Resident KV Claims: A Conformance Contract for Future Reuse under Active KV Pressure
For systems using KV-cache reuse, this work provides a portable runtime contract to arbitrate between resident and active KV allocations, addressing a gap in current mechanisms.
The paper introduces resident KV claims, a conformance contract for KV-cache reuse that binds future-reuse intent to a materialization predicate, lifecycle state, and feasibility outcome. A vLLM prototype demonstrates that hard protected claims convert unreported resident loss into scheduler-visible active refusal with blocking-claim attribution.
KV-cache reuse mechanisms increasingly expose priority, duration, offload, routing hints, scheduler modes, and event streams. These mechanisms help preserve reusable prefixes, but they do not by themselves define a portable contract for accepted future-reuse state when resident KV and active live KV cannot both fit. We introduce resident KV claims, a conformance contract that binds future-reuse intent to a materialization predicate, lifecycle state, active/resident feasibility outcome, and claim-level telemetry. In controlled vLLM allocator probes, a 60-block resident claim and a 70-block active prefill exceed an 80-block usable KV pool. Write no-admit prevents the active request from becoming future reusable state, but it still allows active allocation to evict residents from the shared pool. A minimal vLLM prototype shows that hard protected resident claims convert this failure mode into scheduler-visible active refusal with direct blocking-claim attribution. The result is not a production speedup or a new cache-replacement algorithm. It is a runtime contract that turns unreported resident loss into reconstructable active/resident arbitration. A companion MicroRuntime and vLLM litmus suite distinguish ordinary eviction, soft priority, write no-admit, accepted hard claims, materialization failure, demotion, expiry, active refusal, and trace-level outcome reconstruction.