Merge WI-1 Injectable RNG (PSP1, issue #1) into main

crates/sb-api/src/routes/mod.rs

@@ -25,6 +25,11 @@ use sb_shared::{
 use std::sync::Arc;
 use tokio::sync::RwLock;
 
+fn request_rng() -> rand::rngs::StdRng {
+    use rand::SeedableRng;
+    rand::rngs::StdRng::from_os_rng()
+}
+
 pub(crate) struct AppState {
     users: RwLock<Vec<User>>,
     items: Vec<Item>,
@@ -285,7 +290,10 @@ async fn create_character(
         return Err(axum::http::StatusCode::BAD_REQUEST);
     }
 
-    let mut char = character::create_character(user_id, name, input.race, input.class);
+    let mut char = {
+        let mut rng = request_rng();
+        character::create_character(&mut rng, user_id, name, input.race, input.class)
+    };
 
     {
         let mut id = state.next_char_id.write().await;
@@ -424,6 +432,8 @@ async fn run_adventure(
         .unwrap()
         .as_millis() as i64;
 
+    let mut rng = request_rng();
+
     let (char, enemy_def) = {
         let mut chars = state.characters.write().await;
         let char = chars.iter_mut().find(|c| c.id == char_id)
@@ -439,7 +449,6 @@ async fn run_adventure(
         }
         char.nerve -= zone.nerve_cost;
 
-        let mut rng = rand::rng();
         let enemy = domain::pick_enemy(&mut rng, &zone.encounters, &state.enemies);
         (char.clone(), enemy)
     };
@@ -494,14 +503,13 @@ async fn run_adventure(
             songs::BARD_SONGS.iter().find(|s| s.id == sid).map(|s| s.combat_effect)
         }),
         spell_effect.as_ref(),
-        &mut rand::rng(),
+        &mut rng,
     );
 
     let (loot_names, updated_char) = {
         let mut chars = state.characters.write().await;
         let dropped_ids: Vec<String> = if let Some(c) = chars.iter_mut().find(|c| c.id == char_id) {
             use rand::Rng;
-            let mut rng = rand::rng();
 
             if log.winner == c.name {
                 c.xp += log.xp_gained as i64;

crates/sb-core/src/character.rs

@@ -126,10 +126,15 @@ pub fn training_cost(stat: i64) -> i32 {
     (5.0_f64 * 1.3_f64.powi(scaled)) as i32
 }
 
-pub fn create_character(user_id: u32, name: String, race: Race, class: Class) -> Character {
-    let mut rng = rand::rng();
+pub fn create_character(
+    rng: &mut impl rand::Rng,
+    user_id: u32,
+    name: String,
+    race: Race,
+    class: Class,
+) -> Character {
     let class_str = class.as_str().to_string();
-    let stats = roll_stats(&mut rng, &race);
+    let stats = roll_stats(rng, &race);
     let max_hp = calc_max_hp(&class, &stats);
     let max_energy = calc_max_energy(&class);
     let max_nerve = calc_max_nerve(&class);
@@ -412,4 +417,28 @@ mod tests {
         assert!(dwarf.strength > human.strength);
         assert!(dwarf.intelligence < human.intelligence);
     }
+
+    #[test]
+    fn create_character_is_deterministic_under_seeded_rng() {
+        use rand::SeedableRng;
+        let first = create_character(
+            &mut rand::rngs::StdRng::seed_from_u64(42),
+            7,
+            "Twin".into(),
+            Race::Human,
+            Class::Warrior,
+        );
+        let second = create_character(
+            &mut rand::rngs::StdRng::seed_from_u64(42),
+            7,
+            "Twin".into(),
+            Race::Human,
+            Class::Warrior,
+        );
+        assert_eq!(format!("{:?}", first.stats), format!("{:?}", second.stats));
+        assert_eq!(first.hp, second.hp);
+        assert_eq!(first.max_hp, second.max_hp);
+        assert_eq!(first.energy, second.energy);
+        assert_eq!(first.nerve, second.nerve);
+    }
 }