feat: index loaded resource discovery

docs/RESOURCE_NODE_MIGRATION.md

@@ -551,11 +551,21 @@ profession, and NPC comfort range. The first scoring pass stores
 `safety_risk`, `comfort_distance`, and `discovery_priority` on resource state
 and uses them when selecting NPC resource targets.
 
-The first validated spread contains twelve finite resources: berry bushes and
-patches, animal camps, trees, and one village woodpile. Placement is guarded by
-headless tests for stable IDs, food/wood coverage, semantic contexts,
-discovery metadata, navigation reachability, and non-overlapping pantry/player
-interaction range.
+The current validated spread contains eighteen finite resources: berry bushes
+and patches, animal camps, farm crops, trees, and village/mill woodpiles.
+Placement is guarded by headless tests for stable IDs, food/wood coverage,
+semantic contexts, discovery metadata, navigation reachability, and
+non-overlapping pantry/player interaction range.
+
+Loaded discovery now goes through a resource-specific horizontal grid owned by
+`ActiveWorldAdapter`. Queries expand from nearby cells until authoritative
+resource metadata proves that no farther source can beat the current scored
+winner. The index preserves stable registration-order ties and contains no
+amount, reservation, or save authority. ResourceNode unload removes only the
+loaded anchor; rebinding the same ID restores its indexed position against the
+existing `ResourceStateRecord`. The reviewed 18/180/1,800-source benchmark and
+exact-selection contract live in
+[Loaded Resource Discovery 01](benchmarks/LOADED_RESOURCE_DISCOVERY_01.md).
 
 ## Test scenarios