Buy the grammar, own the execution: @yarnpkg/parsers parses the command
line - aliased at bundle time to its shell entry so the root barrel's
syml/js-yaml closure stays out of the worker - and a VFS-backed evaluator
with a coreutils command table runs it inside the worker host. Each shell
process is a real child WebWorker spawned from the same bundle (the first
frame decides the role), so the TERM-then-KILL ladder is real - TERM
requests, KILL terminates the worker - and the file face stays
asynchronous end to end, since the deployment target serves no COOP/COEP
headers and SharedArrayBuffer never exists there. node:child_process
reports through the ChildProcess surface the subprocess service consumes;
execSync, execFileSync and fork refuse, and node-pty stays stubbed.
imccyu