntegerChoices):
+        APNS = 1, "APNs"
+        FCM = 2, "FCM"
+
+    token_kind = models.PositiveSmallIntegerField(choices=TokenKind.choices)
+
+    # ID to identify an account within an install of the app.
+    push_account_id = models.BigIntegerField()
+
+    expired_time = models.DateTimeField(null=True)
+
+    # [optional] Contains the app id of the device if it is an iOS device
+    ios_app_id = models.TextField(null=True)
+
+    class Meta:
+        constraints = [
+            UniqueConstraint(
+                # Each app install (token) can have multiple accounts (push_account_id).
+                # The (push_account_id, token) pair needs to be unique to avoid sending
+                # redundant notifications to the same account on a device.
+                fields=["push_account_id", "token"],
+                name="unique_remote_push_device_push_account_id_token",
+            ),
+        ]