diff --git a/data/compostable.lua b/data/compostable.lua
new file mode 100644
index 0000000..bcbb19e
--- /dev/null
+++ b/data/compostable.lua
@@ -0,0 +1,121 @@
+-- Compostable items (pushed into dropper, which distributes to composters via hoppers).
+-- Bone meal returns through hopper.
+-- Each entry is a Minecraft item ID string.
+
+local items = {
+    -- Seeds & crops
+    "minecraft:wheat_seeds",
+    "minecraft:beetroot_seeds",
+    "minecraft:pumpkin_seeds",
+    "minecraft:melon_seeds",
+    "minecraft:torchflower_seeds",
+    "minecraft:pitcher_pod",
+    "minecraft:wheat",
+    "minecraft:beetroot",
+    "minecraft:carrot",
+    "minecraft:melon_slice",
+    "minecraft:pumpkin",
+    "minecraft:carved_pumpkin",
+    "minecraft:sweet_berries",
+    "minecraft:glow_berries",
+    -- Plant blocks
+    "minecraft:tall_grass",
+    "minecraft:short_grass",
+    "minecraft:fern",
+    "minecraft:large_fern",
+    "minecraft:dead_bush",
+    "minecraft:vine",
+    "minecraft:hanging_roots",
+    "minecraft:small_dripleaf",
+    "minecraft:big_dripleaf",
+    "minecraft:moss_block",
+    "minecraft:moss_carpet",
+    "minecraft:azalea",
+    "minecraft:flowering_azalea",
+    "minecraft:spore_blossom",
+    "minecraft:seagrass",
+    "minecraft:sea_pickle",
+    "minecraft:lily_pad",
+    "minecraft:sugar_cane",
+    "minecraft:kelp",
+    "minecraft:dried_kelp",
+    "minecraft:cactus",
+    "minecraft:nether_wart",
+    "minecraft:crimson_fungus",
+    "minecraft:warped_fungus",
+    "minecraft:crimson_roots",
+    "minecraft:warped_roots",
+    "minecraft:shroomlight",
+    "minecraft:weeping_vines",
+    "minecraft:twisting_vines",
+    -- Leaves
+    "minecraft:oak_leaves",
+    "minecraft:spruce_leaves",
+    "minecraft:birch_leaves",
+    "minecraft:jungle_leaves",
+    "minecraft:acacia_leaves",
+    "minecraft:dark_oak_leaves",
+    "minecraft:mangrove_leaves",
+    "minecraft:cherry_leaves",
+    "minecraft:azalea_leaves",
+    "minecraft:flowering_azalea_leaves",
+    -- Flowers
+    "minecraft:dandelion",
+    "minecraft:poppy",
+    "minecraft:blue_orchid",
+    "minecraft:allium",
+    "minecraft:azure_bluet",
+    "minecraft:red_tulip",
+    "minecraft:orange_tulip",
+    "minecraft:white_tulip",
+    "minecraft:pink_tulip",
+    "minecraft:oxeye_daisy",
+    "minecraft:cornflower",
+    "minecraft:lily_of_the_valley",
+    "minecraft:sunflower",
+    "minecraft:lilac",
+    "minecraft:rose_bush",
+    "minecraft:peony",
+    "minecraft:wither_rose",
+    "minecraft:torchflower",
+    "minecraft:pitcher_plant",
+    -- Saplings
+    "minecraft:oak_sapling",
+    "minecraft:spruce_sapling",
+    "minecraft:birch_sapling",
+    "minecraft:jungle_sapling",
+    "minecraft:acacia_sapling",
+    "minecraft:dark_oak_sapling",
+    "minecraft:mangrove_propagule",
+    "minecraft:cherry_sapling",
+    -- Food waste
+    "minecraft:rotten_flesh",
+    "minecraft:spider_eye",
+    "minecraft:poisonous_potato",
+    "minecraft:fermented_spider_eye",
+    "minecraft:apple",
+    "minecraft:bread",
+    "minecraft:cookie",
+    "minecraft:cake",
+    "minecraft:pumpkin_pie",
+    -- Farmer's Delight compostables
+    "farmersdelight:tree_bark",
+    "farmersdelight:straw",
+    "farmersdelight:canvas",
+    "farmersdelight:rice",
+    "farmersdelight:rice_panicle",
+    "farmersdelight:onion",
+    "farmersdelight:tomato",
+    "farmersdelight:cabbage",
+    "farmersdelight:cabbage_leaf",
+}
+
+-- Trash items: compostables with zero reserve (always fully composted)
+local trash = {
+    ["minecraft:rotten_flesh"]         = true,
+    ["minecraft:spider_eye"]           = true,
+    ["minecraft:poisonous_potato"]     = true,
+    ["minecraft:fermented_spider_eye"] = true,
+}
+
+return { items = items, trash = trash }