The B1 write-through: every CP rank runs the IDENTICAL deterministic CpSharedL2PageAllocator.reserve over the replicated event stream -> identical placement with NO broadcast/gather; commit rides the writing_check ReduceOp.MIN frontier (mark_object_committed) instead of a per-(rank,layer,payload) gather quorum.
cache_controller.py: _reserve_write_cp_shared_l2 stripped to every-rank reserve (dropped preflight#2/rank0-gate/broadcast#3/adopt/missing-payloads; per-object contract kept MF3; idempotent abort-on-partial SF3); _submit_write_cp_layer_states drops the 3 gather-commit calls (per-layer D2H + all-payload done-gate MF1 + per-node ack kept); submit_write_cp_all_layer drops both fallback gathers (zero-owned keeps its ack MF2).
hiradix_cache.py: 3-way merge of l2_pooling shared-L2 init (clean, 0-conflict; Phase-1 clock + E1 + reserve-budget preserved) builds the allocator/slab when the flag is on and passes it to HiCacheController WITHOUT collective fns. The #5 deadlock removed: shared_l2_capacity reserve-miss now SKIPS the backup (reactive, rank-uniform) instead of _evict_host_for_physical_slots(synchronize_across_ranks=True) -- the deterministic shared-pool evict is 2b.2. mark_object_committed wired at _commit_pending_backup (the MIN commit). New _cp_assert_placement_replicated (SGLANG_CP_HICACHE_PLACEMENT_ASSERT) in check_hicache_events: MIN/MAX-reduce placement_digest across the CP group, fail-loud on divergence (Theorem 1 runtime gate; rank-uniform entry, cannot deadlock).
environ.py: SGLANG_CP_HICACHE_PLACEMENT_ASSERT (EnvBool, default off).
Tests: 8-rank reserve-determinism (identical placement across 8 ranks + divergence-detectable) + full pool suite 91/91 + import smoke on g0033 syh-dev-new. TWO opus adversarial reviews both SHIP (cache_controller strip + hiradix wiring).
NOTES: default-off (--enable-cp-shared-physical-l2-hicache); validated for write_through policy (prod default). Capacity-miss currently SKIPS (B1 shared-pool evict = 2b.2) so the flag must stay off in real runs until 2b.2. Dead gather island (3 fns + 3 imports, opus-confirmed inert) pending GC follow-up. Design+proof: docs_internal/cp_hicache_2b_pooled_l2_b1_design.md sec 2.4/9.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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