# Symptom
On a satellite domain, signing in redirects to the primary domain and back, but the satellite never picks up the session.
# Confirm the cause
1. Sign-in and sign-up MUST be hosted on the primary domain. If the satellite has its own sign-in pages, the flow is misconfigured.
2. After returning from the primary domain, the satellite needs the sync trigger. With satelliteAutoSync false (the default), your satellite's sign-in links must use the SDK's buildSignInUrl() and buildSignUpUrl() methods, which append the sync parameter automatically. Hardcoded sign-in URLs skip the sync and cause this loop.
3. Check the satellite domain is registered in the dashboard under Domains > Satellites.
# Fix
- Replace hardcoded sign-in/sign-up links on the satellite with buildSignInUrl() and buildSignUpUrl().
- If you prefer automatic sync, setting satelliteAutoSync to true redirects every first visit to the primary domain; it costs one redirect per new visitor.
# Verify
Sign in on the primary domain, then load the satellite in the same browser. The session appears without a second sign-in, and signing out on either domain signs out on both.