feat: follow forward working-checkout changes in diffs

docs/configuration.md

@@ -21,6 +21,7 @@ Vamp.configure do |config|
   config.diff_expand_lines = 15
   config.diff_view_mode = "split" # or "unified"
   config.diff_split_orientation = "vertical" # or "horizontal"
+  config.diff_follow_working_copy = true
   config.bind "ctrl+h", config.core.left, mode: config.modes.tree
   config.bind "ctrl+l", config.core.right, mode: config.modes.tree
   config.plugin "plugins/greeting.rb"
@@ -51,6 +52,8 @@ Plugin paths resolve relative to the config file, not the shell's working direct
 
 `config.diff_view_mode` selects the initial view for each new comparison: `"split"` (default) or `"unified"`. `config.diff_split_orientation` selects `"vertical"` (left/right, default) or `"horizontal"` (above/below) for split views. Invalid values reject the configuration. Normal-mode **Space v** cycles split/unified; **Space s** flips split orientation. These controls affect the current comparison, not startup defaults, and retain their choices across file switches and tabs. Orientation changes apply only in split view.
 
+`config.diff_follow_working_copy` defaults to `true`. A Working-checkout After follows descendant checkouts automatically, including in inactive tabs; `false` disables endpoint following without disabling ordinary live-buffer editing or reload. Only literal booleans are accepted. Historical After endpoints never follow. See [repository diff](editing.md#repository-diff) for ancestry and refresh behavior.
+
 ```ruby
 config.bind "ctrl+b", config.core.diff.mode.toggle
 config.bind "leader v", config.core.diff.view.toggle