Crate batpak 

batpak: Event Sourcing Runtime with DAG Causation Tracking.

Batpak provides a complete event sourcing platform with:

• Event Sourcing: Immutable event log with hash chain integrity
• DAG Causation: Tracks causation relationships between events
• Gate Evaluation: Pluggable policy enforcement before event commitment
• Persistent Storage: Segment-based append-only store with fast querying

The core pattern: acquire a Proposal, evaluate it through Gate instances, then commit to the Store.

use batpak::prelude::*;

let store = Store::open(StoreConfig::new("./my-store"))?;
let gates: GateSet<()> = GateSet::new();
let pipeline = Pipeline::new(gates);

let coord = Coordinate::new("entity:1", "scope:test")?;
let kind = EventKind::custom(0xF, 1);
let payload = serde_json::json!({"hello": "world"});

let proposal = Proposal::new(payload.clone());
let receipt = pipeline.evaluate(&(), proposal)?;
let committed = pipeline.commit(receipt, |p| -> Result<_, StoreError> {
    let r = store.append(&coord, kind, &p)?;
    Ok(Committed { payload: p, event_id: r.event_id, sequence: r.sequence, hash: [0u8; 32] })
})?;

Reading order:

1. coordinate: Identify entities and scopes
2. event: Structure your events
3. guard: Build policy gates
4. pipeline: Propose and commit
5. store: Persist and query

Modules

coordinate

Entity and scope addressing for events.

event

Event types, headers, and sourcing traits.

guard

Policy gate evaluation before event commitment.

id

UUID v7 identifier generation.

outcome

Result-like type for pipeline operations.

pipeline

Propose-evaluate-commit workflow.

prelude

Common re-exports for convenient use.

store

Persistent event storage and querying.

typestate

Compile-time state machine transitions.

wire

Module declarations in DEPENDENCY ORDER: wire → coordinate → outcome → event → guard → pipeline → store → typestate → id → prelude [SPEC:src/lib.rs — Module declarations in DEPENDENCY ORDER] Serde serialization helpers.

Macros

define_entity_id

define_entity_id!: Layer 1+ macro. Uses generate_v7_id() helper. Downstream crates do NOT need uuid as a direct dependency.

define_state_machine

define_state_machine!: generates a sealed marker trait + zero-sized state structs. [SPEC:src/typestate/mod.rs — 99 LOC of macros]

define_typestate

define_typestate!: generates a PhantomData wrapper for typed state machines. [SPEC:src/typestate/mod.rs]