diff --git a/Library/Homebrew/aliases/aliases.rb b/Library/Homebrew/aliases/aliases.rb
index b8aa064a4b..0b95596dea 100644
--- a/Library/Homebrew/aliases/aliases.rb
+++ b/Library/Homebrew/aliases/aliases.rb
@@ -43,7 +43,7 @@ module Homebrew
         next if !only.empty? && only.exclude?(name)
 
         lines.reject! { |line| line.start_with?("#") || line =~ /^\s*$/ }
-        first_line = T.must(lines.first)
+        first_line = lines.fetch(0)
         command = first_line.chomp
         command.sub!(/ \$\*$/, "")
 
diff --git a/Library/Homebrew/cask/caskroom.rb b/Library/Homebrew/cask/caskroom.rb
index 1b83d33feb..c0e88584fd 100644
--- a/Library/Homebrew/cask/caskroom.rb
+++ b/Library/Homebrew/cask/caskroom.rb
@@ -61,7 +61,7 @@ module Cask
       tokens.sort.filter_map do |token|
         CaskLoader.load_prefer_installed(token, config:, warn: false)
       rescue TapCaskAmbiguityError => e
-        T.must(e.loaders.first).load(config:)
+        e.loaders.fetch(0).load(config:)
       rescue
         # Don't blow up because of a single unavailable cask.
         nil
diff --git a/Library/Homebrew/cmd/deps.rb b/Library/Homebrew/cmd/deps.rb
index 1c1e6634b0..47be13dd97 100644
--- a/Library/Homebrew/cmd/deps.rb
+++ b/Library/Homebrew/cmd/deps.rb
@@ -91,7 +91,7 @@ module Homebrew
         raise UsageError, "`brew deps --os=all` is not supported." if args.os == "all"
         raise UsageError, "`brew deps --arch=all` is not supported." if args.arch == "all"
 
-        os, arch = T.must(args.os_arch_combinations.first)
+        os, arch = args.os_arch_combinations.fetch(0)
         eval_all = args.eval_all?
 
         Formulary.enable_factory_cache!
diff --git a/Library/Homebrew/cmd/log.rb b/Library/Homebrew/cmd/log.rb
index e76f131b87..9cb9e302de 100644
--- a/Library/Homebrew/cmd/log.rb
+++ b/Library/Homebrew/cmd/log.rb
@@ -44,7 +44,7 @@ module Homebrew
         if args.no_named?
           git_log(HOMEBREW_REPOSITORY)
         else
-          path = T.must(args.named.to_paths.first)
+          path = args.named.to_paths.fetch(0)
           tap = Tap.from_path(path)
           git_log path.dirname, path, tap
         end
diff --git a/Library/Homebrew/cmd/untap.rb b/Library/Homebrew/cmd/untap.rb
index 17c5c11af6..fdac754001 100644
--- a/Library/Homebrew/cmd/untap.rb
+++ b/Library/Homebrew/cmd/untap.rb
@@ -49,7 +49,7 @@ module Homebrew
       sig { params(tap: Tap).returns(T::Array[Formula]) }
       def installed_formulae_for(tap:)
         tap.formula_names.filter_map do |formula_name|
-          next unless installed_formulae_names.include?(T.must(formula_name.split("/").last))
+          next unless installed_formulae_names.include?(formula_name.split("/").fetch(-1))
 
           formula = begin
             Formulary.factory(formula_name)
@@ -68,7 +68,7 @@ module Homebrew
       sig { params(tap: Tap).returns(T::Array[Cask::Cask]) }
       def installed_casks_for(tap:)
         tap.cask_tokens.filter_map do |cask_token|
-          next unless installed_cask_tokens.include?(T.must(cask_token.split("/").last))
+          next unless installed_cask_tokens.include?(cask_token.split("/").fetch(-1))
 
