Hi everyone,

I wanted to share one of the most technically challenging projects I've built over the past few months.

The original idea sounded simple: build a 3D AI companion that could chat with me.

It eventually grew into a system featuring:

• 🧠 Long-term memory with RAG and pgvector
• 🎙️ Real-time voice conversations
• 🎭 3D facial expressions and lip sync
• ❤️ Relationship/personality system
• 🤖 Autonomous behaviors and proactive conversations
• ⚡ Node.js + TypeScript + PostgreSQL + Prisma backend

The biggest surprise wasn't the engineering.

It was realizing that inference and Text-to-Speech costs become the real challenge when you start thinking about scaling to thousands of users.

Although I decided to stop the project, it taught me more than any course or tutorial could. It gave me hands-on experience designing AI systems, memory architectures, streaming pipelines, vector databases, and agent workflows.

I documented the entire project in a 5-part technical series for anyone interested in how these systems are built.

Articles

• Part 1 — Introduction & Architecture https://mohamedabusaif.hashnode.dev/building-my-ai-companion-from-a-simple-chatbot-to-a-system-that-can-remember-part-1
• Part 2 — Database Schema Breakdown https://mohamedabusaif.hashnode.dev/building-my-ai-companion-from-a-simple-chatbot-to-a-system-that-can-remember-part-2
• Part 3 — RAG & Vector Memory https://mohamedabusaif.hashnode.dev/building-my-ai-companion-from-a-simple-chatbot-to-a-system-that-can-remember-part-3
• Part 4 — Feature Breakdown https://mohamedabusaif.hashnode.dev/building-my-ai-companion-from-a-simple-chatbot-to-a-system-that-can-remember-part-4
• Part 5 — Why I Stopped Building It https://mohamedabusaif.hashnode.dev/building-my-ai-companion-from-a-simple-chatbot-to-a-system-that-can-remember-part-5

Demo Videos

Version 1
https://www.youtube.com/watch?v=s5s87c845xI

Version 2
https://www.youtube.com/watch?v=6esXviAIhTM

If you're an engineer working on LLMs, AI agents, or companion apps, I'd love to hear what technical challenge surprised you the most.

And if you're hiring engineers in this space, I'd be happy to connect and discuss the project in more detail.

My LinkedIn Post for more details:
https://www.linkedin.com/posts/mohamed-abusaif-050_ai-softwareengineering-llm-share-7476743528967114752-5KQ2/?utm_source=share&utm_medium=member_desktop&rcm=ACoAADLKhdkBx-oCy9dCS11RpiVRHPBe7Pjbupo

So I don't know if posting links is allowed or not in this sub reddit but I'm not posting to promote I'm just sharing my technical experience during this project.

Here is my Story:
A few weeks ago I decided to see how far I could push an AI companion project.

It started as a simple 3D character that could chat with me.

Then it slowly evolved into something much bigger:

• Long-term memory using vector embeddings
• Voice conversations
• 3D facial expressions and lip sync
• Relationship/personality system
• Autonomous behaviors and proactive conversations

The interesting part wasn't actually building the features.

It was discovering that the biggest challenge wasn't technical it was economic. Once I started estimating inference and Text-to-Speech costs at scale, I realized building the product was only half of the problem.

I ended up stopping the project, but I learned a huge amount about AI systems, real-time streaming, memory architectures, vector databases, and agent design.

I wrote a 5-part technical series documenting everything I learned, including the architecture, mistakes, and design decisions, in case anyone else is building something similar.

Part 1: Introduction to the problem and tools I used

https://mohamedabusaif.hashnode.dev/building-my-ai-companion-from-a-simple-chatbot-to-a-system-that-can-remember-part-1

Part 2: Database Schema Breakdown

https://mohamedabusaif.hashnode.dev/building-my-ai-companion-from-a-simple-chatbot-to-a-system-that-can-remember-part-2

Part 3: The AI's Brain: A Complete Guide to RAG and Vector Memory

https://mohamedabusaif.hashnode.dev/building-my-ai-companion-from-a-simple-chatbot-to-a-system-that-can-remember-part-3

Part 4: Features Breakdown

https://mohamedabusaif.hashnode.dev/building-my-ai-companion-from-a-simple-chatbot-to-a-system-that-can-remember-part-4

Part 5: Why I stopped building the project?

https://mohamedabusaif.hashnode.dev/building-my-ai-companion-from-a-simple-chatbot-to-a-system-that-can-remember-part-5

Demo Videos:

Version 1: https://www.youtube.com/watch?v=s5s87c845xI

Version 2: https://www.youtube.com/watch?v=6esXviAIhTM

Details On LinkedIn:

https://www.linkedin.com/posts/mohamed-abusaif-050_ai-softwareengineering-llm-share-7476743528967114752-5KQ2/?utm_source=share&utm_medium=member_desktop&rcm=ACoAADLKhdkBx-oCy9dCS11RpiVRHPBe7Pjbupo

I'd love to hear from others who've built AI companions or agent-based systems. What was the hardest problem you ran into?

https://preview.redd.it/9dnc605zaw9h1.jpg?width=1024&format=pjpg&auto=webp&s=34dae09cfb77d0967d25a719d41ce9f1a2228e2c