neuron-tai/.scratch/distributed-gguf-runtime/issues/08-build-the-standalone-c-grpc-shard-worker.md

08 — Build the standalone C++ gRPC Shard worker

Status: ready-for-agent

Mandatory fresh-session context

• Read RALPH-CONTEXT.md completely before changing code.
• This issue is DGR-008 in 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 node runtime, I need one supervised native process so that llama.cpp internals remain behind a stable project-owned protocol.

Expected durable outputs

• Standalone C++ gRPC worker
• Fake-model Python/C++ integration tests
• Lifecycle and bounded-failure evidence
• evidence/DGR-008/README.md

Acceptance criteria

• Worker exposes capability, health, session stream, release, cancellation, and metrics services from DGR-002.
• Worker loads one exact Artifact/recipe/Shard identity and refuses mismatched requests.
• Streaming path enforces bounded messages, flow control, deadlines, idempotency, and independent session cancellation.
• Worker does not expose raw llama.cpp RPC or arbitrary GGML graph execution.
• Graceful shutdown releases sessions; crash behavior is bounded and observable.
• Python integration tests run against a fake model mode without model downloads.
• 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-008/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 must have passes: true; read ../evidence/DGR-002/README.md and verify its referenced files/commands.
• DGR-003 must have passes: true; read ../evidence/DGR-003/README.md and verify its referenced files/commands.
• DGR-004 must have passes: true; read ../evidence/DGR-004/README.md and verify its referenced files/commands.
• DGR-006 must have passes: true; read ../evidence/DGR-006/README.md and verify its referenced files/commands.
• DGR-007 must have passes: true; read ../evidence/DGR-007/README.md and verify its 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
• PRD
• Implementation strategy
• Current architecture
• Architecture decision