NOT AVAILABLE: Bumble retired the API these routes speak. Its endpoint answers every call, the anonymous handshake included, with 'Session not found (0030-3001-0051)', and the Bumble app does not use that endpoint at all: it speaks a binary protocol over a TLS socket to bma.bumble.com:443. No credentials get through until that transport is built, so these calls answer 502 instead of pretending to sign in. Open a Bumble session with the account's own credentials. Returns an opaque session id to carry in the x-session-id header on the session routes. The portal's own session is the only thing kept, sealed at rest; the password is not stored and cannot be read back out of the session. Bumble has no password: call POST /v1/bumble/challenge first, then send the phone number (or e-mail) as `username`, the code that arrived as `password`, and the challenge's `login_token` alongside them.