The background memory/skill review thread wrapped its whole body in
process-global contextlib.redirect_stdout/stderr(devnull). Those rebind
sys.stdout/sys.stderr for the ENTIRE process, so for the full duration of
the review (tens of seconds) every other thread — including a gateway
event-loop thread driving a Telegram long-poll — also wrote to devnull.
Any bare print/sys.stderr.write from those threads during the window was
silently lost (#55769 / #55925).
Replace the global redirect with thread_scoped_silence(): a per-thread
routing proxy installed once as sys.stdout/sys.stderr that sends only the
registered (bg-review) thread's writes to devnull and passes every other
thread through to the real stream. Depth-counted so nested use composes.
Verified: a concurrent thread writing while the bg-review thread is inside
the silence window keeps its output on the real stream.
