feat: implement JMAP push notification handling and subscription management

lib/push/expo.ts

@@ -0,0 +1,61 @@
+import { logger } from '@/lib/logger';
+import type { StateChange, SubscriptionRecord } from './types';
+
+// Expo's push API. Swap via env when self-hosting.
+function getExpoPushUrl(): string {
+  return process.env.EXPO_PUSH_URL ?? 'https://exp.host/--/api/v2/push/send';
+}
+
+export async function sendExpoPush(
+  record: SubscriptionRecord,
+  change: StateChange,
+): Promise<boolean> {
+  // Summarize the JMAP StateChange into a hint the user can see on lock
+  // screen. The app wakes on receipt, re-fetches via JMAP with its own creds,
+  // and can replace the notification via `presentNotificationAsync` if
+  // subject/sender should be shown.
+  const types = new Set<string>();
+  for (const perAccount of Object.values(change.changed)) {
+    for (const type of Object.keys(perAccount)) types.add(type);
+  }
+  const hasEmail = types.has('Email') || types.has('EmailDelivery');
+
+  const message = {
+    to: record.expoPushToken,
+    title: hasEmail ? 'New mail' : 'Mailbox updated',
+    body: record.accountLabel ?? '',
+    sound: 'default',
+    priority: 'high' as const,
+    channelId: 'mail',
+    data: {
+      kind: 'jmap-state-change',
+      changed: change.changed,
+    },
+    _contentAvailable: true,
+  };
+
+  try {
+    const res = await fetch(getExpoPushUrl(), {
+      method: 'POST',
+      headers: {
+        'content-type': 'application/json',
+        accept: 'application/json',
+        'accept-encoding': 'gzip, deflate',
+      },
+      body: JSON.stringify(message),
+    });
+    if (!res.ok) {
+      logger.warn('push: expo delivery failed', {
+        status: res.status,
+        body: await res.text().catch(() => ''),
+      });
+      return false;
+    }
+    return true;
+  } catch (error) {
+    logger.warn('push: expo delivery error', {
+      error: error instanceof Error ? error.message : 'Unknown error',
+    });
+    return false;
+  }
+}