[gedaiu]

Closes #1269.

What happened

"Which members of this class have no link of this kind" had no read. The instance list (GET /kbs/{id}/ontology/entity-types/{type_id}/entities) lists a class's members but cannot filter by what they lack, so a client asked once per member or exported the base.

What changed

Two optional query parameters: missing_predicate (a relation key or an open phrase) and missing_direction (out, the default, in or either). With them, a member stays only when no live fact links it by that predicate, and the response adds missing: {relation_type_id, phrases} so a typo shows up as "matched nothing" rather than as every member. Without them the route answers as before.

• ontology::link_predicate resolves the predicate in one query: the relation by key, its inverses (both ways of inverse_of, and the relation itself when symmetric), and the phrases bound to either in phrase_bindings, filed by which end of the relation the member is on. The normalized predicate also counts as an open phrase.
• entity_instances takes Option<Lacking> and adds one condition, shared by the page and the count: per end, a NOT EXISTS on live facts (typed predicate, or layer = 'open' with a matching normalized phrase) and one on live derived_facts. Both use the existing live subject/object indexes. in swaps the ends, either checks both.
• Membership is unchanged (e.type_id). A bound phrase counts whatever the binding's signature, since a filter for what is missing should lean towards counting a link.
• A blank predicate or unknown direction is a 422 (bad_missing_predicate, bad_missing_direction), checked in a pure missing_link before the access check.
• phrase_bindings::phrase_sql becomes pub(crate) so both sides normalize the same way. One paragraph in docs/design/ontology.md.

No migration.

Tests

an_instance_list_names_what_a_type_lacks (utopia-store): six members of one class, linked by a typed relation, an open phrase with odd spacing and case, the inverse relation, a bound phrase, a derived fact, and nothing. missing_predicate=works_for returns only the last, and the echo names the relation and its phrases; an open phrase on the in end returns the members that are not its object. Each arm was checked by removing it: the test fails for the filter, the typed, open, derived, inverse and bound-phrase arms, and normalization. Two unit tests cover the 422s.

Run in rust:1-slim-bookworm against Postgres with UTOPIA_TEST_REQUIRE_DB=1: cargo fmt --all --check and cargo clippy --workspace --all-targets -- -D warnings clean; cargo test -p utopia-store --test store 312 passed; cargo test -p utopia-server ontology 18 passed.

[WaylandYang]

Thank you, this is a clean, contained addition. The anti-join handles inverses both ways, symmetric relations, reverse bindings, derived rows, invalidated facts and merged entities; the page and the total share one condition; and the response is unchanged without the parameters. The two clarifications from #1269 (key-only link_predicate, ended facts still counting) can follow. This and #1265 touch list_entity_instances in the same lines, so #1265 will need a rebase. Merging.