Companion to BLOCK_LEVEL_EVICTION_DESIGN_ZH. Specifies the
three-layer contract (mooncake / SGLang / agentic-pd-hybrid)
that the empty feat/d-to-p-sync branch is meant to fill.
Contents:
- §1 staleness budget β as a first-class system parameter,
with recommended default (page_size .. 4096 tokens)
- §2.1 mooncake double-role API: KVRole enum extension,
DecodeKVSender / PrefillKVReceiver class shapes,
independent bootstrap channel
- §2.2 SGLang RadixCache.insert_external signature with
five concrete design decisions (re-mapping policy,
failure handling, lock_ref discipline, evict
interaction, multi-P backup view)
- §2.3 agentic-pd-hybrid CLI flags, DirectSessionState
additions, hook points in _invoke_session_direct
and _invoke_kvcache_seeded_router
- §3 candidate Theorem 4 (reseed_cost upper bound under
staleness budget β)
- §4 P1..P4 rollout with validation criteria per phase
- §5 five enumerated risks + mitigation
- §6 explicit decoupling: block-level eviction first,
then D->P sync; do NOT bundle in one PR
Makes the feat/d-to-p-sync branch actionable for the next
collaborator without GPU until P2 microbench phase.
Gahow Wang
fd37eda367