deprecated sonnet model

[fujibearly]

First of all, thank you, I think this is a great tool in its simplicity.

For me wut broke with 404 not found for the sonnet 3.5 model. Likely deprecated.

I tested the simple change in the utils file by swapping the hardcoded 3.5 model for the 4.5 and it worked

--> claude-sonnet-4-5-20250929

After going through the migration instructions here: https://docs.claude.com/en/docs/about-claude/models/migrating-to-claude-4 , it seems none of the gotchas are applicable to your implementation, so I did not have to change anything else.