Question 1

Which decision models can SystemOneClient talk to?

Accepted Answer

TypeSafe Jev is the default provider, alongside Cloudflare Clef, OpenRouter's decisions endpoint, and any self-hosted server speaking the /v1/systemone wire format; the CLM project is the self-hosted example named in the README.

Question 2

How do I test code that calls SystemOneClient?

Accepted Answer

Configure client: SystemOneClient.Stub in your test config and pass an answers map of structs or raw API maps, or for HTTP-level tests pass a Req.Test plug. Either way no network access is needed, and network conditions return tagged error tuples rather than raising.

Question 3

How do I add SystemOneClient to an Elixir project and call it?

Accepted Answer

Add {:system_one_client, "~> 0.1"} to deps. There is one behaviour, SystemOneClient.evaluate(state, questions, opts), returning {:ok, answers, meta}, where meta carries model, usage, latency_ms and provider. Answers are typed structs: a Choice gives %Answer.Choice{choice:, confidence:, probabilities:}, a Noul gives %Answer.Noul{noul:}, and a Score gives %Answer.Score{score:, probabilities:, confidence:, legend:}.

Question 4

Do I have to learn a new schema for the questions I send?

Accepted Answer

No. Question maps are the API wire format verbatim and the library adds no schema of its own, so noul, choice and score maps go straight through. The library adds no options helper and no option validation beyond what the API documents, so the primitives docs remain the reference for how each question is shaped.

Question 5

How are retries, timeouts and provider overrides configured?

Accepted Answer

Retries cover 429, 529, 502, 503, 504 and transport errors, honouring Retry-After or retry-after-ms when present over the 250 ms base backoff. Defaults are receive_timeout of 2,000 ms per attempt and max_retries of 2. Explicit url: and model: always win over provider defaults, provider defaults to :typesafe on jev-latest, and network conditions never raise: they come back as tagged error tuples.

Question 6

What does an error look like, and what does telemetry expose?

Accepted Answer

Configuration problems give {:error, :missing_api_key}, :missing_account_id, :missing_url or {:unknown_provider, p}; bad questions give {:invalid_question, id, reason}; the call gives {:http, status, body} or {:transport, reason}; and the response gives {:malformed_answers, reason} or {:provider_error, errors}. Telemetry is [:system_one_client, :request, :start | :stop | :exception], carrying provider, model, question_count and, on stop, status, latency_ms and error. State, question text, bodies and keys are never included.

Question 7

How mature is this library, and where did it come from?

Accepted Answer

It depends only on req, jason and telemetry, and is Apache 2.0 licensed. It was extracted from an experiment that used Jev as a tool and model router inside a Jido AI agent; that experiment, its benchmarks and the transformer that consumes this client live on the schainks/jido repository on the experiment/jev-tool-routing branch, so treat the client as a small, early-stage library and pin the version. mix test runs the suite, or ./run.sh test does the same inside the hexpm/elixir:1.20.4 image.

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