@welshman/router

Utilities for selecting nostr relays.

What's Included

• Router - A configurable router class usable as a singleton which provides common relay selection scenarios.
• RouterScenario - A scenario class which scores relays based on policy.
• getFilterSelections - A high-level utility for inferring relay selections from filters.
• Fallback Policies - Functions to determine how many fallback relays to add.

Quick Example

import {Router, addMaximalFallbacks, getFilterSelections} from '@welshman/router'

// Configure the global router instance
Router.configure({
  getDefaultRelays: () => ['wss://relay.example.com/'],
  getPubkeyRelays: (pubkey, mode) => ['wss://myrelay.example.com/'],
  getIndexerRelays: () => ['wss://indexer.example.com/'],
  getUserPubkey: () => 'user-pubkey',
  getRelayQuality: (url) => 0.8,
  getLimit: () => 5
})

const router = Router.get()

// Get relays for reading events from specific pubkeys
const readRelays = router.FromPubkeys(['pubkey1', 'pubkey2']).getUrls()

// Get relays for publishing an event (author's outbox + mentions' messaginges)
const publishRelays = router.PublishEvent(event).getUrls()

// Try hard to find a quoted note with maximal fallbacks
const searchRelays = router
  .Quote(event, quotedEventId, hints)
  .allowLocal(true)
  .allowOnion(true)
  .allowInsecure(true)
  .policy(addMaximalFallbacks)
  .limit(10)
  .getUrls()

// Automatically select relays based on filters
const relaysAndFilters = getFilterSelections([
  {kinds: [1], authors: ['pubkey1', 'pubkey2']},
  {kinds: [0], search: 'bitcoin'}
])

Installation

npm install @welshman/router

Core Concepts

Router

The main class for relay selection. Configure it once with your relay discovery functions, then use scenario methods to select relays for different purposes.

Configuration Options:

• getUserPubkey() - Returns the current user's pubkey
• getPubkeyRelays(pubkey, mode) - Returns relays for a pubkey ("read", "write", or "messaging")
• getDefaultRelays() - Returns fallback relays
• getIndexerRelays() - Returns relays that index profiles and relay lists
• getSearchRelays() - Returns relays that support NIP-50 search
• getRelayQuality(url) - Returns quality score (0-1) for a relay
• getLimit() - Returns maximum number of relays to select

Scenario Methods:

• FromRelays(relays) - Use specific relays
• ForUser() / FromUser() / UserMessaging() - User's read/write/messaging relays
• ForPubkey(pubkey) / FromPubkey(pubkey) / PubkeyMessaging(pubkey) - Pubkey's relays
• ForPubkeys(pubkeys) / FromPubkeys(pubkeys) - Multiple pubkeys' relays
• Event(event) - Relays for an event's author
• PublishEvent(event) - Relays for publishing (author + mentions)
• Quote(event, id, hints) - Relays for finding a quoted event
• Search() / Index() / Default() - Special relay types

RouterScenario

Represents a relay selection with scoring and filtering options.

Methods:

• getUrls() - Returns selected relay URLs
• getUrl() - Returns first selected relay URL
• limit(n) - Limit number of relays
• weight(scale) - Scale selection weight
• policy(fallbackPolicy) - Set fallback policy
• allowLocal(bool) / allowOnion(bool) / allowInsecure(bool) - Filter relay types

Fallback Policies

Functions that determine how many fallback relays to add:

• addNoFallbacks - Never add fallbacks
• addMinimalFallbacks - Add 1 fallback if no relays found
• addMaximalFallbacks - Fill up to the limit with fallbacks

Filter Selection

getFilterSelections(filters) automatically chooses appropriate relays based on filter content:

• Search filters → search relays
• Wrap events → user's messaging
• Profile/relay kinds → indexer relays
• Author filters → authors' relays
• Everything else → user's relays (low weight)

Returns RelaysAndFilters[] with optimized relay-filter combinations.