@testa-soft/experiment-core

The host-neutral decision core for Testa experiments. Given a project config and a request context, it decides which variation a visitor gets — deterministic bucketing, sticky assignment via a packed cookie, split-URL redirect resolution, targeting/exclusion evaluation, and cross-domain assignment transfer. It touches no framework and no DOM, so it runs identically in the Edge Runtime, Node, and the browser.

You usually don't install this directly. It's the shared engine behind the framework integrations — @testa-soft/next and the client SDK. Install one of those instead; this comes along as a dependency. It's published so the integrations can share one implementation (no duplicated bucketing logic → a visitor buckets identically everywhere).

What's inside

• Deterministic bucketing — assign(), bucketOf(), pickByWeight() (xxhash32 of visitorId:experimentId, mod 100; no Math.random() → no sample-ratio mismatch).
• Sticky assignment — one packed _testa_exp cookie (parsePacked/serializePacked), read cookie-first so a returning visitor never re-rolls.
• Split-URL redirects — decideRedirect / resolveRedirectDestination / buildRedirectUrl with exact/contains/regex/query match modes + matchesForMode.
• Targeting & exclusions — passesTargeting (AND) / isExcludedByRules (OR) over UTM, url, cookie, device, and geo dimensions.
• Cross-domain — encodeCrossDomainData / decodeCrossDomain to carry an assignment across domains.
• CookieStore — the tiny read/write cookie interface each host adapter implements.

Install

npm install @testa-soft/experiment-core

Ships ESM + CJS + types. No runtime dependencies.

License

UNLICENSED — © testa-soft.