open-standards/wai/live-conformance/signal-health/README.md

live-conformance/signal-health — what a monitor measured on an input

The corpus of extensions/signal-health.md §9, in one file, vectors.json.

Provenance. Generated here by wai_signal_health_vectors gen (wai-rs, feature signal_health), from Ed25519 keys on fixed 32-byte seeds, constant instants, and media the generator writes from a linear congruential generator with fixed seeds: luma planes of 16 × 8 and 8 × 8 samples, two channels of 16-bit samples at 800 Hz, caption and cue instants, and transport streams of 40 packets at 30 080 bit/s (a packet every 50 ms) holding a program association and a program map section with their CRCs and packets of two elementary streams; no recording and no input from outside this repository.

keys names every key by its role, as 64 lowercase hexadecimal digits: two monitors a switch trusts (monitor_a, monitor_b) and one it does not (rogue). profile gives the operator's thresholds, per check by name; switch the switch's inputs in its order, the keys it trusts and max_age_ms.

• records (§4, §6.1, §6.2) are each a record's bytes in hexadecimal, and its outcome: read, with its digest, input and the names of its faulted checks (faults); or refuse and its reason.
• checks (§6.3, §6.4) are each a record, the profile a verifier expects (or null) and the media it holds: frames (each at_ms, width, height and luma in hexadecimal), audio (at_ms, rate, channels and samples, the little-endian bytes in hexadecimal), captions and cues (instants), and transport (first_us, rate_bps and bytes in hexadecimal), each present only where held. outcome.record is stands or reject reason=…, and outcome.checks gives each check of a record that stands, in its order: recomputed, not_held or reject reason=….
• switches (§7) are each the records a switch holds, the instant at_ms and the input it carries (current); outcome gives each record's state, each input's state in the switch's order and the input it selected.

Everything is synthetic: keys attest nothing, and the media is the generator's. Each media case's values are declared in the generator, which requires the reference to measure them, and each case states the outcome it was written to have, never copied from a verifier.

wai_signal_health_vectors verify and tests/signal_health.rs check that the file regenerates byte for byte and that wai-rs reaches every stated outcome. ../signal_health_verify.py is the second implementation, written from the extension's text, which also mutates copies of the corpus and drops each of its own checks in turn and requires each to be caught.