Summary

Fixes #26628. deno compile produced binaries that failed with ERR_MODULE_NOT_FOUND when the configured npm registry URL contained a sub-path (e.g. http://mirrors.example.com/npm/).

The on-disk cache layout for such a registry is <global_cache>/<host>/<sub>/<pkg>/..., but build_vfs_consolidating_global_npm_cache in cli/standalone/binary.rs flattened the cache by iterating each top-level entry under <global_cache> exactly one level deep — collapsing <global_cache>/<host>/<pkg> directly into the embedded localhost/. With a sub-path registry the loop instead picks up the intermediate <sub> directory and embeds packages at localhost/<sub>/<pkg>/..., which then can't be found at runtime (where the binary expects localhost/<pkg>/...).

This PR uses the known_registries_dirnames already tracked by NpmCacheDir (built from .npmrc resolution) to walk to each registry's actual package root before flattening, and to know which top-level host directories under the global cache are registry roots that should be dropped after their packages are moved into localhost/. The default no-sub-path case is unchanged.

To make this accessible from cli/standalone/binary.rs, the PR adds:

• NpmCacheDir::known_registries_dirnames()
• ManagedCliNpmResolver::known_registries_dirnames()

Manual repro

I verified end-to-end with a Deno-script proxy that mirrors registry.npmjs.org at a sub-path:

// proxy.ts - listens at http://localhost:4873/sub/path/npm/
const target = "https://registry.npmjs.org";
const prefix = "/sub/path/npm";
Deno.serve({ port: 4873 }, async (req) => {
  const url = new URL(req.url);
  if (!url.pathname.startsWith(prefix)) {
    return new Response("nf", { status: 404 });
  }
  const rest = url.pathname.slice(prefix.length) + url.search;
  const res = await fetch(target + rest, { redirect: "follow" });
  const ctype = res.headers.get("content-type") ?? "";
  if (!ctype.includes("application/json")) return res;
  const text = (await res.text()).replaceAll(
    "https://registry.npmjs.org/",
    \`http://localhost:4873${prefix}/\`,
  );
  const h = new Headers(res.headers);
  h.delete("content-encoding");
  h.delete("content-length");
  return new Response(text, { status: res.status, headers: h });
});

// main.ts
import { say } from "npm:[email protected]";
console.log(say({ text: "Hello from Deno!" }));

Before this PR:

$ NPM_CONFIG_REGISTRY="http://localhost:4873/sub/path/npm/" \
    deno compile --allow-read -o main main.ts
... .deno_compile_node_modules/localhost/sub/path/* ...
$ ./main
error: [ERR_MODULE_NOT_FOUND] Cannot find module
  'file:///tmp/deno-compile-main/.deno_compile_node_modules/localhost/cowsay/1.5.0/index.js'

After:

... .deno_compile_node_modules/localhost/cowsay/1.5.0/* ...
$ ./main
 __________________
< Hello from Deno! >
...

I also re-checked the default (no sub-path) registry case end-to-end to confirm no regression — embedded layout and runtime behaviour are unchanged.

A spec test is now included. handle_req_for_registry in tests/util/server/servers/npm_registry.rs strips a fixed /sub/path prefix before serving package files, so the test registry can be driven through a sub-path url. The spec at tests/specs/compile/npm_registry_subpath/ compiles a package cached through http://localhost:4260/sub/path/ and asserts the embedded layout flattens to localhost/@denotest/esm-basic/* rather than localhost/sub/path/..., then runs the binary to confirm it resolves at runtime.

Test plan

• New compile/npm_registry_subpath spec asserts the flattened layout and runtime behaviour
• Existing compile/npm/npmrc spec tests stay green (audit sub-path + global-cache compile specs verified locally)
• Manual repro above before/after on a sub-path registry
• Default registry (no sub-path) still works end-to-end