fix(yes-core): restore the failed-subscription Sentry notifier (B2BY-5189)

yes-core/lib/yes/core/failed_subscription_notifier.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+module Yes
+  module Core
+    # Reports a permanently dead pg_eventstore subscription to Sentry.
+    #
+    # pg_eventstore calls its +failed_subscription_notifier+ exactly once, when a
+    # subscription exhausts its restarts and stays dead — it is the gem's only
+    # death signal, and without it that death is silent (B2BY-5189). Per-failure
+    # errors are only recorded on the subscription row, never raised into Sentry.
+    class FailedSubscriptionNotifier
+      # @param subscription [PgEventstore::Subscription]
+      # @param error [StandardError]
+      # @return [void]
+      def call(subscription, error)
+        Sentry.with_scope do |scope|
+          scope.set_tags(failed_subscription_notifier: true) # used in Sentry Alerts
+
+          Sentry.capture_exception(
+            error,
+            # a death report must never be swallowed by Sentry's excluded_exceptions
+            hint: { ignore_exclusions: true },
+            extra: { id: subscription.id, set: subscription.set, name: subscription.name }
+          )
+        end
+      end
+    end
+  end
+end

yes-core/lib/yes/core/railtie.rb

@@ -16,6 +16,11 @@ class Railtie < Rails::Railtie
             with_indifferent_access: Yes::Core::Middlewares::WithIndifferentAccess.new,
             timestamp: Yes::Core::Middlewares::Timestamp.new
           }
+
+          # pg_eventstore's only death signal — without it a subscription that
+          # exhausts its restarts dies silently (B2BY-5189). Present in
+          # yousty-eventsourcing's Railtie; dropped when it was ported here.
+          config.failed_subscription_notifier = FailedSubscriptionNotifier.new if defined?(Sentry)
         end
       end
 

yes-core/spec/lib/yes/core/failed_subscription_notifier_spec.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+RSpec.describe Yes::Core::FailedSubscriptionNotifier do
+  subject(:notify) { described_class.new.call(subscription, error) }
+
+  let(:subscription) { PgEventstore::Subscription.new(id: 42, set: 'Yes', name: 'SomeProcessManager') }
+  let(:error) { StandardError.new('handler exploded') }
+  let(:sentry) { class_double('Sentry') }
+  let(:scope) { double('Sentry::Scope', set_tags: nil) }
+
+  before do
+    # Sentry is not a dependency of this gem — the railtie only registers the
+    # notifier when the host app loaded it, so the constant is stubbed here.
+    stub_const('Sentry', sentry)
+    allow(sentry).to receive(:with_scope).and_yield(scope)
+    allow(sentry).to receive(:capture_exception)
+  end
+
+  it 'reports the death to Sentry with the subscription identity' do
+    notify
+
+    aggregate_failures do
+      expect(scope).to have_received(:set_tags).with(failed_subscription_notifier: true)
+      expect(sentry).to have_received(:capture_exception).with(
+        error,
+        hint: { ignore_exclusions: true },
+        extra: { id: 42, set: 'Yes', name: 'SomeProcessManager' }
+      )
+    end
+  end
+end