fix(@angular/build): strip all vite id prefixes from minified code wi…

[FestimShyti]

PR Checklist

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• The commit message follows our guidelines: https://github.com/angular/angular-cli/blob/main/CONTRIBUTING.md#-commit-message-guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the current behavior?

Issue Number: #33524

When the dev server serves an optimized/minified build and externalDependencies are in
effect, the angular-plugin-remove-id-prefix transform strips Vite's /@id/ prefix only from
the first external import per line. Its regex appends a greedy (?:/.+)? to each external
name, so on minified single-line output the first match on an external with a deep import path
(e.g. @angular/common/http) consumes the remainder of the line into the capture group, and
every later /@id/ occurrence on that line is never matched. The browser then requests e.g.
http://localhost:4200/@id/@angular/router, receives the index.html fallback, and module
loading fails:

Error: Unsupported Content-Type "text/html" loading http://localhost:4200/@id/@angular/router
Modules must be served with a valid MIME type like application/javascript.

Deterministic repro of the defect:

const escapeRegexSpecialChars = (s) => s.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
const externals = ['@angular/common', '@angular/common/http', '@angular/core', '@angular/router'].sort();
const escaped = externals.map((e) => escapeRegexSpecialChars(e) + '(?:/.+)?');
const reg = new RegExp('/@id/(' + escaped.join('|') + ')', 'g');

const code =
  'import{a}from"/@id/@angular/common/http";import{b}from"/@id/@angular/router";import{c}from"/@id/@angular/core";';

console.log(code.replace(reg, (_, name) => name));
// Actual:   import{a}from"@angular/common/http";import{b}from"/@id/@angular/router";import{c}from"/@id/@angular/core";
// Expected: import{a}from"@angular/common/http";import{b}from"@angular/router";import{c}from"@angular/core";

What is the new behavior?

The path suffix in the regex is bounded ((?:/[^'"\\s]+)?) so a match can never extend past the end of an import specifier string literal. Every /@id/` occurrence is stripped — including
on minified single-line bundles — while deep import paths are still fully captured and
multi-line (unminified) behavior is unchanged.

A regression spec (id-prefix-plugin_spec.ts) is added covering: the minified single-line
case, deep import paths, non-root base, multi-line code, non-external @id/ imports
(untouched), and the empty-externals no-op. The new spec fails against the previous
implementation and passes with this change (pnpm bazel test //packages/angular/build:test).

Does this PR introduce a breaking change?

• Yes
• No

Other information

The fix was also verified end-to-end against @angular/build 21.2.0 by patching
node_modules in a real application that previously failed to bootstrap under an optimized
ng serve — it starts correctly with the bounded regex.

#30642 reported the same symptom earlier and was closed as not reproducible — a default
(unoptimized) ng serve never triggers the bug; optimization must be enabled so the output
is single-line.

[gemini-code-assist]

Code Review

This pull request updates the createRemoveIdPrefixPlugin Vite plugin to use a bounded regex pattern (?:/[^'"\s]+)?instead of a greedy wildcard(?:/.+)?` when matching external import paths. This prevents incorrect stripping of prefixes in minified, single-line code. Additionally, a comprehensive suite of unit tests has been added to verify this behavior under various scenarios. There are no review comments, so I have no feedback to provide.