pub fn set_hermetic(on: bool)Expand description
Default-ON switch for MID-CHUNK tail SSM capture (opt-out ATLAS_SSM_TAIL_MIDCHUNK=0).
Default ON => mid-chunk capture fires on prefill passes spanning the
block-floored matched-prefix boundary. When disabled, the prefill
chunk is NOT clamped to ssm_tail_boundary; instead each GDN layer’s
recurrent (h_state) and conv (conv_state) kernels are split at the block-
floored matched-prefix boundary and the @tb state is copied into a reserved
Marconi snapshot slot in-pass, removing the ~868 ms extra forward pass the
clamp-based ATLAS_SSM_TAIL_CKPT path costs.
Publish the command line’s --ssm-tail-midchunk. Call once, at serve time,
before any prefill runs.
None means THE FLAG WAS NOT GIVEN, and is not the same as Some(default).
Publishing the clap default sealed this cell on every spark serve, which
made the documented ATLAS_SSM_TAIL_MIDCHUNK=0 opt-out a silent no-op — an
operator could set it, see the flag echoed in the startup log, and get the
opposite behaviour with nothing anywhere saying so. A knob that looks like an
opt-out and is not costs more than no knob at all, so an absent flag now
publishes nothing and leaves the environment fallback below to decide.
Publish spark serve --hermetic. Call once, at serve time.
Takes a plain bool rather than the Option its neighbours take, and
publishes ONLY when true. The Option dance next door exists because those
flags are default-ON and an absent flag publishing the clap default sealed
a documented opt-out into a no-op. --hermetic is opt-IN: there is no
opt-out to seal, and “not given” and “given false” are the same request.
So absent leaves ATLAS_HERMETIC live, and passing the flag wins.