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0.27.0

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@cBournhonesque cBournhonesque released this 22 Jun 00:53
· 151 commits to main since this release
0.27.0
4c88229

Changelog

This release is still compatible with bevy 0.18. I will submit another release soon for compatibility with bevy 0.19.

Major changes

  • Switched the replication backend to bevy_replicon.

    • The goal is to reuse the wider Bevy networking ecosystem's work, avoid splitting contributor efforts, and benefit from Replicon's well-optimized and documented code.
    • Lightyear still provides its own higher-level replication API for prediction, interpolation, authority metadata, visibility, hierarchy propagation, and pre-spawning.
    • The old lightyear_replication implementation was more tightly integrated with Lightyear and supported having multiple replication senders/receivers per app by adding ReplicationSender and ReplicationReceiver components. Replicon is centered on server-to-client replication, so other replication patterns (client-to-server replication, distributed authority, etc.) are now unsupported.
    • Some old replication-layer features are not yet at parity, including component-level delta compression, authority switching, per-component priority, and some advanced sender/receiver topologies.
    • The move also brings useful Replicon features into Lightyear, including marker-specific replication rules, a flexible visibility-filter system, and mutation/checkpoint information that can be used by prediction and interpolation.
    • Removed the ReplicationGroup API.

  • Added a structured lightyear_debug tracing layer through lightyear_tools.

    • Debug events are emitted as JSONL rows with stable categories such as timeline, prediction, interpolation, input, sync, messages, entities, transport, components, and manual events.
    • Components can be sampled with typed debug or structured JSON formatters by adding LightyearDebug.
    • Structured debug coverage now spans more of the runtime path, including sync/ping, input buffering, prediction rollback, visual correction, frame interpolation, and replication tick advancement. This is intended to make desync investigations easier to automate and easier to inspect with LLM-assisted analysis.

  • Switched Tick from u16 to u32.

    • This avoids practical tick wraparound during normal game sessions and removes a lot of complicated sync/rollback edge cases.
    • Replicon's replication tick is now treated as a transport/checkpoint index and mapped back to Lightyear's authoritative simulation Tick.

  • Improved component registration API.

    • The preferred component registration API is now
app.component::<C>()
   .replicate()
   .predict()
   .with_rollback_condition(f)
   .add_interpolation_with(f);

The main benefits is that you can register a component with lightyear, and then use any replicon function for the replication logic, e.g. app.component::<C>().replicate_once()
Also now you can only call prediction related functions (with_rollback_condition, etc.) after having called predict().
Enabling rollback without replication has now been renamed to local_rollback instead of add_rollback.

Migration notes

  • Naming between Lightyear and Replicon does not line up one-to-one.

    • Replicon's native send-side marker is Replicated, and received entities use Remote.
    • Lightyear keeps Replicate as the user-facing send-side component. Code that previously queried Lightyear receive-side replication markers may need to move to Replicon's Remote, ConfirmHistory, or the Lightyear compatibility exports depending on intent.

  • The visibility API now uses Replicon's visibility filters under the hood.

    • Room-based visibility changed significantly: use RoomAllocator to allocate global RoomIds and add Rooms to entities/clients.
    • Room ids are no longer ad-hoc local values; they must be allocated globally so Replicon's filter bitsets can reason about them consistently.

  • bevy_enhanced_input integration no longer relies on general client-to-server entity replication for action entities.

    • Action entities are now expected to use the pre-spawning flow and must be spawned on both the client and server.
    • Input action replication now serializes the action context through NetworkActionOf and handles rebroadcasted action entities explicitly.

Added

  • Added deterministic-replication late-join catch-up support.

    • New clients can join a running deterministic game without replaying the full historical input log. The catch-up flow combines deterministic input replication with a one-time state snapshot gated through Replicon visibility filters. After receiveing the state snapshot, the new client can just simulate the rest of the game in a deterministic fashion with just input replication.

  • Added optional LZ4 transport packet compression.

    • Compression keeps packet headers uncompressed, validates decompressed payload limits, respects MTU constraints, and includes benchmark coverage.

Prediction and interpolation

  • Prediction and interpolation now use Replicon's confirmation and mutation-checkpoint data to reason about entities/components that did not change. This avoids false predictions where an entity was assumed to have changed simply because no correction arrived.

  • Interpolation is more robust under packet loss and visibility changes.

    • Interpolated entities now delay despawn until the interpolation timeline reaches the authoritative server despawn tick.

  • Fixed several rollback and confirmed-history edge cases.

    • Prediction can now handle predicted entities whose latest confirmed states are not all at the same tick.

Transport and networking fixes

  • Timeline sync is more stable under very low latency, keeping the client timeline at least one tick ahead of the remote/server timeline so deterministic inputs can arrive before the server simulates the target tick.
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