Release lexicon schemas 0.9.0

[aaronstevenwhite]

Releases pub.layers.* lexicon schemas 0.9.0. Lexicon JSON, docs, and CHANGELOG only, matching the shape of the 0.8.0 release (no generated bindings, no Rust). The version-control and migration tooling built alongside this release is tracked separately and gitignored here.

New namespaces

• pub.layers.catalog: a nestable, citable, cross-repo grouping of the browsable artifact (collection, membership, and five query methods). A child-held parentRef forms a strict tree that counts sum over; membership edges render but never sum, so one dataset can annotate another without perturbing its totals. Supersedes the earlier artifact and dataset proposals.
• pub.layers.acquisition: de-identified participants, sessions, consent, ethics, and funding, grounded in BIDS and NWB (participant, session, and query methods).

Modality and signal coverage

media.media gains signal, motion, and volume kinds with twelve new BIDS/NWB-grounded metadata defs; a new defs#signalSpan anchor; the #anchor union widened to ten members; and a relaxed #temporalSpan minimum for session-relative clocks.

Shared defs and conventions

Seven new shared defs (contentDigest, signalSpan, mediaScope, frequencyBand, fundingRef, ethicsApproval, languageRef), the <x>Uri plus knownValues convention applied throughout, and languageRefs[] on the browse-relevant records.

Breaking change

Exactly one, confirmed by a pairwise def and property comparison against v0.8.0: defs#annotationMetadata.digest (a packed string) is replaced outright by contentDigest (a structured object). Every other change is additive or a backward-compatible constraint relaxation. Record keys move from tid to any across all record types, reflecting that rkeys are content-derived and not chronologically ordered.

Verification

• The full tree bundle-parses as a valid ATProto schema (1506 vertices, 1724 edges), every cross-reference resolving, under panproto 0.66.0.
• Full description coverage: every property carries a description.
• The v0.8.0 to v0.9.0 migration lens passes forward-soundness laws for all record types, verified by scripts/verify_lens_laws.py (in the migration tooling, tracked separately).

For downstream consumers

Once tagged, the lexicons/pub/layers subtree hash to pin is:

162f8f1c79676cd87a8f6f705de468ddc9efbb51