ue5-save-load-replication

Quick Start

• Define what must persist and what must replicate.
• Separate local save state from network runtime state.
• Output data schema, save flow, load flow, and net flow.

UE5.7 API Anchors

• Save pipeline anchors:
  • USaveGame
  • UGameplayStatics::CreateSaveGameObject(...)
  • UGameplayStatics::SaveGameToSlot(...), LoadGameFromSlot(...)
  • UGameplayStatics::AsyncSaveGameToSlot(...), AsyncLoadGameFromSlot(...)
• Replication anchors:
  • GetLifetimeReplicatedProps(...)
  • DOREPLIFETIME(...)
  • ReplicatedUsing=OnRep_*
  • UFUNCTION(Server/Client/NetMulticast, ...)
• Authority anchors:
  • server-authoritative mutation path
  • client requests routed through validated server RPC entry points

State Contract

• Every state field must be classified as one of:
  • Persistent-only (SaveGame, not replicated)
  • Replicated-only (runtime sync, not persisted)
  • Persistent + replicated (authoritative state with save restore)
• Every persisted schema must include:
  • explicit version integer
  • stable identifiers/keys (avoid index-based implicit ordering)
  • migration behavior for older versions
• Every replicated field must define:
  • replication condition or scope
  • OnRep_* behavior on clients
  • server write ownership

Workflow

1) Partition State

• Identify gameplay state by ownership: local player, world/shared, match/session.
• Split ephemeral runtime values from persistent values.
• Mark authoritative write path for each field.

2) Save Schema

• Define save structs/objects with explicit schema version.
• Use stable keys/IDs for actors, components, and inventory-like entries.
• Include optional migration metadata for backward compatibility.

3) Save Pipeline

• Gather runtime state into save schema in deterministic order.
• Write through sync or async slot APIs based on latency sensitivity.
• Return structured save result (success, failure reason, version used).

4) Load and Restore Pipeline

• Load save object, validate version, run migration if needed.
• Apply restore in dependency-safe order (owners before dependents).
• Resolve missing assets/entities with explicit fallback policy.