pub fn set_ssm_tail_midchunk(on: Option<bool>)Expand description
2026-09-25: Publish --no-ssm-tail-midchunk: the serve plan passes
Some(false) when the flag is given and None otherwise. None publishes
nothing, so METRALE_SSM_TAIL_MIDCHUNK still decides. The cell is set once:
the first published value, or the first ssm_tail_midchunk_enabled read, wins.