welshman-content

name	welshman-content
description	Use this skill when working with @welshman/content: parsing nostr note content, extracting mentions/links/media/topics, or rendering parsed content to HTML or custom formats.

welshman/content — Note Content Parsing

@welshman/content parses raw nostr event content strings into structured typed elements (links, profiles, events, topics, media, etc.) and renders them back to text or HTML. It is a standalone package with no welshman sibling dependencies — it sits at the bottom of the stack and can be used independently or alongside @welshman/app, @welshman/net, etc.

Installation

npm install @welshman/content
# or
pnpm add @welshman/content
yarn add @welshman/content

Key Exports

Parsing

Export	Description
parse({ content?, tags? })	Main entry point. Parses a content string (and optional event tags) into a Parsed[] array. Falls back to the alt tag if content is empty.
truncate(content, opts?)	Truncates a Parsed[] array, appending an Ellipsis element. Leaves content unchanged if it fits within maxLength.
reduceLinks(content)	Collapses consecutive block-level links (each on its own line) into a single LinkGrid element for gallery rendering.
urlIsMedia(url)	Returns true if the URL has a media file extension (jpg, png, gif, webp, mp4, etc.).

Parsed Types

ParsedType enum values and their corresponding type shapes:

ParsedType	value type	Notes
Text	string	Plain text
Newline	string	One or more \n characters
Topic	string	Hashtag text without the #; numeric-only tags are skipped
Link	{ url: URL, meta: Record<string, string> }	URLs with any scheme (http, https, ftp, ws, wss, etc.) and bare domains without a protocol; meta is populated from imeta tags or URL hash params
LinkGrid	{ links: ParsedLinkValue[] }	Produced by reduceLinks; a collection of adjacent block links
Profile	ProfilePointer ({ pubkey, relays? })	nostr:npub / nostr:nprofile / @nostr:npub / @nostr:nprofile references (the nostr: prefix is required)
Event	EventPointer ({ id, relays?, author?, kind? })	note / nevent references
Address	AddressPointer ({ identifier, pubkey, kind, relays? })	naddr references
Emoji	{ name: string, url?: string }	:shortcode: — url resolved from emoji tags
Code	string	Backtick inline code or triple-backtick blocks
Cashu	string	cashu: token strings
Invoice	string	Bare lightning invoice string (without lightning: prefix); the lightning: prefix is in raw
Email	string	Email addresses (with or without mailto:)
Ellipsis	string	Appended by truncate to indicate truncated content

Every Parsed element also has a raw: string field holding the original matched text (empty string for synthetic elements like LinkGrid and Ellipsis).

Type Guards

All guards narrow the union type:

isAddress  isCashu    isCode    isEllipsis  isEmail
isEmoji    isEvent    isImage   isInvoice   isLink
isLinkGrid isNewline  isProfile isText      isTopic

isImage(parsed) — special guard: true only for ParsedLink elements whose URL ends in .jpg/.jpeg/.png/.gif/.webp.

Rendering

Export	Description
renderAsText(parsed, options?)	Renders Parsed | Parsed[] to a Renderer; call .toString() to get a string. Text rendering shows links as full raw URLs and entities as their full bech32 string (the renderEntity truncation is discarded in text mode since renderLink returns the href).
renderAsHtml(parsed, options?)	Same, but produces sanitized HTML with <a> tags. Default entityBase is https://njump.me/.
render(parsed, renderer)	Low-level: renders into an existing Renderer instance.
makeTextRenderer(options?)	Creates a Renderer pre-configured for text output.
makeHtmlRenderer(options?)	Creates a Renderer pre-configured for HTML output.
Renderer	Class with addText, addLink, addEntityLink, addNewlines, toString.

RenderOptions fields (all optional when using the convenience functions):

Field	Default (HTML)	Description
newline	"\n"	String emitted for each newline character
entityBase	"https://njump.me/"	Base URL prepended to bech32 entity strings
renderLink(href, display)	<a href=... target=_blank>display</a>	Custom link HTML/text
renderEntity(entity)	entity.slice(0, 16) + "…"	Display text for entity links
createElement(tag)	document.createElement(tag)	DOM element factory; override for SSR/non-browser

Individual per-type render helpers are also exported (renderText, renderLink, renderProfile, renderEvent, renderAddress, renderTopic, renderEmoji, renderCode, renderCashu, renderInvoice, renderEmail, renderNewline, renderEllipsis, renderOne, renderMany).

