Available from version 1.41.0 (Gerrit change 921773)
Allows to change the HTML that is included in a prefix container directly before the diff table
Define function:
public static function onTextSlotDiffRendererTablePrefix( TextSlotDiffRenderer $textSlotDiffRenderer, IContextSource $context, array &$parts ) { ... }
Attach hook: In extension.json:
	"Hooks": {
		"TextSlotDiffRendererTablePrefix": "MediaWiki\\Extension\\MyExtension\\Hooks::onTextSlotDiffRendererTablePrefix"
Called from: File(s): includes/diff/TextSlotDiffRenderer.php
Function(s): getTablePrefix
Interface: TextSlotDiffRendererTablePrefixHook.php

For more information about attaching hooks, see Manual:Hooks .
For examples of extensions using this hook, see Category:TextSlotDiffRendererTablePrefix extensions.