feat: dictionaries hold words or characters, and are asked by their source

A dictionary source now says what it holds (`kind`: `words`, the default
for files from before, or `characters`), a string so that an app older
than a new kind leaves it out. Search, countLabelled and labelled take the
dictionary by its source and meaning language, as the unique index names
it, rather than by the language: with KANJIDIC2 beside JMdict, a search
for words would otherwise bring kanji, and JLPT N5 would hold both. The
search reads the language for its query variants from the source's row;
a dictionary the instance doesn't hold finds nothing. The rank index goes
by source too.

Migration: drops and recreates dictionary_entry_rank_idx on (source,
glossLanguage, rank), and adds dictionary_source.kind, text NOT NULL
DEFAULT 'words', so a JMdict loaded before is a dictionary of words. Both
tables are reference data, never synced; the old server keeps working
until the switch (its queries by language just lose the index).

In the app, a studyset's dictionary is one of words unless a kind is
asked for.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MMm7usAo6q9ZZRoPkWjoxi
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

halkyon_learn_flutter/lib/src/feature/dictionary/data/dictionary_repository.dart

@@ -16,17 +16,21 @@ class DictionaryRepository(final DictionaryGateway _gateway) {
   Future<List<Dictionary>> dictionaries() async =>
       _known ??= await _gateway.dictionaries();
 
-  /// The dictionary for a studyset in [languages]: of its front's
-  /// language, with meanings in its back's, else in English, else in any;
-  /// null when there is none, or no front language.
-  Future<Dictionary?> dictionaryFor(StudysetLanguages languages) async {
+  /// The dictionary of [kind] (words unless given) for a studyset in
+  /// [languages]: of its front's language, with meanings in its back's,
+  /// else in English, else in any; null when there is none, or no front
+  /// language.
+  Future<Dictionary?> dictionaryFor(
+    StudysetLanguages languages, {
+    DictionaryKind kind = DictionaryKind.words,
+  }) async {
     final front = languages.front;
     if (front == null) {
       return null;
     }
     final ofLanguage = [
       for (final dictionary in await dictionaries())
-        if (dictionary.language == front) dictionary,
+        if (dictionary.language == front && dictionary.kind == kind) dictionary,
     ];
     return ofLanguage
             .where((dictionary) => dictionary.glossLanguage == languages.back)

halkyon_learn_flutter/lib/src/feature/dictionary/data/serverpod_dictionary_gateway.dart

@@ -5,26 +5,30 @@ import 'package:halkyon_learn_flutter/src/feature/dictionary/model/dictionary.da
 /// [DictionaryGateway] asking the instance through the Serverpod client.
 class ServerpodDictionaryGateway(final protocol.Client _client)
     implements DictionaryGateway {
+  /// The dictionaries, but those of a kind this app doesn't know (a newer
+  /// instance's).
   @override
   Future<List<Dictionary>> dictionaries() async => [
     for (final source in await _client.dictionary.dictionaries())
-      Dictionary(
-        source: source.source,
-        sourceVersion: source.sourceVersion,
-        language: source.language,
-        glossLanguage: source.glossLanguage,
-        license: source.license,
-        credits: [
-          for (final credit in source.credits)
-            (
-              name: credit.name,
-              by: credit.by,
-              license: credit.license,
-              url: credit.url,
-            ),
-        ],
-        entryCount: source.entryCount,
-      ),
+      if (DictionaryKind.values.asNameMap()[source.kind] case final kind?)
+        Dictionary(
+          source: source.source,
+          sourceVersion: source.sourceVersion,
+          kind: kind,
+          language: source.language,
+          glossLanguage: source.glossLanguage,
+          license: source.license,
+          credits: [
+            for (final credit in source.credits)
+              (
+                name: credit.name,
+                by: credit.by,
+                license: credit.license,
+                url: credit.url,
+              ),
+          ],
+          entryCount: source.entryCount,
+        ),
   ];
 
