Bug: HMR stops working on child component after updating parent

[mwojick]

Describe the bug

See reproduction steps below. I tested it on the current latest versions (Vite 8 and vite-plugin-svelte 7 with Svelte 5.55), but also reproduced with Vite 7 and vite-plugin-svelte 5 and 6, so this doesn't seem to be a recent issue.

Reproduction URL

https://github.com/mwojick/svelte-vite-hmr-bug

Reproduction

1. Scaffold a Svelte project (TS or JS) with Vite: pnpm create vite, or use the linked repro, it's the same thing. Start dev server with pnpm run dev
2. Change some text in Counter.svelte -> see UI update
3. Change some text in App.svelte -> see UI update
4. Change some text again in Counter.svelte -> no longer see a UI update, but there is a [vite] hot updated: /src/lib/Counter.svelte in the dev console, so Vite is doing something, but it seems like it's trying to update a stale version of Counter that is no longer in the UI. Because when you change App again, the change to Counter finally shows up.

Logs

System Info

System:
    OS: Linux 6.6 Ubuntu 24.04.2 LTS 24.04.2 LTS (Noble Numbat)
    CPU: (24) x64 AMD Ryzen AI 9 HX 370 w/ Radeon 890M
    Memory: 13.46 GB / 15.18 GB
    Container: Yes
    Shell: 5.9 - /home/mwojick/.nix-profile/bin/zsh
  Binaries:
    Node: 24.14.0 - /home/mwojick/.nix-profile/bin/node
    Yarn: 4.13.0 - /home/mwojick/.nix-profile/bin/yarn
    npm: 11.9.0 - /home/mwojick/.nix-profile/bin/npm
    pnpm: 10.33.0 - /home/mwojick/.nix-profile/bin/pnpm
    bun: 1.3.11 - /home/mwojick/.nix-profile/bin/bun
  npmPackages:
    @sveltejs/vite-plugin-svelte: ^7.0.0 => 7.0.0
    svelte: ^5.55.1 => 5.55.3
    vite: ^8.0.4 => 8.0.8