Plugin and Extension System

A formal plugin system that lets users extend the build pipeline without forking. Hugo's and Zola's #1 perennial community request. Users who hit a wall in a non-extensible SSG leave and don't return.

Possible approach

• Lifecycle hooks: before_build, after_markdown, after_render, after_build events
• Hook-based shortcode registration: plugins can register custom shortcodes with processing logic beyond template rendering
• WASM or script plugins: execute user-defined transformations during build steps
• Plugin manifest: [plugins] section in seite.toml with install-from-URL support

Current extensibility points (user shortcodes in templates/shortcodes/, data files, skill packs) cover many use cases but don't allow build-pipeline modifications.