A provider plugin reports `controls` and the `providerOptions` it runs in
`session.config`, and receives running-session changes as
`session.configure` `changes.providerOptions` (null returns a key to its
default), under the same apply-or-throw contract as built-in providers.
A control may declare a `defaultValue`; a value a plugin reports at that
default for a key nobody set stays unset instead of being pinned to the agent.
A plugin that still reports `settings` keeps working: the daemon reads each
setting as a control plus an option and sends changes in both shapes
(COMPAT(plugin-provider-settings)).
The app resolves a control's icon as a Lucide name when it is not one of the
built-in kebab-case names, so a plugin's icon shows live and in drafts.
Public docs and the provider-direct example use only `providerOptions` and
controls; the migration doc gains the rows.
Allow trusted local plugins to register complete coding-agent providers through the existing agent lifecycle. Includes direct and ACP implementations, SVG provider icons, custom timeline items, runnable examples, and public authoring documentation.
Closes#3547Closes#3556
Mohamed Boudra