Fix Idempotency-Key ignored when scheduling a post (mastodon#30084)

app/services/post_status_service.rb

@@ -231,7 +231,7 @@ def idempotency_given?
 
   def idempotency_duplicate
     if scheduled?
-      @account.schedule_statuses.find(@idempotency_duplicate)
+      @account.scheduled_statuses.find(@idempotency_duplicate)
     else
       @account.statuses.find(@idempotency_duplicate)
     end
@@ -292,12 +292,12 @@ def poll_attributes
   end
 
   def scheduled_options
-    @options.tap do |options_hash|
-      options_hash[:in_reply_to_id]       = options_hash.delete(:thread)&.id&.to_s
+    @options.dup.tap do |options_hash|
+      options_hash[:in_reply_to_id]       = options_hash.delete(:thread)&.id
       options_hash[:application_id]       = options_hash.delete(:application)&.id
       options_hash[:scheduled_at]         = nil
       options_hash[:idempotency]          = nil
-      options_hash[:status_reference_ids] = options_hash[:status_reference_ids]&.map(&:to_s)&.filter{ |id| id != options_hash[:quote_id] }
+      options_hash[:status_reference_ids] = options_hash.delete(:status_reference_ids)&.map(&:to_s)&.filter{ |id| id != options_hash[:quote_id] }
       options_hash[:with_rate_limit]      = false
     end
   end

spec/services/post_status_service_spec.rb

@@ -68,6 +68,22 @@
     expect(status.params['text']).to eq 'Hi future!'
     expect(media.reload.status).to be_nil
     expect(Status.where(text: 'Hi future!').exists?).to be_falsey
+
+  it 'does not change statuses count' do
+    account = Fabricate(:account)
+    future = Time.now.utc + 2.hours
+    previous_status = Fabricate(:status, account: account)
+
+    expect { subject.call(account, text: 'Hi future!', scheduled_at: future, thread: previous_status) }.not_to change { [account.statuses_count, previous_status.replies_count] }
+  end
+
+  it 'returns existing status when used twice with idempotency key' do
+    account = Fabricate(:account)
+    future = Time.now.utc + 2.hours
+
+    status1 = subject.call(account, text: 'test', idempotency: 'meepmeep', scheduled_at: future)
+    status2 = subject.call(account, text: 'test', idempotency: 'meepmeep', scheduled_at: future)
+    expect(status2.id).to eq status1.id
   end
 
   it 'creates response to the original status of boost' do