# lww-register

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## Purpose

Provides `LWWRegister<T>`, a Last-Write-Wins Register CRDT. The register holds a single value; when two replicas have different values, the one with the higher timestamp wins during merge. Ties are broken by node ID lexicographic order, ensuring deterministic convergence.

## Features

- `set(value, timestamp?)` — sets the value with optional explicit timestamp (defaults to `Date.now()`)
- `get()` — returns the current value or `undefined`
- `merge(state)` — higher timestamp wins; tie-broken by nodeId lexicographic order
- `toJSON()` / `fromJSON()` — serialization round-trip
- `clone()` — deep copy

## Usage: Basic Example

```ts
import { LWWRegister } from "@suaveplan/crdt";

const reg = new LWWRegister<string>("node-1");
reg.set("hello");
console.log(reg.get()); // "hello"
```

## Usage: Advanced Example

```ts
import { LWWRegister } from "@suaveplan/crdt";

const a = new LWWRegister<number>("n1");
a.set(42, 1000);

const b = new LWWRegister<number>("n2");
b.set(99, 2000);

a.merge(b.state());
console.log(a.get()); // 99 (higher timestamp)
```

## API Reference

### `LWWRegister<T>`

- `constructor(nodeId, id?)` — nodeId is required for tie-breaking
- `set(value, timestamp?)` — sets value with timestamp
- `get(): T | undefined` — current value
- `merge(state: LWWRegisterState<T>): void`

## Implementation Notes

Wall-clock timestamps from `Date.now()` can cause issues if clocks are not synchronized. For distributed deployments, use a monotonic or hybrid logical clock and pass the timestamp explicitly via `set(value, timestamp)`.