           cask = begin
             Cask::CaskLoader.load(cask_token)
diff --git a/Library/Homebrew/cmd/update-report.rb b/Library/Homebrew/cmd/update-report.rb
index 70ec32074c..13bed07d10 100644
--- a/Library/Homebrew/cmd/update-report.rb
+++ b/Library/Homebrew/cmd/update-report.rb
@@ -500,7 +500,7 @@ class Reporter
       case status
       when "A", "D"
         full_name = tap.formula_file_to_name(src)
-        name = T.must(full_name.split("/").last)
+        name = full_name.split("/").fetch(-1)
         new_tap = tap.tap_migrations[name]
         @report[T.must(status).to_sym] << full_name unless new_tap
       when "M"
@@ -614,7 +614,7 @@ class Reporter
   sig { void }
   def migrate_tap_migration
     (Array(report[:D]) + Array(report[:DC])).each do |full_name|
-      name = T.must(full_name.split("/").last)
+      name = full_name.split("/").fetch(-1)
       new_tap_name = tap.tap_migrations[name]
       next if new_tap_name.nil? # skip if not in tap_migrations list.
 
@@ -901,7 +901,7 @@ class ReporterHub
       true
     end
     casks.each do |cask|
-      cask_token = T.must(cask.split("/").last)
+      cask_token = cask.split("/").fetch(-1)
       if should_display_descriptions && (desc = cask_description(cask))
         puts "#{cask_token}: #{desc}"
       else
@@ -924,7 +924,7 @@ class ReporterHub
     return if Homebrew::SimulateSystem.simulating_or_running_on_linux?
 
     casks = select_formula_or_cask(:DC).sort.filter_map do |name|
-      name = T.must(name.split("/").last)
+      name = name.split("/").fetch(-1)
       pretty_uninstalled(name) if cask_installed?(name)
     end
 
diff --git a/Library/Homebrew/dev-cmd/bump-formula-pr.rb b/Library/Homebrew/dev-cmd/bump-formula-pr.rb
index d08fedd671..9f39c870b5 100644
--- a/Library/Homebrew/dev-cmd/bump-formula-pr.rb
+++ b/Library/Homebrew/dev-cmd/bump-formula-pr.rb
@@ -464,7 +464,7 @@ module Homebrew
           odie "`brew audit` failed for #{commit[:formula_name]}!"
         end
 
-        new_formula_version = T.must(commits.first)[:new_version]
+        new_formula_version = commits.fetch(0)[:new_version]
 
         pr_title = if args.bump_synced.nil?
           "#{formula.name} #{new_formula_version}"
diff --git a/Library/Homebrew/formulary.rb b/Library/Homebrew/formulary.rb
index 4c4235d38d..e76fa53e3f 100644
--- a/Library/Homebrew/formulary.rb
+++ b/Library/Homebrew/formulary.rb
@@ -1332,7 +1332,7 @@ module Formulary
     if (possible_alias = tap.alias_table[alias_table_key].presence)
       # FIXME: Remove the need to split the name and instead make
       #        the alias table only contain short names.
-      name = T.must(possible_alias.split("/").last)
+      name = possible_alias.split("/").fetch(-1)
       type = :alias
     elsif (new_name = tap.formula_renames[name].presence)
       old_name = tap.core_tap? ? name : tapped_name
diff --git a/Library/Homebrew/language/python.rb b/Library/Homebrew/language/python.rb
index 87f1f41ee0..e0e030192b 100644
--- a/Library/Homebrew/language/python.rb
+++ b/Library/Homebrew/language/python.rb
@@ -252,7 +252,7 @@ module Language
           raise FormulaUnknownPythonError, self if wanted.empty?
           raise FormulaAmbiguousPythonError, self if wanted.size > 1
 
-          python = T.must(wanted.first)
+          python = wanted.fetch(0)
           python = "python3" if python == "python"
         end
 
diff --git a/Library/Homebrew/postinstall.rb b/Library/Homebrew/postinstall.rb
index 67184b2760..bc89cce9f4 100644
--- a/Library/Homebrew/postinstall.rb
+++ b/Library/Homebrew/postinstall.rb
@@ -25,7 +25,7 @@ begin
 
   trap("INT", old_trap)
 
-  formula = T.must(args.named.to_resolved_formulae.first)
+  formula = args.named.to_resolved_formulae.fetch(0)
   if args.debug? && !Homebrew::EnvConfig.disable_debrew?
     require "debrew"
     formula.extend(Debrew::Formula)
diff --git a/Library/Homebrew/test.rb b/Library/Homebrew/test.rb
index f8eda3f715..1146a0dd99 100644
--- a/Library/Homebrew/test.rb
+++ b/Library/Homebrew/test.rb
@@ -37,7 +37,7 @@ begin
     raise "Cannot kill child processes without `pkill`, please install!" unless which("pkill")
   end
 
