Protect action identity from mutation

Keep action identity and display metadata
constructor-set so registry keys cannot drift
from the objects they index.

Require sources to publish unique ownership while
the registry retains shared keepalive for runs.

Preserve opaque IDs and persisted state keys.

src/slic3r/GUI/ActionRegistry.hpp

@@ -33,11 +33,9 @@ struct AppActionRunResult
 // UnsavedChangesDialog's exit-action enum, and this header reaches most GUI TUs.
 struct AppAction
 {
-    std::string id;           // speed_dial_action_id(...) - stable identity + AppConfig key
-    std::string title;        // display name
-    // Where the action comes from. Each subclass sets it in its constructor, so the
-    // base cannot be built without one.
-    std::string source;
+    const std::string& id() const { return m_id; }
+    const std::string& title() const { return m_title; }
+    const std::string& source() const { return m_source; }
 
     // seeded from AppConfig for the snapshot / sort:
     bool        favourite = false;
@@ -48,9 +46,15 @@ struct AppAction
     virtual AppActionRunResult run() const = 0; // re-resolves + runs (UI thread)
 
 protected:
-    // why: protected + no default forces every subclass to supply id/title/source.
+    // The definition is constructor-set and immutable. Refreshes replace an action
+    // instead of mutating identity after the registry has indexed it by id.
     AppAction(std::string id, std::string title, std::string source)
-        : id(std::move(id)), title(std::move(title)), source(std::move(source)) {}
+        : m_id(std::move(id)), m_title(std::move(title)), m_source(std::move(source)) {}
+
+private:
+    std::string m_id;       // speed_dial_action_id(...) - stable identity + AppConfig key
+    std::string m_title;    // display name
+    std::string m_source;   // display name of the action's source
 };
 
 // Generic sink and single owner of runnable actions for the app session.
@@ -74,9 +78,9 @@ public:
     // until init() starts it.
     void add_source(std::unique_ptr<IActionSource> source);
 
-    // Seeds persisted state, then inserts the action or replaces the action with the
-    // same id. A null action is ignored.
-    void upsert(std::shared_ptr<AppAction> action);
+    // Takes ownership, seeds persisted state, then inserts the action or replaces
+    // the action with the same id. A null action is ignored.
+    void upsert(std::unique_ptr<AppAction> action);
 
     // Removes the action with this id. Missing ids are a harmless no-op.
     void remove(const std::string& id);