   @override
@@ -33,7 +37,7 @@ class ServerpodDictionaryGateway(final protocol.Client _client)
     String query,
   ) async => [
     for (final hit in await _client.dictionary.search(
-      dictionary.language,
+      dictionary.source,
       dictionary.glossLanguage,
       query,
     ))
@@ -43,7 +47,7 @@ class ServerpodDictionaryGateway(final protocol.Client _client)
   @override
   Future<int> countLabelled(Dictionary dictionary, String label) =>
       _client.dictionary.countLabelled(
-        dictionary.language,
+        dictionary.source,
         dictionary.glossLanguage,
         label,
       );
@@ -56,7 +60,7 @@ class ServerpodDictionaryGateway(final protocol.Client _client)
     required int limit,
   }) async => [
     for (final hit in await _client.dictionary.labelled(
-      dictionary.language,
+      dictionary.source,
       dictionary.glossLanguage,
       label,
       offset: offset,

halkyon_learn_flutter/lib/src/feature/dictionary/model/dictionary.dart

@@ -13,11 +13,22 @@ typedef DictionaryCredit = ({
   String url,
 });
 
-/// A dictionary the instance holds: words of [language] with meanings in
-/// [glossLanguage] (BCP 47 tags), from [source] at [sourceVersion].
+/// What a dictionary holds.
+enum DictionaryKind() {
+  /// Words (JMdict).
+  words,
+
+  /// The characters words are written in (KANJIDIC2, with the kana).
+  characters,
+}
+
+/// A dictionary the instance holds: words or characters ([kind]) of
+/// [language] with meanings in [glossLanguage] (BCP 47 tags), from [source]
+/// at [sourceVersion].
 final class const Dictionary({
   required final String source,
   required final String sourceVersion,
+  required final DictionaryKind kind,
   required final String language,
   required final String glossLanguage,
   required final String license,
@@ -28,6 +39,7 @@ final class const Dictionary({
   List<Object?> get props => [
     source,
     sourceVersion,
+    kind,
     language,
     glossLanguage,
     license,

halkyon_learn_flutter/test/feature/dictionary/dictionary_data_test.dart

@@ -102,10 +102,12 @@ void main() {
     });
 
     test("finds a studyset's dictionary by its front's language, with "
-        "meanings in its back's, else in English", () async {
+        "meanings in its back's, else in English; one of words unless a "
+        'kind is asked for', () async {
       const german = Dictionary(
         source: 'jmdict',
         sourceVersion: '1',
+        kind: DictionaryKind.words,
         language: 'ja',
         glossLanguage: 'de',
         license: 'CC-BY-SA-4.0',
@@ -113,7 +115,7 @@ void main() {
         entryCount: 1,
       );
       final repository = DictionaryRepository(
-        FakeDictionaryGateway(available: [jmdict, german]),
+        FakeDictionaryGateway(available: [kanjidic, jmdict, german]),
       );
 
       expect(await repository.dictionaryFor((front: 'ja', back: 'de')), german);
@@ -121,6 +123,13 @@ void main() {
       expect(await repository.dictionaryFor((front: 'ja', back: null)), jmdict);
       expect(await repository.dictionaryFor((front: 'ko', back: 'en')), isNull);
       expect(await repository.dictionaryFor((front: null, back: 'en')), isNull);
+      expect(
+        await repository.dictionaryFor((
+          front: 'ja',
+          back: 'en',
+        ), kind: DictionaryKind.characters),
+        kanjidic,
+      );
     });
 
     test('brings every word of a level, a page at a time', () async {

halkyon_learn_flutter/test/support/fake_dictionary_gateway.dart

@@ -6,6 +6,7 @@ import 'package:halkyon_learn_flutter/src/feature/dictionary/model/dictionary.da
 const jmdict = Dictionary(
   source: 'jmdict',
   sourceVersion: '3.6.2 (2026-10-05)',
+  kind: DictionaryKind.words,
   language: 'ja',
   glossLanguage: 'en',
   license: 'CC-BY-SA-4.0',
@@ -20,6 +21,26 @@ const jmdict = Dictionary(
   entryCount: 3,
 );
 
+/// KANJIDIC2 in English, with the kana, as an instance that loaded it lists
+/// it.
+const kanjidic = Dictionary(
+  source: 'kanjidic',
+  sourceVersion: '2026-282',
+  kind: DictionaryKind.characters,
+  language: 'ja',
+  glossLanguage: 'en',
+  license: 'CC-BY-SA-4.0',
+  credits: [
+    (
+      name: 'KANJIDIC2',
+      by: 'Electronic Dictionary Research and Development Group (EDRDG)',
+      license: 'CC-BY-SA-4.0',
+      url: 'https://www.edrdg.org/edrdg/licence.html',
+    ),
+  ],
+  entryCount: 2,
+);
+
 /// A JMdict word: [headword] read [reading], meaning [glosses], [labels]
 /// and the parts of speech [pos] on its one sense.
 DictionaryWord word(