Extract relationship builder into relationships module

Acceptance Criteria

• New file runes/plan/src/relationships.ts exists
• relationships.ts has zero imports from node:fs, node:path, or node:child_process
• buildRelationships() function is exported and produces a Map<string, EntityRelationship[]>
• EntityRelationship interface is exported with all relationship kinds: blocks, blocked-by, depends-on, dependency-of, implements, implemented-by, informs, informed-by, related
• Source references produce implements/implemented-by edges (or informs/informed-by for decisions)
• Scanner dependencies produce depends-on/dependency-of edges
• ID references produce related edges (or blocked-by/blocks when entity status is blocked)
• Duplicate edge suppression works: source-linked and dep-linked pairs are excluded from text-based ID reference edges
• Pipeline's aggregate hook calls buildRelationships() instead of inlining the logic
• All existing relationship behaviour is preserved — same edges, same directions, same deduplication
• Existing tests pass without modification

Approach

1. Create relationships.ts. Define the EntityRelationship interface (currently inline in pipeline.ts). Move the addRel helper function and the three reference-processing loops (source refs, scanner deps, ID refs) into a buildRelationships() function.
2. The function accepts the same data the aggregate hook currently uses: an entity map, source references, scanner dependencies, and ID references. The entity map uses a minimal shape ({ type: string; data: Record<string, any> }) rather than requiring the full EntityRegistration type, to keep the module self-contained.
3. In pipeline.ts, import buildRelationships and call it from the aggregate hook, passing the existing allEntities, _sourceReferences, _scannerDependencies, and _idReferences maps.
4. Remove the EntityRelationship interface definition from pipeline.ts — import it from relationships.ts instead.
5. Run existing tests to confirm no regressions.

Dependencies

None — independent of the scanner and diff extractions.

References

• Edge Runtime Compatibility for Plan Package — Edge Runtime Compatibility for Plan Package

Resolution

Completed: 2026-04-14

Branch: claude/edge-runtime-refactor-HOg8v

What was done

• Created runes/plan/src/relationships.ts with buildRelationships() function and EntityRelationship interface
• Defined RelationshipEntity minimal interface so the module doesn't depend on @refrakt-md/types
• Pipeline's aggregate hook now calls buildRelationships() with allEntities, _sourceReferences, _scannerDependencies, _idReferences
• Removed inline EntityRelationship interface from pipeline.ts; re-exports from relationships.ts for backwards compatibility

Notes

• relationships.ts has zero external dependencies — pure TypeScript only
• All 10 relationship-related tests pass (implements, informed-by, blocks, deduplication)