User Story

As a registered player, I want the Velocity proxy to recognize my approved Java account, so that I can join while unknown identities are rejected.

Acceptance Criteria

The plugin sends request ID, server ID, online-mode UUID, username, IP, and occurrence time.
Every request uses a high-entropy per-server bearer credential stored only as a hash by the service.
Requests outside the 45-second clock window are rejected.
Database-unique request IDs reject cross-instance replay attempts.
UUID matching is attempted before username fallback.
Username fallback applies only when the stored account has no UUID.
Successful fallback backfills UUID and canonical username.
Changed usernames are persisted and audited.
Registered players are allowed only when their single effective group has access enabled; explicit assignments override the default group.
Unknown players, group-disabled players, API failures, malformed responses, and unauthorized requests fail closed with registration guidance.
The plugin records the real Velocity connection IP and supports Java Edition online mode only.
After admission, Velocity reports PostLoginEvent as best-effort authenticated telemetry without disconnecting an admitted player when reporting fails.
Confirmed-connection reports use fresh timestamps and database replay protection.