* fix(desktop): re-download Electron binary via mirror when pack fails (#47266)
Since #38673 pinned build.electronDist to node_modules/electron/dist,
electron-builder reads the Electron binary straight from there and never
downloads it during `npm run pack`. That dist tree is only produced by the
electron package's postinstall (install.js) during `npm ci`. When that
download is blocked or throttled (GitHub's release host is unreachable in
some regions), the dist is missing and the build dies with:
The specified electronDist does not exist: .../node_modules/electron/dist
The existing ELECTRON_MIRROR fallback in all three desktop-build paths
(scripts/install.ps1, scripts/install.sh, and `hermes desktop` in
hermes_cli/main.py) re-ran `npm run pack` with ELECTRON_MIRROR set — but
pack never downloads Electron anymore, so the mirror was never used and the
retry re-read the same missing dist. The fallback was effectively dead.
Drive the mirror through electron's own downloader instead:
- Add a dist-presence check + a downloader helper (Test-ElectronDist /
Restore-ElectronDist, _electron_dist_ok / _restore_electron_dist,
_electron_dist_ok / _redownload_electron_dist) that wipes a partial dist
+ the path.txt version marker (electron's install.js short-circuits on it)
and re-runs `node install.js`, optionally via a mirror.
- On the first retry, repopulate a missing dist from the canonical source;
on the mirror retry, re-fetch through npmmirror.com, then pack.
- Gate the re-download on the dist check so an unrelated build failure
(tsc/vite) doesn't trigger a pointless ~200 MB refetch, and skip the final
pack when the binary still can't be fetched instead of failing the same way.
* test(desktop): cover Electron dist re-download mirror fallback (#47266)
Add behavior coverage for the electronDist re-download fix:
- _electron_dist_ok across linux/win32/darwin, including the partial-dist
case (dir present but binary missing) that makes the pinned electronDist
fail.
- _redownload_electron_dist: no-op when the binary is present, bail when
install.js is absent, wipe a stale dist + path.txt marker and run
electron's downloader with ELECTRON_MIRROR injected, and report failure
when the download still produces no binary.
- `hermes desktop`: the mirror fallback now drives electron's own downloader
before re-running pack, and skips the final pack entirely when the binary
can't be fetched.
Replaces the old mirror test that asserted the (now-fixed) dead behavior of
re-running `npm run pack` with ELECTRON_MIRROR set — pack never downloads
Electron under the pinned electronDist, so that retry could never help.
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