Custom Views break when admin route is set to "/"

[rubyjasmin]

Describe the Bug

When making the admin route "/" custom views are unreachable as the forward slash is removed from path for instance "/custom-view" becomes "custom-view" which leads to 404.

Link to the code that reproduces this issue

https://github.com/rubyjasmin/custom-components-bug-reproduction

Reproduction Steps

1. Run npx create-payload-app --example custom-components
2. Move files inside admin to root path and modify import paths
3. Config routes:{ admin:"/" } and importMapFile: path.resolve(dirname, "app", "importMap.js")
4. Run app and visit /custom

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

area: ui

Environment Info

Binaries:
  Node: 22.15.1
  npm: 10.9.2
  Yarn: 1.22.22
  pnpm: 10.11.0
Relevant Packages:
  payload: 3.42.0
  next: 15.3.3
  @payloadcms/db-postgres: 3.42.0
  @payloadcms/graphql: 3.42.0
  @payloadcms/next/utilities: 3.42.0
  @payloadcms/richtext-lexical: 3.42.0
  @payloadcms/translations: 3.42.0
  @payloadcms/ui/shared: 3.42.0
  react: 19.1.0
  react-dom: 19.1.0
Operating System:
  Platform: darwin
  Arch: x64
  Version: Darwin Kernel Version 24.5.0: Tue Apr 22 19:53:26 PDT 2025; root:xnu-11417.121.6~2/RELEASE_X86_64
  Available memory (MB): 8192
  Available CPU cores: 4

[github-actions]

Please add a reproduction in order for us to be able to investigate.

Depending on the quality of reproduction steps, this issue may be closed if no reproduction is provided.

Why was this issue marked with the invalid-reproduction label?

To be able to investigate, we need access to a reproduction to identify what triggered the issue. We prefer a link to a public GitHub repository created with create-payload-app@latest -t blank or a forked/branched version of this repository with tests added (more info in the reproduction-guide).

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I added a link, why was it still marked?

Ensure the link is pointing to a codebase that is accessible (e.g. not a private repository). "example.com", "n/a", "will add later", etc. are not acceptable links -- we need to see a public codebase. See the above section for accepted links.

Useful Resources

• Reproduction Guide
• Contributing to Payload