Fix world generation interface architecture

- Simplify IWorldGenerationFunction interface (5 required + 4 optional methods)
- Remove over-engineered methods (getProducedData, getRequiredPreviousFunctions, canExecute)
- Correct execute() signature to match implementations: execute(WorldData&, PlanetaryCore&)
- Add UniversalRegionFusionFunctionAdapter wrapper for template compatibility
- Update all 8 Phase 0/1 functions to implement corrected interface
- Delete unnecessary AWorldGenerationFunction abstract class

Phase 0 (2/2): InitializeWorldTerrain, InitializePlanetaryCore
Phase 1 (6/6): MeteoriteImpact, ImpactEffects, PlanetaryDifferentiation,
               VolcanicRedistribution, Cooling, UniversalRegionFusion

All functions now properly inherit from IWorldGenerationFunction with
consistent configure/execute pattern.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/modules/world-generation-realist/include/WorldGenerationFunctions/CoolingPhaseFunction.h

@@ -1,6 +1,8 @@
 #pragma once
 
+#include "IWorldGenerationFunction.h"
 #include "PlanetaryCore.h"
+#include "WorldData.h"
 #include "warfactory/IDataNode.h"
 #include <vector>
 
@@ -20,7 +22,7 @@ namespace warfactory {
  *
  * Process: Surface cools → Energy accumulated → Split between space loss and core transfer
  */
-class CoolingPhaseFunction {
+class CoolingPhaseFunction : public IWorldGenerationFunction {
 private:
     float surface_cooling_rate_per_cycle;         // °C reduction per cycle for surface tiles (base rate)
     float energy_to_core_ratio;                   // Fraction of accumulated energy transferred to core
@@ -34,24 +36,18 @@ public:
     CoolingPhaseFunction();
 
     // ========================================
-    // CONFIGURATION
+    // IWorldGenerationFunction Implementation
     // ========================================
 
-    /**
-     * @brief Configure cooling process from JSON parameters
-     * @param config_node JSON configuration containing gradual_cooling parameters
-     * Expected structure:
-     * {
-     *   "surface_cooling_rate_per_cycle": 50,
-     *   "energy_to_core_ratio": 0.3,
-     *   "energy_to_space_ratio": 0.7,
-     *   "minimum_surface_temperature": -273,
-     *   "minimum_core_temperature": 1000,
-     *   "optimal_cooling_core_temperature": 2000,
-     *   "reference_surface_temperature": 1000
-     * }
-     */
-    void configure(const IDataNode& config_node);
+    void configure(const IDataNode& config) override;
+    void execute(WorldData& world, PlanetaryCore& core) override;
+    std::string getStepName() const override;
+    bool isConfigured() const override;
+    void reset() override;
+
+    // ========================================
+    // CONFIGURATION (Advanced)
+    // ========================================
 
     /**
      * @brief Set surface cooling rate per geological cycle

src/modules/world-generation-realist/include/WorldGenerationFunctions/IWorldGenerationFunction.h

@@ -1,10 +1,13 @@
 #pragma once
 
 #include <string>
-#include <vector>
 #include "warfactory/IDataNode.h"
 
-class WorldData;
+// Forward declarations
+namespace warfactory {
+    class WorldData;
+    class PlanetaryCore;
+}
 
 namespace warfactory {
 
@@ -13,34 +16,81 @@ namespace warfactory {
  *
  * Each function represents a specific operation like crater generation,
  * volcanic activity, or meteorite impacts within a broader phase.
+ *
+ * PATTERN: Configure-Execute
+ * 1. configure(config) - Load parameters from JSON (called once)
+ * 2. execute(world, core) - Apply generation to world data (can be called multiple times)
+ * 3. reset() - Clear state for re-execution
  */
 class IWorldGenerationFunction {
 public:
     virtual ~IWorldGenerationFunction() = default;
 
-    virtual std::string getFunctionName() const = 0;
+    /**
+     * @brief Configure the function with JSON parameters
+     * @param config Configuration node from Regular_world.json
+     *
+     * Called ONCE before execution to load all parameters.
+     */
+    virtual void configure(const IDataNode& config) = 0;
 
-    virtual bool execute(WorldData& world, const IDataNode& config) = 0;
+    /**
+     * @brief Execute the generation function
+     * @param world World terrain data to modify
+     * @param core Planetary core data to modify
+     *
+     * Can be called multiple times after configuration.
+     * Modifies world terrain and/or planetary core based on function purpose.
+     */
+    virtual void execute(WorldData& world, PlanetaryCore& core) = 0;
 
-    virtual bool canExecute(const WorldData& world) const = 0;
+    /**
+     * @brief Get the name of this generation step
+     * @return Step name matching Regular_world.json "name" field
+     */
+    virtual std::string getStepName() const = 0;
 
-    virtual float getProgress() const = 0;
-
-    virtual bool isComplete() const = 0;
+    /**
+     * @brief Check if function has been properly configured
+     * @return True if configure() was called successfully
+     */
+    virtual bool isConfigured() const = 0;
 
