<!-- GENERATED FROM prd.json — DO NOT EDIT AS AN INDEPENDENT SOURCE. prd.json IS AUTHORITATIVE. -->
# DGR-067: Certify the backend capability matrix

- **Status / triage:** specification only; `ready-for-human`; `passes: false`
- **Execution mode:** `HITL`
- **Milestone:** `M4`
- **Dependencies:** `DGR-030`, `DGR-053`, `DGR-062`, `DGR-066`
- **Blocks (derived):** `DGR-068`, `DGR-070`
- **Labels:** `area:hardware`, `area:admission`, `type:certification`, `priority:p1`, `gate:hitl`, `ready-for-human`
- **Evidence class:** `real-hardware`
- **Hardware:** `required`
- **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/067-certify-the-backend-capability-matrix.md`, and evidence READMEs for dependencies (DGR-030, DGR-053, DGR-062, DGR-066) before changing code. Inspect live source/tests rather than trusting legacy pass states. Objective: Publish only backend/model/recipe lanes proven on actual CPU, CUDA, ROCm, Vulkan, or Metal hardware.

## Acceptance criteria

- [ ] Maintain independent build and certification status for CPU, CUDA, ROCm, Vulkan, and Metal.
- [ ] Each advertised lane includes real hardware/driver/runtime/model evidence for parity, concurrency, cancellation, cleanup, and useful speed.
- [ ] Build success alone never makes a lane routable; unavailable hardware remains explicitly dark.
- [ ] Tracker admission consumes signed/versioned certification records rather than backend-name allowlists.
- [ ] Mixed-backend routes require exact compatibility evidence and fail closed otherwise.
- [ ] 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-067/README.md`. Until every criterion and applicable gate has real evidence, this story remains `passes: false`. Legacy evidence is provenance only, not completion credit.
