create-payload-app in existing Next.js project replaces .env and .env.example contents

[smoores-dev]

Describe the Bug

On the tin! I had a .env file with several variables in it; after running npx create-payload-app, the entire contents were replaced with:

# Added by Payload
DATABASE_URI=your-database-uri
PAYLOAD_SECRET=your-payload-secret
POSTGRES_URL=<postgres-url>

Link to the code that reproduces this issue

https://github.com/smoores-dev/payload-dotenv-clear-repro

Reproduction Steps

You can just see the issue by looking at the .env.example file between the two commits in that repo. To reproduce:

1. git checkout init to check out the initial commit
2. Add a .env file and put an environment variable in it
3. npx create-payload-app (choose whatever options)
4. Observe the replaced content in the .env.example file and .env file

Which area(s) are affected? (Select all that apply)

Not sure

Environment Info

Binaries:
  Node: 22.10.0
  npm: 10.9.0
  Yarn: 4.5.0
  pnpm: N/A
Relevant Packages:
  payload: 3.14.0
  next: 15.1.3
  @payloadcms/email-nodemailer: 3.14.0
  @payloadcms/graphql: 3.14.0
  @payloadcms/next/utilities: 3.14.0
  @payloadcms/payload-cloud: 3.14.0
  @payloadcms/richtext-lexical: 3.14.0
  @payloadcms/translations: 3.14.0
  @payloadcms/ui/shared: 3.14.0
  react: 19.0.0
  react-dom: 19.0.0
Operating System:
  Platform: linux
  Arch: x64
  Version: #1 SMP PREEMPT_DYNAMIC Sun Dec 15 16:48:23 UTC 2024
  Available memory (MB): 64001
  Available CPU cores: 16