AR 3D Object Anchoring Feature

I need an AR camera feature to my app that detects real-world surfaces in real time and lets the user place, move and scale any 3D model so it stays locked to that spot as the camera moves around it.

The code has to be clean, well-commented and built with production-ready tools such as ARKit, ARCore, Unity or Unreal (I’ll take your recommendation once you’ve seen the larger project scope). Please expose a simple API so my app can feed in a model file at runtime and receive back the anchor’s world coordinates for later sessions.

Deliverables:
• Mobile demo project with an in-camera view, surface detection and persistent anchoring
• Ability to load at least one common 3D format (glTF, FBX or OBJ)
• Short integration guide and build instructions
• Source code with any custom shaders, prefabs or helper scripts

I’ll test on multiple phone models, so a quick test build or TestFlight link would be appreciated before the final handoff.