fix(config): make default seed deterministic

src/encoding/config.rs

@@ -82,7 +82,7 @@ pub struct Config {
 }
 
 /// Reasonable starting point: dictionary capped at 4 096 tokens, dynamic
-/// threshold sampling 15 %.
+/// threshold sampling 15 %, and deterministic sampling with seed 42.
 pub const DEFAULT_CONFIG: Config = Config {
     max_dict_bits: match MaxDictBits::new(12) {
         Ok(b) => b,
@@ -92,7 +92,7 @@ pub const DEFAULT_CONFIG: Config = Config {
         Ok(t) => t,
         Err(_) => unreachable!(),
     },
-    seed: None,
+    seed: Some(42),
 };
 
 impl Default for Config {
@@ -186,3 +186,14 @@ impl From<Config> for TrainingConfig {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn default_config_uses_a_deterministic_seed() {
+        assert_eq!(DEFAULT_CONFIG.seed, Some(42));
+        assert_eq!(Config::default().seed, Some(42));
+    }
+}