Framework Mode build hooks run for external server environments with v8_viteEnvironmentApi

[p-dubovitsky]

Reproduction

Link to reproduction:
https://stackblitz.com/edit/github-ygcrztk9

Steps to reproduce:

1. Run react-router build
2. Observe the build failure: ENOENT: no such file or directory, open '/home/projects/github-ygcrztk9/dist/.vite/manifest.json'

System Info

System:
    OS: macOS 26.3.1
    CPU: (8) arm64 Apple M1 Pro
    Memory: 133.17 MB / 16.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 24.14.0 - /Users/paveldubovitsky/.local/share/mise/installs/node/24.14.0/bin/node
    npm: 11.9.0 - /Users/paveldubovitsky/.local/share/mise/installs/node/24.14.0/bin/npm
    pnpm: 10.30.3 - /Users/paveldubovitsky/.local/share/mise/installs/pnpm/10.30.3/pnpm
    bun: 1.3.5 - /Users/paveldubovitsky/.local/share/mise/installs/bun/1.3.5/bin/bun
  Browsers:
    Chrome: 146.0.7680.165
    Safari: 26.3.1
  npmPackages:
    @react-router/dev: 7.13.1 => 7.13.1 
    @react-router/node: 7.13.1 => 7.13.1 
    @react-router/serve: 7.13.1 => 7.13.1 
    react-router: 7.13.1 => 7.13.1 
    vite: ^7.1.7 => 7.3.1

Used Package Manager

npm

Expected Behavior

React Router build hooks should only run for actual React Router server environments.

Actual Behavior

React Router build hooks also run for external server environments introduced by other Vite plugins (Nitro in this case).

[p-dubovitsky]

I already opened an MR with a fix and an integration regression test for this case: #14883