Message on low log loss

ftl/core/deck-config.ftl

@@ -485,6 +485,14 @@ deck-config-percent-input = { $pct }%
 deck-config-optimizing-preset = Optimizing preset { $current_count }/{ $total_count }...
 deck-config-fsrs-must-be-enabled = FSRS must be enabled first.
 deck-config-fsrs-params-optimal = The FSRS parameters currently appear to be optimal.
+deck-config-fsrs-bad-fit-warning = Your memory is difficult for FSRS to predict. Recommendations:
+
+    - Suspend or reformulate leeches.
+    - Use the answer buttons consistently. Keep in mind that "Hard" is a passing grade, not a failing grade.
+    - Understand before you memorize.
+
+    It may take weeks or months before parameters become optimal.
+
 deck-config-fsrs-params-no-reviews = No reviews found. Make sure this preset is assigned to all decks (including subdecks) that you want to optimize, and try again.
 
 deck-config-wait-for-audio = Wait for audio

proto/anki/scheduler.proto

@@ -359,6 +359,7 @@ message ComputeFsrsParamsRequest {
 message ComputeFsrsParamsResponse {
   repeated float params = 1;
   uint32 fsrs_items = 2;
+  optional float logLoss = 3;
 }
 
 message ComputeFsrsParamsFromItemsRequest {

rslib/src/scheduler/fsrs/params.rs

@@ -75,6 +75,7 @@ impl Collection {
             return Ok(ComputeFsrsParamsResponse {
                 params: current_params.to_vec(),
                 fsrs_items,
+                log_loss: None
             });
         }
         // adapt the progress handler to our built-in progress handling
@@ -108,12 +109,13 @@ impl Collection {
 
         let (progress, progress_thread) = create_progress_thread()?;
         let fsrs = FSRS::new(None)?;
-        let mut params = fsrs.compute_parameters(ComputeParametersInput {
+        let input = ComputeParametersInput {
             train_set: items.clone(),
             progress: Some(progress.clone()),
             enable_short_term: true,
             num_relearning_steps: Some(num_of_relearning_steps),
-        })?;
+        };
+        let mut params = fsrs.compute_parameters(input.clone())?;
         progress_thread.join().ok();
         if let Ok(fsrs) = FSRS::new(Some(current_params)) {
             let current_log_loss = fsrs.evaluate(items.clone(), |_| true)?.log_loss;
@@ -146,7 +148,15 @@ impl Collection {
             }
         }
 
-        Ok(ComputeFsrsParamsResponse { params, fsrs_items })
+        let fsrs = FSRS::new(None)?;
+        let log_loss = fsrs
+            .evaluate_with_time_series_splits(input, |_| true).ok().map(|eval| eval.log_loss);
+
+        Ok(ComputeFsrsParamsResponse {
+            params,
+            fsrs_items,
+            log_loss,
+        })
     }
 
     pub(crate) fn revlog_for_srs(

rslib/src/scheduler/service/mod.rs

@@ -372,7 +372,7 @@ impl crate::services::BackendSchedulerService for Backend {
             enable_short_term: true,
             num_relearning_steps: None,
         })?;
-        Ok(ComputeFsrsParamsResponse { params, fsrs_items })
+        Ok(ComputeFsrsParamsResponse { params, fsrs_items, log_loss: None })
     }
 
     fn fsrs_benchmark(

ts/routes/deck-options/FsrsOptions.svelte

@@ -41,6 +41,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     const defaults = state.defaults;
     const fsrsReschedule = state.fsrsReschedule;
     const daysSinceLastOptimization = state.daysSinceLastOptimization;
+    const logLossBadThreshold = 0.5;
 
     $: lastOptimizationWarning =
         $daysSinceLastOptimization > 30 ? tr.deckConfigTimeToOptimize() : "";
@@ -195,6 +196,10 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
                     } else {
                         $config.fsrsParams6 = resp.params;
                         optimized = true;
+                        console.log(resp.logLoss)
+                        if (resp.logLoss && resp.logLoss > logLossBadThreshold) {
+                            setTimeout(() => alert(tr.deckConfigFsrsBadFitWarning()));
+                        }
                     }
                     if (computeParamsProgress) {
                         computeParamsProgress.current = computeParamsProgress.total;