Read-only pre-filled email in checkout sessions

[rishi-raj-jain]

Summary:

Allowing checkout sessions to be created with customer_email field as pre-filled and not editable (disabled).

Description:

From https://x.com/botsboss/status/1944781268446794057

• This would help generate checkout sessions for a particular user (email) ensuring that the generated checkout session is only limited and usable to the user pre-filled.
• Other services provide customer email to be pre-filled & disabled (/not editable).

Thank you for considering!

[pieterbeulque]

Opened a PR & chatted things through with @frankie567, but we decided against the change to keep the API cleaner.

For now, the recommended way to do this is by creating a customer for that email first, and then using the customer_id parameter when creating the checkout session. This will have the same effect of pre-filling & disabling the email input field.