ADR-0015 — The core model: properties, no GraphView, content ids, changes_since

Accepted 2026-10-03 (Milestone 18 phase 6.2; decisions left to “free hand” by Daniel, 2026-10-01). Context: Graph-Native Model, Milestone 18 - Library Refactor, Lenticulum and Sophia as the outside users the library is for.

Context

moonkale-core becomes something other repositories depend on (by git tag lib-vN, phase 6.3). Its design note described four things the code never had — node/edge properties, GraphView, Source::subscribe, and (as a candidate) content-addressed ids. Before the first tag each one is either built or removed from the design, because adding a field to Node later breaks every source.

Decisions

1. Properties on nodes and edges — built. Node::props and Edge::props: Properties = BTreeMap<String, Value>, empty by default and not serialized when empty, so stored and transmitted shapes are unchanged for every source that has none. Sorted for stable comparison and serialization. Value compares floats by their bits, so Node stays Eq. Users: a factor’s parameters (Lenticulum), a declaration’s hash and kind (Sophia), later a row’s columns. Edge ids and weight are not added: an edge is identified by (source, from, to, kind), and a weight is a property.
2. GraphView — dropped. Editors hold QueryResults and re-run the query when a source reports a change. “Apply events above a watermark” needs per-node change events no source produces; until one does, a view is a query.
3. Content-addressed ids — an option, built. NodeId::from_content(digest): UUID v5 of a caller-computed digest of the normalised structure, in a namespace of its own (never equal to a derived id). The same structure is the same node in every source and on every machine — Sophia’s model, where many names point at one node (names are edges). Ids stay 128-bit; a source that must verify keeps the full digest as a property. derive(source, key) stays the default.
4. changes_since, not subscribe — decided. The long poll of Milestone 16 works over HTTP server functions and in wasm, needs no stream type in core, and survives reconnects (seq, reset). subscribe() -> Stream leaves the design.

Consequences

• 38 Node/Edge literals across the sources gained props: Default::default() (one mechanical commit). Shapes on disk (the entity log) and on the wire are unchanged when props is empty.
• Graph-Native Model shows the model as built; the design diagram is updated to match.
• lib-v1 (phase 6.3) is tagged with this model.