Slots, users, platforms, and cloud

Slot taxonomy

Use explicit namespaces, for example:

• global machine/user settings;
• account/profile unlocks;
• manual playthrough slots;
• autosave/checkpoint ring;
• optional per-world/server cache.

Store display metadata in a small header/index that can be read without loading the entire world payload when the platform permits. Rebuild a cacheable index from authoritative slots when it is missing.

UserIndex identifies the platform user but is ignored on some platforms. ULocalPlayerSaveGame binds a SaveGame to a Local Player and supplies load/create, version, pre/post-save, and async helper lifecycle. Use it for per-local-player state; keep machine-wide settings separate.

The lower-level ISaveGameSystem exposes platform capabilities including multiple-user support, native UI, async operations, and save-name enumeration. Enumeration is not possible on every platform. Query capability rather than assuming desktop behavior.

Cloud/backend

The Online Services User File Interface is Beta in UE 5.8. If used, treat local and remote copies as two versioned replicas with account identity, revision/generation, timestamp, and conflict policy. Time alone is not enough when clocks differ.

Offer keep-local/keep-cloud/manual resolution when merging is unsafe. Never upload before validating the account, schema, payload, and entitlement. Test offline creation, reconnect, concurrent devices, sign-out, account switching, deletion, quota, and interrupted transfer.