+    /**
+     * @brief Reset function state for re-execution
+     *
+     * Clears any internal state but keeps configuration.
+     * After reset(), configure() must be called again.
+     */
     virtual void reset() = 0;
 
-    virtual std::string getFunctionDescription() const = 0;
+    // ========================================
+    // OPTIONAL: Progress Tracking (for UI/debug)
+    // ========================================
 
-    virtual float getEstimatedDuration() const = 0;
+    /**
+     * @brief Get execution progress (optional - default implementation)
+     * @return Progress from 0.0 (not started) to 1.0 (complete)
+     */
+    virtual float getProgress() const { return 0.0f; }
 
-    virtual std::vector<std::string> getRequiredPreviousFunctions() const = 0;
+    /**
+     * @brief Check if execution is complete (optional - default implementation)
+     * @return True if function finished execution
+     */
+    virtual bool isComplete() const { return false; }
 
-    virtual std::vector<std::string> getProducedData() const = 0;
+    /**
+     * @brief Get human-readable description (optional - default implementation)
+     * @return Description of what this function does
+     */
+    virtual std::string getFunctionDescription() const { return getStepName(); }
 
-    virtual int getFunctionOrder() const = 0;
-
-    virtual std::string getParentPhase() const = 0;
+    /**
+     * @brief Get parent phase name (optional - default implementation)
+     * @return Phase name from Regular_world.json
+     */
+    virtual std::string getParentPhase() const { return "unknown"; }
 };
 
 } // namespace warfactory

src/modules/world-generation-realist/include/WorldGenerationFunctions/ImpactEffectsApplicationFunction.h

@@ -32,7 +32,10 @@ private:
 public:
     ImpactEffectsApplicationFunction();
 
-    // Inherited from IWorldGenerationFunction
+    // ========================================
+    // IWorldGenerationFunction Implementation
+    // ========================================
+
     void configure(const IDataNode& config) override;
     void execute(WorldData& world, PlanetaryCore& core) override;
     std::string getStepName() const override;

src/modules/world-generation-realist/include/WorldGenerationFunctions/InitializePlanetaryCoreFunction.h

@@ -23,7 +23,10 @@ private:
 public:
     InitializePlanetaryCoreFunction();
 
-    // Inherited from IWorldGenerationFunction
+    // ========================================
+    // IWorldGenerationFunction Implementation
+    // ========================================
+
     void configure(const IDataNode& config) override;
     void execute(WorldData& world, PlanetaryCore& core) override;
     std::string getStepName() const override;

src/modules/world-generation-realist/include/WorldGenerationFunctions/InitializeWorldTerrainFunction.h

@@ -22,7 +22,10 @@ private:
 public:
     InitializeWorldTerrainFunction();
 
-    // Inherited from IWorldGenerationFunction
+    // ========================================
+    // IWorldGenerationFunction Implementation
+    // ========================================
+
     void configure(const IDataNode& config) override;
     void execute(WorldData& world, PlanetaryCore& core) override;
     std::string getStepName() const override;

src/modules/world-generation-realist/include/WorldGenerationFunctions/MeteoriteImpactGenerationFunction.h

@@ -35,7 +35,10 @@ private:
 public:
     MeteoriteImpactGenerationFunction();
 
-    // Inherited from IWorldGenerationFunction
+    // ========================================
+    // IWorldGenerationFunction Implementation
+    // ========================================
+
     void configure(const IDataNode& config) override;
     void execute(WorldData& world, PlanetaryCore& core) override;
     std::string getStepName() const override;

src/modules/world-generation-realist/include/WorldGenerationFunctions/PlanetaryDifferentiationFunction.h

@@ -1,6 +1,8 @@
 #pragma once
 
+#include "IWorldGenerationFunction.h"
 #include "PlanetaryCore.h"
+#include "WorldData.h"
 #include "warfactory/IDataNode.h"
 #include "warfactory/ResourceRegistry.h"
 #include <unordered_map>
@@ -23,7 +25,7 @@ namespace warfactory {
  * Process operates over 100M year cycles during early planetary formation when
  * core is still molten and gravitational sorting is active.
  */
-class PlanetaryDifferentiationFunction {
+class PlanetaryDifferentiationFunction : public IWorldGenerationFunction {
 private:
     float heavy_metal_threshold_density;           // g/cm³ - threshold for heavy metal classification
     float sinking_rate_per_cycle;                  // Fraction of heavy metals that sink per cycle
@@ -42,20 +44,18 @@ public:
     PlanetaryDifferentiationFunction();
 
     // ========================================
-    // CONFIGURATION
+    // IWorldGenerationFunction Implementation
     // ========================================
 
