kh2coop_server runs without KH2 attached. It admits peers, assigns canonical slots and routes host-native avatar/world/session traffic. Native traffic is the default; synthetic physics is available only with --simulate for tests. Steam sessions use the in-game broker and do not start this separate ENet server.

Build with cmake --build build --target kh2coop_server --config Release. For a local development session:

.\build\Release\kh2coop_server.exe --bind 127.0.0.1 --port 7946 --build dev --content none --mod none

Select matching game/content/mod labels and port on every runtime. The server's default port is 7782, while the standalone runtime defaults to 7946. Without --bind, the server listens on all interfaces; use an explicit loopback or authorized private address for development.

• SessionHost gates protocol/build/content/mod compatibility, maintains the roster and routes admitted host world authority.
• Host-agreed settings include room-locked co-op difficulty and friendly fire; a friend's environment does not override them.
• Native world caching, ordered HP/death, resync and diagnostic collection are implemented. See forced resync, HP ordering and desync reports for their bounds.
• SimulationState provides fake movement/combat only when explicitly enabled. It does not replace the host's live game simulation.
• ServerMain services ENet on an approximately 16 ms loop and stops on Ctrl+C.

Current source requires protocol 34 peers. Compatibility labels are handshake values, not binary provenance; rebuild and select a coherent source cohort. The project plan records current native acceptance and remaining route/reconnect work. Public-realm session/instance splitting is not the current campaign milestone.

For headless regression use the serial CTest suite and kh2coop_fake_sim described in setup; these do not establish live gameplay correctness.