Agents ended turns with "I'll wait … I'll be notified" expecting a
background-completion callback that this environment never delivers, so
the turn hung and left the planning sentence stuck in the channel. Add a
claude-platform rule that no such notification exists — finish within the
turn (foreground/poll) or ask the user for a follow-up.
Also suppress the elapsed-time suffix on progress messages until at least
one 5s bucket has elapsed, so freshly-created progress no longer shows a
meaningless "0초". Update the affected message-runtime expectations.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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