Fix QuickBooks OAuth Redirect

I’m hitting the “redirect_uri query parameter value is invalid” wall while authenticating against the QuickBooks Online production API. The app is written in plain Python—no Flask, no Django—so the OAuth 2.0 flow is all hand-rolled. Everything works fine until Intuit kicks back that error right after the user grants consent.

I need someone who knows the Intuit Developer portal inside out to walk through my current settings, verify the exact redirect URI configuration, and confirm that the Python logic for state, scopes, and exchange tokens lines up with what QuickBooks expects. A quick screen-share or well-commented code patch is all it should take; once the callback is accepted and I can pull a live company file, we’re done.

Deliverables:
• Correct redirect accepted in production
• Brief outline of the fix so I can repeat it in the future

If you’ve debugged this specific error before, let’s get it sorted today.