• Preserve the requested key order in ActiveSupport::Cache::Store#fetch_multi when a local cache is active.

  Previously, if some keys were served from the local cache and others from the underlying store, fetch_multi returned the local cache hits first instead of following the order of the requested keys.

  Mueez Afzal

• Return a UTC time from Time.rfc3339 for strings with the "Z" UTC designator.

  Time.rfc3339("2026-08-07T10:00:00Z")
  # Before: 2026-08-07 10:00:00 +0000 (utc? => false)
  # After:  2026-08-07 10:00:00 UTC   (utc? => true)

  This matches Ruby's Time.rfc3339, which is expected to be included in Ruby 4.1. The resulting time value is unchanged, but serialized forms such as as_json now end in "Z" instead of "+00:00". Call getlocal("+00:00") to keep the previous representation:

  Time.rfc3339("2026-08-07T10:00:00Z").getlocal("+00:00")
  # => 2026-08-07 10:00:00 +0000 (utc? => false)

  Yasuo Honda

• Add Pacific {Time} (Canada) and Alberta to ActiveSupport::TimeZone::MAPPING.

  British Columbia and Alberta no longer share winter clocks with US Pacific and Mountain time. The existing Pacific Time (US & Canada) and Mountain Time (US & Canada) entries remain mapped to America/Los_Angeles and America/Denver for compatibility. Prefer Pacific Time (Canada) / Alberta (or the IANA identifiers America/Vancouver / America/Edmonton) for users in those regions.

  Said Kaldybaev

• Fix Range#sum with a falsey initial value.

  Summing an integer range with a falsey starting value (such as nil or false) treated that value as zero. It now keeps the starting value as given, matching array and enumerable sum.

  Said Kaldybaev

• Add ActiveSupport#raise_on_invalid_time_zone_parse.

  Raise ArgumentError on ActiveSupport::TimeZone#parse for any invalid string. Historically, strings without recognizable date information (e.g. "foobar") returned nil, while strings with out-of-range date components (e.g. "9000") raised ArgumentError. When enabled, both cases raise ArgumentError, matching the Ruby standard library's Time.parse.

  Said Kaldybaev

• Raise ::ActiveSupport::ConfigurationFile::FormatError when parsing malformed YAML.

  Nikita Vasilevsky

• Preserve sub-second precision when subtracting a DateTime from a Time.

  Time - DateTime converted both sides via to_f, so microsecond-level DateTime values lost precision. The difference is now computed from exact rational timestamps, matching Time.at(DateTime) and ActiveSupport::TimeWithZone - DateTime.

  Said Kaldybaev

• Deprecate ActiveSupport::Cache::RedisCacheStore::DEFAULT_REDIS_OPTIONS.

  The redis-client implementation no longer reads this constant. Pass timeout options to RedisCacheStore or a configured RedisClient instead.

  Nikita Vasilevsky

• Add #this_quarter? to Date/Time.

  It returns true if the date/time falls within the current quarter.

  Date.current #=> Tue, 15 Feb 2000
  Date.new(2000, 3, 31).this_quarter?  # => true
  Date.new(2000, 4, 1).this_quarter?   # => false

  Kenta Ishizaki

• Added ::ActiveSupport::ProxyLogger.

  The proxy logger, is a logger that forwards all received logs to another logger, but has its own independent severity level.

  This is useful when you want some library you have no control over to use the same logger as the rest of your application, but to have a different severity level because it is logging too much:

  SomeLibrary.logger = ActiveSupport::ProxyLogger.new(Rails.logger, :error)

  Almost all of the standard Logger interface is supported.

  In addition it can be set to ignore messages matching given patterns.

  Useful to silence noisy logs from gems that your application may not care about, without needing to change the log level and losing other useful logs.

  SomeLibrary.logger = ActiveSupport::ProxyLogger.new(Rails.logger).ignore(/Noisy/)

  Jean Boussier, Federico Carrocera

• Include call options in Cache#exist? instrumentation payload, consistent with read, write, and delete.

