fix(rails): make Action Cable handle_open/handle_close overrides public for Rails 8.2

[kylekeesling]

Description

Rails 8.2 decoupled the Action Cable connection from the socket in rails/rails#50979 (merged 2026-05-28): ActionCable::Server::Socket now invokes connection.handle_open and connection.handle_close from outside the connection object.

Sentry::Rails::ActionCableExtensions::Connection declares its handle_open/handle_close overrides as private, which shadows the (public) framework methods through the prepend chain. On Rails main / 8.2, every cable connection then raises:

NoMethodError (private method 'handle_open' called for an instance of ApplicationCable::Connection)
  actioncable/lib/action_cable/server/socket.rb:127:in 'ActionCable::Server::Socket#handle_open'

before the welcome message is sent. The practical effect is severe and silent: the WebSocket upgrade succeeds (101), but clients never receive welcome or pings, so they treat the connection as stale and reconnect in a loop forever — no broadcasts (e.g. Turbo Streams) are ever delivered. The exception only hits the Rails logger, not Sentry, since it occurs in the instrumentation wrapper itself.

We hit this in production on a Rails edge app with sentry-rails 6.6.0 and confirmed the root cause by inspecting method visibility:

ApplicationCable::Connection.instance_method(:handle_open).owner
# => Sentry::Rails::ActionCableExtensions::Connection
ApplicationCable::Connection.private_method_defined?(:handle_open)
# => true

Fix

Make the two overrides public. On Rails < 8.2 they are only invoked internally on self (visibility is irrelevant there), so this is safe across all supported Rails versions. Added a regression spec asserting the visibility and a changelog entry.

bundle exec rspec spec/sentry/rails/action_cable_spec.rb → 12 examples, 0 failures.