# 07 — Add isolated concurrent local Hot KV State

Status: ready-for-agent

## Mandatory fresh-session context

- Read [RALPH-CONTEXT.md](../RALPH-CONTEXT.md) completely before changing code.
- This issue is `DGR-007` in [prd.json](../prd.json).
- Read the evidence README for every dependency listed below.
- Inspect current code and `git status`; historical text and previous agent claims are not evidence.

## Description

As a client, I need concurrent Route Sessions to retain independent per-Shard cache so that one request cannot clear or corrupt another.

## Expected durable outputs

- Concurrent local KV/session manager
- Isolation, eviction, cancellation and cleanup tests
- evidence/DGR-007/README.md

## Acceptance criteria

- [ ] Map `(Route Session ID, route epoch)` to an isolated llama sequence or bounded context.
- [ ] Allocate KV only for owned layers.
- [ ] Support prefill append, decode append, truncate, release, TTL/LRU eviction, and explicit cache-miss response.
- [ ] Reject stale epochs and incompatible cache recipes.
- [ ] At least four concurrent sessions on a small model complete without token or KV cross-talk.
- [ ] Cancellation/release of one session leaves other sessions intact and memory returns to the configured budget.
- [ ] Targeted pytest tests pass
- [ ] python -m compileall packages tests passes for Python changes
- [ ] git diff --check passes
- [ ] Default tests remain deterministic, model-download-free, API-credit-free, and GPU-free
- [ ] Full deterministic pytest -q passes, or the exact pre-existing unrelated failure is recorded with a clean-tree reproduction
- [ ] Pinned native C++ target builds and focused CTest/protocol tests pass where native code is touched
- [ ] llama.cpp patch stack applies cleanly to the exact pinned commit where patch code is touched
- [ ] Read .scratch/distributed-gguf-runtime/RALPH-CONTEXT.md and this story issue completely before changing code
- [ ] Read and verify every dependency evidence README before relying on dependency behavior
- [ ] Preserve all pre-existing working-tree changes and stage only files belonging to this story
- [ ] Write .scratch/distributed-gguf-runtime/evidence/DGR-007/README.md with files changed, exact commands and real results, limitations, compatibility notes, and dependent-story handoff
- [ ] Update only this story issue to Status: done after every acceptance criterion and quality gate passes

## Dependency handoff

- `DGR-006` and `DGR-019` must have `passes: true`; read both evidence READMEs and verify their referenced files/commands.

## Finish contract

- Create the task evidence directory and durable handoff required above.
- Preserve real failures and blockers; never fabricate benchmark, model, test or hardware output.
- Change this issue to `Status: done` only after all criteria pass.
- Emit `<promise>COMPLETE</promise>` only after the evidence handoff exists.

## References

- [Ralph execution context](../RALPH-CONTEXT.md)
- [PRD](../PRD.md)
- [Implementation strategy](../implementation-strategy.md)
- [Current architecture](../architecture.md)
- [Architecture decision](../ADR-0020-distributed-gguf-runtime.md)