jevkit-drift

TypeSafe's docs warn that jev-latest moves when a new version ships, and that confidence thresholds tuned against one version do not automatically hold on the next. jevkit-drift answers the question that warning implies: for the requests you actually care about, what changed?

Unofficial and unaffiliated with TypeSafe.

npm install jevkit-drift

Two kinds of change

A flip is a changed decision. Your code takes a different branch. This is what breaks things.

A shift is movement in the probability distribution with the same decision still on top. Harmless on its own, but it is what walks an answer toward a threshold, so a large shift is an early warning before anything has flipped.

Both are reported separately, because conflating them is how a drift report ends up either too noisy to read or too quiet to help.

Use

import { readRecords, writeRecords } from "jevkit-core";
import { compareSets, replay } from "jevkit-drift";

const baseline = readRecords("golden.jevl");
const candidate = await replay(baseline, (s, q) =>
  client.systemOne(s, q, { model: "jev-1.14.0" }),
);
writeRecords("candidate.jevl", candidate);

const report = compareSets(baseline, candidate);
console.log(report.summary());

for (const [requestId, delta] of report.flips) {
  console.log(requestId, delta.describe());
}

CLI

npx jevkit-drift golden.jevl candidate.jevl
npx jevkit-drift golden.jevl candidate.jevl --max-flips 3
npx jevkit-drift golden.jevl candidate.jevl --max-shift 0.15
npx jevkit-drift golden.jevl candidate.jevl --format json

Exit codes: 0 within tolerance, 1 drifted, 2 bad usage.

How records are paired

On request_id, the digest of state plus questions with the model deliberately excluded. That is the whole reason the record format keeps two digests: the full id changes when the model changes, so it cannot pair a baseline with its replay, while request_id can.

Change the state or a question and the records stop pairing, which is correct. They are no longer the same request, and comparing them would be meaningless. The CLI says so rather than reporting zero drift.

License

MIT