diff --git a/Library/Homebrew/env_config.rb b/Library/Homebrew/env_config.rb
index 84fed24b19..d1cfb673df 100644
--- a/Library/Homebrew/env_config.rb
+++ b/Library/Homebrew/env_config.rb
@@ -613,7 +613,6 @@ module Homebrew
         boolean:     :set,
       },
       HOMEBREW_NO_SANDBOX_CASK:                  {
-        # odeprecated: make cask executable sandboxing mandatory in a future release.
         description: "If set, disable sandboxing for cask artifacts that generate files by running " \
                      "executables.",
         boolean:     true,
diff --git a/Library/Homebrew/install_steps.rb b/Library/Homebrew/install_steps.rb
index 3f25067968..1210e24760 100644
--- a/Library/Homebrew/install_steps.rb
+++ b/Library/Homebrew/install_steps.rb
@@ -509,16 +509,19 @@ module Homebrew
 
       sig {
         params(
-          path:    ::T.any(::String, ::Pathname),
-          content: ::String,
-          base:    ::T.nilable(::T.any(::String, ::Symbol)),
+          path:           ::T.any(::String, ::Pathname),
+          content:        ::String,
+          base:           ::T.nilable(::T.any(::String, ::Symbol)),
+          overwrite:      ::T::Boolean,
+          append_newline: ::T::Boolean,
         ).void
       }
-      def write_file(path, content, base: nil)
+      def write_file(path, content, base: nil, overwrite: true, append_newline: false)
+        content = "#{content}\n" if append_newline && !content.end_with?("\n")
         add_step("write",
                  "path"      => path_spec(path, base:, default_base: @default_base),
                  "content"   => content,
-                 "overwrite" => true)
+                 "overwrite" => (true if overwrite))
       end
 
       sig {
@@ -553,6 +556,11 @@ module Homebrew
         add_rebuild_action("gio_querymodules", "lib/gio/modules")
       end
 
+      sig { void }
+      def update_gio_modules_cache
+        add_rebuild_action("gio_querymodules", "lib/gio/modules")
+      end
+
       # odeprecated
       sig { void }
       def gdk_pixbuf_query_loaders
diff --git a/Library/Homebrew/rubocops/cask/install_steps.rb b/Library/Homebrew/rubocops/cask/install_steps.rb
index e86d825c73..e184b90469 100644
--- a/Library/Homebrew/rubocops/cask/install_steps.rb
+++ b/Library/Homebrew/rubocops/cask/install_steps.rb
@@ -76,6 +76,7 @@ module RuboCop
             next unless stanza.method_node.block_type?
 
             block_node = T.cast(stanza.method_node, RuboCop::AST::BlockNode)
+            add_compatibility_step_offenses(block_node, allowed_methods: CASK_ALLOWED_STEP_METHODS)
             if (offense_node = brew_ruby_step_node(block_node))
               add_offense(offense_node, message: BREW_RUBY_STEP_MSG)
               next
diff --git a/Library/Homebrew/rubocops/install_steps.rb b/Library/Homebrew/rubocops/install_steps.rb
index ae5d877c67..be8b6e1c6e 100644
--- a/Library/Homebrew/rubocops/install_steps.rb
+++ b/Library/Homebrew/rubocops/install_steps.rb
@@ -12,9 +12,7 @@ module RuboCop
         extend AutoCorrector
         include InstallStepsHelper
 
-        # TODO: Re-enable when formula `post_install` and `post_install_steps`
-        # cannot coexist after the incremental conversion bridge is removed.
-        # CONFLICT_MSG = "`post_install` and `post_install_steps` cannot both be used."
+        CONFLICT_MSG = "`post_install` and `post_install_steps` cannot both be used."
         LEGACY_POST_INSTALL_MSG =
           "Formulae in official Homebrew taps must use `post_install_steps` instead of `post_install`."
         REDUNDANT_SERVICE_PATH_DIRS_MSG = "`%<block>s` only creates directories created by `brew services`."
@@ -91,13 +89,10 @@ module RuboCop
           post_install_steps_block = find_block(body_node, :post_install_steps)
           post_install_method = find_method_def(body_node, :post_install)
 
-          # TODO: Re-enable when formula `post_install` and
-          # `post_install_steps` cannot coexist after the incremental
-          # conversion bridge is removed.
-          # if post_install_steps_block && post_install_method
-          #   offending_node(post_install_steps_block)
-          #   problem CONFLICT_MSG
-          # end
+          if post_install_steps_block && post_install_method
+            offending_node(post_install_steps_block)
+            problem CONFLICT_MSG
+          end
 
           redundant_post_install_steps = post_install_steps_block.present? &&
                                          redundant_service_path_dirs_block?(post_install_steps_block,
@@ -126,6 +121,8 @@ module RuboCop
         def audit_step_block(block_node)
           return if block_node.nil?
 
