When new users register with trial subscription enabled, the subscription
link fails to connect in Clash clients. This is caused by missing cache
invalidation after transaction commit.
Changes:
- Add cache clearing after successful trial subscription creation
- Clear user subscription cache, subscription details cache, and server cache
- Modify activeTrial functions to return subscription object for cache clearing
- Apply fix to all registration methods: email, phone, device, and OAuth
This ensures subscription links work immediately after registration without
requiring manual subscription reset.
- Add optional short_code parameter to DeviceLoginRequest
- Add ShortCode field to Device model
- Save short_code to database during device registration
- Add database migration for user_device.short_code column
- Fix duplicate variable declaration in routes.go
