feat(iid, iid-spec): typed Wikidata identity int:wd:<slug>:Q… — spec amendment and reference implementation (P16)

[jonathanprozzi]

Child PR of the v1.1.0-alpha umbrella (#15). Tracking: ENG-15883. First of three stacked typed-wd PRs (this → iid-ladder → iid-registry).

Current (train)

The wd scheme is bare: int:wd:Q42, polymorphic at scheme level, never anchor-eligible, with no notion of what kind of thing a QID names.

Need

The reference implementation (intuition-v2 feat/intuition-app @ 1b877506d) types the value: int:wd:<slug>:Q…, where the slug is one of eleven pinned Wikidata EntitySchema bindings (three active: film, television-series, human). A typed value with an active binding is unambiguous and anchor-eligible; a dormant binding is valid but not mintable; bare values are unchanged. Ruled canonical for the packages.

Reconciliation

One unit, because the iid conformance test executes the iid-spec vectors.

• iid-spec: schemes/wd.md (grammar ^(?:<slug>:)?Q[1-9]\d*$, ordered canonicalization, value-typed typing, the closed binding table with pinned revisions, vectors); spec §7.3 defines value-typed schemes; spec §9.3.1 adds the additive value-grammar extension clause; the conformance corpus gains valueTyped on scheme entries and optional per-vector typing; 18 new wd vectors, all 145 base vectors unchanged apart from one note.
• iid: pinned, deep-frozen bindings table; typed-aware wd canonicalizer (URL forms never infer a slug; slug lowercased and must be registered; QID uppercased); per-value inspection (wdSlug on the valid branch, dormant-wd-binding ineligibility reason); typed derivation on the train's declarative ladder engine (the reference's callback engine is not ported); SCHEME_TYPING.wd stays polymorphic.

Defaults in effect, for ratification in this review

• Spec freeze rule: typed-wd lands as an in-place MINOR amendment under a new §9.3.1 clause (every existing canonical value byte-identical, no existing identifier changes validity or eligibility, the new forms were previously invalid, vectors prove it). The external spec-repo PR is a separate governance step.
• Slugless rungs keep minting bare values, and bare values only; a typed raw value (human:Q42) cannot mint through a rung that declares no slug. The classifications package has 13 generated ladders with slugless rungs; refusing them now would silently drop a rung from each. Flips with the classifications follow-on.
• Typing is per value, not per scheme, so existing scheme-level reads in registry, classifications and primitives keep working until their own PRs.
• The train's ratified whitespace trim is kept for every wd form; the reference's stricter ASCII-only trim would change canonicalization of existing inputs, which the freeze rule forbids.

Surfaced, pre-existing, not changed here

Weak account handles (int:acct:x:@jack): the ratified spec says both forms are anchor-eligible; the reference floors the weak form. Outside typed-wd; to be reconciled when the app swaps to this package.

Evidence

• iid-spec: 163 vectors. iid: 263 tests, typecheck, check, build. Consumers against the rebuilt dist: iid-registry 42, iid-ladder 12, classifications 38, primitives 140. Pack dry run.
• Independent review: round 1 found three real issues (a trim regression, typed values minting through slugless rungs, a mutable bindings table), all fixed; combined re-review found no new defect.

Review notes

CI shows the base branch's expired supply-chain exception until the CI-fix child PR merges; this branch is rebased after that. Merge before the iid-ladder PR.

Update 2026-10-03: this week's reference changes folded in

The reference moved to develop (the feature branch was consolidated into main on 9/24). Per the maintainers' call, this week's iid changes (through develop @ 83a003bc1) are folded into this PR as a second commit rather than a follow-up.

• Music identity policy (MUSIC_IDENTITY_RUNG_POLICY, isPlainWdPrimaryAllowed): verbatim data and predicate. Nothing in iid mints on them; the ladder PR consumes them for policy-gated plain-QID primaries (see feat(iid-ladder): typed-wd ladder policy, category rungs, rung aliases and pinned P31 closure (P16b) #29).
• normalizePodcastFeedUrl: folds scheme and host case, strips the scheme and trailing slashes, preserves userinfo, port, path and query bytes. derivePodcastGuid is unchanged.
• ISNI URL form: the canonicalizer also accepts https://isni.org/isni/<id> (with or without www., host case-insensitive), stripping it to the bare form before the existing canonicalization. Every existing canonical output is byte-identical. Recorded in the spec's ISNI scheme doc as an additive value-grammar extension under §9.3.1, with four additive conformance vectors. For ratification in this review.
• Typed-wd itself is unchanged by this commit: SCHEME_TYPING, the bindings table, parse.ts and derive.ts have no diff.
• Gates after the refresh: spec corpus 167 vectors; iid 270 tests, typecheck, check, build; iid-ladder 12, iid-registry 42, classifications 38, primitives 140 against the rebuilt dist; pack dry run. Independent conformance and adversarial review on the refresh commit: round 1 found one wording gap (the spec note said scheme and host are case-insensitive; the ported regex folds the whole prefix including the /isni/ path, as the reference does), fixed by aligning the note, adding a vector and a test; round 2 clean on both gates.