diff --git a/init.lua b/init.lua
index 9f9fcd2..5e48247 100644
--- a/init.lua
+++ b/init.lua
@@ -344,6 +344,20 @@ function M.tile_size(map_id)
     return map_registry[id].tile_size
 end
 
+function M.tile_at_layer(layer_name, x, y, map_id)
+    local id = map_id or current_map_id
+    if not id then error("maps.tile_at_layer: no current map") end
+    local m = map_registry[id]
+    if x < 0 or x >= m.size.w or y < 0 or y >= m.size.h then return nil end
+    if not m.layers or not m.layers[layer_name] then return nil end
+    local gid = m.layers[layer_name].tiles[y * m.size.w + x + 1] or 0
+    if gid == 0 then return nil end
+    local atlas_idx, tile_id, _rot = decode_gid(gid)
+    local atlas = m.atlases[atlas_idx + 1]
+    if not atlas then return nil end
+    return atlas.tiles[tile_id]
+end
+
 -- Arity-flex sugar: tile_at(tx, ty) uses current_map_id; tile_at(map_id, tx, ty)
 -- is explicit. Both forms accept nil map_id and fall back to current_map_id.
 function M.tile_at(a, b, c)
@@ -361,21 +375,12 @@ function M.tile_at(a, b, c)
     if not m then
         error(string.format("maps.tile_at: unknown map-id '%s'", tostring(map_id)))
     end
-    if tx < 0 or tx >= m.size.w or ty < 0 or ty >= m.size.h then
-        return nil
-    end
-    -- v2 path: read from surface layer using GID encoding
+    -- v2 path: query surface layer for back-compat
     if m.schema_version == 2 then
-        local surface = m.layers and m.layers.surface
-        if not surface then return nil end
-        local gid = surface.tiles[ty * m.size.w + tx + 1]
-        if not gid or gid == 0 then return nil end
-        local atlas_index, tile_id, _ = decode_gid(gid)
-        local atlas = m.atlases[atlas_index + 1]
-        if not atlas then return nil end
-        return atlas.tiles[tile_id]
+        return M.tile_at_layer("surface", tx, ty, map_id)
     end
-    -- v1 legacy path (should not be reached after M.load auto-upgrades, kept for M.create)
+    -- v1 path (legacy): kept for any non-upgraded maps that bypass M.load
+    if tx < 0 or tx >= m.size.w or ty < 0 or ty >= m.size.h then return nil end
     local palette_id = m.tiles[ty * m.size.w + tx + 1]
     return m.tilemap.tiles[palette_id]
 end