Address the second inline review of the features framework

- Feature.register returns the config as a second value, so files
  write `local feature, config = Feature.register(...)`.
- The lib is ExpScenario.Features and the instance class with its
  fields sits on Feature._prototype, which is the __index, the same
  shape as exp_commands.
- update_config only looks at values whose override was added,
  removed, or replaced. _apply_field sets one value and returns it, so
  the comparison happens while applying and the second loop only
  raises. Overrides dropped from the previous set count as candidates
  because the value reverts to its default.
- The `@setting name` tags are gone from the config comments.
- Protection is guarded as a whole instead of checking config.enabled
  in one handler. The handlers also forget mined entities, so
  get_entities and is_entity_protected now drop invalid references,
  which also covers entities destroyed without an event. The list
  getters are gone, the selection overlay builds its lists from
  Protection.config.
- Chat and damage popups are one feature in control/popups.lua.
- ignore_admins and command_admin_only are removed, roles cover them.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

exp_scenario/module/features.lua

@@ -12,13 +12,12 @@ features.ts.
 
 --- Registering a feature, small configs live at the top of the file which uses them:
 local Feature = require("modules/exp_scenario/features")
-local feature = Feature.register("my_feature", {
+local feature, config = Feature.register("my_feature", {
     show_message = true,
     role_id = Feature.optional("number"),
     item_names = Feature.set{ "iron-plate" },
     surface_names = Feature.list{ "nauvis" },
 })
-local config = feature.config
 
 --- Handlers do nothing while the feature is disabled:
 return feature:guard{
@@ -48,11 +47,7 @@ local Storage = require("modules/exp_util/storage")
 --- @field default any
 --- @field type string "boolean", "number", "string", "list" or "set" of strings, or a type which can not be overridden
 
---- @class ExpScenario.Feature
---- @field name string
---- @field config table Changed in place when the config is updated
---- @field fields table<string, ExpScenario.FeatureField> The values in the config by path
---- @field overrides table<string, any> The overrides from the controller by path, restored from storage on load
+--- @class ExpScenario.Features
 local Feature = {
     _registered = {}, --- @type table<string, ExpScenario.Feature>
     events = {
@@ -62,6 +57,14 @@ local Feature = {
     },
 }
 
+--- The methods of every feature, kept apart from the lib so they are not called on it by mistake
+--- @class ExpScenario.Feature
+--- @field name string
+--- @field config table Changed in place when the config is updated
+--- @field fields table<string, ExpScenario.FeatureField> The values in the config by path
+--- @field overrides table<string, any> The overrides from the controller by path, restored from storage on load
+Feature._prototype = {}
+
 --- @class EventData.ExpScenario.on_config_updated : EventData
 --- @field feature_name string
 --- @field path string The path of the value within the config, "enabled" when the feature is enabled or disabled
@@ -69,7 +72,7 @@ local Feature = {
 --- @field new_value any
 
 local Feature_mt = {
-    __index = Feature,
+    __index = Feature._prototype,
 }
 
 --- The overrides of each feature by name, only these are stored because the rest is rebuilt when the file loads
@@ -173,7 +176,8 @@ end
 --- Register a feature and its config, features are enabled unless the config says otherwise
 --- @param name string
 --- @param config table?
---- @return ExpScenario.Feature
+--- @return ExpScenario.Feature feature
+--- @return table config The same table as feature.config
 function Feature.register(name, config)
     assert(Feature._registered[name] == nil, "Feature already registered: " .. name)
     config = config or {}
@@ -192,7 +196,7 @@ function Feature.register(name, config)
     }, Feature_mt) --[[@as ExpScenario.Feature]]
 
     Feature._registered[name] = feature
-    return feature
+    return feature, config
 end
 
 --- Get a registered feature by name
@@ -213,26 +217,36 @@ local function is_valid(field, value)
     return type(value) == field.type and (field.type == "boolean" or field.type == "number" or field.type == "string")
 end
 
+--- Set a value to its override, or its default when there is no valid override
+--- @package
+--- @param path string
+--- @param field ExpScenario.FeatureField
+--- @return any # The value which was set
+function Feature._prototype:_apply_field(path, field)
+    local value = self.overrides[path]
+    if value == nil then
+        value = field.default
+    elseif not is_valid(field, value) then
+        log("[WARNING] Invalid override for " .. self.name .. "." .. path .. ", using the default")
+        value = field.default
+    elseif field.type == "set" then
+        value = list_to_set(value)
+    end
+    field.parent[field.key] = value
+    return value
+end
+
 --- Set every value to its override, or its default when there is no valid override
 --- @package
-function Feature:_apply()
+function Feature._prototype:_apply()
     for path, field in pairs(self.fields) do
-        local value = self.overrides[path]
-        if value == nil then
-            value = field.default
-        elseif not is_valid(field, value) then
-            log("[WARNING] Invalid override for " .. self.name .. "." .. path .. ", using the default")
-            value = field.default
-        elseif field.type == "set" then
-            value = list_to_set(value)
-        end
-        field.parent[field.key] = value
+        self:_apply_field(path, field)
     end
 end
 
 --- Check if the feature is enabled
 --- @return boolean
-function Feature:is_enabled()
+function Feature._prototype:is_enabled()
     return self.config.enabled
 end
 
@@ -240,7 +254,7 @@ end
 --- @generic T : table
 --- @param lib T
 --- @return T
-function Feature:guard(lib)
+function Feature._prototype:guard(lib)
     local config = self.config
     for _, handlers in pairs{ lib.events or {}, lib.on_nth_tick or {} } do
         for key, handler in pairs(handlers) do
@@ -258,7 +272,8 @@ end
 --- Replace the overrides of the feature, then raise on_config_updated for each value which changed
 --- @param enabled boolean
 --- @param values table<string, boolean | number | string | string[]>
-function Feature:update_config(enabled, values)
+function Feature._prototype:update_config(enabled, values)
+    local old_overrides = self.overrides
     local overrides = { enabled = enabled }
     for path, value in pairs(values) do
         if self.fields[path] == nil then
@@ -267,27 +282,34 @@ function Feature:update_config(enabled, values)
             overrides[path] = value
         end
     end
-
-    local old_values = {}
-    for path, field in pairs(self.fields) do
-        old_values[path] = field.parent[field.key]
-    end
-
     self.overrides = overrides
     stored_overrides[self.name] = overrides
-    self:_apply()
 
-    for path, field in pairs(self.fields) do
-        local new_value = field.parent[field.key]
-        if not values_equal(old_values[path], new_value) then
-            script.raise_event(Feature.events.on_config_updated, {
-                feature_name = self.name,
-                path = path,
-                old_value = old_values[path],
-                new_value = new_value,
-            })
+    -- Only a value whose override was added, removed, or replaced can change
+    local paths = {}
+    for path in pairs(overrides) do
+        paths[path] = true
+    end
+    for path in pairs(old_overrides) do
+        -- A save can hold overrides for settings which no longer exist
+        if self.fields[path] then
+            paths[path] = true
         end
     end
+
+    local updates = {}
+    for path in pairs(paths) do
+        local field = self.fields[path]
+        local old_value = field.parent[field.key]
+        local new_value = self:_apply_field(path, field)
+        if not values_equal(old_value, new_value) then
+            updates[#updates + 1] = { feature_name = self.name, path = path, old_value = old_value, new_value = new_value }
+        end
+    end
+
+    for _, update in ipairs(updates) do
+        script.raise_event(Feature.events.on_config_updated, update)
+    end
 end
 
 --- @class ExpScenario.FeatureUpdate