checkpoint

Signed-off-by: Sienna Meridian Satterwhite <sienna@r3t.io>

crates/lib/src/networking/mod.rs

@@ -46,6 +46,7 @@ mod operations;
 mod orset;
 mod plugin;
 mod rga;
+mod sync_component;
 mod tombstones;
 mod vector_clock;
 
@@ -67,5 +68,6 @@ pub use operations::*;
 pub use orset::*;
 pub use plugin::*;
 pub use rga::*;
+pub use sync_component::*;
 pub use tombstones::*;
 pub use vector_clock::*;

crates/lib/src/networking/sync_component.rs

@@ -0,0 +1,160 @@
+//! Sync Component trait and supporting types for RFC 0003
+//!
+//! This module defines the core trait that all synced components implement,
+//! along with the types used for strategy selection and merge decisions.
+
+use bevy::prelude::*;
+
+/// Sync strategy enum - determines how conflicts are resolved
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum SyncStrategy {
+    /// Last-Write-Wins: Newer timestamp wins, node ID tiebreaker for concurrent
+    LastWriteWins,
+    /// OR-Set: Observed-Remove Set for collections
+    Set,
+    /// Sequence: RGA (Replicated Growable Array) for ordered lists
+    Sequence,
+    /// Custom: User-defined conflict resolution
+    Custom,
+}
+
+/// Result of comparing vector clocks
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ClockComparison {
+    /// Remote vector clock is strictly newer
+    RemoteNewer,
+    /// Local vector clock is strictly newer
+    LocalNewer,
+    /// Concurrent (neither is newer)
+    Concurrent,
+}
+
+/// Decision made during component merge operation
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ComponentMergeDecision {
+    /// Kept local value
+    KeptLocal,
+    /// Took remote value
+    TookRemote,
+    /// Merged both (for CRDTs)
+    Merged,
+}
+
+/// Core trait for synced components
+///
+/// This trait is automatically implemented by the `#[derive(Synced)]` macro.
+/// All synced components must implement this trait.
+///
+/// # Example
+/// ```
+/// use bevy::prelude::*;
+/// use lib::networking::{SyncComponent, SyncStrategy, ClockComparison, ComponentMergeDecision};
+///
+/// // Example showing what the trait looks like - normally generated by #[derive(Synced)]
+/// #[derive(Component, Reflect, Clone, serde::Serialize, serde::Deserialize)]
+/// struct Health(f32);
+///
+/// // The SyncComponent trait defines these methods that the macro generates
+/// // You can serialize and deserialize components for sync
+/// ```
+pub trait SyncComponent: Component + Reflect + Sized {
+    /// Schema version for this component
+    const VERSION: u32;
+
+    /// Sync strategy for conflict resolution
+    const STRATEGY: SyncStrategy;
+
+    /// Serialize this component to bytes
+    ///
+    /// Uses bincode for efficient binary serialization.
+    fn serialize_sync(&self) -> anyhow::Result<Vec<u8>>;
+
+    /// Deserialize this component from bytes
+    ///
+    /// Uses bincode to deserialize from the format created by `serialize_sync`.
+    fn deserialize_sync(data: &[u8]) -> anyhow::Result<Self>;
+
+    /// Merge remote state with local state
+    ///
+    /// The merge logic is strategy-specific:
+    /// - **LWW**: Takes newer value based on vector clock, uses tiebreaker for concurrent
+    /// - **Set**: Merges both sets (OR-Set semantics)
+    /// - **Sequence**: Merges sequences preserving order (RGA semantics)
+    /// - **Custom**: Calls user-defined ConflictResolver
+    ///
+    /// # Arguments
+    /// * `remote` - The remote state to merge
+    /// * `clock_cmp` - Result of comparing local and remote vector clocks
+    ///
+    /// # Returns
+    /// Decision about what happened during the merge
+    fn merge(&mut self, remote: Self, clock_cmp: ClockComparison) -> ComponentMergeDecision;
+}
+
+/// Marker component for entities that should be synced
+///
+/// Add this to any entity with synced components to enable automatic
+/// change detection and synchronization.
+///
+/// # Example
+/// ```
+/// use bevy::prelude::*;
+/// use lib::networking::Synced;
+/// use sync_macros::Synced as SyncedDerive;
+///
+/// #[derive(Component, Reflect, Clone, serde::Serialize, serde::Deserialize)]
+/// #[derive(SyncedDerive)]
+/// #[sync(version = 1, strategy = "LastWriteWins")]
+/// struct Health(f32);
+///
+/// #[derive(Component, Reflect, Clone, serde::Serialize, serde::Deserialize)]
+/// #[derive(SyncedDerive)]
+/// #[sync(version = 1, strategy = "LastWriteWins")]
+/// struct Position { x: f32, y: f32 }
+///
+/// let mut world = World::new();
+/// world.spawn((
+///     Health(100.0),
+///     Position { x: 0.0, y: 0.0 },
+///     Synced,  // Marker enables sync
+/// ));
+/// ```
+#[derive(Component, Reflect, Default, Clone, Copy)]
+#[reflect(Component)]
+pub struct Synced;
+
+/// Diagnostic component for debugging sync issues
+///
+/// Add this to an entity to get detailed diagnostic output about
+/// its sync status.
+///
+/// # Example
+/// ```
+/// use bevy::prelude::*;
+/// use lib::networking::DiagnoseSync;
+///
+/// let mut world = World::new();
+/// let entity = world.spawn_empty().id();
+/// world.entity_mut(entity).insert(DiagnoseSync);
+/// // A diagnostic system will check this entity and log sync status
+/// ```
+#[derive(Component, Reflect, Default)]
+#[reflect(Component)]
+pub struct DiagnoseSync;
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn strategy_enum_works() {
+        assert_eq!(SyncStrategy::LastWriteWins, SyncStrategy::LastWriteWins);
+        assert_ne!(SyncStrategy::LastWriteWins, SyncStrategy::Set);
+    }
+
+    #[test]
+    fn clock_comparison_works() {
+        assert_eq!(ClockComparison::RemoteNewer, ClockComparison::RemoteNewer);
+        assert_ne!(ClockComparison::RemoteNewer, ClockComparison::LocalNewer);
+    }
+}