MudEngine Part 7: Save & Load

In Part 6 the game world (room names, descriptions, exits) was hardcoded in static arrays in main.rs. Every time the server restarts, all state resets — rooms and connected players are gone.

In this part we make the game data-driven again, following the pattern from Part 3:

• The full 9-room world moves into a game.toml file in the project root
• The server loads game.toml at startup — if the file is missing, the server panics
• Every connected player and their position is tracked in the same file
• On every player join, move, and disconnect, the server writes the updated player list back to disk

This gives us two things: the world definition is editable without recompiling, and player positions survive a server restart (until you restart with real players, at which point they reconnect fresh).

Architecture

game.toml ──load──▶  GameState { rooms, players }
                        │
            ┌───────────┼───────────┐
            ▼           ▼           ▼
        Player join  Player move  Player leave
            │           │           │
            └───────────┼───────────┘
                        ▼
            save_game_state() ──▶ game.toml

On the client side, the hardcoded ROOM_NAMES and ROOM_DESCS statics disappear. The server now sends room data as part of the initial State message, and the client renders room names from that data.