-    /**
-     * @brief Configure differentiation process from JSON parameters
-     * @param config_node JSON configuration containing heavy_metal_sinking parameters
-     * Expected structure:
-     * {
-     *   "heavy_metal_threshold_density": 5.0,
-     *   "sinking_rate_per_cycle": 0.7,
-     *   "differentiation_efficiency": 1.0
-     * }
-     */
-    void configure(const IDataNode& config_node);
+    void configure(const IDataNode& config) override;
+    void execute(WorldData& world, PlanetaryCore& core) override;
+    std::string getStepName() const override;
+    bool isConfigured() const override;
+    void reset() override;
+
+    // ========================================
+    // CONFIGURATION (Advanced)
+    // ========================================
 
     /**
      * @brief Set density threshold for heavy metal classification

src/modules/world-generation-realist/include/WorldGenerationFunctions/UniversalRegionFusionFunctionAdapter.h

@@ -0,0 +1,118 @@
+#pragma once
+
+#include "IWorldGenerationFunction.h"
+#include "UniversalRegionFusionFunction.h"
+#include "../WorldData.h"
+#include "../PlanetaryCore.h"
+#include "../TectonicRegion.h"
+#include "../ClimateRegion.h"
+
+namespace warfactory {
+
+/**
+ * @brief Adapter wrapper for UniversalRegionFusionFunction template
+ *
+ * Since UniversalRegionFusionFunction is a template that operates on different
+ * region types, this adapter provides the standard IWorldGenerationFunction
+ * interface for integration into the world generation pipeline.
+ *
+ * The adapter manages separate fusion instances for each region type:
+ * - TectonicRegion (plate boundaries, continental drift)
+ * - ClimateRegion (weather patterns, climate zones)
+ * - Future region types can be added as needed
+ */
+class UniversalRegionFusionFunctionAdapter : public IWorldGenerationFunction {
+private:
+    // Template instances for different region types
+    UniversalRegionFusionFunction<TectonicRegion> tectonic_fusion;
+    UniversalRegionFusionFunction<ClimateRegion> climate_fusion;
+
+    // Cycle duration for fusion calculations
+    double current_cycle_duration_years;
+
+    // Configuration state
+    bool configured;
+
+public:
+    /**
+     * @brief Construct adapter with step name
+     */
+    UniversalRegionFusionFunctionAdapter();
+
+    // ========================================
+    // IWorldGenerationFunction Implementation
+    // ========================================
+
+    /**
+     * @brief Configure all fusion instances with same parameters
+     * @param config Configuration node from Regular_world.json
+     *
+     * Expected structure:
+     * {
+     *   "enabled": true,
+     *   "radius_calculation": "natural_logarithm",
+     *   "base_radius": 1.5,
+     *   "mass_reference": 5.0,
+     *   "fusion_threshold_percentage": 0.3,
+     *   "use_largest_radius_for_threshold": true,
+     *   "weighted_position_update": true,
+     *   "mass_combination": "additive",
+     *   "applies_to_all_region_types": true
+     * }
+     */
+    void configure(const IDataNode& config) override;
+
+    /**
+     * @brief Execute fusion for all region types in the world
+     * @param world World data containing all region collections
+     * @param core Planetary core (not used by fusion, but required by interface)
+     *
+     * Applies fusion to:
+     * - Tectonic regions (continental plates, oceanic plates, volcanic zones)
+     * - Climate regions (weather cells, wind patterns, climate zones)
+     */
+    void execute(WorldData& world, PlanetaryCore& core) override;
+
+    /**
+     * @brief Get the name of this generation step
+     * @return "universal_region_fusion"
+     */
+    std::string getStepName() const override;
+
+    /**
+     * @brief Check if function has been properly configured
+     * @return True if configure() was called successfully
+     */
+    bool isConfigured() const override;
+
+    /**
+     * @brief Reset all fusion instances
+     *
+     * Clears state and sets configured = false
+     */
+    void reset() override;
+
+private:
+    /**
+     * @brief Apply fusion to tectonic regions
+     * @param world World data to process
+     * @return Number of fusion operations performed
+     */
+    int applyTectonicFusion(WorldData& world);
+
+    /**
+     * @brief Apply fusion to climate regions
+     * @param world World data to process
+     * @return Number of fusion operations performed
+     */
+    int applyClimateFusion(WorldData& world);
+
+    /**
+     * @brief Extract cycle duration from configuration if present
+     * @param config Configuration node
+     * @return Cycle duration in years (default: 100 million)
+     */
+    double extractCycleDuration(const IDataNode& config);
+};
+
+} // namespace warfactory

src/modules/world-generation-realist/include/WorldGenerationFunctions/VolcanicRedistributionFunction.h

@@ -25,7 +25,10 @@ private:
 public:
     VolcanicRedistributionFunction();
 
-    // Inherited from IWorldGenerationFunction
+    // ========================================
+    // IWorldGenerationFunction Implementation
+    // ========================================
+
     void configure(const IDataNode& config) override;
     void execute(WorldData& world, PlanetaryCore& core) override;
     std::string getStepName() const override;