Add web push

app/push/send.py

@@ -0,0 +1,45 @@
+"""Thin wrapper around pywebpush for sending push notifications.
+
+Isolates the pywebpush dependency and runs the synchronous send in
+a thread executor to avoid blocking the event loop.
+"""
+
+import asyncio
+import logging
+
+from pywebpush import webpush
+
+logger = logging.getLogger(__name__)
+
+
+async def send_push(
+    subscription_info: dict,
+    payload: str,
+    vapid_private_key: str,
+    vapid_claims: dict,
+) -> int:
+    """Send an encrypted push notification.
+
+    Args:
+        subscription_info: {"endpoint": ..., "keys": {"p256dh": ..., "auth": ...}}
+        payload: JSON string to encrypt and send
+        vapid_private_key: PEM-encoded VAPID private key
+        vapid_claims: {"sub": "mailto:..."} or {"sub": "https://..."}
+
+    Returns:
+        HTTP status code from the push service.
+
+    Raises:
+        WebPushException: on push service error (caller handles 404/410 cleanup).
+    """
+    loop = asyncio.get_running_loop()
+    response = await loop.run_in_executor(
+        None,
+        lambda: webpush(
+            subscription_info=subscription_info,
+            data=payload,
+            vapid_private_key=vapid_private_key,
+            vapid_claims=vapid_claims,
+        ),
+    )
+    return response.status_code  # type: ignore[union-attr]