  Kenta Ishizaki

• Declare assert_not_pattern as an alias for refute_pattern

  Sean Doyle

• assert_difference, assert_no_difference, assert_changes, and assert_no_changes now raise ArgumentError when given an expression that is not a callable (like a Proc), String, or Symbol.

  This helps catch issues where you accidentally pass a single static value (like assert_no_changes(a.size)). The same value would seen before and after the block, so no change would ever be found, silently passing the assertion even if there was an unexpected change.

  To be reevaluated correctly, the expression should wrapped in a lambda like assert_no_changes(-> { a.size }), or quoted in a String that can be eval-ed.

  Alexander Momchilov

• Add ::ActiveSupport::Notifications::NullInstrumenter, a stateless no-op instrumenter that executes blocks without publishing any notifications.

  Available via ActiveSupport::Notifications.null_instrumenter, this is useful for suppressing instrumentation on specific components, such as database connections that don't need SQL notification overhead.

  Rosa Gutierrez

• ::ActiveSupport::Cache::RedisCacheStore entirely reimplemented.

  Now depends on the much lighter redis-client >= 0.28.0 instead of redis >= 4.0.1.

  The change shouldn't be noticeable unless the cache is configured with the :redis argument. In such case it will keep working for now, but will issue a deprecation warning.

  Prefer configuring Redis Cache Store with an :url argument instead, but if you need advanced options not supported by Redis Cache Store constructor, you can alternatively pass a custom RedisClient::Config instance via the :client argument.

  Jean Boussier

• Fix NumberHelper raising FloatDomainError for Infinity / NaN with significant: true.

  number_to_rounded(Float::INFINITY, precision: 3, significant: true) (and its callers number_to_percentage, number_to_currency, etc.) raised FloatDomainError because RoundingHelper#digit_count called Math.log10(Float::INFINITY).floor. The non-significant path already formatted these values as "Inf" / "-Inf" / "NaN"; the two paths now agree.

  Kenta Ishizaki

• Fix number_to_delimited mangling non-finite floats.

  number_to_delimited(Float::INFINITY) returned "In,fin,ity" because the fast-path manual slicing introduced in commit 2d485aecf5 and made the default in commit 33fbedb1b1 treated Float::INFINITY.to_s (the string "Infinity") as a sequence of digits to group every three characters. -Float::INFINITY was similarly mangled to "-In,fin,ity". Float::NAN happened to survive only because "NaN" is exactly three characters long.

  Now returns the underlying string representation ("Infinity", "-Infinity", "NaN") for non-finite floats, matching the pre-2d485aecf5 behavior.

  Kenta Ishizaki

• Duplicate the context hash passed to ActiveSupport::ErrorReport#handle for each subscriber. This prevents mutations done on the context by one subscriber from effecting the others.

  Andrew Novoselac

• Fix ::ActiveSupport::Concurrency::ShareLock to honor isolation_level.

  Lock ownership was keyed on Thread.current. Under config.active_support.isolation_level = :fiber, all request fibers on the same thread were treated as a single owner, and the reloader interlock could admit an exclusive :unload while another fiber still held a share — clearing autoloaded constants mid-request.

  ShareLock now keys ownership on ActiveSupport::IsolatedExecutionState.context, the same scope used by CurrentAttributes and other per-execution state. Behavior under :thread isolation is unchanged.

  Joel Junström

• Introduce ::ActiveSupport::TimeFormats and ::ActiveSupport::DateFormats for registering custom date formats.

  This allows adding custom date formats to to_fs without modifying the global Time::DATE_FORMATS or Date::DATE_FORMATS hashes. Custom formats are added via ActiveSupport::TimeFormats.register or ActiveSupport::DateFormats.register, and will only be available to Time#to_fs, and Date#to_fs respectively.

