open-standards/wai/extensions/state-feeds.md

WAI Extension: State-Feeds

Status: Draft. Phase 3 of the cargo roadmap. State as instructions: ship a signed op log of typed-field updates — a scoreboard, a telemetry stream, a market tape — not a recorded video of a dashboard. A state-feed is a non-physics world, so conformance is replay-equivalence, reused wholesale from interactive-worlds. Reference impl: the world feature of wai-rs (sim wai.world.sim.feed0); corpus: feed-conformance/; live sink: wai.transaction.science/feed. Keywords MUST, MUST NOT, SHOULD, MAY are RFC 2119/8174.

1. Scope and model

A wai.feed.state object is a non-physics world: the same WWLD container, op log, canonical ordering, causality, sealing, state hash, and receipt chain as interactive-worlds (see interactive-worlds.md), with one difference — the simulation step is the identity. Nothing is integrated; state changes only when a signed op applies a typed-field update. It is lever 3 (instructions-at-the-sink) for live state: a scoreboard update is a few signed bytes ("add 7 to field 1"), not a frame of a broadcast.

In scope: the record/cell model, the registered feed sim (wai.world.sim.feed0) and its mutation kinds, the broadcast profile, and the statement that conformance is exactly worlds' replay-equivalence.

Out of scope: everything interactive-worlds already defines (it is normative here unchanged); a transport; a schema language (a declared schema is an edge-level validation/labelling layer — the floor parses self-describing cells without one).

Relationship to the core spec: a registration under interactive-worlds, not a new container. media takes the value "feed"; the authoritative capability is wai.feed.state, carried in a WWLD whose contract names sim = wai.world.sim.feed0.

2. Records and cells

A node is a record: an ordered vector of self-describing typed cells. Canonical field order is index order (hence hash order). Three cell types cover scoreboards, telemetry, and market data:

tag	type	encoding	use
0x01	Int	i64 LE	scores, counts, volumes, enums, booleans
0x02	Fixed	i64 LE (Q32.32 Fx bits)	gauges, prices, percentages
0x03	Text	u16 len + UTF-8	names, ticker symbols, labels

A record body is n_cells u16 | cells…; each cell is tag u8 | payload. Cells being self-describing is deliberate: the canonical state bytes — and therefore the state hash — parse with no external schema, so the determinism contract has no schema dependency.

3. The feed sim — wai.world.sim.feed0

Registers these mutation kinds (a field-update kind carries a field_idx u16 prefix). The step is the identity.

kind	payload	resolution	effect
0x0001 CREATE	record body	LWW	insert; target MUST equal mint_node_id(actor, lamport)
0x0002 DELETE	(empty)	LWW	remove the node
0x0010 SET_CELL	field_idx u16 | cell	LWW	replace one cell
0x0011 ADD_INT	field_idx u16 | i64	SUM	add to an Int cell (saturating)
0x0012 ADD_FIXED	field_idx u16 | i64 Fx bits	SUM	add to a Fixed cell (saturating)

An op targeting an absent node, an out-of-range index, or a wrong-typed cell is a deterministic no-op (an op set MUST mean the same thing on every sink — interactive-worlds §6.4). LWW rides the canonical total order for free; SUM kinds accumulate, and because every op within a tick applies in canonical order, the result is deterministic regardless of arrival.

4. Conformance — replay-equivalence

Given the same feed container and the same signed op set, a conforming sink MUST compute the identical BLAKE3 state hash at every checkpoint — on every machine, no tolerance parameter.

This is interactive-worlds' criterion verbatim; the feed adds no new conformance idea. state_hash = BLAKE3("wai:world-state\x01" || canonical_state_bytes), the canonical bytes being the records in node-id order, each as id | len | record-body.

5. Broadcast profile

The commercial shape of a feed is one authoritative publisher and many read-only sinks ("ship state, not pixels" for sports, events, telemetry). This is a deployment profile of wai.world.live, not a new format: the publisher signs ops and fans them out over the same relay; a read-only sink simply never publishes. A sink that wants a literal picture falls back to a spectator AV1 stream of a capable participant's render (interactive-worlds §9) — presentation, never conformance. The authoritative artifact a spectator can audit is the op log + the sealed state hash.

6. Receipt (JWP profile)

The interactive-worlds session receipt (jwp-receipts.md) applies unchanged: world identity over contract + tick-0 graph; the group's objects are the op batches, Merkle-bound; one Ed25519 seal over world hash + root + checkpoints + exact signed work + carried joules_micro; parent_receipt_hash chains a feed's seals into a timeline.

Appendix

A state-feed is the minimal world: drop the physics and you are left with exactly the part of interactive-worlds that was always doing the load-bearing work — a signed, canonically-ordered, content-addressed, sealed-and-receipted log that every sink replays to the same state. That the same machinery covers a multiplayer game and a stock ticker is the point: the cargo class is "any live state worth auditing", and the verification is identical to sight (worlds), sound (mixdown), and touch (sample).