Character movement networking

Standard flow

• Autonomous proxy performs local movement, records FSavedMove_Character, and sends packed move data.
• Server reproduces and validates movement, then acknowledges or corrects.
• Owning client replays unacknowledged saved moves after a correction.
• Simulated proxies receive replicated movement and use network smoothing.

Standard CMC modes implement this. New custom state does not become predicted merely because it lives on an ACharacter.

Custom predicted state

When a custom movement flag/value changes physics:

1. Add it to a custom FSavedMove_Character and clear/store/combine it correctly.
2. Extend FCharacterNetworkMoveData with values the server must receive.
3. Serialize them.
4. Provide a custom FCharacterNetworkMoveDataContainer.
5. Install it through SetNetworkMoveDataContainer in the custom CMC.
6. Apply the data before the server reproduces movement.
7. Test move combining; moves with incompatible state must not combine.

Use compressed flags only when their limited space and boolean semantics fit. Follow current 5.8 engine headers/source for signatures.

Corrections and smoothing

• Fix deterministic divergence before tuning smoothing.
• NetworkSmoothingMode affects simulated-proxy presentation, not server authority.
• Location/rotation smoothing times and no-smooth distances are advanced levers; do not use them to conceal constant corrections.
• Keep visual mesh smoothing separate from authoritative capsule state.

Verification matrix

Run standalone, listen server, and dedicated server where relevant:

• owning autonomous proxy;
• server-controlled AI;
• remote simulated proxy;
• 0/medium/high artificial latency;
• packet loss and jitter;
• low and high frame rates;
• sprint/crouch/custom-mode transitions while moves combine;
• moving platforms and jump-off velocity;
• root motion start/cancel/finish;
• teleport;
• server rejection/correction.

Log role, movement/custom mode, acceleration, velocity, location error, correction count, saved custom flags/data, and root-motion sources. Never ship with client-authoritative position or correction bypasses enabled as a workaround.