Single-Root JSON-LD Knowledge Graphs & SHACL Validation

A Single-Root JSON-LD Knowledge Graph compiles every page’s structured metadata into a unified W3C JSON-LD 1.1 @graph array [Spo20] anchored by deterministic @id URIs [GBM16] [Hog21], verified at build time by a six-gate SHACL-inspired constraint validator [KK17] and synchronized with llms.txt for zero-drift search and LLM discovery.

Consolidating these four architectural dimensions shifts structured metadata from ad-hoc template strings to a verified build-time compilation graph.

Why Do Fragmented JSON-LD Snippets Fail Entity Disambiguation?

Fragmented JSON-LD templates emit isolated <script> islands without shared @id anchors [Spo20], forcing search crawlers and LLM retrieval pipelines to guess whether anonymous Person or Organization blocks represent the same real-world entity [Hog21]. Centralizing schema synthesis in json-ld.ts eliminates blank-node ambiguity through deterministic URI fragments and normalized relation pointers [GBM16].

When components inject separate Schema.org snippets, RDF parsers allocate distinct blank nodes (_:b0, _:b1) for every unanchored object [Spo20]. Conversely, emitting bare {"@id": "..."} pointers without summary labels fails Google’s single-page Rich Results parser. In src/commons/server/json-ld.ts and src/components/JsonLd.astro, we flatten all page schemas into a single @graph root where PERSON_REF (https://hackenberg.tech/#person), Wikidata-backed OFFICIAL_ORG_LABELS, buildTagAboutRefs() (Person.knowsAbout -> DefinedTerm), and buildCitationList() resolve into a connected star graph.

Anchoring every page entity to #webpage ensures that both RDF graph expanders and single-page search extractors traverse a connected, cycle-free star topology.

How Does Our Six-Gate Postbuild Validator Enforce Graph Coherence?

Inspired by the W3C Shapes Constraint Language (SHACL) [KK17], validate-jsonld.ts parses every generated HTML document inside dist/ after image-sitemap.ts enriches scoped DOM ImageObject nodes, evaluating six deterministic governance gates across global entity definitions, relation pointers, and cached external authority registries.

To prevent any unanchored node or broken pointer from reaching production, the postbuild pipeline executes these six sequential verification gates across all 433 rendered HTML pages:

• Gate 1 & Gate 2 (Single-Root Syntax, 3NF Consistency & Rich Results Self-Containment): Gate 1 enforces a single @context: "https://schema.org" root with an @graph array and absolute http(s):// URIs [Spo20]. Gate 2 enforces cross-page property equivalence (3NF), restricts relation pointers to SUMMARY_PROPS (@id, @type, name, url, sameAs), and guarantees that every RICH_RESULT_ACTOR_PROPS target (author, creator, publisher, provider, instructor) carries inline or same-page @type and name.
• Gate 3, Gate 4 & Gate 5 (Zero Blank-Node Clones, Referential Closure & Domain Coverage): Gate 3 blocks anonymous Person, EducationalOrganization, or primary artifact clones; Gate 4 verifies 100% global @id resolution (definedEntityIds.has(ref.targetId)); and Gate 5 audits route-specific schemas, BreadcrumbList names, citation completeness, and scoped DOM ImageObject parity (excluding favicons and #related-content cards).
• Gate 6 (External Authority & Vocabulary Verification): Validates every @type and property domain against schemaorg-current-https.jsonld [GBM16] and verifies Wikidata Q-IDs (P31/P856), O*NET-SOC codes, ISO 7064 Mod 11,2 ORCID checksums, Crossref DOIs, and GitHub repositories via .cache/jsonld-authorities.json.

If any page violates a single SHACL-equivalent invariant across the 3,074 unique @id entities and 14,221 cross-referenced pointers, npm run postbuild aborts the release before deployment.

Synchronizing Schema.org Entities with Dynamic llms.txt Feeds

Maintaining separate metadata pipelines for search engines and autonomous LLM agents inevitably causes semantic drift [Hog21]. By driving both json-ld.ts and the build-time llms.txt.ts endpoint from identical Astro content collections, every entity modification propagates simultaneously to JSON-LD @graph nodes and agentic Markdown indexes.

When an LLM agent fetches /llms.txt, src/pages/llms.txt.ts queries all 8 content collections alongside degrees, experiences, and src/content/profiles/—the exact records used by buildAboutPageSchemas() and buildTagsOverviewSchemas() to populate Person.sameAs, alumniOf, hasCredential, and knowsAbout:

// Excerpt from src/commons/server/json-ld.ts & src/pages/llms.txt.ts
export const PERSON_REF = {
  '@type': 'Person',
  '@id': 'https://hackenberg.tech/#person',
  name: 'Dr. Georg Hackenberg',
  url: 'https://hackenberg.tech/about/'
};

const degreeLines = sortedDegrees
  .map((d) => `  - ${d.data.degree} in ${d.data.program} - ${d.data.organization.name}`)
  .join('\n');
const profileLines = sortedProfiles
  .map((p) => `  - ${p.data.name}: ${p.data.url}`)
  .join('\n');

Coupling the JSON-LD @graph compiler and the /llms.txt endpoint to the same typed Astro collections—and pairing them with Schema.org ImageObject Asset Governance, Consent-Free Markov Visitor Flow Telemetry, Focus-Aware Hop Attenuation in Knowledge Graphs, and Astro Content-Layer Merkle Asset Digesting—guarantees that search crawlers and RAG agents always ingest identical academic credentials, ORCID identifiers, and publication graphs.