fix: oversized message cursors (#15400)

Message pagination now constrains client-provided cursors to the
PostgreSQL integer range used by `messages.id`, preventing oversized
values from raising database errors while preserving before/after
pagination semantics.

## Closes

-
[CW-7922](https://linear.app/chatwoot/issue/CW-7922/harden-backend-paths-causing-production-sentry-errors)
- [Sentry 7663397140](https://chatwoot-p3.sentry.io/issues/7663397140/)
- [Sentry 7663397546](https://chatwoot-p3.sentry.io/issues/7663397546/)
- [Sentry 7663464772](https://chatwoot-p3.sentry.io/issues/7663464772/)

## How to reproduce

Request conversation messages with an extremely large `before` or
`after` cursor, such as `4611686018427387903`. PostgreSQL previously
rejected the value as outside the range for the integer `messages.id`
column.

## What changed

- Normalize message cursors before they reach the query.
- Clamp them to the valid signed 32-bit integer ID range.
- Cover oversized `before` and `after` cursors with finder specs.

app/finders/message_finder.rb

@@ -1,4 +1,6 @@
 class MessageFinder
+  MESSAGE_ID_MAX = 2_147_483_647
+
   def initialize(conversation, params)
     @conversation = conversation
     @params = params
@@ -21,12 +23,14 @@ class MessageFinder
   end
 
   def current_messages
+    return messages.none if oversized_message_id?(@params[:after])
+
     if @params[:after].present? && @params[:before].present?
-      messages_between(@params[:after].to_i, @params[:before].to_i)
+      messages_between(normalized_message_id(@params[:after]), @params[:before].to_i)
     elsif @params[:before].present?
       messages_before(@params[:before].to_i)
     elsif @params[:after].present?
-      messages_after(@params[:after].to_i)
+      messages_after(normalized_message_id(@params[:after]))
     else
       messages_latest
     end
@@ -37,16 +41,29 @@ class MessageFinder
   end
 
   def messages_before(before_id)
+    return messages_latest if oversized_message_id?(before_id)
+
+    before_id = normalized_message_id(before_id)
     messages.reorder('created_at desc').where('id < ?', before_id).limit(20).reverse
   end
 
   def messages_between(after_id, before_id)
-    messages.reorder('created_at asc').where('id >= ? AND id < ?', after_id, before_id).limit(1000)
+    message_scope = messages.reorder('created_at asc').where('id >= ?', after_id)
+    message_scope = message_scope.where('id < ?', normalized_message_id(before_id)) unless oversized_message_id?(before_id)
+    message_scope.limit(1000)
   end
 
   def messages_latest
     messages.reorder('created_at desc').limit(20).reverse
   end
+
+  def normalized_message_id(value)
+    value.to_i.clamp(0, MESSAGE_ID_MAX)
+  end
+
+  def oversized_message_id?(value)
+    value.to_i > MESSAGE_ID_MAX
+  end
 end
 
 MessageFinder.prepend_mod_with('MessageFinder')

spec/finders/message_finder_spec.rb

@@ -48,6 +48,17 @@ describe MessageFinder do
       end
     end
 
+    context 'with a before attribute above the message id range' do
+      let!(:max_id_message) do
+        create(:message, id: described_class::MESSAGE_ID_MAX, account: account, inbox: inbox, conversation: conversation)
+      end
+      let(:params) { { before: 4_611_686_018_427_387_903 } }
+
+      it 'includes the maximum valid message id without overflowing the database column' do
+        expect(message_finder.perform).to include(max_id_message)
+      end
+    end
+
     context 'with after attribute' do
       let(:params) { { after: conversation.messages.first.id } }
 
@@ -59,6 +70,14 @@ describe MessageFinder do
       end
     end
 
+    context 'with an after attribute above the message id range' do
+      let(:params) { { after: 881_965_304_328 } }
+
+      it 'returns no messages without overflowing the database column' do
+        expect(message_finder.perform).to be_empty
+      end
+    end
+
     context 'with after and before attribute' do
       let(:params) do
         {
@@ -73,5 +92,24 @@ describe MessageFinder do
         expect(result.last.id).to be conversation.messages[-2].id
       end
     end
+
+    context 'with after and before attributes above the message id range' do
+      let!(:max_id_message) do
+        create(:message, id: described_class::MESSAGE_ID_MAX, account: account, inbox: inbox, conversation: conversation)
+      end
+      let(:params) do
+        {
+          after: 881_965_304_328,
+          before: 4_611_686_018_427_387_903
+        }
+      end
+
+      it 'returns no messages' do
+        result = message_finder.perform
+
+        expect(result).to be_empty
+        expect(result).not_to include(max_id_message)
+      end
+    end
   end
 end