Question 1

Will a TypeSafe outage take down my service?

Accepted Answer

No, fail-open by design. Any API error, timeout or malformed response is treated as not a failure and scores 0.0, so a Jev outage cannot trip your circuit breaker or interrupt request processing. The evaluation is one non-blocking WebClient call with a 750ms default timeout, composed into the returned Mono or Flux with flatMap, adding no threads.

Question 2

Is this just Resilience4j with extra steps?

Accepted Answer

Different job. Standard circuit breakers only see transport-level failures such as 5xx, timeouts and connection errors, and miss silent failures: HTTP 200 responses whose body encodes an error, a stack trace or a maintenance notice. This catches those, and SemanticFailureException is a plain RuntimeException you can add to a Resilience4j CircuitBreaker's recordExceptions to count toward the failure rate.

Question 3

How much latency does it add to every reactive call?

Accepted Answer

One evaluation per emitted item. Annotate a method returning Mono or Flux with @SemanticCircuitBreaker(confidenceThreshold = 0.85); each item is serialized and submitted as a single Noul question asking whether the payload is a silent failure, maintenance window or error state disguised as success. Above the threshold the item is replaced with Mono.error, otherwise it passes through unchanged.

Question 4

Can I test it without spending a real key?

Accepted Answer

Yes. JevEvaluationServiceMockWebServerTest runs offline against a local MockWebServer and asserts the path, Authorization header and JSON body of the POST /v1/systemone request, plus the fail-open behaviour on a 5xx. JevEvaluationServiceRealApiIT is opt-in and only runs when TYPESAFE_API_KEY is set, so it is skipped in a normal build.

Question 5

How do I add this starter to a project?

Accepted Answer

Add the JitPack repository and the dependency `com.github.vicente-md:jev-resilience:0.1.1` to pom.xml. Java 17+ and Spring Boot 3.x are required, and the consuming application must provide spring-boot-starter-webflux.

Question 6

How do I configure the API key and endpoint?

Accepted Answer

Set `typesafe.jev.api-key`, with TYPESAFE_API_KEY as the usual source, and optionally base-url and model, which default to https://api.typesafe.ai and jev-latest. Auto-configuration activates once the api-key is set; configure only the raw key because the starter adds the Bearer prefix.

Question 7

How do I apply the semantic circuit breaker to a method?

Accepted Answer

Annotate any WebFlux service method returning Mono or Flux with `@SemanticCircuitBreaker(confidenceThreshold = 0.85)`. When Jev's confidence that a response is a disguised failure exceeds the threshold, the pipeline emits a SemanticFailureException instead of the original item.

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