Reproduction link or steps

I created a repository that reproduces the bug. Please refer to the code in that repository.
repro-rolldown-chunk-bug

This repository uses bun and tsdown. If you determine that this is an issue with another library (like tsdown) rather than rolldown, please let me know and I will open an issue in that repository.

What is expected?

single file, no chunks.

What is actually happening?

I'm generating a single bundle file together with dts. However, chunks are only created when dts is enabled.

A virtual entry is being added via emitFile, and it seems rolldown recognizes it as multiple entries. Because of this, __defProp and __exportAll appear to be extracted into a separate chunk. For now I'm fixing it using plugin, but I don't think this is the correct approach.

System Info

System:
    OS: Linux 6.6 Ubuntu 24.04.3 LTS 24.04.3 LTS (Noble Numbat)
    CPU: (16) x64 AMD Ryzen 7 7800X3D 8-Core Processor
    Memory: 10.41 GB / 15.15 GB
    Container: Yes
    Shell: 5.9 - /home/linuxbrew/.linuxbrew/bin/zsh
  Binaries:
    Node: 24.13.0 - /run/user/1000/fnm_multishells/21886_1772342545583/bin/node
    npm: 11.6.2 - /run/user/1000/fnm_multishells/21886_1772342545583/bin/npm
    pnpm: 10.28.2 - /home/phi/.local/share/pnpm/pnpm
    bun: 1.3.10 - /home/phi/.bun/bin/bun
  Browsers:
    Chrome: 142.0.7444.59
  npmPackages:
    rolldown: ^1.0.0-rc.6 => 1.0.0-rc.6

Any additional comments?

I have already filed a bug issue in the dts plugin repository and received a response that there is no way to fix it within the plugin.
sxzz/rolldown-plugin-dts#195