Add warning about all clients needing to support FSRS

ftl/core/deck-config.ftl

@@ -328,6 +328,9 @@ deck-config-desired-retention = Desired retention
 deck-config-smaller-is-better = Smaller numbers indicate better memory estimates.
 deck-config-steps-too-large-for-fsrs = When FSRS is enabled, interday (re)learning steps are not recommended.
 deck-config-get-params = Get Params
+deck-config-fsrs-on-all-clients =
+    Please ensure all of your Anki clients are Anki(Mobile) 23.10+ or AnkiDroid 2.17+. FSRS will
+    not work correctly if one of your clients is older.
 
 ## NO NEED TO TRANSLATE. This text is no longer used by Anki, and will be removed in the future.
 

ts/deck-options/AdvancedOptions.svelte

@@ -20,6 +20,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     import type { DeckOptionsState } from "./lib";
     import SpinBoxFloatRow from "./SpinBoxFloatRow.svelte";
     import SpinBoxRow from "./SpinBoxRow.svelte";
+    import Warning from "./Warning.svelte";
 
     export let state: DeckOptionsState;
     export let api: Record<string, never>;
@@ -74,6 +75,8 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
         modal.show();
         carousel.to(index);
     }
+
+    $: fsrsClientWarning = $config.fsrsEnabled ? tr.deckConfigFsrsOnAllClients() : "";
 </script>
 
 <TitledContainer title={tr.deckConfigAdvancedTitle()}>
@@ -94,6 +97,8 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
                     <SettingTitle>FSRS</SettingTitle>
                 </SwitchRow>
             </Item>
+
+            <Warning warning={fsrsClientWarning} />
         {/if}
 
         <Item>