Federation Phase 0: registry producer contract + SPEC §11

[nicholsn]

First slice of meta-lokf — a registry that aggregates independent lokf bundles into one cross-repo graph, with no central database. Design context: SPEC §11 (added here).

What ships

Producer contract — lokf export now additively writes two artifacts a registry harvests, alongside the existing graph.json + datasets.jsonld:

New artifact	Role
graph.nt	The whole bundle as N-Triples — the RDF a registry loads for cross-bundle SPARQL.
concepts.jsonld	Every concept's frontmatter + body under one @context/@graph — offline access to a concept's source document without re-fetching markdown.

The two are isomorphic (86 triples on the acme example); concepts.jsonld additionally carries raw frontmatter+body. Both are gitignored under web/public/.

SPEC §11 "Federation: registries of bundles" (Versioning → §12) documents the whole design so this groundwork has a north star:

• the producer contract above;
• the lokf-registry.yaml DCAT/VoID manifest (one entry per bundle, keyed by base_iri);
• owner(iri) = longest-base_iri-prefix match — the exact inverse of §7 IRI minting, so cross-bundle resolution is pure string math (no network, no shared DB) — plus its three guards (explicit-id index, namespace precedence/non-nesting, ownership validation);
• the forthcoming lazy named-graph-per-repo traversal + lokf registry CLI / lokf-registry MCP surface (marked informative);
• governance: public-artifact/local-checkout membership only in v0.1 (no credentials in the shared manifest), metadata not row-level data with a sensitivity gate, best-effort freshness.

Adds the void: prefix to Appendix B.

Why this slice first

It's independently useful (any bundle can now publish a complete harvestable footprint) and unblocks every later phase, with zero new runtime surface. Later phases (registry manifest + routing, document access, lazy federated store, agent MCP tools) build on it.

Verification

• lokf export examples/acme-knowledge → all four artifacts; graph.nt ≅ concepts.jsonld (86 triples), both parse cleanly.
• 135 tests pass (2 new asserting the producer contract + round-trip).
• Docs site builds; Specification page renders §11 with Versioning correctly renumbered to §12.

Decisions folded in (from discussion)

PHI/governance and PURL operation are owned by @nicholsn; freshness is best-effort; private/perimeter-bound bundles are explicitly a future extension (v0.1 is public-artifact/local only).