+          add_compatibility_step_offenses(block_node)
+
           if (offense_node = brew_ruby_step_node(block_node))
             offending_node(offense_node)
             problem BREW_RUBY_STEP_MSG
diff --git a/Library/Homebrew/rubocops/shared/install_steps_helper.rb b/Library/Homebrew/rubocops/shared/install_steps_helper.rb
index 2e94fc991d..32c072c581 100644
--- a/Library/Homebrew/rubocops/shared/install_steps_helper.rb
+++ b/Library/Homebrew/rubocops/shared/install_steps_helper.rb
@@ -13,8 +13,8 @@ module RuboCop
       CONFIG_WRITE_STEP_METHODS = [:write, :write_file].freeze
       SERVICE_DATA_STEP_METHODS = [:init_data_dir].freeze
       REBUILD_ACTION_STEP_METHODS =
-        [:compile_gsettings_schemas, :gio_querymodules, :gdk_pixbuf_query_loaders, :update_gdk_pixbuf_loaders_cache,
-         :gtk_update_icon_cache, :update_gtk_icon_cache,
+        [:compile_gsettings_schemas, :gio_querymodules, :update_gio_modules_cache, :gdk_pixbuf_query_loaders,
+         :update_gdk_pixbuf_loaders_cache, :gtk_update_icon_cache, :update_gtk_icon_cache,
          :update_mime_database, :update_desktop_database].freeze
       KEYCHAIN_STEP_METHODS = [:delete_keychain_certificate, :delete_keychain_certificates].freeze
       PERMISSION_STEP_METHODS = [:set_permissions, :set_ownership].freeze
@@ -25,10 +25,36 @@ module RuboCop
         [:configure_gcc_runtime, :install_gzipped_executable, :configure_glibc_runtime,
          :configure_clang_system, :configure_php, :bootstrap_cpython, :bootstrap_pypy].freeze
       STEP_SCOPE_METHODS = [:if_path_exists, :unless_path_exists, :on_macos, :on_linux].freeze
-      # odeprecated
-      COMPATIBILITY_STEP_METHODS =
-        [:mkdir, :mv, :move_children, :ln_s, :ln_sf, :link_dir, :link_children, :write, :gio_querymodules,
-         :gdk_pixbuf_query_loaders, :gtk_update_icon_cache, :delete_keychain_certificate].freeze
+      COMPATIBILITY_STEP_METHOD_REPLACEMENTS = T.let(
+        {
+          mkdir:                       :mkdir_p,
+          mv:                          :move,
+          move_children:               :move_contents,
+          ln_s:                        :symlink,
+          ln_sf:                       :symlink,
+          link_dir:                    :symlink_tree,
+          link_children:               :symlink_children,
+          write:                       :write_file,
+          gio_querymodules:            :update_gio_modules_cache,
+          gdk_pixbuf_query_loaders:    :update_gdk_pixbuf_loaders_cache,
+          gtk_update_icon_cache:       :update_gtk_icon_cache,
+          delete_keychain_certificate: :delete_keychain_certificates,
+        }.freeze,
+        T::Hash[Symbol, Symbol],
+      )
+      COMPATIBILITY_STEP_METHODS = T.let(COMPATIBILITY_STEP_METHOD_REPLACEMENTS.keys.freeze, T::Array[Symbol])
+      COMPATIBILITY_STEP_KEYWORD_REPLACEMENTS = T.let(
+        {
+          move:                         { force: :overwrite }.freeze,
+          mv:                           { force: :overwrite }.freeze,
+          symlink:                      { force: :overwrite, uninstall: :remove_on_uninstall }.freeze,
+          ln_s:                         { force: :overwrite, uninstall: :remove_on_uninstall }.freeze,
+          ln_sf:                        { uninstall: :remove_on_uninstall }.freeze,
+          delete_keychain_certificate:  { matching_certificate: :fingerprint_of }.freeze,
+          delete_keychain_certificates: { matching_certificate: :fingerprint_of }.freeze,
+        }.freeze,
+        T::Hash[Symbol, T::Hash[Symbol, Symbol]],
+      )
       ALLOWED_STEP_METHODS = T.let(
         [*FILE_PREPARATION_STEP_METHODS, *LINK_STEP_METHODS, *CONFIG_WRITE_STEP_METHODS, *SERVICE_DATA_STEP_METHODS,
          *REBUILD_ACTION_STEP_METHODS, :set_permissions, *COMMAND_STEP_METHODS, *NOTICE_STEP_METHODS,
@@ -52,6 +78,8 @@ module RuboCop
         String,
       )
       BREW_RUBY_STEP_MSG = "Install steps must not use `brew ruby` because it enables developer mode."
+      LEGACY_STEP_METHOD_MSG = "Use `%<replacement>s` instead of legacy install step `%<method>s`."
+      LEGACY_STEP_KEYWORD_MSG = "Use `%<replacement>s:` instead of legacy install step keyword `%<keyword>s:`."
       SIMPLE_STEP_CONVERSION_MSG = "Use `%<steps_block>s` for simple file preparation."
       REBUILD_ACTION_STEP_LINES = T.let(
         T.let([
@@ -95,6 +123,29 @@ module RuboCop
           "#{(allowed_methods - COMPATIBILITY_STEP_METHODS).map { |method| "`#{method}`" }.join(", ")}."
       end
 
