_turn_transcript_messages pre-classified every message with
_is_compressed_summary_message (full content flatten + prefix scan), then
_message_response re-ran the same classifier inside its projection --
2x per non-summary row, 3x per summary row on every run.completed emit.
The outer guard was redundant: _message_response already yields
display_kind hidden for pure handoffs. One projection call per row now.
Surfaced by the post-merge simplify re-review of #91517/#91535.