Skip to content
yanox BUILD SHARED TRUST

Attestation Feed

The Attestation Feed (ADR-052) is an experimental starter: the observation ledger that ADR-046 §4.6 sequences last and that Yano ADR app-layer/014 lists as available today. It declares three collections on the stock governed authenticated-map state machine: feeds (unit, scale, round calendar, sources, quorum, outlier rule), observations (one per source and round, signed by the source’s own actor key), and round records (closed through an approval round with two publishers from distinct organizations). The aggregate is a pure function of the proven observations and the proven policy: it is not computed on chain, every verifier recomputes it and compares it with the record, and a disagreement is a flagged failure. It is not the oracle pipeline of ADR app-layer/012, nothing is published to Cardano, and it must not be pitched as a public price oracle.

The journey

Section titled “The journey”
  1. Define. yano-feed feed create writes the feed policy as a feed-admin: description, unit, scale, epochStart and roundSeconds, 1–16 sources, the quorum, the outlier tolerance, and the value bounds.
  2. Observe. Each source records its reading for a round with yano-feed observe (or the console’s Source view through the gateway): a signed integer at the feed’s scale and the source’s signed time, under <feed>/<round>/<source>, with PUT_IF_ABSENT.
  3. Close. A feed-operator proposes the round record computed at one height (round propose); two publishers from distinct organizations approve, each after recomputing the round at that height (the CLI and the gateway refuse an approval whose numbers they cannot reproduce); round apply submits the map command with the approval reference, applied once.
  4. Read and verify. yano-feed round get, the portal (/feeds/{id}/rounds/{n}), or the console: the policy, every source with its disposition (ACCEPTED, OUTLIER, ABSENT, FOREIGN_WRITER, EQUIVOCATED, WRONG_ROUND, OUT_OF_RANGE), the recomputed result beside the record, and the candidate datum. yano-feed verify checks a bundle offline at the ADR-047 trust levels.

What it proves

Section titled “What it proves”

A verified feed-round-v1 bundle says: at the closing height the policy was this and each configured source had exactly this observation or none; the feed-aggregation-v1 rule (the lower median after outlier and quorum rules, ADR app-layer/012 §8.4 reduced to one reporter per source) yields this result; the consortium recorded exactly that result at a later height through a proven approval consumption and never rewrote it; the roots were certified by the pinned members. It does not say that a reading is true, that sources are independent, that the closing height was fair (re-answer the round later and compare), or that anything reached Cardano.

Modules and setup

Section titled “Modules and setup”

products/attestation-feed/{profile,client,cli,ui,harness} on the Trust Registry’s map client and the DPP Starter’s approval-round patterns. The launcher feed.sh up | demo | portal | gateway starts a three-member chain, runs the cold-store temperature demo (three simulated sources with one outlier, a same-organization approval refused, the round closed, a NO_QUORUM round), and serves the portal on 8680 and the gateway on 8690. The full guide is docs/appchain/ATTESTATION_FEED.md.

Deferred

Section titled “Deferred”

The Cardano publication executor and thread-token UTxO model, the consumer validator, the aggregation composite component that would make admission and closure consensus rules, the L1-slot round clock, the round-jump circuit breaker, source-auth profiles and relays, and anchored verification across the bundle’s two heights (ADR-052 §8).