big ass modding update

src/script/Flags.lua

@@ -1,14 +1,28 @@
 -- Event flags stored in the save table, keyed by pokered event constant
 -- names (e.g. "EVENT_FOLLOWED_OAK_INTO_LAB").
+--
+-- flag.changed fires through the runtime bus only on an actual
+-- transition -- a redundant set of an already-true flag is silent -- and
+-- the null bus makes the module usable headless.
+
+local Runtime = require("src.mods.Runtime")
 
 local Flags = {}
 
 function Flags.set(save, name)
+  local changed = save.flags[name] ~= true
   save.flags[name] = true
+  if changed and Runtime.wants("flag.changed") then
+    Runtime.emit("flag.changed", { name = name, value = true })
+  end
 end
 
 function Flags.clear(save, name)
+  local changed = save.flags[name] == true
   save.flags[name] = nil
+  if changed and Runtime.wants("flag.changed") then
+    Runtime.emit("flag.changed", { name = name, value = false })
+  end
 end
 
 function Flags.get(save, name)