xego_check_pairwise_seen_before

com.x-ego/x-ego · Verify this server

Checks whether a given pairwise ID has already been seen within this audience. It protects against one person acting as several different users (multiple accounts, repeat voting, and similar). WHEN TO USE: returning-user checks and one-human-one-vote. Requires a pairwise_id previously obtained from a verify call for YOUR audience. Only the pair (audience, pairwise_id) and the time of first occurrence are recorded. No personal data. The ledger is PERMANENT and shared across every instance and session of the server (Postgres) — it survives restarts and new MCP sessions. record_if_new=true writes atomically (no window for a concurrent write). Args: - audience (string): the service domain or URL. Normalized to a bare lowercase hostname — the same key the proof was issued under, so a domain and its URL form are the same audience. - pairwise_id (string): the identifier from xego_verify_proof. - record_if_new (boolean): record the user if they are new. Returns (JSON): { "seen_before": boolean, // true = already on record "first_seen": number|null, // Unix time of first occurrence "recorded_now": boolean // true = recorded just now } Errors (free, no sybil check performed): invalid_audience (the audience cannot be normalized to a domain), dedup_store_unavailable (temporary — retry). Neither ever means 'not seen before'. PAID TOOL (x402): this call costs $0.01 USD in USDC per execution, unless you send a valid X-EGO pilot operator key as an 'Authorization: Bearer <key>' HTTP header (operator calls are free). Calling without payment returns an x402 error whose _meta["x402/error"] contains payment requirements (accepts) and step-by-step instructions how to pay and retry. Invalid input is rejected for free before any payment is taken.