implement backend components for push notifications

go/internal/human/pushnotify/token.go

@@ -0,0 +1,43 @@
+// Package pushnotify owns mobile push notification delivery: storage of per-device
+// Expo push tokens, and the worker-side orchestration of sending notifications
+// to offline recipients via the Expo Push API.
+package pushnotify
+
+import (
+	"errors"
+	"strings"
+	"time"
+)
+
+type Platform string
+
+const (
+	PlatformIOS     Platform = "ios"
+	PlatformAndroid Platform = "android"
+)
+
+func (p Platform) Valid() bool {
+	return p == PlatformIOS || p == PlatformAndroid
+}
+
+type PushToken struct {
+	Token       string
+	HumanID     string
+	Platform    Platform
+	AppVersion  string
+	CreatedAt   time.Time
+	LastSeenAt  time.Time
+}
+
+var (
+	ErrInvalidPlatform = errors.New("invalid platform")
+	ErrInvalidToken    = errors.New("invalid expo push token")
+	ErrNotFound        = errors.New("push token not found")
+)
+
+// IsValidExpoToken matches the two prefix formats Expo currently uses.
+// We don't validate the inner contents — Expo's server will reject malformed
+// tokens with a per-message error and we'll clean those up via DeviceNotRegistered.
+func IsValidExpoToken(token string) bool {
+	return strings.HasPrefix(token, "ExponentPushToken[") || strings.HasPrefix(token, "ExpoPushToken[")
+}