# 03 — Define exact Artifact and runtime recipe identity

Status: ready-for-agent

## Mandatory fresh-session context

- Read [RALPH-CONTEXT.md](../RALPH-CONTEXT.md) completely before changing code.
- This issue is `DGR-003` 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 the Tracker, I need exact compatibility identity so that only numerically and operationally compatible Shards form an Inference Route.

## Expected durable outputs

- Exact runtime recipe/fingerprint implementation
- Tracker/node fail-closed admission tests
- evidence/DGR-003/README.md

## Acceptance criteria

- [x] Separate weight quantization, activation dtype, compute dtype, KV dtype/layout, tokenizer revision, architecture adapter, backend, and runtime version.
- [x] Bind derivative or split artifacts to an exact source Model Artifact hash and Shard range.
- [ ] Produce a stable compatibility fingerprint used by live capability emission/admission and the gRPC handshake. The tracker parses, re-derives, admits, partitions, and certifies supplied exact identities, but the current production doctor/backend path does not yet derive one from authoritative loaded-artifact/runtime state. It must stay dark rather than be claimed complete.
- [x] Fail closed on mismatched artifact, tokenizer, architecture, range, boundary schema, activation recipe, or cache layout.
- [x] Keep unsupported recipes registered-but-dark until a real distributed forward certifies them.
- [x] Targeted pytest tests pass
- [x] python -m compileall packages tests passes for Python changes
- [x] git diff --check passes
- [x] Default tests remain deterministic, model-download-free, API-credit-free, and GPU-free
- [x] Full deterministic pytest -q passes, or the exact pre-existing unrelated failure is recorded with a clean-tree reproduction
- [x] Read .scratch/distributed-gguf-runtime/RALPH-CONTEXT.md and this story issue completely before changing code
- [x] Read and verify every dependency evidence README before relying on dependency behavior
- [x] Preserve all pre-existing working-tree changes and stage only files belonging to this story
- [x] Write .scratch/distributed-gguf-runtime/evidence/DGR-003/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-002` and `DGR-017` 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)