# DGR-032: Implement deterministic fake `ShardEngine` - **Status / triage:** specification only; `ready-for-agent`; `passes: false` - **Execution mode:** `AFK` - **Milestone:** `M1` - **Dependencies:** `DGR-031` - **Blocks (derived):** `DGR-033` - **Labels:** `area:engine`, `area:testing`, `type:fixture`, `priority:p0`, `ready-for-agent` - **Evidence class:** `fixture` - **Hardware:** `none` - **Model:** `fake` - **Upstream:** `no` ## Objective / description Fresh Ralph session: read `.scratch/distributed-gguf-runtime/RALPH-CONTEXT.md`, source issue `.scratch/distributed-gguf-runtime/issues/032-implement-deterministic-fake-shardengine.md`, and evidence READMEs for dependencies (DGR-031) before changing code. Inspect live source/tests rather than trusting legacy pass states. Objective: Provide an engine fixture that deterministically transforms typed boundary bundles and session state. ## Acceptance criteria - [ ] Support head, middle, tail, prefill, decode, cancellation, and release with deterministic outputs. - [ ] Model isolated session/epoch state and deterministic cache-miss/stale-epoch failures. - [ ] Support configurable delay, memory pressure, malformed output, and crash injection. - [ ] Contract tests distinguish fixture evidence from real-model certification. - [ ] 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-032/README.md`. Until every criterion and applicable gate has real evidence, this story remains `passes: false`. Legacy evidence is provenance only, not completion credit.