Surface area, not the machinery, was the problem: 16 flags crowded the
bare --help. Re-tag so basic shows only the 10 outcome-changing flags;
every other flag still works behind --help=<group>.
- cut --bt-metadata-timeout, an invented flag with no real counterpart. Keep
its 60s magnet-metadata stall as a fixed internal default (bt.go), not a
user knob.
- fix the parallelism footgun: a bare `got URL` used min(split,x)=1
connection. When -x is unset, let --split drive per-host connections
(capped at 16), so `got URL` gets 5 and `-s16` gets 16. An explicit -x
is honored verbatim, including -x1. Locked by TestHTTPConnDefault.
- -s is the per-download speed dial now, so it moves to basic; -x (a
per-server cap) moves to the http group. -j help says "files at once,
not connections within one file".
Two Pike cleanups.
--auto-split was a third connection-count policy (beside -x and -s) that added
an extra knob rather than keeping the model minimal. Removing it also retires the
now-dead autoConns/maxAutoConns and the per-host transport cap that existed only
to scale for it; min(split, M*-x) is the sole policy again.
main's exit-code mapping fell back to substring-matching third-party error text
(strings.Contains "connection refused"/"timeout"/...), which rots when a
dependency rewords a message. The typed checks (errors.Is on the syscall errno,
*net.DNSError, net.Error.Timeout, context.DeadlineExceeded) already cover the
real stdlib errors -- verified end to end: refused -> 6, bad host -> 19. The two
cases that genuinely needed the text match are our own errors, now typed
sentinels: httpdl.ErrTimeout (idle timeout) and the bt metadata timeout wrapping
context.DeadlineExceeded.
an idle worker now steals the back half of the busiest in-flight segment
instead of exiting, so one slow segment no longer drains alone over a single
connection. control file persists stolen tails; resume re-tiles.
add --auto-split (opt-in): derive the connection count from file size (one
per min-split-size, up to 16), overriding -x/-s. default stays at 1
connection for a single server.
