Add `Sphinx.add_html_assets_in_all_pages`

This new method in the `Sphinx` object allows extensions to communicate to
Sphinx that it's preferred to include HTML assets in all the pages. However,
it's extensions developers' responsability to follow this config and decide
whether or not include the assets required.

Extensions developers' can check `Sphinx.html_assets_in_all_pages` together with
any other logic they may have to decide if the assets will be included in the
rendered page or not.

Closes #9115

1 files changed, 8 insertions, 0 deletions

diff --git a/sphinx/application.py b/sphinx/application.py
index 4735beffd..59e1683b3 100644
--- a/sphinx/application.py
+++ b/sphinx/application.py
@@ -146,6 +146,7 @@ class Sphinx:
         self.project: Project = None
         self.registry = SphinxComponentRegistry()
         self.html_themes: Dict[str, str] = {}
+        self.html_assets_in_all_pages: bool = False
 
         # validate provided directories
         self.srcdir = abspath(srcdir)
@@ -1181,6 +1182,13 @@ class Sphinx:
         logger.debug('[app] adding environment collector: %r', collector)
         collector().enable(self)
 
+    def add_html_assets_in_all_pages(self):
+        """Tell extensions to insert HTML assets in all the pages.
+
+        .. versionadded: 4.1
+        """
+        self.html_assets_in_all_pages = True
+
     def add_html_theme(self, name: str, theme_path: str) -> None:
         """Register a HTML Theme.