diff --git a/api.lua b/api.lua
new file mode 100644
index 0000000..f868734
--- /dev/null
+++ b/api.lua
@@ -0,0 +1,50 @@
+local _G = ShaguTweaks.GetGlobalEnv()
+
+-- Central capability layer for ClassicAPI / SuperWoW integration.
+-- Keep feature checks here so individual modules don't scatter DLL-specific
+-- detection logic all over the codebase.
+ShaguTweaks.API = ShaguTweaks.API or {}
+local API = ShaguTweaks.API
+
+API.classicapi_version = tonumber(_G.CLASSIC_API_VERSION) or 0
+API.classicapi = type(_G.C_NamePlate) == "table"
+  or type(_G.C_Spell) == "table"
+  or type(_G.UnitGUID) == "function"
+
+API.nameplates = type(_G.C_NamePlate) == "table"
+  and type(_G.C_NamePlate.GetNamePlateForUnit) == "function"
+
+API.casts = type(_G.C_Spell) == "table"
+  and type(_G.C_Spell.UnitCastingInfo) == "function"
+  and type(_G.C_Spell.UnitChannelInfo) == "function"
+
+API.unitguid = type(_G.UnitGUID) == "function"
+
+-- SuperWoW remains optional. It can still provide useful extra cast/GUID
+-- information, but ClassicAPI is the primary compatibility layer.
+API.superwow = type(_G.SpellInfo) == "function"
+  and type(_G.CombatLogAdd) == "function"
+
+API.GetNamePlateForUnit = function(unit)
+  if API.nameplates then
+    return _G.C_NamePlate.GetNamePlateForUnit(unit)
+  end
+end
+
+API.UnitCastingInfo = function(unit)
+  if API.casts then
+    return _G.C_Spell.UnitCastingInfo(unit)
+  end
+end
+
+API.UnitChannelInfo = function(unit)
+  if API.casts then
+    return _G.C_Spell.UnitChannelInfo(unit)
+  end
+end
+
+API.UnitGUID = function(unit)
+  if API.unitguid then
+    return _G.UnitGUID(unit)
+  end
+end