The repo's .npmrc sets engine-strict=true and package.json pins
engines.npm, so an npm outside that range aborts every npm ci /
npm install we run inside the checkout:
npm error code EBADENGINE
npm error notsup Required: {"npm":"<11.10.0 || >=12.0.0"}
npm error notsup Actual: {"npm":"11.10.0"}
Our callers made that worse: _run_npm_install_deterministic sees
`npm ci` fail and falls through to `npm install`, which fails
identically, so the user got a buried EBADENGINE and no remedy.
React to the failure instead of predicting it. npm states the
required range in its own error, so there is no need for a version
probe on the happy path or a semver range matcher — the recovery
reads the constraint out of the output it just produced, upgrades,
and retries once.
Scope is deliberately narrow. Hermes only upgrades an npm inside its
own managed Node tree ($HERMES_HOME/node), installing with --prefix
so bin/npm keeps resolving to the upgraded lib/node_modules/npm; a
managed install writes prefix=~/.local into node/etc/npmrc, so
without the override the "upgrade" would land elsewhere while the
managed npm stayed stale. A system / nvm / brew / Nix npm belongs to
the user, so that case prints the exact command and lets the original
failure stand.
The upgrade runs from a temp cwd with npm_config_min_release_age=0,
otherwise the checkout's own min-release-age gate would refuse the
npm release we need.
_run_npm_install_deterministic's capture_output=False callers (the
desktop install) streamed npm output and returned stderr=None, which
would leave the recovery nothing to read — stderr is now teed, so
live output is unchanged and the text stays inspectable.
Verified end to end against real npm binaries on copies of a managed
tree: managed npm 11.10.0 -> EBADENGINE -> upgraded to 12.0.2 ->
retry exits 0; a foreign npm 11.10.0 hard-fails with the manual
command and is left untouched.
