initialize app Firebase configuration multiple apps emulator connection App Check initialization environment configuration project aliases Firebase CLI local emulator suite deployment targets

email password signup email password signin signout auth state listener Google provider password reset email verification custom claims ID token auth emulator

collection reference document reference add document set document update document delete document get document get collection where query orderBy query

limit query cursor pagination composite indexes transaction batched writes realtime listener server timestamp arrayUnion increment offline persistence

authenticated rule owner rule field validation rule role claim rule query-aware rule Storage rule rule helper function emulator rule test deny by default rule version

upload file download URL upload progress delete file storage metadata Realtime Database set Realtime Database update Realtime Database push Realtime Database listener Realtime Database transaction

callable function HTTP function Firestore trigger Auth trigger scheduled function secret parameter FCM token send notification topic messaging function emulator

hosting rewrite hosting redirect cache headers Remote Config Analytics event Crashlytics concept Performance Monitoring concept deployment preview channel Firebase deploy production checklist