Advanced Personal Business AI Assistant Development

I'm looking for an experienced AI automation developer to build me a personal AI assistant that can think, research, and act on my behalf across my businesses. This isn't a simple chatbot, it needs persistent memory of my business context so it holds a real ongoing relationship with me rather than starting fresh every conversation.

Core capabilities needed: the assistant should be able to do open-ended research on request, create written and video content, manage and post to social media accounts, and eventually help build simple digital assets like a one-page website, all directed through natural conversation, ideally delivered to me via WhatsApp.

I have a complete technical brief already written, covering the full roadmap in stages, so you'll know exactly what's being asked for from day one. I want to start with a first working stage, basic AI brain plus WhatsApp conversation and memory, then expand from there once that's proven, with payment released as each stage is completed and tested.

Please reply with your relevant experience, example projects using n8n, Claude or GPT, and WhatsApp integrations, and a rough estimate for the first stage.