diff --git a/game/scripts/main.gd b/game/scripts/main.gd
index 81cb828..ea5dbb1 100644
--- a/game/scripts/main.gd
+++ b/game/scripts/main.gd
@@ -8,7 +8,7 @@ const PLAYER_NAME := "Spieler"
 ## How far the pickaxe reaches, in tiles from the figure to the tile centre.
 const REACH_TILES := 2.5
 ## Ticks between two automatic saves: two minutes.
-const AUTOSAVE_TICKS := 2400
+const AUTOSAVE_TICKS := 2 * 60 * GwSession.TICKS_PER_SECOND
 const CAMERA_ZOOM := Vector2(3.0, 3.0)
 
 ## Folder for the player key, the save and the recordings. Tests use their
@@ -154,8 +154,10 @@ func _try_dig() -> void:
 		dig_at(marker.tile)
 
 
-## Queues a pickaxe hit on `tile`, at most once per cooldown. The core checks
-## everything else.
+## Queues a pickaxe hit on `tile`, at most once per cooldown. The caller must
+## check the reach: figures move outside the lockstep, so the core does not
+## know where the figure is. The core checks the cooldown, the tile, its
+## terrain, the tool tier and the free space in the inventory.
 func dig_at(tile: Vector2i) -> void:
 	if session.tick() < _next_dig_tick:
 		return