No admin UI to assign a plugin `fieldWidget` to a field in Content Types (seed/SQL only)

[DavidPivert]

Summary

A plugin can register a field widget via admin.fieldWidgets (native format now works since #1483). The widget renders correctly in the entry editor once a field's widget is set to "pluginId:name". However, there appears to be no way to set that widget from the admin UI: the Content Types field editor offers no widget picker.

In the admin bundle, fieldWidgets is only ever consumed to resolve a widget at render time:

fieldWidgets?.find((w) => w.name === widgetName)

There is no code building a list of available widgets (filtered by the field's type) for the schema editor. So the only ways to assign a plugin widget to a field are:

• a seed entry ({ "slug": "seo", "type": "json", "widget": "pluginId:name" }), or
• writing _emdash_fields.widget directly (SQL/migration).

Steps to reproduce

1. Install a plugin that declares admin.fieldWidgets: [{ name: "x", label: "X", fieldTypes: ["json"] }].
2. In the admin, Content Types → a collection → add or edit a json field.
3. Look for a way to select the plugin widget "X" for that field.

Expected

When editing a field whose type is in a registered widget's fieldTypes, the field editor offers a "Widget" selector listing the matching plugin field widgets (label + pluginId:name), so a non-technical editor can assign it without touching seed/SQL.

Actual

No such selector. The field saves with an empty widget, so the default editor for that type is used. The only way to wire the plugin widget is seed or a direct DB write.

Question / possible intent

Is seed-only assignment by design (matching how @emdash-cms/plugin-field-kit documents usage — seed "widget": "field-kit:list")? If so, a note in the docs plus surfacing the available pluginId:name values somewhere in the admin would help. If not, a widget picker in the field editor would close the loop between "plugin registers a widget" and "editor can use it".

Environment

• emdash 0.29.x, native-format plugin, fieldWidgets for json.
• Related but distinct: Standard/sandboxed plugins can't contribute Portable Text blocks or field widgets #1483 fixed contribution of field widgets for non-native plugins; this is about assignment via the schema editor UI.

[swissky]

Thanks for the clear write-up, @DavidPivert! You're right that the field editor has no widget picker yet. Until it does, widget can be set through a seed, the schema API (widget on field create and update), or the MCP field tools, as described in the React admin field widget docs. Editing the field in the admin keeps an existing widget. A picker is a new admin feature, so I'm moving this to an Ideas discussion where we can settle how it should list widgets from both admin.fieldWidgets and React fields exports.