Stacks Stx

STX Templating Engine

STX is the full-stack templating and component framework for Stacks. It handles template rendering, reactivity, SSR, streaming, hydration, and more.

Design & anti-slop skills

When the task is how a page should look (not just how stx renders), pair this skill with the design-taste family: stacks-design-taste (flagship), the aesthetic presets stacks-design-soft / stacks-design-minimalist / stacks-design-brutalist, stacks-redesign, stacks-design-output, and the image-first stacks-image-to-code / stacks-imagegen-web / stacks-imagegen-mobile / stacks-brandkit. They translate premium design rules into stx + Crosswind + composables.

Key Paths

• STX config: config/ui.ts
• STX plugin: bun-plugin-stx (loaded via bunfig.toml)
• STX build cache + route manifest: storage/framework/stx/ (stx's stateDir, set in config/ui.ts)
• Components: resources/components/
• Layouts: resources/layouts/
• Partials: resources/partials/
• Views: resources/views/
• Package: @stacksjs/stx

CRITICAL Rules

1. ALWAYS use STX for templating — never write vanilla JS
2. NEVER use var, document.*, window.* in STX templates
3. STX <script> tags should ONLY contain stx-compatible code (signals, composables, directives)

Pre-paint appearance

Use @appearanceBootstrap({...}) when persisted appearance must be applied before the browser parses the application shell. Do not add a raw inline script for localStorage, document, or matchMedia. The directive emits the synchronous compiler-owned guard, validates storage through explicit allowlists, applies the root data attributes and dark class, and receives the request CSP nonce when nonce support is enabled.

@appearanceBootstrap({
  storageKey: 'app-appearance',
  appearance: {
    key: 'sidebarStyle',
    attribute: 'appearance',
    allowed: ['macos', 'arc'],
    default: 'macos',
  },
  colorMode: {
    key: 'colorMode',
    attribute: 'color-mode',
    default: 'system',
  },
})

Persist a JSON object under storageKey. Invalid JSON, storage errors, unknown appearance values, and unsupported color modes all fall back to the declared defaults before first paint.

Template Structure

<script client>
const count = state(0)
const title = state('Hello STX')
const showDescription = state(true)

function increment(): void {
  count.update(value => value + 1)
}
</script>

<template>
  <div class="container">
    <h1>{{ title() }}</h1>
    <p :if="showDescription()">Rendered reactively</p>
    <button type="button" @click="increment()">Count: {{ count() }}</button>
  </div>
</template>

<style>
/* Use crosswind utility classes or custom CSS */
.container { max-width: 1200px; margin: 0 auto; }
</style>

STX signals are callable. Read with count(), replace with count.set(value), and update from the current value with count.update(value => value + 1). Do not use Vue-style .value access in STX templates or resources/functions.

Client loop conditionals

Attribute loops create a client-owned scope. Their item and index aliases may be used with either reactive attribute conditionals or STX block conditionals. The compiler promotes a block chain that reads those aliases into one reactive runtime chain:

<template :for="(field, index) in fields()">
  @if(field.editable)
    <input x-model="drafts[field.key]">
  @elseif(index === 0)
    <span>First read-only field</span>
  @else
    <span>{{ field.value }}</span>
  @endif
</template>

Loop aliases are scoped to the owning element and inherited by nested client loops. A condition outside that element remains server-owned. Do not mix a server context value into a client loop chain. Serialize the value into client state when the browser must reevaluate it.

Native form binding

Use x-model for two-way form state instead of pairing :value with a manual @input or @change handler. The expression is the signal name without parentheses:

<script client>
const query = state('')
const quantity = state(1)
const enabled = state(false)
const categories = state<string[]>([])
</script>

<input x-model.trim="query" type="search">
<input x-model.number="quantity" type="number">
<input x-model="enabled" type="checkbox">
<input x-model="categories" type="checkbox" value="news">
<select x-model="query">
  <option value="">All</option>
  <option value="active">Active</option>
</select>

x-model supports text inputs, textareas, selects, radio buttons, boolean checkboxes, and checkbox arrays. Use .trim when whitespace should be removed and .number when the signal should receive a number. Keep a dedicated signal for each binding. Arbitrary expressions such as x-model="user.name" are not writable bindings.