+      sig {
+        params(
+          block_node:      RuboCop::AST::BlockNode,
+          allowed_methods: T::Array[Symbol],
+        ).void
+      }
+      def add_compatibility_step_offenses(block_node, allowed_methods: ALLOWED_STEP_METHODS)
+        block_node.each_descendant(:send) do |node|
+          send_node = T.cast(node, RuboCop::AST::SendNode)
+          method = send_node.method_name
+          next if send_node.receiver || !allowed_methods.include?(method)
+
+          if (replacement = COMPATIBILITY_STEP_METHOD_REPLACEMENTS[method])
+            add_offense(send_node.loc.selector,
+                        message: Kernel.format(LEGACY_STEP_METHOD_MSG, method:, replacement:)) do |corrector|
+              corrector.replace(send_node.loc.selector, replacement.to_s)
+              add_compatibility_step_method_corrections(corrector, send_node)
+            end
+          end
+          add_compatibility_step_keyword_offenses(send_node)
+        end
+      end
+
       class InstallStepPath < T::Struct
         const :path, String
         const :base, T.nilable(Symbol)
@@ -211,6 +262,114 @@ module RuboCop
 
       private
 
+      sig { params(send_node: RuboCop::AST::SendNode).void }
+      def add_compatibility_step_keyword_offenses(send_node)
+        replacements = COMPATIBILITY_STEP_KEYWORD_REPLACEMENTS[send_node.method_name]
+        return if replacements.nil?
+
+        options = send_node.last_argument
+        return unless options&.hash_type?
+
+        options = T.cast(options, RuboCop::AST::HashNode)
+        options.pairs.each do |pair|
+          next unless pair.key.sym_type?
+          next unless (replacement = replacements[pair.key.value])
+
+          message = Kernel.format(LEGACY_STEP_KEYWORD_MSG, keyword: pair.key.value, replacement:)
+          add_offense(pair.key.source_range, message:) do |corrector|
+            correct_compatibility_step_keyword(corrector, send_node, options, pair, replacement)
+          end
+        end
+      end
+
+      sig {
+        params(
+          corrector:   RuboCop::Cop::Corrector,
+          send_node:   RuboCop::AST::SendNode,
+          options:     RuboCop::AST::HashNode,
+          legacy_pair: RuboCop::AST::PairNode,
+          replacement: Symbol,
+        ).void
+      }
+      def correct_compatibility_step_keyword(corrector, send_node, options, legacy_pair, replacement)
+        if replacement == :fingerprint_of
+          corrector.replace(legacy_pair.key.source_range, replacement.to_s)
+          return
+        end
+        return if !legacy_pair.value.true_type? && !legacy_pair.value.false_type?
+
+        canonical_pair = options.pairs.find do |pair|
+          pair != legacy_pair && pair.key.sym_type? && pair.key.value == replacement
+        end
+        if legacy_pair.value.true_type? && canonical_pair.nil?
+          corrector.replace(legacy_pair.key.source_range, replacement.to_s)
+          return
+        end
+
+        if legacy_pair.value.true_type? && canonical_pair && !canonical_pair.value.true_type?
+          corrector.replace(canonical_pair.value.source_range, "true")
+        end
+        pairs = options.pairs
+        index = pairs.index(legacy_pair)
+        return if index.nil?
+
+        range = if (next_pair = pairs[index + 1])
+          legacy_pair.source_range.begin.join(next_pair.source_range.begin)
+        elsif (previous_pair = pairs[index - 1]) && index.positive?
+          previous_pair.source_range.end.join(legacy_pair.source_range.end)
+        else
+          send_node.arguments.fetch(-2).source_range.end.join(legacy_pair.source_range.end)
+        end
+        corrector.remove(range)
+      end
+
+      sig {
+        params(
+          corrector: RuboCop::Cop::Corrector,
+          send_node: RuboCop::AST::SendNode,
+        ).void
+      }
+      def add_compatibility_step_method_corrections(corrector, send_node)
+        case send_node.method_name
+        when :ln_sf
+          add_step_keyword(corrector, send_node, "overwrite: true")
+        when :write
+          options = send_node.last_argument
+          overwrite = options&.hash_type? && T.cast(options, RuboCop::AST::HashNode).pairs.any? do |pair|
+            pair.key.sym_type? && pair.key.value == :overwrite
+          end
+          keyword = "append_newline: true"
+          keyword = "overwrite: false, #{keyword}" unless overwrite
+          add_step_keyword(corrector, send_node, keyword)
+        end
+      end
+
+      sig {
+        params(
+          corrector: RuboCop::Cop::Corrector,
+          send_node: RuboCop::AST::SendNode,
+          keyword:   String,
+        ).void
+      }
+      def add_step_keyword(corrector, send_node, keyword)
+        options = send_node.last_argument
+        if options&.hash_type?
+          options = T.cast(options, RuboCop::AST::HashNode)
+          if (pair = options.pairs.last)
+            corrector.insert_after(pair.source_range, ", #{keyword}")
+          else
+            corrector.replace(options, keyword)
+          end
+        elsif (argument = send_node.last_argument)
+          range = if argument.loc.respond_to?(:heredoc_end) && argument.loc.heredoc_end
+            argument.loc.expression
+          else
+            argument.source_range
+          end
+          corrector.insert_after(range, ", #{keyword}")
+        end
+      end
+
       sig {
         params(
           node:            RuboCop::AST::Node,
diff --git a/Library/Homebrew/rubocops/shared/install_steps_helper.rbi b/Library/Homebrew/rubocops/shared/install_steps_helper.rbi
new file mode 100644
index 0000000000..951e6638d4
--- /dev/null
+++ b/Library/Homebrew/rubocops/shared/install_steps_helper.rbi
@@ -0,0 +1,5 @@
+# typed: strict
+
+module RuboCop::Cop::InstallStepsHelper
+  requires_ancestor { RuboCop::Cop::Base }
+end
diff --git a/Library/Homebrew/test/install_steps_spec.rb b/Library/Homebrew/test/install_steps_spec.rb
index d87ffdf53b..a70b8190db 100644
--- a/Library/Homebrew/test/install_steps_spec.rb
+++ b/Library/Homebrew/test/install_steps_spec.rb
@@ -349,6 +349,20 @@ RSpec.describe Homebrew::InstallSteps do
     expect([(root/"var/config/example.conf").read, (root/"var/empty").read]).to eq(["replacement", ""])
   end
 
