RUDPClient/openspec/changes/archive/2026-03-28-replace-remote-movement-smoothing-with-snapshot-interpolation/tasks.md

1. Remote Snapshot Buffer

• 1.1 Add a focused client-side remote snapshot interpolation helper that stores accepted authoritative PlayerState samples in tick order with bounded buffer size and receive-time metadata.
• 1.2 Ensure stale or duplicate remote PlayerState samples are rejected before they can enter the interpolation buffer, while keeping ClientAuthoritativePlayerState as the latest authoritative owner.
• 1.3 Document the chosen interpolation delay and sample-selection strategy in code comments or adjacent docs where the helper is introduced.

2. Client Presentation Integration

• 2.1 Update remote-player presentation in MovementComponent to read from the interpolation helper and interpolate authoritative position and rotation between buffered snapshots instead of lerping directly to the latest snapshot.
• 2.2 Keep the local-player reconcile path unchanged and ensure remote fallback behavior clamps to the latest accepted authoritative snapshot when interpolation cannot bracket two samples.
• 2.3 Keep remote players presentation-only by avoiding extrapolation or any new remote prediction path while continuing to consume authoritative ownership from Player.

3. Validation

• 3.1 Add or extend edit-mode tests for remote snapshot buffering, stale-packet rejection, and bounded-buffer behavior.
• 3.2 Add or extend regression tests for remote interpolation output or fallback-to-latest behavior when samples are insufficient or out of order.
• 3.3 Run the relevant validation flow and confirm the new remote snapshot interpolation path works in editor or CLI testing.