My current favorite (and free) workflow:

1. Drop project files into https://files2prompt.com to copy a prompt with all file contents

2. Paste into https://aistudio.google.com/ and set a low (or 0) temperature and low top_p

Since Gemini 2.5 Pro is free in AI Studio at the moment, and there's a 1M token limit, this works for most things I need. Cursor is better in some cases where I need a bunch of small edits across a bunch of different files.