topic()

Create a persistent append-only message stream.

Signature

function topic<T>(name: string, opts?: TopicOptions<T>): Topic<T>

Parameters

Parameter	Type	Description
name	string	Topic name (used for identification and namespacing).
opts	TopicOptions<T>	Optional configuration.

Returns

Topic<T> — publish messages, read by seq, reactive companions, lifecycle control.

Options / Behavior Details

• Backed by reactiveLog: Messages are stored as LogEntry<MessageMeta<T>> in an append-only log with monotonic sequence numbers and optional bounded buffer.
• Schema validation: Pass { parse(v): T } (Zod/Valibot/ArkType compatible) to validate messages at publish time. Invalid messages throw.
• Dedup: Pass dedupKey in publish options. Duplicate keys within the dedup window (default 60s) are silently dropped.
• Delayed messages: Pass delay in publish options. Message is published after the delay via setTimeout.
• Compaction: Configure compaction.keyFn to enable log compaction (retains latest entry per key). Manual via topic internals or auto-triggered at threshold.
• Namespacing: Pass a Namespace to scope the topic name and persistence keys.