Common Patterns

Parse and render a note to HTML

import { parse, renderAsHtml } from '@welshman/content'

const event = {
  content: "Hello #nostr! Check out nostr:npub1jlrs53pkdfjnts29kveljul2sm0actt6n8dxrrzqcersttvcuv3qdjynqn",
  tags: []
}

const parsed = parse({ content: event.content, tags: event.tags })
const html = renderAsHtml(parsed, {
  entityBase: 'https://njump.me/',
  renderEntity: (entity) => entity.slice(0, 12) + '…',
}).toString()
// → 'Hello nostr! Check out <a href="https://njump.me/nprofile1..." target="_blank">nprofile1qqsj…</a>'

Truncate long notes for a feed preview

import { parse, truncate, reduceLinks, renderAsHtml } from '@welshman/content'

const parsed = parse({ content: event.content, tags: event.tags })
const withGrids = reduceLinks(parsed)
const preview = truncate(withGrids, { minLength: 300, maxLength: 500 })
const html = renderAsHtml(preview).toString()

Extract all mentioned pubkeys

import { parse, isProfile, isAddress } from '@welshman/content'

const parsed = parse({ content: event.content, tags: event.tags })

const pubkeys = parsed
  .filter(isProfile)
  .map(p => p.value.pubkey)

const addressPubkeys = parsed
  .filter(isAddress)
  .map(p => p.value.pubkey)

Extract all links and check for images

import { parse, isLink, isImage, isLinkGrid } from '@welshman/content'

const parsed = parse({ content: event.content, tags: event.tags })

const images = parsed.filter(isImage)
// images[0].value.url  → URL object
// images[0].value.meta → Record<string, string> from imeta tags

const allLinks = parsed.filter(isLink)

Render with a custom link handler (e.g. Svelte/React)

import { parse, renderAsHtml } from '@welshman/content'

const html = renderAsHtml(parse({ content }), {
  renderLink: (href, display) =>
    `<a href="${href}" class="text-blue-500 underline" rel="noopener">${display}</a>`,
  renderEntity: (entity) => entity.slice(0, 16) + '…',
}).toString()

Server-side rendering (no DOM)

The default createElement calls document.createElement, which fails in Node/SSR environments. Override it:

import { parse, renderAsHtml } from '@welshman/content'
import { JSDOM } from 'jsdom'

const dom = new JSDOM('')

const html = renderAsHtml(parse({ content }), {
  createElement: (tag: string) => dom.window.document.createElement(tag),
}).toString()

Using custom emoji tags

import { parse, isEmoji } from '@welshman/content'

const tags = [
  ['emoji', 'parrot', 'https://example.com/parrot.gif'],
]

const parsed = parse({ content: 'Hello :parrot:!', tags })

const emojiElements = parsed.filter(isEmoji)
// emojiElements[0].value → { name: 'parrot', url: 'https://example.com/parrot.gif' }

Integration Notes

• @welshman/content has no dependencies on other welshman packages. It depends on @braintree/sanitize-url as a direct dependency and requires nostr-tools ^2.x as a peer dependency (consumers must install it).
• In @welshman/app, content parsing is typically done at the component layer. The parse function is called with event.content and event.tags together so that imeta and emoji tags are resolved.
• ParsedLinkValue.meta is populated from imeta tags (NIP-92). When an event carries rich media metadata, the parsed link's meta object will include fields like url, m (MIME type), blurhash, dim, etc.
• reduceLinks should be called after parse and before truncate if you want link grids to count as single media units for truncation purposes.

Gotchas & Tips

• parse trims content before processing. Leading/trailing whitespace in the raw content string is dropped.
• parse fallback: if content is empty or whitespace, parse will use the first alt tag value instead. This is useful for kind-1 reposts and other events with alternative text.
• truncate is non-destructive when content is short: it returns the original array unchanged if the total estimated size is under maxLength.
• reduceLinks requires block-level links: a link is only pulled into a grid if it appears at the start of a block (i.e. preceded by a newline or at the very beginning). Inline links in the middle of a sentence are left as ParsedLink.
• isImage is stricter than urlIsMedia: isImage only matches .jpg/.jpeg/.png/.gif/.webp — it will not match .mp4 or .webm. Use urlIsMedia directly if you need to detect video; note that urlIsMedia takes a URL string, not a Parsed element — usage would be: urlIsMedia(parsed.value.url.toString()).
• Renderer.toString() is how you get the final string out. renderAsHtml and renderAsText both return a Renderer instance, not a string.
• LinkGrid is not rendered by default renderers: renderOne has no case for ParsedType.LinkGrid. You must handle it yourself when building a custom UI (e.g. render each value.links entry as an image or card grid).
• Legacy mentions (#[0], #[1]) are parsed automatically from the tags array and emitted as ParsedProfile or ParsedEvent elements.
• Numeric hashtags are skipped: #42 will not produce a Topic element.
• Email matching strips a leading mailto: — the resulting ParsedEmail.value is always the bare address string.