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Tab registry

Extensions register tabs at boot; the System UI reads the registry to render panels and route PATCH requests.

Boot flow​

Engine initializer decidim_toggle.organization_settings_tabs
  └── OrganizationSettingsTabs.register!
Your engine initializer
  └── Decidim::Toggle.settings_tabs(:organization_settings) { |tabs| tabs.add_tab ... }
        └── SettingsTabRegistry.register_form_tab(identifier, form, command, module_name:)

Key files​

lib/decidim/toggle/settings_tabs.rb           # add_tab / remove_tab DSL
lib/decidim/toggle/settings_tab_registry.rb   # form + command map per tab id
lib/decidim/toggle/settings_tab_item.rb       # tab metadata (position, partials, if:)
lib/decidim/toggle/organization_settings_tabs.rb
app/controllers/decidim_toggle/system/settings_tab_controller.rb

add_tab contract​

One tab = one Decidim::Form subclass + one Decidim::Command.

  • identifier — URL segment and DOM id (panel-toggle-<identifier>)
  • module_name: — optional; links tab to JSON config row (ModuleConfigForm path)
  • remove_tab(id) — drop a built-in tab before registering a replacement

Duplicate registration: last add_tab wins. In development/test, same id with a different form/command raises DuplicateTabRegistrationError.

Save endpoint​

PATCH /decidim_toggle/system/organizations/:organization_id/settings_tab/:tab_id

Controller resolves registry.form_tab(tab_id), builds the form from params, runs the command.

See also​