name	halo-theme-dev
description	Use when creating or modifying a Halo CMS theme: writing Thymeleaf templates, configuring theme.yaml or settings.yaml, calling Finder APIs, using vite-plugin-halo-theme, defining theme settings forms, referencing static assets, implementing halo:comment or halo:footer extension points, or defining model annotation fields (AnnotationSetting).

Halo Theme Development

Halo is built on Spring Boot + Spring WebFlux + Thymeleaf. Themes use Thymeleaf templates for frontend page rendering.

Important: Halo's APIs, VO field names, and template variables evolve across versions. Do not rely on training data for specific field names, method signatures, or type structures. When writing code that accesses template variables or calls Finder API methods, always fetch the relevant online doc from the References section below first.

Thymeleaf Quick Reference

Full docs: https://raw.githubusercontent.com/thymeleaf/thymeleaf-docs/refs/heads/master/docs/tutorials/3.1/usingthymeleaf.md

Core syntax cheatsheet:

<!-- Output text -->
<h1 th:text="${site.title}"></h1>

<!-- Output unescaped HTML -->
<div th:utext="${post.content.content}"></div>

<!-- Links -->
<a th:href="@{${post.status.permalink}}">Post link</a>
<link rel="stylesheet" th:href="@{/assets/dist/style.css}" />

<!-- Loop -->
<li th:each="post : ${posts.items}" th:text="${post.spec.title}"></li>

<!-- Conditionals -->
<div th:if="${posts.hasNext()}">Next page</div>
<div th:unless="${posts.hasNext()}">Last page</div>

<!-- Local variable -->
<div th:with="menu = ${menuFinder.getPrimary()}">...</div>

<!-- Fragment include -->
<div th:replace="~{fragments/header :: header}"></div>

<!-- Layout reuse: pages pass fragments into a parameterized layout -->
<html th:replace="~{layout :: html(head = null, content = ~{::content})}">
  <th:block th:fragment="content"><!-- page body --></th:block>
</html>

<!-- Inline JavaScript -->
<script th:inline="javascript">
  var url = '[(${#theme.assets("/dist/main.iife.js")})]';
</script>

Development Workflow

Create a theme folder under themes/ in the Halo working directory (must match metadata.name in theme.yaml)
Write theme.yaml (required) and settings.yaml (optional)
Create template files under templates/
Install and activate the theme in Console → Theme Management
Visit the frontend to verify

Disable Thymeleaf caching during development: set env var SPRING_THYMELEAF_CACHE=false (Docker), or spring.thymeleaf.cache: false in config (source mode).

Starter Templates

The assets/ directory provides two ready-to-use theme templates:

assets/theme-minimal/ — Zero-build-tool minimal theme with all 8 template files; ideal for quick prototyping or simple themes
assets/theme-vite/ — Vite project template with vite-plugin-halo-theme (recommended for new themes); includes partial layout reuse and CSS toolchain

Usage: copy the directory into themes/ in your Halo working directory, ensure the folder name matches metadata.name in theme.yaml, then install and activate in Console.

References Index

File	Content	When to read
references/structure-and-config.md	Directory structure, theme.yaml fields, settings.yaml form definition	Creating a theme, configuring theme.yaml/settings.yaml
references/vite-plugin.md	vite-plugin-halo-theme integration guide, include/slot template syntax, TailwindCSS integration	Setting up a Vite-based theme (recommended)
references/templates.md	Template route mapping, available variables per template	Writing template files
references/global-variables.md	Global variables (site, theme, theme.config) and type definitions	Accessing site info or theme setting values
references/finder-apis.md	All Finder APIs (postFinder, categoryFinder, tagFinder, menuFinder, singlePageFinder, etc.)	Querying data from any template
references/static-resources.md	Static asset reference methods (`@{}`, `#theme.assets()`)	Referencing CSS/JS/images in plain HTML themes
references/template-tags.md	Custom tags (halo:comment extension point, halo:footer injection)	Integrating comment plugins, injecting footer code
references/official-plugins.md	Official plugin integration: pluginFinder.available(), search widget, dark mode color scheme adaptation	Adding search, adapting dark mode for plugin UI
references/annotations.md	AnnotationSetting for model custom fields, `#annotations` utility for reading metadata in templates	Adding custom fields to menu items/posts/categories and using them in templates
references/packaging.md	Packaging a theme as a ZIP using `@halo-dev/theme-package-cli`	Preparing a theme for release or upload
references/thymeleaf-tips.md	Halo-specific Thymeleaf best practices: literal substitutions, safe navigation, meta tag rules, permalink syntax	Writing any template file

Halo Theme Development

Halo is built on Spring Boot + Spring WebFlux + Thymeleaf. Themes use Thymeleaf templates for frontend page rendering.

Important: Halo's APIs, VO field names, and template variables evolve across versions. Do not rely on training data for specific field names, method signatures, or type structures. When writing code that accesses template variables or calls Finder API methods, always fetch the relevant online doc from the References section below first.

Thymeleaf Quick Reference

Core syntax cheatsheet:

<h1 th:text="${site.title}"></h1>  <div th:utext="${post.content.content}"></div>  <a th:href="@{${post.status.permalink}}">Post link</a> <link rel="stylesheet" th:href="@{/assets/dist/style.css}" />  <li th:each="post : ${posts.items}" th:text="${post.spec.title}"></li>  <div th:if="${posts.hasNext()}">Next page</div> <div th:unless="${posts.hasNext()}">Last page</div>  <div th:with="menu = ${menuFinder.getPrimary()}">...</div>  <div th:replace="~{fragments/header :: header}"></div>  <html th:replace="~{layout :: html(head = null, content = ~{::content})}"> <th:block th:fragment="content"></th:block> </html>  <script th:inline="javascript"> var url = '[(${#theme.assets("/dist/main.iife.js")})]'; </script>

Development Workflow

Create a theme folder under themes/ in the Halo working directory (must match metadata.name in theme.yaml)

Write theme.yaml (required) and settings.yaml (optional)

Create template files under templates/

Install and activate the theme in Console → Theme Management

Visit the frontend to verify

Disable Thymeleaf caching during development: set env var SPRING_THYMELEAF_CACHE=false (Docker), or spring.thymeleaf.cache: false in config (source mode).

Starter Templates

The assets/ directory provides two ready-to-use theme templates:

assets/theme-minimal/ — Zero-build-tool minimal theme with all 8 template files; ideal for quick prototyping or simple themes

assets/theme-vite/ — Vite project template with vite-plugin-halo-theme (recommended for new themes); includes partial layout reuse and CSS toolchain

Usage: copy the directory into themes/ in your Halo working directory, ensure the folder name matches metadata.name in theme.yaml, then install and activate in Console.

References Index

File

Content

When to read

references/structure-and-config.md

Directory structure, theme.yaml fields, settings.yaml form definition

Creating a theme, configuring theme.yaml/settings.yaml

references/vite-plugin.md

vite-plugin-halo-theme integration guide, include/slot template syntax, TailwindCSS integration

Setting up a Vite-based theme (recommended)

references/templates.md

Template route mapping, available variables per template