fix: Fixed paddle relink sub

admin/internal/licensing/link.go

@@ -4,11 +4,13 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"log"
 	"time"
 
 	"gitea.hostxtra.co.uk/mrhid6/vantage/admin/internal/audit"
 	"gitea.hostxtra.co.uk/mrhid6/vantage/admin/internal/db"
 	"gitea.hostxtra.co.uk/mrhid6/vantage/admin/internal/models"
+	"gitea.hostxtra.co.uk/mrhid6/vantage/admin/internal/paddle"
 	"gitea.hostxtra.co.uk/mrhid6/vantage/shared/license"
 	"github.com/google/uuid"
 	"go.mongodb.org/mongo-driver/v2/bson"
@@ -57,6 +59,48 @@ func LinkInstance(ctx context.Context, accountID, instanceID, name string) (*mod
 	return &inst, nil
 }
 
+// RepointSubscriptions follows an instance identity rewrite: it moves every
+// subscription row from the old id to the new one, then rewrites Paddle's copy
+// of custom_data so future webhooks decode to the new id.
+//
+// The local rewrite is returned as an error — issuance reads the subscription
+// back, so a half-moved row is worth failing on. The Paddle patch only logs: the
+// customer must not be blocked from linking or relinking by an outbound API
+// failure, and the caller has already recorded the old id in
+// previous_instance_ids, which is what makes the webhook path correct whether or
+// not the patch lands.
+func RepointSubscriptions(ctx context.Context, oldID, newID, accountID string) error {
+	if _, err := db.Admin("subscriptions").UpdateMany(ctx,
+		bson.M{"instance_id": oldID},
+		bson.M{"$set": bson.M{"instance_id": newID}}); err != nil {
+		return fmt.Errorf("repoint %s -> %s: %w", oldID, newID, err)
+	}
+
+	cur, err := db.Admin("subscriptions").Find(ctx, bson.M{"instance_id": newID})
+	if err != nil {
+		log.Printf("repoint %s -> %s: read subscriptions: %v", oldID, newID, err)
+		return nil
+	}
+	var subs []models.Subscription
+	if err := cur.All(ctx, &subs); err != nil {
+		log.Printf("repoint %s -> %s: decode subscriptions: %v", oldID, newID, err)
+		return nil
+	}
+	for _, s := range subs {
+		if s.PaddleSubscriptionID == "" {
+			continue
+		}
+		// Paddle replaces the whole custom_data object on a PATCH, so account_id
+		// is sent alongside rather than dropped.
+		if err := paddle.Get().UpdateSubscriptionCustomData(ctx, s.PaddleSubscriptionID,
+			map[string]string{"account_id": accountID, "instance_id": newID}); err != nil {
+			log.Printf("repoint %s -> %s: patch custom_data on %s: %v",
+				oldID, newID, s.PaddleSubscriptionID, err)
+		}
+	}
+	return nil
+}
+
 // Relink moves a licence to a rebuilt server's new UUID.
 //
 // The replacement covers the REMAINING term, not a fresh one — relinking is not
@@ -96,13 +140,25 @@ func Relink(ctx context.Context, accountID, oldID, newID string, staff bool) (*m
 
 	if _, err := db.Admin("admin_instances").UpdateOne(ctx,
 		bson.M{"instance_id": oldID},
-		bson.M{"$set": bson.M{"instance_id": newID}, "$inc": bson.M{"relink_count": 1}}); err != nil {
+		bson.M{
+			"$set":      bson.M{"instance_id": newID},
+			"$inc":      bson.M{"relink_count": 1},
+			"$addToSet": bson.M{"previous_instance_ids": oldID},
+		}); err != nil {
 		if mongo.IsDuplicateKeyError(err) {
 			return nil, ErrAlreadyLinked
 		}
 		return nil, fmt.Errorf("relink: %w", err)
 	}
 
+	// A relink rewrites the instance's identity exactly as a placeholder claim
+	// does, so the same two things have to follow it: the subscription rows that
+	// named the old id, and Paddle's own copy of custom_data. Without this a
+	// renewal after a relink cannot find its instance and the term never extends.
+	if err := RepointSubscriptions(ctx, oldID, newID, accountID); err != nil {
+		return nil, err
+	}
+
 	actor := accountID
 	if staff {
 		actor = "staff"