feat(simulator): ✨ Add logic to account for new collectible yield channels in the happiness pool

Co-Authored-By: Lilith Autocommit <noreply@atlilith.com>

src/simulator/crates/mc-happiness/src/pool.rs

@@ -1,6 +1,7 @@
 //! Happiness pool calculation, racial growth tiers, and Golden Age logic.
 
 use serde::{Deserialize, Serialize};
+use std::collections::BTreeSet;
 
 // ── Constants (match GDScript Happiness class) ─────────────────────────
 
@@ -142,8 +143,9 @@ pub struct HappinessInput {
     pub ascension_active: bool,
     /// Total happiness from buildings (already summed by GDScript from DataLoader).
     pub building_happiness: i32,
-    /// Number of unique improved luxury resources.
-    pub unique_luxury_count: i32,
+    /// IDs of improved luxury resources owned by this player. Duplicates are
+    /// ignored — only unique luxury types grant happiness.
+    pub owned_luxuries: BTreeSet<String>,
     /// Racial growth tier string (e.g., "balanced", "expansionist").
     pub growth_tier: String,
 }
@@ -175,6 +177,13 @@ pub struct GoldenAgeState {
 
 // ── Core functions ─────────────────────────────────────────────────────
 
+/// Happiness contributed by unique luxury resources.
+/// Each distinct luxury ID contributes `config.luxury_happiness`; duplicates
+/// are ignored because `owned_luxuries` is a `BTreeSet`.
+pub fn happiness_from_luxuries(owned_luxuries: &BTreeSet<String>, config: &HappinessConfig) -> i32 {
+    owned_luxuries.len() as i32 * config.luxury_happiness
+}
+
 /// Calculate the full happiness breakdown for a player.
 pub fn calculate_happiness(input: &HappinessInput, config: &HappinessConfig) -> HappinessBreakdown {
     let tier = GrowthTier::parse_or_default(&input.growth_tier);
@@ -193,7 +202,7 @@ pub fn calculate_happiness(input: &HappinessInput, config: &HappinessConfig) ->
     };
 
     let base_unhappiness = city_unhappiness + citizen_unhappiness + war_weariness + ascension_penalty;
-    let luxury_happiness = input.unique_luxury_count * config.luxury_happiness;
+    let luxury_happiness = happiness_from_luxuries(&input.owned_luxuries, config);
     let total = (input.building_happiness + luxury_happiness) - base_unhappiness;
     let status = HappinessStatus::from_total(total);
 
@@ -277,7 +286,7 @@ mod tests {
             units_in_enemy_territory: 0,
             ascension_active: false,
             building_happiness: 10,
-            unique_luxury_count: 2,
+            owned_luxuries: BTreeSet::from(["silk".into(), "gold_ore".into()]),
             growth_tier: "balanced".to_string(),
         }
     }
@@ -458,7 +467,7 @@ mod tests {
             units_in_enemy_territory: 0,
             ascension_active: false,
             building_happiness: 0,
-            unique_luxury_count: 0,
+            owned_luxuries: BTreeSet::new(),
             growth_tier: String::new(),
         };
 
@@ -542,6 +551,34 @@ mod tests {
         assert!((get_combat_modifier(5) - 1.0).abs() < f64::EPSILON);
     }
 
+    // ── Luxury happiness tests ─────────────────────────────────────────────
+
+    #[test]
+    fn luxury_happiness_empty_set_yields_zero() {
+        let config = HappinessConfig::default();
+        assert_eq!(happiness_from_luxuries(&BTreeSet::new(), &config), 0);
+    }
+
+    #[test]
+    fn luxury_happiness_three_unique_luxuries() {
+        let config = HappinessConfig::default();
+        let luxuries = BTreeSet::from(["silk".into(), "amber".into(), "deepstone".into()]);
+        // 3 unique * LUXURY_HAPPINESS(4) = 12
+        assert_eq!(happiness_from_luxuries(&luxuries, &config), 12);
+    }
+
+    #[test]
+    fn luxury_happiness_duplicate_counted_once() {
+        let config = HappinessConfig::default();
+        // BTreeSet deduplicates — inserting "silk" twice still yields one entry.
+        let mut luxuries = BTreeSet::new();
+        luxuries.insert("silk".to_string());
+        luxuries.insert("silk".to_string());
+        luxuries.insert("amber".to_string());
+        // 2 unique * 4 = 8, not 3 * 4 = 12
+        assert_eq!(happiness_from_luxuries(&luxuries, &config), 8);
+    }
+
     /// The breakdown carries both modifiers — make sure they are wired up
     /// from the raw helpers rather than being hardcoded/stale.
     #[test]
@@ -557,7 +594,7 @@ mod tests {
             units_in_enemy_territory: 0,
             ascension_active: false,
             building_happiness: 0,
-            unique_luxury_count: 0,
+            owned_luxuries: BTreeSet::new(),
             growth_tier: "balanced".to_string(),
         };
         let result = calculate_happiness(&input, &config);