Existing cookie should be deleted when chunking

[seanparmelee]

Checklist

• The issue can be reproduced in the nextjs-auth0 sample app (or N/A).
• I have looked into the Readme, Examples, and FAQ and have not found a suitable solution or answer.
• I have looked into the API documentation and have not found a suitable solution or answer.
• I have searched the issues and have not found a suitable solution or answer.
• I have searched the Auth0 Community forums and have not found a suitable solution or answer.
• I agree to the terms within the Auth0 Code of Conduct.

Description

While testing the cookie chunking feature that was added in 4.3.0, I ran into an issue. Our flow looks something like this:

1. User logs into the app (cookie size is < 3500 KB so it's saved as __session)
2. User performs an action that results in an additional claim being added to the user's session (cookie size exceeds threshold and gets chunked into __session__0 and __session__1)
3. When retrieving the user's session, the original __session cookie still exists and is returned instead of the chunked cookie.

In v3, the original cookie gets deleted when going from non-chunked -> chunked, which is what I was expecting to happen in v4 as well.

Reproduction

To be able to reproduce, you'll need to start off with a cookie that's just under the chunking threshold and have a mechanism for increasing the size of the cookie (i.e. adding an additional claim). The steps would be something like:

1. Log in
2. Verify __session cookie is set
3. Perform action that results in a larger cookie (i.e. adds an additional claim)
4. Verify __session__0 and __session__1 cookies are set (and __session still exists)
5. Perform an action that depends on the additional claim information that was added in step 3.

Additional context

Relevant code from v3: https://github.com/auth0/nextjs-auth0/blob/v3.7.0/src/auth0-session/session/stateless-session.ts#L149-L151

nextjs-auth0 version

4.3.0

Next.js version

15.2.4

Node.js version

22.14.0

[frederikprijck]

Thanks for reaching out, I have opened a PR to address the part where we switch between chunked and non chunked cookies.

Relevant code from v3: https://github.com/auth0/nextjs-auth0/blob/v3.7.0/src/auth0-session/session/stateless-session.ts#L149-L151

This actually points to something different than being reported in this issue, namely:

• clean up chunks when total cookie size shrinks and results in less chunks.

I will open an additional PR to solve that.

[frederikprijck]

Opened a PR to address the second part as well: #2014

[frederikprijck]

The corresponding PRs are merged and released as part of v4.4.0, let me know if it doesnt resolve the issue.