+  specify "can append a newline without replacing existing files" do
+    steps = Homebrew::InstallSteps::DSL.build(default_base: :var) do
+      write_file "existing", "replacement", overwrite: false, append_newline: true
+      write_file "missing", "new", overwrite: false, append_newline: true
+    end
+
+    (root/"var").mkpath
+    (root/"var/existing").write "original\n"
+
+    Homebrew::InstallSteps::Runner.new(context:).run(steps)
+
+    expect([(root/"var/existing").read, (root/"var/missing").read]).to eq(["original\n", "new\n"])
+  end
+
   specify "preserves meaningful blank values" do
     steps = Homebrew::InstallSteps::DSL.build(default_base: :var) do
       inreplace "remove.txt", "remove", ""
@@ -904,7 +918,7 @@ RSpec.describe Homebrew::InstallSteps do
     end
     steps = Homebrew::InstallSteps::DSL.build do
       compile_gsettings_schemas
-      gio_querymodules
+      update_gio_modules_cache
       update_gdk_pixbuf_loaders_cache
       update_mime_database
       update_desktop_database
diff --git a/Library/Homebrew/test/rubocops/cask/install_steps_spec.rb b/Library/Homebrew/test/rubocops/cask/install_steps_spec.rb
index 9fe81fdcc1..4c19cb9beb 100644
--- a/Library/Homebrew/test/rubocops/cask/install_steps_spec.rb
+++ b/Library/Homebrew/test/rubocops/cask/install_steps_spec.rb
@@ -92,8 +92,6 @@ RSpec.describe RuboCop::Cop::Cask::InstallSteps, :config do
           touch "foo/state"
           touch "#{token}/state"
           move "source", "target"
-          mv "source", "target"
-          move_children "source", "target"
           move_contents "source", "target"
           inreplace "foo.conf", "@PREFIX@", "{{HOMEBREW_PREFIX}}"
           symlink "source", "target", source_base: :relative, overwrite: true, remove_on_uninstall: true
@@ -120,6 +118,84 @@ RSpec.describe RuboCop::Cop::Cask::InstallSteps, :config do
     CASK
   end
 
+  it "autocorrects legacy install step names" do
+    expect_offense <<~CASK
+      cask "foo" do
+        version :latest
+        sha256 :no_check
+
+        preflight_steps do
+          mkdir "foo"
+          ^^^^^ Use `mkdir_p` instead of legacy install step `mkdir`.
+          mv "source", "target"
+          ^^ Use `move` instead of legacy install step `mv`.
+          move_children "source", "target"
+          ^^^^^^^^^^^^^ Use `move_contents` instead of legacy install step `move_children`.
+          ln_s "source", "target"
+          ^^^^ Use `symlink` instead of legacy install step `ln_s`.
+          ln_sf "source", "target"
+          ^^^^^ Use `symlink` instead of legacy install step `ln_sf`.
+          write "foo.conf", "content"
+          ^^^^^ Use `write_file` instead of legacy install step `write`.
+          write "banner", <<~TEXT
+          ^^^^^ Use `write_file` instead of legacy install step `write`.
+            banner
+          TEXT
+          delete_keychain_certificate "Charles", matching_certificate: "certificate.pem"
+                                                 ^^^^^^^^^^^^^^^^^^^^ Use `fingerprint_of:` instead of legacy install step keyword `matching_certificate:`.
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^ Use `delete_keychain_certificates` instead of legacy install step `delete_keychain_certificate`.
+        end
+      end
+    CASK
+
+    expect_correction <<~CASK
+      cask "foo" do
+        version :latest
+        sha256 :no_check
+
+        preflight_steps do
+          mkdir_p "foo"
+          move "source", "target"
+          move_contents "source", "target"
+          symlink "source", "target"
+          symlink "source", "target", overwrite: true
+          write_file "foo.conf", "content", overwrite: false, append_newline: true
+          write_file "banner", <<~TEXT, overwrite: false, append_newline: true
+            banner
+          TEXT
+          delete_keychain_certificates "Charles", fingerprint_of: "certificate.pem"
+        end
+      end
+    CASK
+  end
+
+  it "autocorrects legacy install step keywords" do
+    expect_offense <<~CASK
+      cask "foo" do
+        version :latest
+        sha256 :no_check
+
+        preflight_steps do
+          delete_keychain_certificates "Charles",
+                                       matching_certificate: "certificate.pem"
+                                       ^^^^^^^^^^^^^^^^^^^^ Use `fingerprint_of:` instead of legacy install step keyword `matching_certificate:`.
+        end
+      end
+    CASK
+
+    expect_correction <<~CASK
+      cask "foo" do
+        version :latest
+        sha256 :no_check
+
+        preflight_steps do
+          delete_keychain_certificates "Charles",
+                                       fingerprint_of: "certificate.pem"
+        end
+      end
+    CASK
+  end
+
   it "reports an offense when a step string uses unsupported interpolation" do
     expect_offense <<~'CASK'
       cask "foo" do
diff --git a/Library/Homebrew/test/rubocops/install_steps_spec.rb b/Library/Homebrew/test/rubocops/install_steps_spec.rb
index c9dc254b0e..ed0f884223 100644
--- a/Library/Homebrew/test/rubocops/install_steps_spec.rb
+++ b/Library/Homebrew/test/rubocops/install_steps_spec.rb
@@ -13,12 +13,13 @@ RSpec.describe RuboCop::Cop::FormulaAudit::InstallSteps do
     )
   end
 
