Cookies and storage

The Shuttlebase snippet uses a small, fixed set of cookies and browser storage keys. This page lists all of them and explains what happens when a browser blocks storage.

Cookies

The snippet sets these cookies for normal visitors. Its policy permits no others.

All cookies are set client-side via document.cookie. They are first-party, scoped to domain= the registrable domain (eTLD+1, so shared across subdomains, with a host-only fallback when the browser rejects the domain write), path=/, SameSite=Lax, and Secure on HTTPS.

Cookie	Purpose	Lifetime
msai_user_id	Anonymous visitor UUID. Identifies a returning visitor without any personal data.	365 days
msai_bucketed_experiments	Map of experiment to variant assignments. Keeps a visitor in the same variant across visits.	365 days
msai_should_track	Cached consent decision, so the snippet does not re-query your consent tool on every page. Holds true or false, where true means tracking is allowed.	180 days
msai_uj	Experiment-level state plus a summary of the visitor’s journey across the site.	365 days

localStorage

Key	Purpose	Lifetime
msai_user_id	Mirror of the user ID cookie.	No expiry — persists until the visitor clears site data
msai_bucketed_experiments	Mirror of the assignment cookie.	No expiry — persists until the visitor clears site data
msai_analytics_session_count	Lifetime session and event counters.	No expiry — persists until the visitor clears site data
msai_uj	Full journey record; the cookie holds a summary only.	No expiry — persists until the visitor clears site data
msai_dq	Queue of events pending send, for batching to reduce network traffic.	No expiry — persists until the visitor clears site data

sessionStorage

Key	Purpose	Lifetime
msai_analytics_session	Current session record, including UTM parameters and referrer.	Tab session
msai_session_event_count	Event counter for the current session.	Tab session

What consent revocation clears

When a visitor revokes consent, the snippet clears msai_bucketed_experiments, msai_user_id, msai_analytics_session, and msai_analytics_session_count from cookies, localStorage, and sessionStorage. msai_should_track is deliberately preserved, since it is the record of the refusal.

When consent is later granted, the page reloads so the snippet can start tracking with a clean slate.

QA and developer tooling

These keys exist only for preview, QA, and developer testing. Normal visitors never receive them.

Key	Type	Purpose
msai_deployed_only	Cookie or sessionStorage	Overrides the snippet to show deployed winners without running experiments.
msai_preview_bucketing	sessionStorage	State for preview-mode bucketing.
msai_opt_out	sessionStorage	Session-scoped tracking opt-out for QA.
msai_preview_experiments_cache	localStorage	Cache of preview experiment config. Written by writePreviewExperimentsCache().