Graph Projector

The GraphProjector is a PageFilter registered with the WikiEngine that fires on every page save. It bridges the gap between human-authored wiki content and the knowledge graph by automatically projecting YAML frontmatter into graph nodes and edges.

How It Works

1. Parse — Extracts YAML frontmatter from the saved page via FrontmatterParser
2. Detect — Passes frontmatter to FrontmatterRelationshipDetector, which separates properties from relationships
3. Upsert node — Creates or updates the page's node in kg_nodes with detected properties, node type from the type field, and human-authored provenance
4. Upsert edges — For each detected relationship, resolves the target node by name (creating a stub if it doesn't exist) and upserts the edge
5. Diff and remove — Compares current edges against what was just projected and removes stale human-authored edges that no longer appear in frontmatter
6. Preserve AI edges — Stale-edge removal skips ai-inferred and ai-reviewed edges so approved proposals survive frontmatter edits

Idempotency

Re-saving a page with unchanged frontmatter is a no-op — the upsert logic uses ON CONFLICT (PostgreSQL) or MERGE INTO (H2) to update timestamps without creating duplicates.

Bulk Projection

The admin panel provides a "Project All Pages" button that iterates every wiki page and runs the projector. This is used to seed the graph after initial deployment or schema changes.