feat: pwa notifications

accounts/models.py

@@ -40,3 +40,36 @@ class ApiToken(models.Model):
     def touch(self):
         self.last_used_at = timezone.now()
         self.save(update_fields=["last_used_at"])
+
+
+class PushSubscription(models.Model):
+    """One installed PWA that has agreed to receive reminders.
+
+    The endpoint is issued by the browser's push service; the two keys are what
+    let us encrypt a payload only that device can read.
+    """
+
+    user = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        on_delete=models.CASCADE,
+        related_name="push_subscriptions",
+    )
+    endpoint = models.URLField(max_length=500, unique=True)
+    p256dh = models.CharField(max_length=200)
+    auth = models.CharField(max_length=100)
+    user_agent = models.CharField(max_length=300, blank=True)
+    created_at = models.DateTimeField(auto_now_add=True)
+    last_success_at = models.DateTimeField(null=True, blank=True)
+
+    class Meta:
+        ordering = ["-created_at"]
+
+    def __str__(self):
+        return f"{self.user} — {self.user_agent[:40] or self.endpoint[:40]}"
+
+    def as_subscription_info(self) -> dict:
+        """The shape pywebpush expects, i.e. what the browser handed us."""
+        return {
+            "endpoint": self.endpoint,
+            "keys": {"p256dh": self.p256dh, "auth": self.auth},
+        }