-  it "allows `post_install` and `post_install_steps` in third-party taps during incremental conversion" do
-    expect_no_offenses(<<~RUBY, "/Taps/example/homebrew-core/Formula/f/foo.rb")
+  it "rejects `post_install` and `post_install_steps` in third-party taps" do
+    expect_offense(<<~RUBY, "/Taps/example/homebrew-core/Formula/f/foo.rb")
       class Foo < Formula
         url "https://brew.sh/foo-1.0.tgz"
 
         post_install_steps do
+        ^^^^^^^^^^^^^^^^^^^^^ FormulaAudit/InstallSteps: `post_install` and `post_install_steps` cannot both be used.
           touch "foo/state", base: :var
         end
 
@@ -27,12 +28,13 @@ RSpec.describe RuboCop::Cop::FormulaAudit::InstallSteps do
     RUBY
   end
 
-  it "rejects `post_install` in official Homebrew taps" do
+  it "rejects `post_install` and `post_install_steps` in official Homebrew taps" do
     expect_offense(<<~RUBY, "/Taps/homebrew/homebrew-example/Formula/f/foo.rb")
       class Foo < Formula
         url "https://brew.sh/foo-1.0.tgz"
 
         post_install_steps do
+        ^^^^^^^^^^^^^^^^^^^^^ FormulaAudit/InstallSteps: `post_install` and `post_install_steps` cannot both be used.
           touch "foo/state", base: :var
         end
 
@@ -42,14 +44,15 @@ RSpec.describe RuboCop::Cop::FormulaAudit::InstallSteps do
     RUBY
   end
 
-  it "leaves `post_install_steps` ordering to `ComponentsOrder`" do
-    expect_no_offenses(<<~RUBY)
+  it "rejects coexistence regardless of component order" do
+    expect_offense(<<~RUBY)
       class Foo < Formula
         url "https://brew.sh/foo-1.0.tgz"
 
         def post_install; end
 
         post_install_steps do
+        ^^^^^^^^^^^^^^^^^^^^^ FormulaAudit/InstallSteps: `post_install` and `post_install_steps` cannot both be used.
           touch "foo/state", base: :var
         end
       end
@@ -64,8 +67,8 @@ RSpec.describe RuboCop::Cop::FormulaAudit::InstallSteps do
         post_install_steps do
           mkdir_p "log/foo"
           ^^^^^^^^^^^^^^^^^ FormulaAudit/InstallSteps: Formula install-step paths must specify their base explicitly.
-          write "foo/state", "ready"
-          ^^^^^^^^^^^^^^^^^^^^^^^^^^ FormulaAudit/InstallSteps: Formula install-step paths must specify their base explicitly.
+          write_file "foo/state", "ready"
+          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ FormulaAudit/InstallSteps: Formula install-step paths must specify their base explicitly.
           init_data_dir "foo", using: :postgresql_initdb
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ FormulaAudit/InstallSteps: Formula install-step paths must specify their base explicitly.
           if_path_exists "foo/state" do
@@ -85,7 +88,7 @@ RSpec.describe RuboCop::Cop::FormulaAudit::InstallSteps do
 
         post_install_steps do
           mkdir_p "log/foo", base: :var
-          write "foo/state", "ready", base: :var
+          write_file "foo/state", "ready", base: :var
           init_data_dir "foo", using: :postgresql_initdb, base: :var
           if_path_exists "foo/state", base: :var do
             touch "foo/checked", base: :var
@@ -128,7 +131,7 @@ RSpec.describe RuboCop::Cop::FormulaAudit::InstallSteps do
           mkdir_p "log/foo", base: :var
           touch "{{var}}/foo/state"
           if_path_exists "/etc/foo.conf" do
-            write "foo.conf", "ready", base: :etc
+            write_file "foo.conf", "ready", base: :etc
           end
           run "foo", base: :bin, chdir: "{{libexec}}/foo"
         end
@@ -143,7 +146,7 @@ RSpec.describe RuboCop::Cop::FormulaAudit::InstallSteps do
 
