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Technical page · Models

Evaluation in CI and production

Regression gates, canaries, drift and rollback

Published
8 November 2026
Last reviewed
8 November 2026
Re-checked every
180 days
Reviewed by
Ales Analytics engineering

In one paragraph

Evaluation does not stop at launch. In continuous integration, every change to a prompt, model, adapter or retrieval setting runs the frozen test set, and a regression beyond an agreed threshold blocks the release. In production, new versions run in shadow and then on a small share of traffic, drift signals are watched, a sample of outputs is reviewed by people, and rollback is a configuration change.

How it works

  • Regression gates. Thresholds per metric and per segment (document type, field, question type), not only an overall score.
  • Shadow releases. The candidate receives real traffic and logs outputs without serving them; outputs are compared with the live version.
  • Canary releases. The candidate serves a small share of traffic, widened as metrics hold.
  • Drift signals. Changes in input mix, confidence distributions and review-queue volume, which usually move before accuracy visibly drops.
  • Sampled review. A fixed weekly sample reviewed by people; disagreements are added to the test set as a new version.
  • Rollback. The previous model, adapter, prompt and index stay deployable.
Figure 1. From change to release, with rollback.
Figure 1. From change to release, with rollback.

Design choices and trade-offs

ChoiceTrade-off
Strict vs loose thresholdsStrict thresholds block noise as well as regressions; thresholds are set from the confidence intervals of the test set
Shadow traffic with contentBest comparison; must follow the same retention rules as production logs

When not to use it

A system that never changes would not need it, but models, documents and rules all change.

How we evaluate it

By drills: deliberately ship a degraded candidate to a staging environment and confirm the gate blocks it.

Sources

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