[v3-4-test] Let plugins add their own actions to Dag, run and task instance rows (#75229)

airflow-core/docs/administration-and-deployment/plugins.rst

@@ -397,6 +397,8 @@ definitions in Airflow.
 
 .. seealso:: :doc:`/howto/define-extra-link`
 
+.. _plugin-scoping:
+
 Scoping a view to specific Dags and tasks
 -----------------------------------------
 
@@ -566,6 +568,53 @@ Each invocation is a fresh process, so every warning for every plugin is reporte
     who knows the ``url_route`` can still navigate to it directly. Use access control to
     restrict who may view a plugin's data.
 
+.. _plugin-ui-actions:
+
+UI actions
+----------
+
+``ui_actions`` adds a button beside the actions Airflow already draws for an entity, rather
+than a whole page. See :doc:`/howto/custom-action-plugin` for the full guide; the fields are:
+
+.. code-block:: python
+
+    link_action = {
+        # Required. The button's tooltip and its accessible label, so write it as a label.
+        # A React action is also registered on the page under this name, which must therefore
+        # be unique across every React app and React action in the deployment.
+        "name": "Open runbook",
+        # Required. "link" opens a URL; "react" mounts a component of your own.
+        "action_type": "link",
+        # Required. Which entity the button belongs to, and so which surfaces it appears on:
+        # "dag", "dag_run" or "task_instance".
+        "destination": "dag",
+        # Required for "link". Templated with the entity's context, the same
+        # {DAG_ID}-style tokens an external view's href accepts.
+        "href": "https://runbooks.example.com/{DAG_ID}",
+        # Optional icon, url to an svg file. Defaults to a generic action icon.
+        "icon": "https://example.com/icon.svg",
+        # Optional dark icon for the dark theme, url to an svg file. If not provided, "icon"
+        # will be used for both light and dark themes.
+        "icon_dark_mode": "https://example.com/dark_icon.svg",
+        # Optional scoping, the same block external views and React apps take.
+        # See "Scoping a view to specific Dags and tasks" above.
+        "applies_to": {"dag.tags.name": ["production"]},
+    }
+
+    react_action = {
+        "name": "Inspect payload",
+        "action_type": "react",
+        "destination": "task_instance",
+        # Required for "react". Each React action needs its own bundle: the shared global is
+        # cleared before each import, and a browser will not re-execute a module it already has.
+        "bundle_url": "https://example.com/static/js/inspect_payload.js",
+    }
+
+An action naming a field no record has is withheld rather than shown unscoped, and an action
+Airflow cannot render is skipped with a warning while the plugin's other contributions load.
+
+.. _plugin-react-props:
+
 React app context props
 -----------------------