         post_install_steps do
           system "true"
-          ^^^^^^^^^^^^^ FormulaAudit/InstallSteps: Steps blocks may only contain install step DSL calls. Prefer canonical calls: `mkdir_p`, `touch`, `move`, `move_contents`, `copy`, `remove`, `inreplace`, `symlink`, `symlink_tree`, `symlink_children`, `write_file`, `init_data_dir`, `compile_gsettings_schemas`, `update_gdk_pixbuf_loaders_cache`, `update_gtk_icon_cache`, `update_mime_database`, `update_desktop_database`, `set_permissions`, `run`, `terminate_process`, `warn`, `change_dylib_id`, `configure_gcc_runtime`, `install_gzipped_executable`, `configure_glibc_runtime`, `configure_clang_system`, `configure_php`, `bootstrap_cpython`, `bootstrap_pypy`, `if_path_exists`, `unless_path_exists`, `on_macos`, `on_linux`.
+          ^^^^^^^^^^^^^ FormulaAudit/InstallSteps: Steps blocks may only contain install step DSL calls. Prefer canonical calls: `mkdir_p`, `touch`, `move`, `move_contents`, `copy`, `remove`, `inreplace`, `symlink`, `symlink_tree`, `symlink_children`, `write_file`, `init_data_dir`, `compile_gsettings_schemas`, `update_gio_modules_cache`, `update_gdk_pixbuf_loaders_cache`, `update_gtk_icon_cache`, `update_mime_database`, `update_desktop_database`, `set_permissions`, `run`, `terminate_process`, `warn`, `change_dylib_id`, `configure_gcc_runtime`, `install_gzipped_executable`, `configure_glibc_runtime`, `configure_clang_system`, `configure_php`, `bootstrap_cpython`, `bootstrap_pypy`, `if_path_exists`, `unless_path_exists`, `on_macos`, `on_linux`.
         end
       end
     RUBY
@@ -199,8 +202,7 @@ RSpec.describe RuboCop::Cop::FormulaAudit::InstallSteps do
           symlink_tree "source", "#{formula_name}"
           symlink_children "source", suffix: "-#{version.major}"
           compile_gsettings_schemas
-          gio_querymodules
-          gdk_pixbuf_query_loaders
+          update_gio_modules_cache
           update_gdk_pixbuf_loaders_cache
           update_gtk_icon_cache
           update_mime_database
@@ -220,6 +222,118 @@ RSpec.describe RuboCop::Cop::FormulaAudit::InstallSteps do
     RUBY
   end
 
