Injector.drop knew the precise cause (herdr agent_not_found) but the
sender was told only 'worker unreachable or stuck', so a lead could not
tell a dead pane from a stalled model.
TurnListener.onTurnFailed gains a reason, defaulting to the old one-arg
form. CompletionResolver prefers that reason, then the pane scrape, then
the old fixed text.
drop now fires onTurnFailed unconditionally. That is the substantive
fix: the sender blocks on the rendezvous waiter, not on the delivered
future, so failing delivered() alone never woke it and a queued send sat
until its timeout.
Dai Ha
d5f33f0c6e