Embedded client can't connect when the page is served from a different origin

[elec7reify]

Describe the bug

The client injects fine (see screenshot), but the connection meta goes to /__devtools/ relative to the page origin, i.e. my backend, where nothing serves it runs into 404. Opening http://localhost:5173/__devtools/__connection.json directly works.

Reproduction

Copy this repo https://github.com/elec7reify/dummy, run DemoApplication.java and pnpm dev in vue-project, goto localhost:8080

System Info

System:
    OS: Windows 11 10.0.26200
    CPU: (16) x64 AMD Ryzen 7 7840HS w/ Radeon 780M Graphics
    Memory: 7.32 GB / 30.65 GB
  Binaries:
    Node: 24.18.0 - C:\Program Files\nodejs\node.EXE
    npm: 11.11.0 - C:\Program Files\nodejs\npm.CMD
    pnpm: 11.15.1 - C:\Users\vb\AppData\Local\pnpm\bin\pnpm.CMD
  Browsers:
    Chrome: 150.0.7871.187
    Edge: Chromium (150.0.4078.105)
    Firefox: 153.0 - C:\Program Files\Mozilla Firefox\firefox.exe
    Internet Explorer: 11.0.26100.8115

Used Package Manager

pnpm

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• The provided reproduction is a minimal reproducible of the bug.

[elec7reify]

Thanks for the quick fix! The RPC connection now resolves correctly - the WS connects to the correct Vite origin. One spot still seems to resolve against the page origin though: iframe panel resources 404 on the backend (see screenshot).