checkpoint()

Durable step boundary. Persists values on emit, recovers saved state on re-subscribe (Tier 2).

Signature

function checkpoint<A>(
	id: string,
	adapter: CheckpointAdapter,
	opts?: { name?: string },
): (input: Store<A>) => CheckpointedStore<A>

Parameters

Parameter	Type	Description
id	string	Unique checkpoint identifier for persistence.
adapter	CheckpointAdapter	Storage adapter implementing save/load/clear.
opts	{ name?: string }	Optional configuration.

Returns

StoreOperator<A, A> — pipe-compatible. The returned store has a meta property and clear() method.

Method	Signature	Description
get()	() => A \	undefined
meta	Store\<CheckpointMeta\>	Reactive metadata: recovered, persistCount, id.
clear()	() => void	Clear the saved checkpoint value.
source	callbag	Underlying callbag source for subscriptions.

Basic Usage

import { state, pipe, subscribe } from 'callbag-recharge';
import { checkpoint, memoryAdapter } from 'callbag-recharge/orchestrate';

const adapter = memoryAdapter();
const source = state(0);
const durable = pipe(source, checkpoint("step-1", adapter));
subscribe(durable, v => console.log(v));
source.set(42); // persisted to adapter under "step-1"
// On next subscribe: 42 is emitted immediately from adapter

Options / Behavior Details

• Tier 2: Cycle boundary — each persisted value starts a new DIRTY+value cycle.
• Recovery: On subscribe, loads saved value from adapter. If found, emits it immediately before forwarding upstream values.
• Async load buffering: Upstream values during async load are buffered and replayed after recovery.
• Pluggable: Any adapter implementing { save, load, clear } works. Ships with memoryAdapter().

See Also

• track — lifecycle metadata
• pipeline — workflow builder