Issue Summary

Incorrect serialization of query parameters containing array values in redirect logic.

In getServerSideProps, context.query is cast to Record<string, string> and passed to URLSearchParams. However, Next.js query params can be string | string[], which leads to incorrect serialization of array values.

Steps to Reproduce

1. Open a URL with repeated query params, for example: /john?user=john&user=doe
2. Trigger a flow that causes redirect (e.g., dynamic group redirect).
3. Observe the generated redirect URL.

Actual Results

• Query params with multiple values are serialized incorrectly: user=john,doe
• This changes the structure of the query and may break downstream logic expecting multiple values.

Expected Results

• Query params should preserve multiple values correctly: user=john&user=doe

Technical details

• Affected file: apps/web/server/lib/[user]/getServerSideProps.ts

• Problematic code: new URLSearchParams(context.query as Record<string, string>)

• Environment:

Next.js App Router
Node.js (any version)

Evidence

• Based on inspection of Next.js query typing: context.query: { [key: string]: string | string[] }
• Reproduced by passing multiple query params with the same key and observing incorrect serialization via URLSearchParams.