  At the same time, the existing Time::DATE_FORMATS and Date::DATE_FORMATS constants are still supported for backward compatibility, but they are now deprecated and will be removed in the next version of Rails. This encourages users to migrate to the new approach for better encapsulation and to avoid potential conflicts with other libraries that may also modify the global date formats.

  ActiveSupport::TimeFormats.register(:month_and_year, '%B %Y')
  ActiveSupport::DateFormats.register(
    :short_ordinal,
    ->(date) { date.strftime("%B #{date.day.ordinalize}") }
  )
  
  Time.now.to_fs(:month_and_year) # => "February 2024"
  Date.today.to_fs(:short_ordinal)  # => "February 21st"

  Ufuk Kayserilioglu

• Add start_day argument to this_week? for consistency with all_week

  this_week? now accepts an optional start_day argument, matching the existing interface of all_week, beginning_of_week, and end_of_week.

  date.this_week?              # Uses Date.beginning_of_week (default)
  date.this_week?(:sunday)     # Checks against Sun-Sat week

  Kenta Ishizaki

• Add delete: true option to Rails.cache.read for atomic read-and-delete (only supported by Redis cache store).

  Uses the RedisGETDEL command to atomically return a cached value and remove it in a single operation. Useful for single-use values like OTP codes or one-time tokens.

  Rails.cache.write("otp", "123456")
  Rails.cache.read("otp", delete: true)  # => "123456"
  Rails.cache.read("otp")                # => nil

  Glauco Custodio

• Introduce ActiveSupport::TestCase.around

  Add a callback, which runs between TestCase#setup and TestCase#teardown. Yields the test class instance and the test case to the block:

  class ClientTest < ActiveSupport::TestCase
    around do |test_case, block|
      Client.with(stubbed: true, &block)
    end
  end

  Sean Doyle

• Add prepend: true option to ActiveSupport::Notifications.subscribe.

  When `prepend: true` is passed, the subscriber is added to the front of
  the subscriber list for the given event, ensuring it runs before any
  previously registered subscribers. This allows mutating the event payload
  before other subscribers process it.
  
  ```ruby
  ActiveSupport::Notifications.subscribe("sql.active_record", prepend: true) do |event|
  event.payload[:name] = "[IDC] #{event.payload[:name]}"
  end
  ```
  
  *Jean Boussier*, *Federico Carrocera*

• Deprecate require_dependency.

  require_dependency is deprecated without replacement and will be removed in Rails 9.

  • Recommendations for applications:

    - If the call is an old one written in the days of the classic
    autoloader to ensure a certain constant is loaded for constant lookup
    to work as expected, you can simply remove it.
    
    - In order to preload classes when the application boots, which may be
    necessary for things like STIs or Kafka consumers, please check the
    autoloading guide for modern approaches.

  • Recommendations for engines that depend on Rails >= 7.0:

    Same recommendations as for applications, since the classic autoloader is no longer available starting with Rails 7.0.

  • Recommendations for engines that support Rails < 7.0:

    Guard the call with a version check just in case the parent application is using the classic autoloader:

    require_dependency "some_file" if Rails::VERSION::MAJOR < 7

  Xavier Noria

• Add group method to ::ActiveSupport::ContinuousIntegration for parallel step execution.

  Groups collect steps and run them concurrently using a thread pool, reducing CI times by running independent checks in parallel. Sub-groups run sequentially within a single parallel slot allowing dependent steps to be grouped together.

  CI.run do
    step "Setup", "bin/setup --skip-server"
  
    group "Checks", parallel: 2 do
      step "Style: Ruby", "bin/rubocop"
      step "Security: Brakeman", "bin/brakeman --quiet"
      step "Security: Gem audit", "bin/bundler-audit"
  
      group "Tests" do
        step "Tests: Rails", "bin/rails test"
        step "Tests: Seeds", "env RAILS_ENV=test bin/rails db:seed:replant"
      end
    end
  end

  Donal McBreen

• Introduce this_week?, this_month?, and this_year? methods to Date/Time

  Similar to today?, tomorrow?, and yesterday?, these methods are useful to query time instances against the current period.

  unless post.created_at.this_week?
    link_to "See week recap", week_recap_path(date)
  end

  Matheus Richard

• Removed the deprecated ActiveSupport::Multibyte::Chars class.

