Development of a Chatbot Engine for Automated Customer Service

We are looking for an experienced freelancer to develop the engine for a functional chatbot, capable of managing automated conversations and responding to users in a fluid manner. The focus of this project is the conversational logic and architecture of the bot, not just the interface.

What we expect from the engine:

Management of conversation flows with multiple branches (decision tree)
Recognition of user intent and contextual responses
Ability to maintain context throughout the conversation, without "forgetting" what was said before
Forwarding to a human agent when the request goes outside the automated scope
Organized and documented structure, so we can maintain and expand the bot later
Technical requirements:

Proven experience in chatbot development (please send examples or portfolio)
Proficiency in API integration (the messaging platform or final channel can be defined together)
Clean, commented code delivered ready to use
Desirable differentiators:

Experience with integrating ai/llm models for natural language responses
knowledge of integration with whatsapp, telegram, or webchat
when submitting your proposal, please briefly describe how you would approach the engine architecture and cite a similar project you have already delivered. Generic proposals will be disregarded.