fix(dev): allow aliases starting with //

[HunterLarco]

Description

Fix alias resolution being incorrectly skipped for URL-like patterns in dev server.

Problem

When an alias pattern resembles a URL (e.g., { find: '//', replace: '...' }), the dev server's import analysis plugin incorrectly treats imports like //foo as external URLs and skips alias resolution (codepointer). This causes:

1. Inconsistency with build: vite build correctly applies these aliases while dev server doesn't
2. Broken aliases: Any alias matching URL patterns (scheme-relative, file://, etc.) fails in dev mode

Solution

Check if an import matches an alias before skipping it as an external URL.

Testing

Added test case in playground/alias/ that:

• Defines an alias with URL-like pattern (// prefix)
• Verifies it resolves correctly in dev server
• Test passes with fix, fails without it

Risks

None. Projects with URL-pattern aliases are already broken in dev mode, this fixes them without impacting other flows.

[hi-ogawa]

Makes sense to me. The intent is similar to the one done for ssr external just below by #15602

vite/packages/vite/src/node/plugins/importAnalysis.ts

Lines 520 to 521 in 84079a8

	// skip ssr externals and builtins
	if (ssr && !matchAlias(specifier)) {

[HunterLarco]

Checking in if there's anything I can do to help this land :)

[sapphi-red]

I guess we should remove this if block completely. But I think it's better to keep it for now.

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/vite@20760

commit: 17fe255

[sapphi-red]

/ecosystem-ci run

[vite-ecosystem-ci]

📝 Ran ecosystem CI on a0fabd1: Open

suite	result	latest scheduled
histoire	✅ success	❌ failure
one	❌ failure	❌ failure
laravel	❌ failure	❌ failure
qwik	❌ failure	❌ failure

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