Preview pane blocks local dev-server assets (ERR_BLOCKED_BY_CLIENT) — needs a localhost allowlist

The preview/Browser pane blocks sub-resources of a local dev site served under a custom hostname, so pages render unstyled.

Repro

1. Run any Vite-based dev server locally (e.g. Nuxt 4 + Vite) on 127.0.0.1.
2. Front it with a custom local hostname instead of localhost — a common dev setup: add a hosts entry so the name resolves to loopback (e.g. /etc/hosts: 127.0.0.1 myapp.test), and run a local reverse proxy (nginx/Caddy) that routes myapp.test → the dev server. So http://myapp.test/ is entirely local — the hostname is just an alias for 127.0.0.1, nothing leaves the machine.
3. Open http://myapp.test/ in the preview pane.

Symptom

The document loads (HTTP 200), but every sub-resource fails with net::ERR_BLOCKED_BY_CLIENT:
/_nuxt/@vite/client, virtual:nuxt:…css, /_nuxt/**/*.css, .pnpm/**/entry.async.js, /icon.png → the page renders unstyled.

Not a server or cert issue

• It's plain HTTP; curl http://myapp.test/<asset> returns 200 with correct content-type/size for every asset.
• The error is the pane's client-side content filter (ERR_BLOCKED_BY_CLIENT), not ERR_CERT_* — so it isn't a TLS/certificate problem.
• It appears to over-match Vite dev-mode URLs (@vite/client, virtual:, .pnpm/ paths, the HMR websocket). A production build renders fine because its assets are plain hashed /_nuxt/<hash>.js|.css paths.

Ask

A user-configurable way to relax this for local development — e.g. a settings.json key or /config toggle to disable content blocking for localhost/private hosts (127.0.0.1, *.localhost, custom hosts-mapped local TLDs, RFC1918 ranges), or a per-host allowlist.