feat: improve chat feedback navigation

ai_knowledge_base_v2/apps/backend/app/services/chat_message_navigation_service.py

@@ -0,0 +1,32 @@
+from __future__ import annotations
+
+from sqlalchemy import func, or_, select
+from sqlalchemy.orm import Session
+
+from app.models.chat import ChatMessage
+
+
+class ChatMessageNavigationService:
+    """Shared chronological paging rules for locating a message in a conversation."""
+
+    @staticmethod
+    def page_for_message(
+        db: Session,
+        *,
+        session_id: int,
+        message: ChatMessage,
+        page_size: int,
+    ) -> int:
+        position = db.scalar(
+            select(func.count()).select_from(ChatMessage).where(
+                ChatMessage.session_id == session_id,
+                or_(
+                    ChatMessage.created_at < message.created_at,
+                    (
+                        (ChatMessage.created_at == message.created_at)
+                        & (ChatMessage.id <= message.id)
+                    ),
+                ),
+            )
+        ) or 1
+        return (position - 1) // page_size + 1