RunRecord key 12 LowererReach set by a required --lowerer-reach flag and
shown in round and cycle lines. PROMPT_SOURCE_DIGEST covers packet.rs.
Lowering text is refused when blank, over 4096 bytes or holding a control
character. Unanswered lowering digests are listed once. Tests for the
Prompt::lower build refusal and the packets.cc discard after a port error.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
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