TYPO3 Core

We solved it currently with a custom Hook to DataHandler.

First: we set custom cache-tags

# Add CacheTag to Shortcut Elements
# We need to clear this cachetag on every content edit, to ensure, that referenced objects get updated asap
tt_content.shortcut {
    stdWrap {
        addPageCacheTags {
            stdWrap.cObject = TEXT
            stdWrap.cObject {
                dataWrap = shortcut_{field:records}
            }
        }
    }
}

Second: Use a hook to flush the custom cache-tags
In our scenario we had to respect child-elements in EXT:flux context. The same would apply for EXT:container and EXT:gridelements.
But I think, this is something that has to be handled by the third party extensions, once the cache tag is set by core.

See https://gist.github.com/h3nn3s/b829b9dada68b84fefbd3a0ac2f42786

Hi Georg,

for the extensions I share your opionion. This should be handled by the extensions itself.

For the core-part this should be invalidated by core automatically.

This is how you can add a page cache tag for referenced tt_content records.

tt_content.shortcut {
    variables.shortcuts {
        conf.tt_content.stdWrap.addPageCacheTags = tt_content_{field:uid}
        conf.tt_content.stdWrap.addPageCacheTags.insertData = 1
    }
}

When you edit the referenced record, then the page cache is flushed correctly. Beware: The referenced record must be visible, else no cache tag is added.

You can also use the raw record field. This way, the visibility of the referenced record don't care and cache tags are always added:

tt_content.shortcut {
    variables.shortcuts {
        stdWrap.addPageCacheTags.field = records
        stdWrap.addPageCacheTags.split {
           cObjNum = 1
           1.current = 1
           1.wrap = tt_content_|,
        }
    }
}

Both tested in 13.0.0-dev