pkg/miner: pluggable inference-engine backend interface (closes 3 TODOs)

[abhicris]

Closes #1.

Summary

Replaces three // TODO: Integrate with actual ... stubs in pkg/miner/miner.go with a small pluggable backend interface. The miner's runInference, runChat, and runEmbedding now dispatch through backend.InferenceBackend instead of inlining placeholder output.

Two reference backends ship in-tree:

Package	Name	Purpose
pkg/miner/backend/noop	noop	Deterministic mock, byte-for-byte identical to the pre-refactor inline stubs. Default. Zero config.
pkg/miner/backend/openai	openai	OpenAI-compatible HTTP adapter built on net/http. Covers llama.cpp, vllm, ollama, LocalAI, and api.openai.com via OPENAI_API_BASE.

No new go.mod dependencies.

Why one OpenAI-compatible adapter instead of direct bindings

llama.cpp bindings pull in ~20 MB of C source. vllm is Python-only. MLX bindings require CGo. But all of them — plus ollama and LocalAI — expose an OpenAI-compatible /v1/chat/completions + /v1/embeddings surface. One small Go adapter covers every engine an operator would realistically run, and the interface still lets someone add a direct-binding backend in a follow-up PR if latency-sensitive deployments need it.

Config changes

miner.Config gains five optional fields:

• Backend string — "noop" (default) or "openai"
• OpenAIBase string — e.g. http://localhost:11434/v1 (ollama), http://localhost:8080/v1 (llama.cpp)
• OpenAIAPIKey string — bearer token, empty is fine for local engines
• OpenAIModel string — default model name
• OpenAIEmbeddingModel string — optional override for embed tasks

Unknown Backend values fall back to noop so operator typos don't crash-loop the miner.

Sibling change: GPUStatsProvider hook

Adds a GPUStatsProvider hook on Miner:

m.SetGPUStatsProvider(func() (util float64, mem uint64) { ... })

GetStats merges its output into the returned Stats. Default is nil = no-op, matching current behaviour. A follow-up PR will wire a real NVML/MLX provider; this leaves the seam in place without pulling heavy bindings into the main binary.

Compatibility

• Existing miner_test.go passes unchanged.
• DefaultConfig() keeps producing a noop miner — zero behaviour change for current callers.
• No go.mod churn.

Files

New:

• pkg/miner/backend/backend.go — interface + request/response types
• pkg/miner/backend/backend_test.go — interface contract tests
• pkg/miner/backend/noop/noop.go + noop_test.go — deterministic mock
• pkg/miner/backend/openai/openai.go + openai_test.go — HTTP adapter (httptest-mocked tests)
• pkg/miner/backend/README.md — operator-facing doc with engine pointer commands

Modified:

• pkg/miner/miner.go — backend wiring, Config extensions, GPU hook
• pkg/miner/miner_test.go — added 7 tests for new wiring; existing 10 unchanged

Test output

ok  github.com/luxfi/ai/pkg/miner                   0.522s (17 tests)
ok  github.com/luxfi/ai/pkg/miner/backend           0.185s (3 tests)
ok  github.com/luxfi/ai/pkg/miner/backend/noop      0.336s (5 tests)
ok  github.com/luxfi/ai/pkg/miner/backend/openai    0.508s (10 tests)

Full-repo go build ./..., go vet ./..., and go test ./... all green.

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Contributed by kcolbchain (https://kcolbchain.com) · https://abhishekkrishna.com