+  it "autocorrects legacy install step names" do
+    expect_offense(<<~RUBY)
+      class Foo < Formula
+        url "https://brew.sh/foo-1.0.tgz"
+
+        post_install_steps do
+          mkdir "foo", base: :var
+          ^^^^^ FormulaAudit/InstallSteps: Use `mkdir_p` instead of legacy install step `mkdir`.
+          mv "source", "target",
+          ^^ FormulaAudit/InstallSteps: Use `move` instead of legacy install step `mv`.
+             force: true
+             ^^^^^ FormulaAudit/InstallSteps: Use `overwrite:` instead of legacy install step keyword `force:`.
+          move_children "source", "target"
+          ^^^^^^^^^^^^^ FormulaAudit/InstallSteps: Use `move_contents` instead of legacy install step `move_children`.
+          ln_s "source", "target"
+          ^^^^ FormulaAudit/InstallSteps: Use `symlink` instead of legacy install step `ln_s`.
+          ln_sf "source", "target",
+          ^^^^^ FormulaAudit/InstallSteps: Use `symlink` instead of legacy install step `ln_sf`.
+                uninstall: true
+                ^^^^^^^^^ FormulaAudit/InstallSteps: Use `remove_on_uninstall:` instead of legacy install step keyword `uninstall:`.
+          link_dir "source", "target"
+          ^^^^^^^^ FormulaAudit/InstallSteps: Use `symlink_tree` instead of legacy install step `link_dir`.
+          link_children "source", "target"
+          ^^^^^^^^^^^^^ FormulaAudit/InstallSteps: Use `symlink_children` instead of legacy install step `link_children`.
+          write "foo.conf", "content", base: :var
+          ^^^^^ FormulaAudit/InstallSteps: Use `write_file` instead of legacy install step `write`.
+          gio_querymodules
+          ^^^^^^^^^^^^^^^^ FormulaAudit/InstallSteps: Use `update_gio_modules_cache` instead of legacy install step `gio_querymodules`.
+          gdk_pixbuf_query_loaders
+          ^^^^^^^^^^^^^^^^^^^^^^^^ FormulaAudit/InstallSteps: Use `update_gdk_pixbuf_loaders_cache` instead of legacy install step `gdk_pixbuf_query_loaders`.
+          gtk_update_icon_cache
+          ^^^^^^^^^^^^^^^^^^^^^ FormulaAudit/InstallSteps: Use `update_gtk_icon_cache` instead of legacy install step `gtk_update_icon_cache`.
+        end
+      end
+    RUBY
+
+    expect_correction(<<~RUBY)
+      class Foo < Formula
+        url "https://brew.sh/foo-1.0.tgz"
+
+        post_install_steps do
+          mkdir_p "foo", base: :var
+          move "source", "target",
+             overwrite: true
+          move_contents "source", "target"
+          symlink "source", "target"
+          symlink "source", "target",
+                remove_on_uninstall: true, overwrite: true
+          symlink_tree "source", "target"
+          symlink_children "source", "target"
+          write_file "foo.conf", "content", base: :var, overwrite: false, append_newline: true
+          update_gio_modules_cache
+          update_gdk_pixbuf_loaders_cache
+          update_gtk_icon_cache
+        end
+      end
+    RUBY
+  end
+
+  it "autocorrects legacy install step keywords" do
+    expect_offense(<<~RUBY)
+      class Foo < Formula
+        url "https://brew.sh/foo-1.0.tgz"
+
+        post_install_steps do
+          move "source", "target",
+               force: true
+               ^^^^^ FormulaAudit/InstallSteps: Use `overwrite:` instead of legacy install step keyword `force:`.
+          symlink "source", "target",
+                  force: true,
+                  ^^^^^ FormulaAudit/InstallSteps: Use `overwrite:` instead of legacy install step keyword `force:`.
+                  uninstall: true
+                  ^^^^^^^^^ FormulaAudit/InstallSteps: Use `remove_on_uninstall:` instead of legacy install step keyword `uninstall:`.
+          move "redundant", "false",
+               force: false
+               ^^^^^ FormulaAudit/InstallSteps: Use `overwrite:` instead of legacy install step keyword `force:`.
+          move "combined", "options",
+               force: true,
+               ^^^^^ FormulaAudit/InstallSteps: Use `overwrite:` instead of legacy install step keyword `force:`.
+               overwrite: false
+          symlink "combined", "options",
+                  force: true,
+                  ^^^^^ FormulaAudit/InstallSteps: Use `overwrite:` instead of legacy install step keyword `force:`.
+                  overwrite: false,
+                  uninstall: true,
+                  ^^^^^^^^^ FormulaAudit/InstallSteps: Use `remove_on_uninstall:` instead of legacy install step keyword `uninstall:`.
+                  remove_on_uninstall: false
+        end
+      end
+    RUBY
+
+    expect_correction(<<~RUBY)
+      class Foo < Formula
+        url "https://brew.sh/foo-1.0.tgz"
+
+        post_install_steps do
+          move "source", "target",
+               overwrite: true
+          symlink "source", "target",
+                  overwrite: true,
+                  remove_on_uninstall: true
+          move "redundant", "false"
+          move "combined", "options",
+               overwrite: true
+          symlink "combined", "options",
+                  overwrite: true,
+                  remove_on_uninstall: true
+        end
+      end
+    RUBY
+  end
+
   it "reports an offense when a scope contains Ruby code" do
     expect_offense(<<~RUBY)
       class Foo < Formula
@@ -228,7 +342,7 @@ RSpec.describe RuboCop::Cop::FormulaAudit::InstallSteps do
         post_install_steps do
           on_macos do
             system "true"
-            ^^^^^^^^^^^^^ FormulaAudit/InstallSteps: Steps blocks may only contain install step DSL calls. Prefer canonical calls: `mkdir_p`, `touch`, `move`, `move_contents`, `copy`, `remove`, `inreplace`, `symlink`, `symlink_tree`, `symlink_children`, `write_file`, `init_data_dir`, `compile_gsettings_schemas`, `update_gdk_pixbuf_loaders_cache`, `update_gtk_icon_cache`, `update_mime_database`, `update_desktop_database`, `set_permissions`, `run`, `terminate_process`, `warn`, `change_dylib_id`, `configure_gcc_runtime`, `install_gzipped_executable`, `configure_glibc_runtime`, `configure_clang_system`, `configure_php`, `bootstrap_cpython`, `bootstrap_pypy`, `if_path_exists`, `unless_path_exists`, `on_macos`, `on_linux`.
+            ^^^^^^^^^^^^^ FormulaAudit/InstallSteps: Steps blocks may only contain install step DSL calls. Prefer canonical calls: `mkdir_p`, `touch`, `move`, `move_contents`, `copy`, `remove`, `inreplace`, `symlink`, `symlink_tree`, `symlink_children`, `write_file`, `init_data_dir`, `compile_gsettings_schemas`, `update_gio_modules_cache`, `update_gdk_pixbuf_loaders_cache`, `update_gtk_icon_cache`, `update_mime_database`, `update_desktop_database`, `set_permissions`, `run`, `terminate_process`, `warn`, `change_dylib_id`, `configure_gcc_runtime`, `install_gzipped_executable`, `configure_glibc_runtime`, `configure_clang_system`, `configure_php`, `bootstrap_cpython`, `bootstrap_pypy`, `if_path_exists`, `unless_path_exists`, `on_macos`, `on_linux`.
           end
         end
       end
@@ -242,7 +356,7 @@ RSpec.describe RuboCop::Cop::FormulaAudit::InstallSteps do
 
