feat(@projects/@magic-civilization): ✨ add city-center baseline constants

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

src/simulator/crates/mc-city/src/city.rs

@@ -105,6 +105,36 @@ impl TileYield {
 /// median p0_pop_peak ≥ 30 at T300 (Civ5-like capital size).
 pub const FOOD_PER_POP: f64 = 1.0;
 
+// ── City-center baseline yields ─────────────────────────────────────────────
+//
+// Every city center tile produces these yields regardless of worked-tile data.
+// The food baseline is set to 4 (not 3) so pop-1 cities have +3 surplus against
+// FOOD_PER_POP=1, reaching growth threshold 15 in 5 turns — the tempo Civ5
+// ships. Science baseline 5 (not 1) calibrates tech flow so the ≥20-techs-by-
+// T150 checklist target hits from a single city without requiring a library.
+
+/// City-center baseline food yield — ensures pop-1 cities grow at a Civ5
+/// tempo without needing any tile yields attached.
+pub const CITY_CENTER_BASELINE_FOOD: f64 = 4.0;
+
+/// City-center baseline production yield — 2 lets pop-1 cities queue a
+/// warrior or worker without tile yields; any boost comes from tiles.
+pub const CITY_CENTER_BASELINE_PRODUCTION: f64 = 2.0;
+
+/// City-center baseline gold yield — 3 keeps a fresh city cash-positive
+/// against unit upkeep until marketplace/tile income takes over.
+pub const CITY_CENTER_BASELINE_GOLD: f64 = 3.0;
+
+/// City-center baseline science yield — calibrated to hit the ≥20 techs /
+/// 150 turns checklist target from a single city. Was 1.0, bumped to 5.0
+/// when tech costs scale 20..320 across the 50-tech tree; at 1/turn capital
+/// empires capped at ~7 techs by T150.
+pub const CITY_CENTER_BASELINE_SCIENCE: f64 = 5.0;
+
+/// City-center baseline culture yield — drives first border expansion at
+/// roughly 5 turns against the linear threshold `5+n`.
+pub const CITY_CENTER_BASELINE_CULTURE: f64 = 2.0;
+
 /// Fraction of the previous growth threshold retained as stored food on
 /// growth (Civ5-style always-on granary effect). Each new pop starts with a
 /// head-start toward the next pop, cutting the cumulative food needed to
@@ -313,23 +343,17 @@ impl City {
     /// Compute aggregate city yields from worked tile yields plus building bonuses.
     /// The `tile_yields` slice should contain yields for all owned tiles.
     /// Only tiles in `worked_tiles` are summed (citizens working them).
-    /// The city center tile always produces a base 3 food, 2 production, 1 gold,
-    /// 1 science, 2 culture even if no tile yield data is provided for it.
+    /// The city center tile always produces a baseline {food, production,
+    /// gold, science, culture} regardless of tile-yield data — see the
+    /// `CITY_CENTER_*` constants below for the values and their rationale.
     pub fn get_yields(&self, tile_yields: &[TileYield]) -> CityYields {
         let mut yields = CityYields::default();
 
-        // City center baseline: 3f/2p/1g/1s/2c. The 3 food ensures pop-1 cities
-        // have +1.0 surplus (FOOD_PER_POP=2.0) so they always grow. 2 culture
-        // means first border expansion in ~5 turns.
-        yields.food += 3.0;
-        yields.production += 2.0;
-        yields.gold += 3.0;
-        // Science baseline 5.0 (was 1.0): tech costs in age-of-dwarves scale
-        // 20..320 across a 50-tech tree, so 1 sci/turn/city caps empires at
-        // ~7 techs by T150. 5 sci/turn/city reaches the ≥20 techs/150-turn
-        // target from a single city even without library; library adds +2.
-        yields.science += 5.0;
-        yields.culture += 2.0;
+        yields.food += CITY_CENTER_BASELINE_FOOD;
+        yields.production += CITY_CENTER_BASELINE_PRODUCTION;
+        yields.gold += CITY_CENTER_BASELINE_GOLD;
+        yields.science += CITY_CENTER_BASELINE_SCIENCE;
+        yields.culture += CITY_CENTER_BASELINE_CULTURE;
 
         // Sum worked tile yields
         for wt in &self.worked_tiles {
@@ -736,12 +760,12 @@ mod tests {
         city.worked_tiles = vec![(5, 5), (6, 5)];
         let ty = sample_tile_yields();
         let yields = city.get_yields(&ty);
-        // Center baseline: 4f + 2p + 3g + 1s
-        // Center tile yield: 2f + 1p + 0g
-        // (6,5) tile: 3f + 0p + 1g
-        assert_eq!(yields.food, 3.0 + 2.0 + 3.0);
-        assert_eq!(yields.production, 2.0 + 1.0 + 0.0);
-        assert_eq!(yields.gold, 3.0 + 0.0 + 1.0);
+        // Center baseline: 4f + 2p + 3g + 5s + 2c
+        // Center tile yield (worked): 2f + 1p + 0g
+        // (6,5) tile yield (worked):  3f + 0p + 1g
+        assert_eq!(yields.food, CITY_CENTER_BASELINE_FOOD + 2.0 + 3.0);
+        assert_eq!(yields.production, CITY_CENTER_BASELINE_PRODUCTION + 1.0 + 0.0);
+        assert_eq!(yields.gold, CITY_CENTER_BASELINE_GOLD + 0.0 + 1.0);
     }
 
     #[test]