olivere/systemone is a standard-library-only Go package for Jev and compatible decision backends. Its useful contribution is the application boundary: define questions once, validate returned answers, and compare a replacement without making it the production decision-maker.

I inspected the client, Jev adapter, response validator and shadow worker implementation. go test -race ./... and go vet ./... passed locally. These are offline tests with scripted backends and local HTTP servers—not a reproduction of live Jev accuracy, latency or calibration, and not a security audit.

Types with checks behind them

  • Question handles connect each request to its typed result; an unrelated handle with the same text key cannot retrieve that answer.
  • Choice results must cover the offered options, sum to one within tolerance, and select a highest-probability option.
  • Score results must agree with the probability-weighted, zero-based level; malformed responses are rejected rather than silently normalized.
  • Probability provenance distinguishes native model output from estimates; neither label establishes calibration.

Typed output is not a correct decision. These checks catch protocol mistakes, not mistaken judgments or unjustified confidence.

Compare before switching

The shadow wrapper returns a valid primary answer without waiting for the candidate. A bounded worker pool evaluates the same request in the background and reports both distributions, including unchanged labels and candidate failures.

  • Candidate work has its own timeout and follows the application lifetime rather than the caller’s request deadline.
  • Saturation drops comparisons instead of growing an unbounded queue; the drop counter matters when interpreting the sample.
  • Shutdown cancels comparisons, but backends and reporting callbacks must cooperate or shutdown can still stall.

Operational limits are explicit

The Jev adapter disables redirects, bounds response size, and performs no automatic retries or fallback. Optional HTTP debugging redacts sensitive headers but not bodies—customer data can enter logs.

The inspected revision requires Go 1.27.2, which the Go command downloaded for this check. The repository does not claim measured live calibration or confirmed compatibility with every OpenJev server. Pin a model version, collect representative labels, and test thresholds before allowing a probability to authorize an action.