The channel manager coalesces consecutive _stream_delta messages and
forwards a single merged message with _stream_end=True. In that path
no individual delta events ever reach the WebUI client, so the
stream_end frame is the only carrier of the text. The previous guard
only attached text when media-URL rewriting changed the string, which
silently dropped entire turns of plain-text output whenever the
agent generated tokens faster than the queue drained.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
