Introduces the brain.graph namespace and its first op, subgraph() — bounded
multi-hop neighborhood extraction returning a hydrated GraphView (nodes with hop
depth + type/subtype, edges as Relations, a truncated flag). The one-call answer
to 'show me everything around this node, N hops out' the graph-viz path needs.
- brain.graph.subgraph(seeds, { depth, direction, type, subtype, includeInternal,
includeSystem, maxNodes, maxEdges, hydrateNodes }). seeds: id or id[].
- Feature-detect routing: when a GraphAccelerationProvider is registered
(isGraphAccelerationProvider on the 'graphAcceleration' provider) it routes to
native traverse() and hydrates the columnar Subgraph (node ints↔ids paired with
depth position-preserving, edge verb ints → Relations); otherwise a pure-TS BFS
fallback expands each frontier through the O(degree) related() adjacency.
- Both paths produce the identical GraphView, so CI exercises the shape via the
fallback; the native path is cross-layer-tested against cor's provider.
- New public types: GraphView, GraphNode, SubgraphOptions, GraphApi (the surface
grows: export/rank/path/communities follow). isGraphAccelerationProvider guard
added to plugin.ts.
Test: graph-subgraph.test.ts — depth tracking, direction, type filter, default-
hides-internal, node hydration on/off, maxNodes truncation, multi-seed.
