From d95f385418d3be12ec5d551dee06f659d71bf623 Mon Sep 17 00:00:00 2001
From: Eremey Valetov <eremey@valetov.com>
Date: Mon, 16 Feb 2026 18:14:03 -0500
Subject: [PATCH] feat(moeo): add finalize() lifecycle hook for algorithm
 post-processing

Add virtual finalize() and hasFinalize() to moeoAlgo/moeoPopAlgo hierarchy.
NSGA-II implements finalize() to recompute fitness and diversity assignments
after population modifications (e.g. immigrant integration in island model).
---
 moeo/src/algo/moeoAlgo.h    |  8 +++++++-
 moeo/src/algo/moeoNSGAII.h  | 11 +++++++++++
 moeo/src/algo/moeoPopAlgo.h | 10 +++++++++-
 3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/moeo/src/algo/moeoAlgo.h b/moeo/src/algo/moeoAlgo.h
index 39b01f394..3458ec0c4 100644
--- a/moeo/src/algo/moeoAlgo.h
+++ b/moeo/src/algo/moeoAlgo.h
@@ -42,6 +42,12 @@
  * Abstract class for multi-objective algorithms.
  */
 class moeoAlgo
-  {};
+{
+public:
+    virtual ~moeoAlgo() = default;
+
+    /** Whether this algorithm supports finalize() for post-integration updates. */
+    virtual bool hasFinalize() const { return false; }
+};
 
 #endif /*MOEOALGO_H_*/
diff --git a/moeo/src/algo/moeoNSGAII.h b/moeo/src/algo/moeoNSGAII.h
index 137592865..68e0cd200 100644
--- a/moeo/src/algo/moeoNSGAII.h
+++ b/moeo/src/algo/moeoNSGAII.h
@@ -148,6 +148,17 @@ public:
         while (continuator (_pop));
     }
 
+    /**
+     * Recompute fitness and diversity assignments on the population.
+     * Useful after integrating immigrants from an island model.
+     * @param _pop the population to finalize
+     */
+    void finalize(eoPop<MOEOT>& _pop) override {
+        fitnessAssignment(_pop);
+        diversityAssignment(_pop);
+    }
+
+    bool hasFinalize() const override { return true; }
 
 protected:
 
diff --git a/moeo/src/algo/moeoPopAlgo.h b/moeo/src/algo/moeoPopAlgo.h
index a3b948a3e..1caa40744 100644
--- a/moeo/src/algo/moeoPopAlgo.h
+++ b/moeo/src/algo/moeoPopAlgo.h
@@ -47,6 +47,14 @@
  */
 template < class MOEOT >
 class moeoPopAlgo : public moeoAlgo, public eoAlgo < MOEOT >
-  {};
+{
+public:
+    /**
+     * Recompute fitness/diversity after external population changes (e.g. immigrant integration).
+     * Default implementation is a no-op. Override in subclasses that need it.
+     * @param _pop the population to finalize
+     */
+    virtual void finalize(eoPop<MOEOT>&) {}
+};
 
 #endif /*MOEOPOPALGO_H_*/