The protocol

Where a moeba is

A moeba is a URIToken on Xahau issued by one account, the species: rMmx5nHzoVJAoMTFWkgCCMrZryTaD682tr on Xahau testnet. A URIToken from any other issuer is not a moeba, whatever its URI says; that check comes before any other. Three places hold everything:

• The URI — the identity: model, kind, generation, birth ledger, fertility, rules version, maturity deadline, serial, commitment. Fifty-two bytes, immutable by construction, because a URIToken's id is derived from its issuer and its URI together.
• The Remarks — six named records, three immutable (birth, audit, rules) and three the issuer rewrites at a keeper's signed request (use, terms, name). Only the issuer can write a Remark on its own token, so each record is a statement by the species.
• Hook state on the species account — the birth queue and the counters. Live, not part of any creature; read it through account_namespace or the API.

One genetic model has ever been minted on chain: v0.1-32-deep, model byte 1. The URI reserves a byte for the model so a wider genome can be added later without touching a creature that exists; a reader that meets a model byte it does not know should say so rather than guess. Everything below describes v0.1-32-deep.

Numbers are big-endian throughout. Hex is upper-case where the ledger shows it; base64url is the RFC 4648 §5 alphabet, no padding, and a decoder must reject a string that does not re-encode to itself.

The identity URI

urn:creature:birth:2: followed by 52 bytes as base64url: 91 characters in all. A URIToken's URI is stored as hex on the ledger; decode the hex to ASCII first.

The token id is Xahau's URIToken keylet — a SHA-512-half over the ledger-space prefix, the issuer's AccountID and the URI bytes — so the id is fixed the moment the URI is, and the species can retry a failed mint without producing a second token.

The records

Six Remarks by name. Each value begins with a version byte; a reader that meets a version it does not know reports it as unknown rather than parsing on assumption. Values are at most 256 bytes. The three immutable records and the URI are covered by the token's Digest.

The Digest. SHA-512-half( "KIN/digest/1\0" ‖ len(uri) ‖ uri ‖ len(birth) ‖ birth ‖ len(audit) ‖ audit ‖ len(rules) ‖ rules ), each length a u32, the URI as ASCII. It is fixed before the mint, so it cannot name the mint transaction; what it commits to is the identity and the three immutable records in one fixed order.

The genome

Thirty-two bytes: two haplotypes of 16 bytes, the first from parent P, the second from parent Q. Within a haplotype the 36 loci are packed at the bit offsets below, MSB-first — bit 0 of the haplotype is the top bit of its first byte — using 128 of 128 bits. A locus's value on haplotype h is the bits-wide unsigned integer at h × 128 + offset.14 loci are discrete and choose an allele from a table; the rest are quantitative and add up into 22 traits.

A reserved allele index is invalid: a genome that carries one is malformed, and no birth produces one. Mutation-only alleles have founder weight 0 and appear only through the mutation pathways at birth.

Expression

What the two copies come to, per locus. This is all a reader needs to name a moeba and list its traits; the body that is drawn from the traits is presentation and may change, the traits do not.

• Discrete. Read the allele index on each haplotype. If they are equal, that allele shows. If not, the one with the higher dominance rank in the table shows; the other is carried and can be inherited.
• Quantitative. For each trait, over the loci that feed it: sum = Σ (a + b + ⌊|a − b| · k / 256⌋), max = Σ 2 · (2^bits − 1), and the trait is ⌊sum · 255 / max⌋, an integer 0–255. k is the trait's dominance deviation from the spec, 0 for every trait in v0.1-32-deep, so it is purely additive.
• The name. The taxon is a Latin binomial fixed by four discrete loci — BODY_PLAN, APPENDAGE_FAMILY, SYMMETRY and PATTERN_FAMILY — with a fixed table of genus and epithet stems; the variant is the words for PIGMENT_CLASS and MOVEMENT_FAMILY; the fingerprint is a 32-bit FNV-1a over the 32 genome bytes, folded to 20 bits ((h ^ h >>> 20) & 0xFFFFF) and written as four Crockford base32 characters, so two moebas of one taxon still differ. The API returns all of it, so a reader need not carry the stem tables.

Asking the species

Every request except the poke is an XAH Payment to the species account with hook parameters: one-letter names (as hex: F is 46, P is 50) and values as below. The species' Hooks read them and nothing else; memos and destination tags mean nothing to it. No partial payments, no SendMax, no paths: the amount must be the amount delivered.

The amounts are quoted from the ledger at the moment of the request and refused below the quote; an overpayment is kept as budget. The protocol fee for a birth, the founder curve and the name fee are Hook parameters on the species account and are read for you at /v1/issuer (birthFeeDrops, founderCurve, nameFeeDrops, tickDrops). The budget a birth carries is 16 × tickDrops for the clock plus 37 emitted transactions at the network's emission price; what a birth does not spend stays with the species. The founder price is FFEE × (FMUL/100)^⌊n/FTRN⌋ with n the founders admitted so far, all from founderCurve. The site's own arithmetic for this is in its request pages; a wallet can copy it or over-quote slightly.

A request is accepted when the Payment succeeds and the species' Hooks return accept; a refusal is a tecHOOK_REJECTED with the reason in the Hook execution's return string, in plain words. After admission nothing more is signed: the species' own clock fixes the randomness, breeds, mints and delivers by Remit. A receiving account with lsfDisallowIncomingRemit set is refused at admission, since the child could never land.

The API

Everything above is what the ledger says; the API says the same in words and pictures, from an index that re-reads the ledger every few seconds. It is read-only, allows any origin, and every JSON answer carries headLedger so you know what ledger you are looking at. This deployment's is at https://api.xahmoeba.com.

Each client has a budget — a few hundred requests a minute, a fresh picture costing several — and gets 429 with Retry-After over it. Pictures and the population are cacheable; please cache them. A marketplace that shows moebas needs only metadata.json and the picture, and can verify either against the ledger with this page.

Try it on a real one

Choose a moeba, or paste a token id. Its URI is decoded byte by byte on this device by the rules above, the genome is unpacked locus by locus, and each API link opens what the index says about it.

If this page and the ledger disagree, the ledger is right and this page has a fault. Tell us.