         post_install_steps do
           write_file "foo.conf", "prefix = #{prefix}", base: :var
-                                           ^^^^^^^^^ FormulaAudit/InstallSteps: Steps blocks may only contain install step DSL calls. Prefer canonical calls: `mkdir_p`, `touch`, `move`, `move_contents`, `copy`, `remove`, `inreplace`, `symlink`, `symlink_tree`, `symlink_children`, `write_file`, `init_data_dir`, `compile_gsettings_schemas`, `update_gdk_pixbuf_loaders_cache`, `update_gtk_icon_cache`, `update_mime_database`, `update_desktop_database`, `set_permissions`, `run`, `terminate_process`, `warn`, `change_dylib_id`, `configure_gcc_runtime`, `install_gzipped_executable`, `configure_glibc_runtime`, `configure_clang_system`, `configure_php`, `bootstrap_cpython`, `bootstrap_pypy`, `if_path_exists`, `unless_path_exists`, `on_macos`, `on_linux`.
+                                           ^^^^^^^^^ FormulaAudit/InstallSteps: Steps blocks may only contain install step DSL calls. Prefer canonical calls: `mkdir_p`, `touch`, `move`, `move_contents`, `copy`, `remove`, `inreplace`, `symlink`, `symlink_tree`, `symlink_children`, `write_file`, `init_data_dir`, `compile_gsettings_schemas`, `update_gio_modules_cache`, `update_gdk_pixbuf_loaders_cache`, `update_gtk_icon_cache`, `update_mime_database`, `update_desktop_database`, `set_permissions`, `run`, `terminate_process`, `warn`, `change_dylib_id`, `configure_gcc_runtime`, `install_gzipped_executable`, `configure_glibc_runtime`, `configure_clang_system`, `configure_php`, `bootstrap_cpython`, `bootstrap_pypy`, `if_path_exists`, `unless_path_exists`, `on_macos`, `on_linux`.
         end
       end
     RUBY
@@ -366,6 +480,7 @@ RSpec.describe RuboCop::Cop::FormulaAudit::InstallSteps do
         url "https://brew.sh/foo-1.0.tgz"
 
         post_install_steps do
+        ^^^^^^^^^^^^^^^^^^^^^ FormulaAudit/InstallSteps: `post_install` and `post_install_steps` cannot both be used.
           touch "postgresql/state", base: :var
         end
 
diff --git a/docs/Cask-Cookbook.md b/docs/Cask-Cookbook.md
index 054b99fb8c..13f626fdc5 100644
--- a/docs/Cask-Cookbook.md
+++ b/docs/Cask-Cookbook.md
@@ -646,7 +646,7 @@ Relative paths default to `staged_path` for `base:`, `source_base:` and `target_
 * `remove`: remove one or more paths; example: `remove ["Shared/old", "Shared/*.bak"], recursive: true`.
 * `inreplace`: replace a string or regular expression in a file; example: `inreplace "Shared/foo.conf", "@PREFIX@", "{{HOMEBREW_PREFIX}}"`.
 * `symlink`: create a symlink; example: `symlink "Shared/payload", "Payload", source_base: :relative`.
-* `write_file`: atomically write exact literal content, replacing an existing file; example: `write_file "Shared/foo.conf", "key = value\n"`.
+* `write_file`: atomically write literal content, replacing an existing file by default; pass `append_newline: true` to ensure a trailing newline or `overwrite: false` to preserve it; example: `write_file "Shared/foo.conf", "key = value\n"`.
 * `delete_keychain_certificates`: delete macOS keychain certificates whose common name matches the argument; example: `delete_keychain_certificates "Charles"`. Pass `fingerprint_of:` with a local certificate path to delete only the matching SHA-256 fingerprint; example:
   `delete_keychain_certificates "NodeMITMProxyCA", fingerprint_of: "~/Library/Application Support/betwixt/ssl/certs/ca.pem"`.
 * `set_permissions`: recursively change existing path permissions with `chmod`; example: `set_permissions "Shared/payload", "0755"`.
diff --git a/docs/Formula-Cookbook.md b/docs/Formula-Cookbook.md
index 782efde688..28cb6ce625 100644
--- a/docs/Formula-Cookbook.md
+++ b/docs/Formula-Cookbook.md
@@ -1067,7 +1067,7 @@ end
 
 Formulae in official Homebrew taps must represent post-install work with [`post_install_steps`](/rubydoc/Formula.html#post_install_steps-class_method); new `post_install` methods are rejected. These steps can be re-run separately with `brew postinstall <formula>`, are stored in the JSON API and do not require downloading source formula Ruby. A `post_install_steps` block may only contain the supported step calls with literal arguments. It cannot call the wider formula DSL or arbitrary Ruby code. Homebrew executes the steps with the same post-install sandbox policy.
 
-The legacy `post_install` method remains available temporarily for third-party tap compatibility, but is not an authoring interface for official formulae.
+The legacy `post_install` method remains available temporarily for third-party tap compatibility, but is not an authoring interface for official formulae. A formula cannot define both `post_install` and `post_install_steps`.
 
 ```ruby
 class Foo < Formula
@@ -1114,7 +1114,7 @@ end
 
 #### Default config and template steps
 
-`write_file` atomically writes its exact literal content, replacing an existing file. Specify its `base:`, such as `base: :etc`. Use `unless_path_exists` when a default file should preserve user edits across upgrades:
+`write_file` atomically writes its literal content, replacing an existing file by default. Specify its `base:`, such as `base: :etc`. Pass `append_newline: true` to ensure the content ends in a newline, `overwrite: false` to preserve an existing file or use `unless_path_exists` to guard a group of default-file steps:
 
 ```ruby
 unless_path_exists "foo.conf", base: :etc do
@@ -1195,6 +1195,7 @@ symlink_children "bin", suffix: "-{{version.major}}"
 These steps rebuild shared desktop and cache state using Homebrew-owned tools.
 
 * `compile_gsettings_schemas`: compile GSettings schemas in `share/glib-2.0/schemas`.
+* `update_gio_modules_cache`: update the GIO module cache in `lib/gio/modules`.
 * `update_gdk_pixbuf_loaders_cache`: update the GDK Pixbuf loader cache.
 * `update_gtk_icon_cache`: refresh the `hicolor` GTK icon cache.
 * `update_mime_database`: rebuild the shared MIME database in `share/mime`.