Plugins

Accent CMS supports a WebAssembly plugin system built on the WebAssembly Component Model and WIT. Plugins are sandboxed components that extend the CMS without compromising the host process. Each plugin is a compiled .wasm component paired with a plugin.toml manifest that declares which capabilities it provides.

Unlike a stringly-typed bytes-in/bytes-out protocol, the contract between host and plugin is a set of typed WIT worlds: records, result<T, E> error handling, and structural capabilities. The contract is the source of truth and both sides generate their bindings from it – the host with wasmtime::component::bindgen!, the guest with cargo-component (Rust) or jco/componentize-js (JavaScript).

The Capability Surface

Plugins can provide several kinds of capabilities, each modelled as a WIT world:

Capability	Description	Example
Content hooks	Transform content at lifecycle points	SEO injection, link rewriting
Filters	Custom template filters	{{ value | my_filter }}
Shortcodes	Inline content processors	[gallery]...[/gallery]
Routes	Custom HTTP endpoints	/api/search, /api/contact
Media hooks	Augment media discovery and processing	EXIF extraction, watermarking
Diagram renderers	Render fenced code blocks of a language	a custom [d2] renderer

Because capabilities are structural, a plugin can reach only what its WIT world imports. The three host capabilities every plugin may use – configuration, logging, and runtime context – are always granted; outbound HTTP and filesystem access are deny-by-default and present only when a world imports them.

Enabling Plugins

Plugins are disabled by default. Enable them in config.yaml:

plugins:
  enabled: true
  directory: ./plugins    # default location

When enabled is false (the default), no plugins are loaded and no WASM runtime overhead is incurred. The plugin system is also resilient by design: a missing directory, an invalid plugin.toml, or a runtime error never prevents the server from starting or serving content.

Quick Start

Scaffold a complete, buildable plugin with the CLI and pick your language:

accent plugin new my-plugin --lang rust   # or: --lang js

The generated project is a working content-hook plugin you can build and install in minutes. See Writing a Plugin for the full walkthrough.

To install someone else’s instead of writing your own, browse the Hub – the signed registry accent plugin install resolves against.

In This Chapter

• Structure and Metadata – the plugin directory layout and the plugin.toml file: required fields, hooks, filters, shortcodes, routes, and per-plugin configuration.
• The Plugin Contract – the typed WIT worlds, the structural capability model, and the data types that cross the host/plugin boundary.
• Writing a Plugin – a complete walkthrough for both toolchains: Rust with cargo-component and JavaScript with jco, from scaffold through build, install, and verify.
• Media Hooks – the on_media_discover and on_media_process hooks for enriching media metadata and transforming processed images.
• Managing Plugins – the accent plugin CLI for scaffolding, listing, inspecting, installing, and removing plugins, plus hot reload and graceful error handling.
• Security – the structural capability model, metering (fuel, epoch, and the per-plugin memory cap), scoped filesystem access, the outbound-HTTP allowlist, and API version compatibility.
• Configuration Reference – the full config.yaml reference for the plugin system and where to go next.
• Publishing Artifacts – accent package, which turns a plugin, theme, or starter template into the archive, checksum, and manifest a registry submission needs.