@dif.sh/client

Tiny runtime SDK for dif.sh.

You almost never call this directly. The dif build step emits .dif/generated/client.ts which imports from this package and exposes one typed export per active experiment. You import the named export and call it at the render site:

import { checkoutCta } from "../.dif/generated/client";

function CheckoutButton() {
  return <button>{checkoutCta()}</button>;
}

Configure once, at app boot

import { configure } from "@dif.sh/client";

configure({
  userId: () => currentUser?.id ?? null,
  sink: { kind: "segment", analytics: window.analytics },
});

That's it. Exposure events fire on render, deduped per session per (experiment, user).

What this package does, what it doesn't

Does:

• Variant lookup, given a generated experiment spec.
• Deterministic SHA-256 bucketing — byte-compatible with dif-core (Rust).
• Audience predicate evaluation.
• Exclusion-group resolution.
• One exposure event per (experiment, user) per session, to a configurable sink.

Does not:

• Store events.
• Compute lift, p-values, or any analytics.
• Talk back to the CLI at runtime — the generated TS file is the entire contract.

See ../../PLAN.md for the architectural rationale.