@lettera/renderer

EmailDocument → email-safe HTML + plain text. No React, no browser APIs — runs anywhere Node / Deno / edge workers run.

pnpm add @lettera/renderer @lettera/blocks-standard

Usage

import { render, BlockRegistry } from '@lettera/renderer';
import { standardBlocks } from '@lettera/blocks-standard';

const registry = new BlockRegistry();
registry.registerAll(standardBlocks);

const { html, text, warnings } = render(doc, {
  registry,
  device: 'desktop',          // 'desktop' (default) | 'mobile'
  mode: 'export',             // 'export' (default) | 'preview'
  schema,                     // optional typed VariableSchema
  data,                       // optional runtime values
  variables,                  // optional legacy flat list
  mergeTagFormatter,          // optional — default {{path}}
  formatters,                 // optional — override scalar formatters
});

Output

• html — a complete HTML document using table-based layout, inlined styles where appropriate, and <style>-scoped responsive overrides keyed on data-lettera-id selectors. Ready to hand off to an ESP.
• text — plain-text fallback derived from the same AST so it never goes out of sync.
• warnings — LintResult[] from block-level ctx.warn() calls and built-in rules (unresolved variables, unsafe URLs, missing alt text, …).

Registry

BlockRegistry resolves a block type string to a BlockDefinition.exportRender. Pass the same registry instance to every call so repeated renders hit its internal cache.

registry.register(MyCustomBlock);
registry.registerAll([HeadingBlock, TextBlock]);
registry.get('block.heading');

See also

• @lettera/sdk — author custom blocks with defineBlock
• @lettera/blocks-standard — built-in library
• docs/variables.md — merge-tag model