reactiveLog()

Creates an append-only reactive log with optional bounded circular buffer semantics.

Signature

function reactiveLog<V>(opts?: ReactiveLogOptions): ReactiveLog<V>

Parameters

Parameter	Type	Description
opts	ReactiveLogOptions	Optional configuration.

ReactiveLogOptions

Property	Type	Default	Description
id	string	undefined	User-specified ID. Auto-generated if omitted.
maxSize	number	0	Maximum number of entries. 0 = unlimited. Oldest trimmed on overflow.

Returns

ReactiveLog<V> — a reactive log with the following API:

Method	Signature	Description
append(value)	(value: V) => number	Append a value. Returns the assigned sequence number.
appendMany(values)	(values: V[]) => number[]	Batch append. Returns sequence numbers.
get(seq)	(seq: number) => LogEntry<V> \	undefined
slice(from?, to?)	(from?: number, to?: number) => LogEntry<V>[]	Range read by sequence number (inclusive).
toArray()	() => LogEntry<V>[]	Snapshot of all entries.
tail(n?)	(n?: number) => Store<LogEntry<V>[]>	Reactive derived store of the last n entries.
events	Store<LogEvent<V> \	undefined>
length	number	Current number of entries.
clear()	() => void	Remove all entries.
destroy()	() => void	Tear down all reactive stores.

Basic Usage

import { reactiveLog } from 'callbag-recharge';

const log = reactiveLog<string>({ maxSize: 100 });
log.append('hello');
log.toArray(); // [{ seq: 1, value: 'hello' }]

Options / Behavior Details

• Circular buffer: When maxSize > 0, the log uses a fixed-size circular buffer for O(1) appends. Oldest entries are silently overwritten when the buffer is full.
• Reactive views: tail() returns a derived store that updates whenever the log changes. Multiple calls with the same n share the same derived store.

See Also

• executionLog — pipeline execution log
• pipeline — workflow builder