[bradhilton]

Agent: Shazeer

Problem. ART's admission control refused context-parallel work that fits. Before this change, CP8 refused even a 32K forward, predicting 128.6 GiB of extra memory against 61.3 GiB available. The CP>1 profile extrapolated fixed small-root scratch as if it scaled per token. The long-context lanes also found a planner-replay crash at CP>1.

What this changes.

• Bounded calibration for matching MoE and dense CP2/4/8 geometries. It keeps the worst-rank physical-row floors, full-output charges and collective admission, and never divides a CP1 peak.
• Dense CP backward charges LoRA workspace (saved factor products and backward workspace) from the selected adapter ranks and target counts. Adapter owners are recognized by type, subclasses included. Any inventory the readers can't fully classify falls back to main's conservative per-layer allowance.
• CP>1 planner replay records the runtime shape and MoE layer count, so replay works. Older incomplete reports decline replay explicitly.
• Not included: host activation offload, an earlier prototype here, is excluded. Its per-forward host usage could desynchronize ranks, and it's tracked separately.

Validation.

• Tests: Megatron CPU CI 1,783 passed / 14 skipped; backend 4,250 passed. Ruff, format and lock pass, and ty has the same 18 diagnostics as main.
• CP1 unchanged: the 8 pinned values plus 135/144/432 differential cases are identical to main.
• Measured cells: all five measured rank-8 dense lifecycle cells stay admitted, with predictions at or above measured peaks.
• Adversarial probes are refused: both rank-768 dense probes at a 550 MB cap, and a GLM rank-512 subclass witness at a 1.15 GB cap.
• Review: three exact-head Sol review rounds. The final round, at 60b9de6d, is CLEAR-WITH-NOTES.

Limits.

• No numerical change and no CP numerical qualification; that's separate.
• The scoped-report replay TypeError already exists on main at CP1.
• With the opt-in bounded calibration scope enabled, estimates can be below main's by design.

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