refactor(time_slice): add convergence field, rename iterate_to_convergence

TimeSlice<T> gains a pub(crate) convergence: ConvergenceOptions field
set at construction. TimeSlice::new now takes it as a third parameter
(breaking change to the pub constructor, acceptable in 0.1.x).
History::add_events_with_prior passes self.convergence so the propagated
value reaches every TimeSlice. The pre-existing convergence-the-method
is renamed to iterate_to_convergence to disambiguate from the new
convergence-the-field.

The field is wired but not yet read by inference -- the three
Game::*_with_arena callsites in time_slice.rs still hardcode
ConvergenceOptions::default(). Task 2 changes that. Bit-equal because
the propagated value equals the hardcoded value end-to-end.

Also updated benches/batch.rs which has a fourth TimeSlice::new
callsite (not enumerated in the plan -- only src/ files were).

benches/batch.rs

@@ -1,7 +1,7 @@
 use criterion::{Criterion, criterion_group, criterion_main};
 use trueskill_tt::{
-    BETA, Competitor, EventKind, GAMMA, KeyTable, MU, P_DRAW, Rating, SIGMA, TimeSlice,
+    BETA, Competitor, ConvergenceOptions, EventKind, GAMMA, KeyTable, MU, P_DRAW, Rating, SIGMA,
-    drift::ConstantDrift, gaussian::Gaussian, storage::CompetitorStore,
+    TimeSlice, drift::ConstantDrift, gaussian::Gaussian, storage::CompetitorStore,
 };
 
 fn criterion_benchmark(criterion: &mut Criterion) {
@@ -35,7 +35,7 @@ fn criterion_benchmark(criterion: &mut Criterion) {
 
     let kinds = vec![EventKind::Ranked; composition.len()];
 
-    let mut time_slice = TimeSlice::new(1, P_DRAW);
+    let mut time_slice = TimeSlice::new(1, P_DRAW, ConvergenceOptions::default());
     time_slice.add_events(composition, results, weights, kinds, &agents);
 
     criterion.bench_function("Batch::iteration", |b| {

src/history.rs

@@ -594,7 +594,7 @@ impl<T: Time, D: Drift<T>, O: Observer<T>, K: Eq + Hash + Clone> History<T, D, O
                     agent.message = time_slice.forward_prior_out(&agent_idx);
                 }
             } else {
-                let mut time_slice = TimeSlice::new(t, self.p_draw);
+                let mut time_slice = TimeSlice::new(t, self.p_draw, self.convergence);
                 time_slice.add_events(composition, results, weights, kinds_chunk, &self.agents);
 
                 self.time_slices.insert(k, time_slice);

src/time_slice.rs

@@ -175,17 +175,20 @@ pub struct TimeSlice<T: Time = i64> {
     pub(crate) skills: SkillStore,
     pub(crate) time: T,
     p_draw: f64,
+    #[allow(dead_code)]
+    pub(crate) convergence: crate::ConvergenceOptions,
     arena: ScratchArena,
     pub(crate) color_groups: ColorGroups,
 }
 
 impl<T: Time> TimeSlice<T> {
-    pub fn new(time: T, p_draw: f64) -> Self {
+    pub fn new(time: T, p_draw: f64, convergence: crate::ConvergenceOptions) -> Self {
         Self {
             events: Vec::new(),
             skills: SkillStore::new(),
             time,
             p_draw,
+            convergence,
             arena: ScratchArena::new(),
             color_groups: ColorGroups::new(),
         }
@@ -444,7 +447,10 @@ impl<T: Time> TimeSlice<T> {
     }
 
     #[allow(dead_code)]
-    pub(crate) fn convergence<D: Drift<T>>(&mut self, agents: &CompetitorStore<T, D>) -> usize {
+    pub(crate) fn iterate_to_convergence<D: Drift<T>>(
+        &mut self,
+        agents: &CompetitorStore<T, D>,
+    ) -> usize {
         let epsilon = 1e-6;
         let iterations = 20;
 
@@ -643,7 +649,7 @@ mod tests {
             );
         }
 
-        let mut time_slice = TimeSlice::new(0i64, 0.0);
+        let mut time_slice = TimeSlice::new(0i64, 0.0, crate::ConvergenceOptions::default());
 
         time_slice.add_events(
             vec![
@@ -690,7 +696,7 @@ mod tests {
             epsilon = 1e-6
         );
 
-        assert_eq!(time_slice.convergence(&agents), 1);
+        assert_eq!(time_slice.iterate_to_convergence(&agents), 1);
     }
 
     #[test]
@@ -720,7 +726,7 @@ mod tests {
             );
         }
 
-        let mut time_slice = TimeSlice::new(0i64, 0.0);
+        let mut time_slice = TimeSlice::new(0i64, 0.0, crate::ConvergenceOptions::default());
 
         time_slice.add_events(
             vec![
@@ -752,7 +758,7 @@ mod tests {
             epsilon = 1e-6
         );
 
-        assert!(time_slice.convergence(&agents) > 1);
+        assert!(time_slice.iterate_to_convergence(&agents) > 1);
 
         let post = time_slice.posteriors();
 
@@ -800,7 +806,7 @@ mod tests {
             );
         }
 
-        let mut time_slice = TimeSlice::new(0i64, 0.0);
+        let mut time_slice = TimeSlice::new(0i64, 0.0, crate::ConvergenceOptions::default());
 
         time_slice.add_events(
             vec![
@@ -814,7 +820,7 @@ mod tests {
             &agents,
         );
 
-        time_slice.convergence(&agents);
+        time_slice.iterate_to_convergence(&agents);
 
         let post = time_slice.posteriors();
 
@@ -848,7 +854,7 @@ mod tests {
 
         assert_eq!(time_slice.events.len(), 6);
 
-        time_slice.convergence(&agents);
+        time_slice.iterate_to_convergence(&agents);
 
         let post = time_slice.posteriors();
 
@@ -898,7 +904,7 @@ mod tests {
             );
         }
 
-        let mut ts = TimeSlice::new(0i64, 0.0);
+        let mut ts = TimeSlice::new(0i64, 0.0, crate::ConvergenceOptions::default());
 
         ts.add_events(
             vec![