Introduction

Introduction

Not released

Mesh is not released yet. These pages describe Mesh 1.0.

Mesh is a TypeScript framework: you describe each thing your program stores once, in one .mesh.mx file, and Mesh writes the TypeScript you call, the checks on what callers send, the rules about who may do it, and the database tables and migrations. The whole interface is one function call, and Mesh runs on Bun.

One file, and what each part gives you

This is a complete src/domain/todo/todo.mesh.mx, top to bottom, as your editor shows it. Point at a numbered marker, or at the lines it sits on, to read what that part gives you; every part is something you would otherwise write by hand.

import { List } from "./list.mesh.mx"entity :Todo table="todos"  attributes    uuid :id primary-key    string :title min=1    boolean :done default=false    timestamp :insertedAt on=:create    timestamp :updatedAt on=:update  relationships    belongs-to :list entity=List  computed    string :label() {      return (&done ? "[x] " : "[ ] ") + &title    }  actions auto=[:read, :destroy]    create :create      input        &title        &list    update :complete      validate        check :notDoneYet [          that=() => !&done          code="already_done"          message="this todo is already complete"        ]      do        set          &done=true    update :rename      input        &title    read :pending      filter=() => &done === false      sort        asc &insertedAt  policies    policy :owner types=[:create, :read, :update, :destroy]      authorize-if=({ actor }) => &list.ownerId === actor.id
  1. Another entity List is imported from the file that declares it. The path tells Mesh which list this todo belongs to.
  2. Name and table a name is written :name, so this is :Todo; it lives in the todos table. The type, the functions and the migration come from this one line.
  3. Fields you send title is a string of at least one character, done a boolean that starts false.
  4. Fields the database fills insertedAt on create, updatedAt on every write. No caller sets either.
  5. Linked to a list this creates the listId column; &list in input is how the caller sets it. todo.list arrives when you ask.
  6. A computed value ask for label and it is on the result; leave it out and it does not exist.
  7. Calling createTodo you call createTodo(input, context). A field it does not accept never reaches your code, and a rule about one field is one word on that field's line.
  8. Rule and change completeTodo({ id }, context) refuses a todo that is already done, then writes it in one turn.
  9. One more action renameTodo({ id, title }, context) accepts a field and changes nothing else.
  10. A query pendingTodo(input, context) filters in SQL, and your call can narrow it with its own filter.
  11. Who may do it an action no policy covers is forbidden, and a todo in someone else's list is simply not found.

What you call

An action becomes an ordinary TypeScript function. Its name is the action name followed by the entity name: create on entity :Todo becomes createTodo, and read :pending becomes pendingTodo.

src/main.ts (excerpt)
import { createTodo } from "#mesh";

const todo = await createTodo({ title: "Buy milk", list: list.id }, { actor });

There is no server, no route and no client to generate. Mesh serves a command line, a worker, a daemon or an HTTP endpoint equally, because the function is the whole interface.

The same file is built in the tutorial, and every declaration in it is in the entity reference.

You write one file per thing and edit that file. Adding a field adds a column, a type field and an input key, and one more thing to push or migrate. Removing an accepted field makes every caller that still passes it a type error.

Who it is for

You are writing TypeScript on Bun and some of your program’s data has rules attached to it: who may read it, what counts as valid, what a completed order means. Those rules usually live in a framework’s models, or in hand-written handlers with hand-written tests.

  • Backend services and APIs. One declaration replaces a table definition, four DTOs, a validation layer and a controller. The HTTP layer stays yours.
  • Command-line tools and workers. The action is a function. Calling it from a task is the same code a request handler runs.
  • Applications with an AI agent in them. An agent editing one small declarative file, then running one command, is a much smaller job than an agent editing a model, a schema and a service layer together.

Where to go next

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