<!-- GENERATED FROM prd.json — DO NOT EDIT AS AN INDEPENDENT SOURCE. prd.json IS AUTHORITATIVE. -->
# DGR-051: Assemble the DeepSeek V4 Flash `ShardEngine` adapter

- **Status / triage:** specification only; `ready-for-agent`; `passes: false`
- **Execution mode:** `AFK`
- **Milestone:** `M3`
- **Dependencies:** `DGR-034`, `DGR-037`, `DGR-047`, `DGR-048`, `DGR-049`, `DGR-050`
- **Blocks (derived):** `DGR-052`, `DGR-060`, `DGR-065`, `DGR-069`
- **Labels:** `area:deepseek-v4`, `area:engine`, `type:vertical-slice`, `priority:p0`, `ready-for-agent`
- **Evidence class:** `real-model`
- **Hardware:** `optional`
- **Model:** `deepseek-v4-flash`
- **Upstream:** `yes`

## Objective / description

Fresh Ralph session: read `.scratch/distributed-gguf-runtime/RALPH-CONTEXT.md`, source issue `.scratch/distributed-gguf-runtime/issues/051-assemble-the-deepseek-v4-flash-shardengine-adapter.md`, and evidence READMEs for dependencies (DGR-034, DGR-037, DGR-047, DGR-048, DGR-049, DGR-050) before changing code. Inspect live source/tests rather than trusting legacy pass states. Objective: Assemble range ownership hooks and boundary/local-state adapters around upstream llama.cpp V4 execution behind the stable ShardEngine interface.

## Acceptance criteria

- [ ] Support valid head, middle, tail, and whole-model ranges over all 43 main layers using the pinned upstream llama.cpp V4 graph/kernels.
- [ ] Integrate exact range ownership, mHC boundary, positions, required token-ID sideband, and shard-local session/epoch state adapters.
- [ ] Report MTP reserved-but-not-executable for alpha and reject unsupported split points or cache expectations.
- [ ] Include exact adapter/schema/runtime/artifact identity and valid split restrictions without reimplementing V4 MoE, attention, mHC, or hash routing.
- [ ] Applicable shared quality gates in `prd.json` pass, and the evidence handoff records exact commands/results, changed files, limitations, and dependency handoff.

## Shared quality gates

- Targeted deterministic tests pass; Python changes also pass `python -m compileall packages tests`.
- `git diff --check` passes.
- Default tests are model-download-free, API-credit-free, and GPU-free.
- Evidence README records exact changed files, commands/results, limitations, and dependency handoff; no fabricated evidence or inherited completion credit.
- Native changes pass focused out-of-tree CMake build and CTest; patch changes verify clean apply/check/reverse against the exact llama.cpp pin.
- Runs are opt-in and record exact artifact/split hashes, runtime/upstream pin, backend/driver, hardware, network, commands, and raw metrics. Model artifacts use configured mounted-drive storage and never `/home`.
- Preserve existing Transformers behavior and backend-agnostic Tracker routing/load balancing/billing/relay semantics unless an explicit versioned contract says otherwise. One scoped story commit is expected during execution, but this specification-materialization change is not committed.

## Evidence handoff

Write and verify `.scratch/distributed-gguf-runtime/evidence/DGR-051/README.md`. Until every criterion and applicable gate has real evidence, this story remains `passes: false`. Legacy evidence is provenance only, not completion credit.
