Lobby image (Paper + felis-paper)

The always-on lobby hub. felis setup provisions it as a system service (DesiredState=Running, reaper-exempt) when [velocity] lobby_image is set in felis.toml.

Code-only. Not built by the Go CI. It compiles the plugins/paper /menu face and bundles it onto a Paper server.

Topology & the one invariant

connect → login (limbo auth gate) → lobby (/menu hub) → target backend

The lobby is reached only when the login gate transfers an authenticated player onward. It is never a fallback or waiting-park target — routing a fresh connection to the lobby would drop the player past authentication. Felis enforces this at every layer:

the login system service has no fallback (refuse if down);
the lobby and every user server fall back to login, never to the lobby;
buildSystemServer refuses to construct any service whose fallback is lobby;
felis setup prints the off-cluster Velocity wiring: default landing and waiting-park both point at login.

Build

docker build -f deploy/lobby/Dockerfile \
  --build-arg PAPER_JAR_URL=https://<mirror>/paper-1.21.x-<build>.jar \
  --build-arg PAPER_JAR_SHA256=<sha256 of that jar> \
  -t felis-lobby:demo .
docker save felis-lobby:demo | sudo k3s ctr images import -
# felis.toml → [velocity] lobby_image = "felis-lobby:demo"
sudo felis setup

Configure (deployer's responsibility)

Game port must be 25565 (the CRD GamePort).
Align online-mode / player forwarding with the off-cluster Velocity proxy.
The lobby speaks only the felis:control plugin-message channel; it holds no felis-api token by design (spec §12).