Also keep app directories with "brew reinstall".

Library/Homebrew/cask/artifact/abstract_uninstall.rb

@@ -270,8 +270,8 @@ module Cask
         end
       end
 
-      def uninstall_login_item(*login_items, command: nil, upgrade: false, **_)
+      def uninstall_login_item(*login_items, command: nil, upgrade_or_reinstall: false, **_)
-        return if upgrade
+        return if upgrade_or_reinstall
 
         apps = cask.artifacts.select { |a| a.class.dsl_key == :app }
         derived_login_items = apps.map { |a| { path: a.target } }

Library/Homebrew/cask/artifact/moved.rb

@@ -35,13 +35,14 @@ module Cask
 
       private
 
-      def move(adopt: false, force: false, verbose: false, upgrade: false, command: nil, **options)
+      def move(adopt: false, force: false, verbose: false, upgrade_or_reinstall: false, reinstall: false,
+               command: nil, **options)
         unless source.exist?
           raise CaskError, "It seems the #{self.class.english_name} source '#{source}' is not there."
         end
 
         if Utils.path_occupied?(target)
-          if upgrade && target.directory? && target.children.empty?
+          if upgrade_or_reinstall && target.directory? && target.children.empty?
             # An upgrade removed the directory contents but left the directory itself (see below).
             unless source.directory?
               if target.parent.writable? && !force
@@ -148,13 +149,13 @@ module Cask
         delete(target, force: force, command: command, **options)
       end
 
-      def delete(target, force: false, upgrade: false, command: nil, **_)
+      def delete(target, force: false, upgrade_or_reinstall: false, command: nil, **_)
         ohai "Removing #{self.class.english_name} '#{target}'"
         raise CaskError, "Cannot remove undeletable #{self.class.english_name}." if MacOS.undeletable?(target)
 
         return unless Utils.path_occupied?(target)
 
-        if upgrade && target.directory?
+        if upgrade_or_reinstall && target.directory?
           # If an app folder is deleted, macOS considers the app uninstalled and removes some data.
           # Remove only the contents to handle this case.
           target.children.each do |child|

Library/Homebrew/cask/cmd/reinstall.rb

@@ -41,6 +41,7 @@ module Cask
           force:          force,
           skip_cask_deps: skip_cask_deps,
           require_sha:    require_sha,
+          reinstall:      true,
           quarantine:     quarantine,
           zap:            zap,
         }.compact
@@ -48,7 +49,7 @@ module Cask
         options[:quarantine] = true if options[:quarantine].nil?
 
         casks.each do |cask|
-          Installer.new(cask, **options).reinstall
+          Installer.new(cask, **options).install
         end
       end
     end

Library/Homebrew/cask/installer.rb

@@ -22,7 +22,7 @@ module Cask
 
     def initialize(cask, command: SystemCommand, force: false, adopt: false,
                    skip_cask_deps: false, binaries: true, verbose: false,
-                   zap: false, require_sha: false, upgrade: false,
+                   zap: false, require_sha: false, upgrade: false, reinstall: false,
                    installed_as_dependency: false, quarantine: true,
                    verify_download_integrity: true, quiet: false)
       @cask = cask
@@ -34,7 +34,7 @@ module Cask
       @verbose = verbose
       @zap = zap
       @require_sha = require_sha
-      @reinstall = false
+      @reinstall = reinstall
       @upgrade = upgrade
       @installed_as_dependency = installed_as_dependency
       @quarantine = quarantine
@@ -143,17 +143,11 @@ on_request: true)
       end
     end
 
-    def reinstall
-      odebug "Cask::Installer#reinstall"
-      @reinstall = true
-      install
-    end
-
     def uninstall_existing_cask
       return unless @cask.installed?
 
       # Always force uninstallation, ignore method parameter
-      cask_installer = Installer.new(@cask, verbose: verbose?, force: true, upgrade: upgrade?)
+      cask_installer = Installer.new(@cask, verbose: verbose?, force: true, upgrade: upgrade?, reinstall: true)
       zap? ? cask_installer.zap : cask_installer.uninstall
     end
 
@@ -234,7 +228,8 @@ on_request: true)
 
         next if artifact.is_a?(Artifact::Binary) && !binaries?
 
-        artifact.install_phase(command: @command, verbose: verbose?, adopt: adopt?, force: force?, upgrade: upgrade?)
+        artifact.install_phase(command: @command, verbose: verbose?, adopt: adopt?, force: force?,
+                               upgrade_or_reinstall: upgrade? || reinstall?)
         already_installed_artifacts.unshift(artifact)
       end
 
@@ -461,7 +456,11 @@ on_request: true)
         if artifact.respond_to?(:uninstall_phase)
           odebug "Uninstalling artifact of class #{artifact.class}"
           artifact.uninstall_phase(
-            command: @command, verbose: verbose?, skip: clear, force: force?, upgrade: upgrade?,
+            command:              @command,
+            verbose:              verbose?,
+            skip:                 clear,
+            force:                force?,
+            upgrade_or_reinstall: upgrade? || reinstall?,
           )
         end
 
@@ -469,7 +468,11 @@ on_request: true)
 
         odebug "Post-uninstalling artifact of class #{artifact.class}"
         artifact.post_uninstall_phase(
-          command: @command, verbose: verbose?, skip: clear, force: force?, upgrade: upgrade?,
+          command:              @command,
+          verbose:              verbose?,
+          skip:                 clear,
+          force:                force?,
+          upgrade_or_reinstall: upgrade? || reinstall?,
         )
       end
     end

Library/Homebrew/test/cask/artifact/app_spec.rb

@@ -323,13 +323,13 @@ describe Cask::Artifact::App, :cask do
       inode = target_path.stat.ino
       expect(contents_path).to exist
 
-      app.uninstall_phase(command: command, force: force, upgrade: true)
+      app.uninstall_phase(command: command, force: force, upgrade_or_reinstall: true)
 
       expect(target_path).to exist
       expect(target_path.children).to be_empty
       expect(contents_path).not_to exist
 
-      app.install_phase(command: command, adopt: adopt, force: force, upgrade: true)
+      app.install_phase(command: command, adopt: adopt, force: force, upgrade_or_reinstall: true)
       expect(target_path).to exist
       expect(target_path.stat.ino).to eq(inode)