diff --git a/src/systems/VillagerSystem.ts b/src/systems/VillagerSystem.ts
index 46960ee..98db8f2 100644
--- a/src/systems/VillagerSystem.ts
+++ b/src/systems/VillagerSystem.ts
@@ -361,7 +361,8 @@ export class VillagerSystem {
         const res = state.world.resources[job.targetId]
         if (res) {
           this.adapter.send({ type: 'VILLAGER_HARVEST_RESOURCE', villagerId: v.id, resourceId: job.targetId })
-          this.adapter.send({ type: 'CHANGE_TILE', tileX: res.tileX, tileY: res.tileY, tile: TileType.GRASS })
+          // ROCK tile stays ROCK after mining — empty rocky ground remains passable
+          // and valid for mine building placement.
           this.worldSystem.removeResourceTile(res.tileX, res.tileY)
           this.resourceSystem.removeResource(job.targetId)
           this.addLog(v.id, '✓ Mined rock (+2 stone)')