-  formula = T.must(args.named.to_resolved_formulae.first)
+  formula = args.named.to_resolved_formulae.fetch(0)
   formula.extend(Homebrew::Assertions)
   formula.extend(Homebrew::FreePort)
   if args.debug? && !Homebrew::EnvConfig.disable_debrew?
diff --git a/Library/Homebrew/unpack_strategy/tar.rb b/Library/Homebrew/unpack_strategy/tar.rb
index ae3ff08cd2..65d5750847 100644
--- a/Library/Homebrew/unpack_strategy/tar.rb
+++ b/Library/Homebrew/unpack_strategy/tar.rb
@@ -59,7 +59,7 @@ module UnpackStrategy
     }
     def subextract(extractor, dir, verbose)
       extractor.new(path).extract(to: dir, verbose:)
-      T.must(dir.children.first)
+      dir.children.fetch(0)
     end
   end
 end
diff --git a/Library/Homebrew/utils/analytics.rb b/Library/Homebrew/utils/analytics.rb
index 5af6765cf8..d9136a168c 100644
--- a/Library/Homebrew/utils/analytics.rb
+++ b/Library/Homebrew/utils/analytics.rb
@@ -313,7 +313,7 @@ module Utils
           )
           next if last_thirty_days_match.blank?
 
-          last_thirty_days_downloads = T.must(last_thirty_days_match.captures.first).tr(",", "")
+          last_thirty_days_downloads = last_thirty_days_match.captures.fetch(0).tr(",", "")
           thirty_day_download_count += if (millions_match = last_thirty_days_downloads.match(/(\d+\.\d+)M/).presence)
             (millions_match.captures.first.to_f * 1_000_000).to_i
           else
diff --git a/Library/Homebrew/utils/cpan.rb b/Library/Homebrew/utils/cpan.rb
index aefdbd89f1..3aad167042 100644
--- a/Library/Homebrew/utils/cpan.rb
+++ b/Library/Homebrew/utils/cpan.rb
@@ -180,7 +180,7 @@ module CPAN
 
     ohai "Updating resource blocks" unless silent
     Utils::Inreplace.inreplace formula.path do |s|
-      if T.must(s.inreplace_string.split(/^  test do\b/, 2).first).scan(inreplace_regex).length > 1
+      if s.inreplace_string.split(/^  test do\b/, 2).fetch(0).scan(inreplace_regex).length > 1
         odie "Unable to update resource blocks for \"#{formula.name}\" automatically. Please update them manually."
       end
       s.sub! inreplace_regex, resource_section
diff --git a/Library/Homebrew/utils/fork.rb b/Library/Homebrew/utils/fork.rb
index 5da2621622..f76a679f27 100644
--- a/Library/Homebrew/utils/fork.rb
+++ b/Library/Homebrew/utils/fork.rb
@@ -109,7 +109,7 @@ module Utils
         raise Interrupt if $CHILD_STATUS.termsig == Signal.list["INT"]
 
         if data.present?
-          error_hash = JSON.parse(T.must(data.lines.first))
+          error_hash = JSON.parse(data.lines.fetch(0))
           raise rewrite_child_error(error_hash)
         end
 
diff --git a/Library/Homebrew/utils/pypi.rb b/Library/Homebrew/utils/pypi.rb
index ace69cab10..fcf8f839dd 100644
--- a/Library/Homebrew/utils/pypi.rb
+++ b/Library/Homebrew/utils/pypi.rb
@@ -441,7 +441,7 @@ module PyPI
 
     ohai "Updating resource blocks" unless silent
     Utils::Inreplace.inreplace formula.path do |s|
-      if T.must(s.inreplace_string.split(/^  test do\b/, 2).first).scan(inreplace_regex).length > 1
+      if s.inreplace_string.split(/^  test do\b/, 2).fetch(0).scan(inreplace_regex).length > 1
         odie "Unable to update resource blocks for \"#{formula.name}\" automatically. Please update them manually."
       end
       s.sub! inreplace_regex, resource_section