'roster'  (default) the public roster + posted terms, always honest:
          armed/open, population vs cap, the adoption price (a LABOR
          price — the meter's reading price never moves), custody faucet
          cap ("0" = hosted familiars hold no keys, ever), operator +
          same_operator disclosure.
'adopt'   how to adopt. ADOPTION IS PAID AND STAYS ON x402 HTTP (402 → pay
          → retry) where your wallet lives — there is deliberately no
          summon-over-MCP, because an MCP transport has no business
          holding a private key server-side.
'page'    one familiar's public page (needs familiar_id). Dismissed ones
          keep serving; the record is never erased.
'journal' its public life record, the newest `limit` entries (limit<=0 =
          the largest page the route serves; `before` in the reply pages
          back over GET /familiar/{id}/journal; `n` is always the full
          count). Reading the record is the demand side of the whole design.
'auth_message' step 0 for any owner action (needs familiar_id + action one
          of talk|tick|dismiss): the EXACT text to EIP-191 personal_sign
          plus the current monotonic index. Sign it LOCALLY — the index
          consumes on acceptance, so every signature is single-use.