Allow External Apps to Login via One Click Login

I was curious if there is currently or any plans for the pipeline to allow an external app to validate and run contracts and login. I think this would be a really useful addition to validate that the user is signed into their wallet and has an address on the blockchain. Also, for apps that will require to run and execute contracts will need to validate that they can run.

Let me know if there is any logistics or hurdles that needs to be explored system wise as I could possibly help.

Thank you,
Nate

The issue names no files, tests, or entry points and proposes a broad external-app login and contract-validation flow. Start by mapping the existing wallet sign-in and contract execution paths, then define the external-app integration requirements and acceptance criteria before identifying implementation work.

Written by the indexing model from the issue text.