Crate nodedb_crdt 

nodedb-crdt

CRDT engine with SQL constraint validation for NodeDB.

The CRDT / SQL Paradox

CRDTs are AP (Available + Partition-tolerant): agents compute optimistic deltas offline and sync later. SQL constraints are CP (Consistent + Partition-tolerant): UNIQUE indexes, foreign keys, etc. must hold globally.

This crate bridges the gap:

1. Optimistic local writes — agents apply deltas to their local LoroDoc without constraint checks (AP behavior for availability).
2. Constraint validation at commit — when deltas sync to the leader, constraints are validated against the committed state.
3. Dead-letter queue — rejected deltas are routed to a DLQ with compensation hints so the application can recover gracefully.
4. Pre-validation — optional fast-reject against the leader’s state before the full Raft round-trip, reducing wasted consensus bandwidth.

Re-exports

pub use constraint::Constraint;

pub use constraint::ConstraintKind;

pub use constraint::ConstraintSet;

pub use dead_letter::CompensationHint;

pub use dead_letter::DeadLetterQueue;

pub use deferred::DeferredQueue;

pub use error::CrdtError;

pub use error::Result;

pub use policy::CollectionPolicy;

pub use policy::ConflictPolicy;

pub use policy::PolicyRegistry;

pub use policy::PolicyResolution;

pub use policy::ResolvedAction;

pub use signing::DeltaSigner;

pub use signing::DeviceRegistry;

pub use state::CrdtState;

pub use validator::ValidationOutcome;

pub use validator::Validator;

Modules

constraint

SQL constraint definitions for CRDT collections.

constraint_checks

Constraint-checking methods for the Validator.

dead_letter

Dead-letter queue for rejected CRDT deltas.

deferred

Deferred retry queue for CASCADE_DEFER policy.

error

Error types for the CRDT engine.

list_ops

LoroMovableList operations for block document model.

policy

Declarative conflict resolution policies for CRDT constraint violations.

pre_validate

Pre-validation: fast-reject before Raft round-trip.

signing

Delta signing and verification using HMAC-SHA256 with replay protection.

state

CRDT state management backed by loro.

validator

Constraint validator — checks deltas against committed state.

Structs

CrdtAuthContext

Authentication context threaded through CRDT validation.