From fe5dfe9ec23130fa4616a4e91f10e5216df19d9d Mon Sep 17 00:00:00 2001
From: Jarrett Ye <jarrett.ye@outlook.com>
Date: Fri, 27 Jun 2025 17:50:29 +0800
Subject: [PATCH] Fix/update card.decay in card_state_updater (#4127)

---
 rslib/src/scheduler/answering/mod.rs     | 5 ++++-
 rslib/src/scheduler/fsrs/memory_state.rs | 2 +-
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/rslib/src/scheduler/answering/mod.rs b/rslib/src/scheduler/answering/mod.rs
index d498f7eaf..8ae1518d0 100644
--- a/rslib/src/scheduler/answering/mod.rs
+++ b/rslib/src/scheduler/answering/mod.rs
@@ -33,6 +33,7 @@ use crate::deckconfig::LeechAction;
 use crate::decks::Deck;
 use crate::prelude::*;
 use crate::scheduler::fsrs::memory_state::fsrs_item_for_memory_state;
+use crate::scheduler::fsrs::memory_state::get_decay_from_params;
 use crate::scheduler::states::PreviewState;
 use crate::search::SearchNode;
 
@@ -433,7 +434,9 @@ impl Collection {
         let config = self.home_deck_config(deck.config_id(), card.original_deck_id)?;
         let fsrs_enabled = self.get_config_bool(BoolKey::Fsrs);
         let fsrs_next_states = if fsrs_enabled {
-            let fsrs = FSRS::new(Some(config.fsrs_params()))?;
+            let params = config.fsrs_params();
+            let fsrs = FSRS::new(Some(params))?;
+            card.decay = Some(get_decay_from_params(params));
             if card.memory_state.is_none() && card.ctype != CardType::New {
                 // Card has been moved or imported into an FSRS deck after params were set,
                 // and will need its initial memory state to be calculated based on review
diff --git a/rslib/src/scheduler/fsrs/memory_state.rs b/rslib/src/scheduler/fsrs/memory_state.rs
index b592e4da4..425d8da69 100644
--- a/rslib/src/scheduler/fsrs/memory_state.rs
+++ b/rslib/src/scheduler/fsrs/memory_state.rs
@@ -32,7 +32,7 @@ pub struct ComputeMemoryProgress {
 
 /// Helper function to determine the appropriate decay value based on FSRS
 /// parameters
-fn get_decay_from_params(params: &[f32]) -> f32 {
+pub(crate) fn get_decay_from_params(params: &[f32]) -> f32 {
     if params.is_empty() {
         FSRS6_DEFAULT_DECAY // default decay for FSRS-6
     } else if params.len() < 21 {