Fix/incorrect memory state inference for incomplete review history (#…

…3599)

make ci happy

rslib/src/scheduler/fsrs/memory_state.rs

@@ -286,7 +286,8 @@ pub(crate) fn single_card_revlog_to_item(
     }
     let first_review = entries
         .iter()
-        .find(|e| e.button_chosen > 0)
+        // ignore manual and rescheduled revlogs and revlogs before the cutoff
+        .find(|e| e.button_chosen > 0 && e.id.0 >= ignore_revlogs_before.0)
         .map(|e| FirstReview {
             interval: e.interval.max(1) as f32,
             ease_factor: if e.ease_factor == 0 {
@@ -307,11 +308,15 @@ pub(crate) fn single_card_revlog_to_item(
             }))
         } else if let Some(first_review) = first_review {
             // the revlog has been truncated, but not fully
-            let starting_state = fsrs.memory_state_from_sm2(
+            let mut starting_state = fsrs.memory_state_from_sm2(
                 first_review.ease_factor,
                 first_review.interval,
                 historical_retention,
             )?;
+            // if the ease factor is less than 1.1, the revlog entry is generated by FSRS
+            if first_review.ease_factor <= 1.1 {
+                starting_state.difficulty = (first_review.ease_factor - 0.1) * 9.0 + 1.0;
+            }
             item.reviews.remove(0);
             if item.reviews.is_empty() {
                 Ok(None)