leasePort({closed:true}) ignored its option: it probed an ephemeral port and
closed it, so a parallel test file could bind it and answer a request the
test expected to fail (preview.test.mjs:209 saw 200 instead of 502).
leaseClosedPort holds a bound, non-listening socket in a perl child until the
test's after hook. Connects still get ECONNREFUSED, bind() from another
process gets EADDRINUSE, and the kernel's ephemeral allocation skips the port.
Lane mode keeps its band and per-port lock, and releases the socket before
the lock. leasePort now refuses a closed option, so a stale call cannot get
the unheld port again.
Unanswerable callers (webui preview, serve, service) move to leaseClosedPort(t).
Callers that listen on the port themselves (stack-release rehearse, control-board
serve, tester-cli) keep leasePort and drop the ignored option.
jason.woltje
1009bbfaf9