- session store + requireSession middleware (signup persists session) - PairingService (8-char code, 5-min TTL, 5-attempt lockout, single-use, https check) - POST /sites/pair, /sites/redeem, /sites/:id/confirm, GET /sites/:id - PluginClient signs HMAC (timestamp+method+path+body-hash), token in Authorization - ADR 0016; 58 api tests green
