A/B experiments — `get_experiment` + `track`

After configure(), an experiment is end-to-end through the bound shipeasy.Client(user) — read the assignment, log exposure, and track the conversion, all on the same handle, with no user argument.

Reading an experiment

get_experiment returns an ExperimentResult with three fields:

• in_experiment (bool) — is the user enrolled?
• group (str | None) — the assigned variation group.
• params (dict) — the variation parameters (falls back to default_params when the user isn't enrolled or no params are set).

# construct once per callsite (cheap; binds the user)
client = shipeasy.Client(current_user)

result = client.get_experiment("checkout_button", default_params={"color": "blue"})
print(result.in_experiment, result.group, result.params)

Pass decode= to project params into a typed shape (applied only when the user is enrolled; failures fall back to default_params).

Logging exposure — log_exposure

The server is stateless and never auto-logs exposure. Call log_exposure at the point you actually present the treatment (parity with the browser's auto-exposure). The bound Client derives the user from the same bound attributes you read the experiment with — no user argument:

result = client.get_experiment("checkout_button", default_params={"color": "blue"})
client.log_exposure("checkout_button")   # at the decision point

It re-evaluates and, if the bound user is enrolled, POSTs a single exposure event; otherwise it's a no-op (also a no-op under configure_for_testing / configure_for_offline).

Tracking conversion events — track

Record a conversion/metric event for the experiment's success metric on the same bound Client, deriving the unit from the bound attributes (user_id else anonymous_id):

client.track("{{SUCCESS_EVENT}}", {"amount": 49})

• event_name — your success-metric event, e.g. {{SUCCESS_EVENT}}.
• properties — optional event payload (any private attributes you configured are stripped before the event leaves the process).

track() is fire-and-forget and a no-op in test/offline mode. If the bound attributes carry no user_id or anonymous_id, the call is a no-op.