The brain.graph.subgraph/export NATIVE routing (graphSubgraphNative /
graphExportNative / hydrateNativeSubgraph + provider resolution) had ZERO brainy
CI coverage — in production it's exercised only cross-layer against cor's engine,
so a columnar return-shape or hydration-alignment drift would pass brainy CI
silently. This registers a faithful MOCK GraphAccelerationProvider returning a
columnar Subgraph built from the brain's REAL ints, locking the seam:
- subgraph() routes native (traverse called) and hydrates node int->id, the
nodeDepth column aligned to the node column, node type via batchGet, and edge
verb-int->Relation via verbIntsToIds + getVerbsBatchCached.
- node<->depth alignment is preserved when a node int does NOT resolve
(deleted/unknown) — the unresolvable int is dropped, not collapsed (which would
shift every later depth). This is the exact hydration risk the release audit flagged.
- export() routes to the graph cursor, hydrates chunks, and ALWAYS closes the handle.
Also fixes a latent contract bug found writing the test: graphAccelerationProvider()
only accepted a ready instance, so a provider registered as a (storage)=>provider
FACTORY (the convention graphIndex/metadataIndex/vector use) would fail the duck-test
and the native path would silently never engage. Now resolves instance OR factory,
cached. Covered by the factory-registration test.