open-standards/wai/live-conformance/cowatch/README.md

live-conformance/cowatch — co-watch

The corpus of extensions/co-watch.md §13: watch rooms of live-rooms, their co-watch policies (WXP1), the controls (WXC1), presentation statements (WXS1) and skew statements (WXK1) their principals sent as meta events, what a verifier states of them, and catch-up cases.

Co-watch equivalence. For each vector, a conforming verifier given its descriptor, grants, key_log, chains, policies and sources (§11.1) reaches the outcome the vector states, with its reason and at when it refuses, and, for an accepted room or a room with a gap (§11.3):

• room, gaps, policy_digests, and starts (each source's start: its instant and the policy's index);
• controls, in the merged order: each one's digest, author, t, action, at, arg and whether it is applied or a later control at its instant overrides it;
• timeline: each change of the controlled state, in the order of §5.4 and §6.4, with whether the source plays, its rate and its position at that instant;
• presentations, in the merged order: each statement's digest, player, at, position, state, the controlled position at its at, its error and whether it is settling;
• skews, in the merged order: each statement's digest, from, to, and its viewers and pairs as recomputed (§8.4), or unchecked in a room with a gap.

about says what each vector is, and is not checked. catch_up holds the policy's catch-up params and cases: a controlled state (playing, rate, controlled, duration) and a player's presented position, with the correction §9 gives. A verifier that reaches another outcome, reason, place, fact or correction does not conform.

Provenance. Generated here: wai_co_watch_vectors gen writes vectors.json from rooms authored in code, from fixed seeds. Each key is SHA-256 of wai:co-watch/corpus/key, a zero byte and the principal's index (principals lists their public keys); each source object's content hash is SHA-256 of a fixed label. Each room is written from a script of acts in room-clock order: the clock's lifecycle, controls, and each viewer's statements at the controlled position plus an error written in the generator; the clock's skew statements are made from the room as it stands when the clock makes them, as a room service makes them. Ed25519 is deterministic, so the file is the same bytes on every machine. The generator asserts that each vector reaches the outcome it was written to have, and that the corpus gives every reason of §12, before it writes. A refused vector holds its room up to the record it is refused at. No recorded data.

Layout

vectors.json: principals (informative), key_seed, vectors and catch_up. The rooms, under one policy unless named otherwise (an hour-long episode; controls 500 ms to 10 s ahead; rates from half to twice normal speed; one-second slots in five-second windows; a 200 ms bound at the 95th percentile; settling 1.5 s; catch-up at 40 ms, 5 % and one second):

• watch_party: the host (the direct power), the guest (watch_control 3: play and pause) and the late joiner (no control, joining at 11 s). The host plays, the guest pauses and plays, the host seeks, sets 1.25 and back; at 20 s the guest's pause and the host's play and seek are for one instant, the host's play, sent later, overriding the pause. Each player states twice a slot, with a transient error just after a control, and the late joiner a seek's error on joining; every five-second window to 25 s is stated, every viewer in sync.
• next_episode: a second policy names another source at 10 s; the controlled position starts again there, paused at 0, and the guest (watch_control 15) plays it; both sources' objects are given.
• drift: four viewers. The fourth states 400 ms ahead (out of sync); the late joiner states nothing for one slot (unknown from 5 s); the guest leaves at 7 s; the window from 5 s is stated in two statements of two viewers each.
• gap: watch_party with one of the guest's statements not delivered.
• Refused, each a control of one defect: a control from a party without the power, one past its attribute, one in the past, one under the lead, one past the horizon, a seek past the end, a rate past the limit, an unknown action, a play with an argument, a control before its sender joined (the room refuses it); a statement of another player, one signed by another key, one ahead of its sending, one of another source, one of state 9, one by the clock; a skew statement that does not recompute, one stating a viewer with no statements in sync, one of another bound, one claiming events the room does not hold, one leaving a viewer out, one by a viewer, one made before its window ends; a watch_control of 16 and of 03; no policy; policies malformed, unlinked, of another duration for one source, not from 0, truncated, of version 2, of another room and signed by the clock; and objects that are not the policy's source.