  As well as String#mb_chars

  Jean Boussier

• Changed ActiveSupport::EventReporter#subscribe to only provide the event name during filtering.

  Otherwise the event reporter would need to always build the expensive payload even when there is no active subscriber, which is very wasteful.

  Jean Boussier

• Fix inflections to better handle overlapping acronyms.

  ActiveSupport::Inflector.inflections(:en) do |inflect|
    inflect.acronym "USD"
    inflect.acronym "USDC"
  end
  
  "USDC".underscore # => "usdc"

  Said Kaldybaev

• Add ::ActiveSupport::CombinedConfiguration to offer interchangeable access to configuration provided by either ENV or encrypted credentials. Used by Rails to first look at ENV, then look in encrypted credentials, but can be configured separately with any number of API-compatible backends in a first-look order.

  The object is inspect safe and will only show keys, not values.

  DHH, Emmanuel Hayford

• Add ::ActiveSupport::EnvConfiguration to provide access to ENV variables in a way that's compatible with ActiveSupport::EncryptedConfiguration and therefore can be used by ActiveSupport::CombinedConfiguration.

  The object is inspect safe and will only show keys, not values.

  Examples:

  conf = ActiveSupport::EnvConfiguration.new
  conf.require(:db_host) # ENV.fetch("DB_HOST")
  conf.require(:aws, :access_key_id) # ENV.fetch("AWS__ACCESS_KEY_ID")
  conf.option(:cache_host) # ENV["CACHE_HOST"]
  conf.option(:cache_host, default: "cache-host-1") # ENV["CACHE_HOST"] || "cache-host-1"
  conf.option(:cache_host, default: -> { "cache-host-1" }) # ENV["CACHE_HOST"] || "cache-host-1"

  DHH, Emmanuel Hayford

• Make flaky parallel tests easier to diagnose by deterministically assigning tests to workers.

  Rails assigns tests to workers in round-robin order so the same --seed and worker count will result in the same sequence of tests running on each worker (whether processes or threads) increasing the odds of reproducing test failures caused by test interdependence.

  This can make test runtime slower and spikier when one worker gets most of the slow tests. Enable work_stealing: true to allow idle workers to steal tests from busy workers in deterministic order, smoothing out runtime at the cost of less reproducible flaky-test failures.

  Jeremy Daer

• Make ActiveSupport::EventReporter#debug_mode? true by default to emit debug events outside of Rails application contexts.

  Gannon McGibbon

• Add SecureRandom.base32 for generating case-insensitive keys that are unambiguous to humans.

  Stanko Krtalic Rusendic & Miha Rekar

• Add a fast failure mode to ::ActiveSupport::ContinuousIntegration that stops the rest of the run after a step fails. Invoke by running bin/ci --fail-fast or bin/ci -f.

  Dennis Paagman

• Implement LocalCache strategy on ::ActiveSupport::Cache::MemoryStore. The memory store needs to respond to the same interface as other cache stores (e.g. ActiveSupport::NullStore).

  Mikey Gough

• Add a detailed failure summary to ::ActiveSupport::ContinuousIntegration.

  Mike Dalessio

• Introduce ::ActiveSupport::EventReporter::LogSubscriber structured event logging.

  class MyLogSubscriber < ActiveSupport::EventReporter::LogSubscriber
    self.namespace = "test"
  
    def something(event)
      info { "Event #{event[:name]} emitted." }
    end
  end

  Gannon McGibbon

Please check8-1-stable for previous changes.