Update FSRS decay defaults to use constants for better maintainabilit…

…y and clarity
ankitects · dae · Apr 25, 2025 · Apr 3, 2025 · Apr 3, 2025 · Apr 17, 2025
commit 4b00a757e0302efef2438d58a569f181ae1e51ac
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
@@ -37,7 +37,7 @@ rev = "184b2ca50ed39ca43da13f0b830a463861adb9ca"
 [workspace.dependencies.fsrs]
 # version = "=2.0.3"
 git = "https://github.com/open-spaced-repetition/fsrs-rs.git"
-rev = "fcbd45a6d49b27a8d1764af528560bfe10c2ff9c"
+rev = "c7717682997a8a6d53d97c7196281e745c5b3c8e"
 # path = "../open-spaced-repetition/fsrs-rs"
 
 [workspace.dependencies]

diff --git a/rslib/src/browser_table.rs b/rslib/src/browser_table.rs
@@ -4,6 +4,7 @@
 use std::sync::Arc;
 
 use fsrs::FSRS;
+use fsrs::FSRS5_DEFAULT_DECAY;
 use itertools::Itertools;
 use strum::Display;
 use strum::EnumIter;
@@ -541,7 +542,7 @@ impl RowContext {
             .memory_state
             .as_ref()
             .zip(self.cards[0].days_since_last_review(&self.timing))
-            .zip(Some(self.cards[0].decay.unwrap_or(0.5)))
+            .zip(Some(self.cards[0].decay.unwrap_or(FSRS5_DEFAULT_DECAY)))
             .map(|((state, days_elapsed), decay)| {
                 let r = FSRS::new(None).unwrap().current_retrievability(
                     (*state).into(),

diff --git a/rslib/src/scheduler/fsrs/memory_state.rs b/rslib/src/scheduler/fsrs/memory_state.rs
@@ -7,6 +7,8 @@ use anki_proto::scheduler::ComputeMemoryStateResponse;
 use fsrs::FSRSItem;
 use fsrs::MemoryState;
 use fsrs::FSRS;
+use fsrs::FSRS5_DEFAULT_DECAY;
+use fsrs::FSRS6_DEFAULT_DECAY;
 use itertools::Itertools;
 
 use super::params::ignore_revlogs_before_ms_from_config;
@@ -78,9 +80,9 @@ impl Collection {
             let fsrs = FSRS::new(req.as_ref().map(|w| &w.params[..]).or(Some([].as_slice())))?;
             let decay = req.as_ref().map(|w| {
                 if w.params.is_empty() {
-                    0.2 // default decay for FSRS-6
+                    FSRS6_DEFAULT_DECAY // default decay for FSRS-6
                 } else if w.params.len() < 21 {
-                    0.5 // default decay for FSRS-4.5 and FSRS-5
+                    FSRS5_DEFAULT_DECAY // default decay for FSRS-4.5 and FSRS-5
                 } else {
                     w.params[20]
                 }

diff --git a/rslib/src/stats/card.rs b/rslib/src/stats/card.rs
@@ -2,6 +2,7 @@
 // License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
 use fsrs::FSRS;
+use fsrs::FSRS5_DEFAULT_DECAY;
 
 use crate::card::CardType;
 use crate::card::FsrsMemoryState;
@@ -37,7 +38,7 @@ impl Collection {
         let fsrs_retrievability = card
             .memory_state
             .zip(Some(days_elapsed))
-            .zip(Some(card.decay.unwrap_or(0.5)))
+            .zip(Some(card.decay.unwrap_or(FSRS5_DEFAULT_DECAY)))
             .map(|((state, days), decay)| {
                 FSRS::new(None)
                     .unwrap()
@@ -76,14 +77,14 @@ impl Collection {
             memory_state: card.memory_state.map(Into::into),
             fsrs_retrievability,
             custom_data: card.custom_data,
-            preset: preset.name.clone(),
+            fsrs_params: preset.fsrs_params().to_vec(),
+            preset: preset.name,
             original_deck: if original_deck != deck {
                 Some(original_deck.human_name())
             } else {
                 None
             },
             desired_retention: card.desired_retention,
-            fsrs_params: preset.fsrs_params().to_vec(),
         })
     }
 

diff --git a/rslib/src/stats/graphs/retrievability.rs b/rslib/src/stats/graphs/retrievability.rs
@@ -3,6 +3,7 @@
 
 use anki_proto::stats::graphs_response::Retrievability;
 use fsrs::FSRS;
+use fsrs::FSRS5_DEFAULT_DECAY;
 
 use crate::prelude::TimestampSecs;
 use crate::scheduler::timing::SchedTimingToday;
@@ -33,7 +34,7 @@ impl GraphsContext {
                 let r = fsrs.current_retrievability(
                     state.into(),
                     elapsed_days,
-                    card.decay.unwrap_or(0.5),
+                    card.decay.unwrap_or(FSRS5_DEFAULT_DECAY),
                 );
 
                 *retrievability

diff --git a/rslib/src/storage/sqlite.rs b/rslib/src/storage/sqlite.rs
@@ -11,6 +11,7 @@ use std::sync::Arc;
 
 use fnv::FnvHasher;
 use fsrs::FSRS;
+use fsrs::FSRS5_DEFAULT_DECAY;
 use regex::Regex;
 use rusqlite::functions::FunctionFlags;
 use rusqlite::params;
@@ -325,7 +326,7 @@ fn add_extract_fsrs_retrievability(db: &Connection) -> rusqlite::Result<()> {
                 let review_day = due.saturating_sub(ivl);
                 days_elapsed.saturating_sub(review_day) as u32
             };
-            let decay = card_data.decay.unwrap_or(0.5);
+            let decay = card_data.decay.unwrap_or_default();
             Ok(card_data.memory_state().map(|state| {
                 FSRS::new(None)
                     .unwrap()
@@ -375,7 +376,7 @@ fn add_extract_fsrs_relative_retrievability(db: &Connection) -> rusqlite::Result
                     {
                         // avoid div by zero
                         desired_retrievability = desired_retrievability.max(0.0001);
-                        let decay = card_data.decay.unwrap_or(0.5);
+                        let decay = card_data.decay.unwrap_or(FSRS5_DEFAULT_DECAY);
 
                         let current_retrievability = FSRS::new(None)
                             .unwrap()

diff --git a/ts/routes/card-info/CardInfo.svelte b/ts/routes/card-info/CardInfo.svelte
@@ -21,10 +21,10 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     $: decay = (() => {
         const paramsLength = stats?.fsrsParams?.length ?? 0;
         if (paramsLength === 0) {
-            return 0.2;
+            return 0.2; // default decay for FSRS-6
         }
         if (paramsLength < 21) {
-            return 0.5;
+            return 0.5; // default decay for FSRS-4.5 and FSRS-5
         }
         return stats?.fsrsParams?.[20] ?? 0.2;
     })();

diff --git a/ts/routes/deck-options/FsrsOptions.svelte b/ts/routes/deck-options/FsrsOptions.svelte
@@ -93,7 +93,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     });
 
     function getRetentionWarning(retention: number, params: number[]): string {
-        const decay = params.length > 20 ? -params[20] : -0.5;
+        const decay = params.length > 20 ? -params[20] : -0.5; // default decay for FSRS-4.5 and FSRS-5
         const factor = 0.9 ** (1 / decay) - 1;
         const stability = 100;
         const days = Math.round(