One contract, proven at the boundary.

Two implementations of the same contract are only safe if they agree, so the boot proves it. The self-check mints, encodes, decodes, and hashes a known id down both paths and asserts the committed vector — the same placement(USR0KHTOWnGLuC) = 234878118 — then returns the mode that served. A node whose native core disagrees with the pure one never reaches its first message.

This is what lets the native path be an optimization rather than a fork. Because the contract is pinned by a vector and checked at start, the question of native or pure is a question of speed, never of meaning: an id placed by the Rust core lands in the same slot the Elixir core would choose, in the tries, in the tables, and in any other runtime that computes the same hash. The boundary is where speed is allowed to vary and meaning is not.

Codemojex spans machines and builds, and this is why they agree. A room on a native node and a worker on a pure node resolve a player’s id to the same value because both proved the contract at boot, not because they happen to share a binary. The gate decides what may enter; the contract decides that everyone who enters is understood the same way.