A user message sent mid-turn (CLI busy_input_mode=interrupt, gateway priority
redirect, ACP redirect) goes through AIAgent.redirect(), which during tool
execution degrades to steer() + request_yield() on the tool worker threads.
The local terminal backend's foreground wait honours the yield (adopting the
process into the background registry), but ProcessRegistry.wait() — the
process_manage(action='wait') path — never checked it: a model sitting in a
wait on an already-background process parked the user's message for up to the
full wait window (default 180s, clamp allows more).
wait() now consumes a pending yield on its own thread each poll pass and
returns status "interrupted" with process_running=true and a note telling the
model to respond to the user; the process is untouched and still
notify-tracked. The plain-interrupt and timeout paths are unchanged.
Live repro: on origin/main, request_yield() against a thread blocked in
wait(timeout=12) had no effect (wait ran to timeout); after this change the
wait releases in <1s with status=interrupted, process still running.
Port of MoonshotAI/kimi-code#3697 ("let steer interrupt background task
waits") adapted to Hermes' per-thread yield mechanism from 463292351f.