Configuration (config/ui.ts)

import type { StxOptions } from '@stacksjs/stx'

export default {
  componentsDir: 'components',
  layoutsDir: 'layouts',
  partialsDir: 'partials',
} satisfies StxOptions

Full StxConfig

interface StxConfig {
  enabled: boolean
  debug: boolean
  componentsDir: string
  partialsDir: string
  layoutsDir?: string
  defaultLayout?: string
  templatesDir?: string
  cachePath: string
  ssr?: boolean
  cache?: boolean
  defaultTitle?: string
  defaultDescription?: string

  // Feature modules
  i18n?: Partial<I18nConfig>
  webComponents?: Partial<WebComponentConfig>
  streaming?: Partial<StreamingConfig>
  hydration?: Partial<HydrationConfig>
  a11y?: Partial<A11yConfig>
  seo?: Partial<SeoFeatureConfig>
  animation?: Partial<AnimationConfig>
  markdown?: Partial<MarkdownConfig>
  forms?: Partial<FormConfig>
  pwa?: Partial<PwaConfig>
  components?: Partial<ComponentConfig>
  media?: Partial<MediaConfig>
  strict?: boolean | StrictModeConfig
  customDirectives?: CustomDirective[]
}

STX Capabilities (118+ modules)

Core

• Template parsing and compilation
• Reactivity system (ref, computed, watch)
• Component composition and lifecycle
• Dependency injection (provide/inject)
• DOM update scheduling with the browser-auto-imported nextTick()

Template refs after structural updates

Use useRef() with nextTick() when an element is inserted by :if, a modal, or another structural directive and must be focused or measured immediately afterward:

const open = state(false)
const searchInput = useRef('searchInput')

function showSearch(): void {
  open.set(true)
  void nextTick(() => searchInput.current?.focus())
}

<template :if="open()">
  <input ref="searchInput" type="search">
</template>

nextTick() runs after the current synchronous signal and effect flush. Prefer it over querySelector, manual DOM polling, or requestAnimationFrame when the task is waiting for STX to materialize reactive markup.

Rendering

• SSR — Server-Side Rendering
• Streaming — Progressive HTML streaming
• Hydration — Progressive and islands-based hydration
• Suspense — Async component loading with fallbacks
• Error boundaries — Graceful error handling in components

Features

• Router — Client-side routing
• Forms — Built-in form handling and validation
• i18n — Internationalization support
• SEO — Meta tags, Open Graph, Twitter cards, structured data
• PWA — Progressive Web App support
• Animation — CSS and JS animation system
• Markdown — Markdown rendering with syntax highlighting
• A11y — Accessibility checking and auto-fixing

Dev Tools

• Dev server with HMR (Hot Module Replacement)
• Image optimization
• Asset pipeline
• Testing utilities

Plugin Loading

# bunfig.toml
[serve]
plugins = ["bun-plugin-stx"]

The STX plugin processes .stx files during serve and build.

Scaffolding

import { createProject, addComponent, addPage, addStore, addLayout } from '@stacksjs/stx'

// Create a new project
await createProject('my-app', { template: 'dashboard' })

// Add to existing project
await addComponent('UserCard', { props: true, styles: true })
await addPage('about', { layout: 'default' })
await addStore('cart', { persist: true, actions: true })
await addLayout('admin', { nav: true, footer: true })

Project Templates

default, minimal, full, blog, dashboard, landing

Gotchas

• STX is the ONLY templating system — do not use other template engines
• bun-plugin-stx must be loaded — without it, .stx files won't be processed
• Auto-imports — browser auto-imports defined in storage/framework/browser-auto-imports.json
• Imported module dependencies - browser auto-imports are injected into the STX script entry only; imported .ts modules must explicitly import every function or store they use
• Project-root server imports - use ~/path or @/path inside <script server> when a layout, partial, or page needs a project file. STX resolves both aliases against the application root before executing the server script. Relative imports still resolve against the .stx file
• Browser package inputs are bundled - core browser helpers and model auto-import bootstraps are compiler bundle inputs. Rendered HTML must never contain a bare import '@stacksjs/browser', because browsers cannot resolve package specifiers without an import map
• Server-to-client values are explicit - a JSON-serializable top-level value exported by <script server> can be referenced by name in <script client>. STX serializes only referenced values and never overwrites a client-owned declaration
• storage/framework/stx/ — stx build cache and the generated route manifest. config/ui.ts sets stx's stateDir here, so nothing lands in the project root. Gitignored; safe to delete
• Reactivity is signal-based - use callable state() and derived() signals, not Vue-style ref() or .value
• Client loop conditions - @if chains that read :for or @for aliases compile into scoped runtime chains; aliases do not leak outside the loop element
• Component tag case is semantic - <Input v-model:value="query"> is a paired component, while lowercase <input v-model="query"> is a native void element. Keep component tags PascalCase, including names that collide with native elements
• Structural DOM timing - use nextTick() with useRef() after opening reactive markup
• Crosswind for styling — use utility classes, not inline styles
• Script block restrictions — only stx-compatible code (signals, composables, directives), no vanilla DOM APIs
• Pre-paint state - use @appearanceBootstrap, never a raw browser script in the template
• Components go in resources/ — not in app/ or storage/
• 118+ modules — STX is a comprehensive framework covering rendering, routing, forms, i18n, SEO, PWA, and more