@lettera/core

Document model, command bus, theme tokens, and merge-tag schemas. Framework-agnostic and side-effect-free.

pnpm add @lettera/core

What's here

| Module | Exports | | --- | --- | | schema/ | Zod schemas for EmailDocument, Section, Row, Column, Block variants | | document.ts | EmailDocument, section/row helpers | | ids.ts | generateId() — stable, URL-safe block ids | | tokens/ | ThemeTokens, StyleDelta, token resolution | | variables.ts | Flat VariableDefinition model + built-in merge-tag formatters | | variableSchema.ts | Typed VariableSchema model + path resolution | | commands/ | Command bus (dispatch, undo, redo) + standard command set | | expressions.ts | Safe expression evaluator for Conditional / Repeater blocks | | formatters.ts | Scalar formatters (currency, date, …) for the typed schema |

Quick reference

import {
  type EmailDocument,
  createDocument,
  BlockRegistry,
  generateId,
} from '@lettera/core';

Command bus

The store in @lettera/editor uses a command bus from this package. Every mutation goes through dispatch(command) which runs it through Immer so undo/redo are free. Commands are plain JSON — safe to log, replay, ship across the wire.

import { applyCommand, standardCommands } from '@lettera/core';

const next = applyCommand(doc, {
  type: 'block.insert',
  payload: { /* ... */ },
});

See docs/custom-blocks.md for the full block authoring guide and docs/variables.md for the variable / merge-tag model.