Question 1

What does this add over calling Jev and branching myself?

Accepted Answer

Versioning, ordering and an audit trail. Deterministic preconditions run before the provider, ordered YAML rules turn normalized signals into a decision, and every result carries the matched rule, the signals and fallback metadata. Policy changes get a deterministic offline diff with rules matched by ID and reordering reported separately, plus shadow mode to compare candidates on live traffic.

Question 2

What happens if Jev is down or answers something malformed?

Accepted Answer

It cannot quietly become an allow. Provider timeouts, invalid responses and other provider failures map only to explicit fallbacks the policy declares; in the bundled support-routing example, provider_error, provider_timeout, invalid_provider_response and no_match all resolve to human_review.

Question 3

Can I replay past decisions without spending more money?

Accepted Answer

Yes, as long as the record holds the signals. Successful provider evaluations are stored with question-fingerprinted normalized signals, and jevpolicy replay re-runs the policy logic from those without touching the provider. Records that ended on a terminating precondition or a fallback can be missing signals, and cannot be replayed against policies that require them.

Question 4

Is it safe in front of real traffic?

Accepted Answer

It depends on your logging choices. Raw state recording defaults to none and full or redacted recording must be opted into, with redacted requiring a programmatic hook, and decision logs can hold sensitive facts, signals and state. Only the active envelope should drive side effects; shadow envelopes are recorded but not acted on, and observer failures are isolated so telemetry cannot change a decision.

Question 5

How do I install it and validate a policy?

Accepted Answer

It needs Node.js 22.18 or later; install with npm install @sanoy24/jevpolicy. The bundled CLI validates without a key: npx jevpolicy validate ./policy.yaml. Comparing a released policy with a candidate is npx jevpolicy diff a.yaml b.yaml, which reports added, removed, changed, and reordered elements matched by ID.

Question 6

What happens when a question is not asked because a precondition stopped it?

Accepted Answer

Deterministic preconditions run before any provider call. A record created by a terminating precondition or a provider fallback may not contain the complete signal set, so it cannot be replayed against a policy that requires those signals. Provider failures map only to explicit policy fallbacks and never silently become an allow.

Question 7

What gets recorded, and what should I keep out of it?

Accepted Answer

Raw state recording defaults to none; a policy can opt into full or, when the runtime supplies a redaction hook, redacted recording. Records contain declared deterministic facts, and successful evaluations add question-fingerprinted normalized signals so replay works without the provider. Do not put credentials or secrets in declared facts, and keep decision logs out of version control.

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