feat(translate): add translation presets and custom instructions

src/translate/translationservice.cpp

@@ -2,6 +2,7 @@
 
 #include "apikeystore.h"
 #include "qtpotatosettings.h"
+#include "translationpresets.h"
 
 #include <KLocalizedString>
 
@@ -34,7 +35,7 @@ constexpr int MaxAttempts = 3;
 // depend on each other.
 constexpr int ParallelRequests = 3;
 // Bump when the prompt changes so old cached translations are not reused.
-constexpr auto CacheVersion = "llm-v1";
+constexpr auto CacheVersion = "llm-v2";
 
 // "Vietnamese" -> "vi", so the file ends in ".vi.srt" like other players expect.
 QString languageSuffix(const QString &language)
@@ -112,6 +113,15 @@ QStringList TranslationService::availableModels() const
     return m_availableModels;
 }
 
+QVariantList TranslationService::translationPresets() const
+{
+    QVariantList result;
+    for (const auto &preset : TranslationPresets::all()) {
+        result.append(QVariantMap{{u"id"_s, preset.id}, {u"name"_s, preset.name}, {u"guidance"_s, preset.guidance}});
+    }
+    return result;
+}
+
 bool TranslationService::isFetchingModels() const
 {
     return m_fetchingModels;
@@ -160,6 +170,8 @@ QCoro::Task<std::pair<LlmClient::Config, QString>> TranslationService::loadConfi
         {},
         settings->model().trimmed(),
         settings->targetLanguage().trimmed(),
+        settings->translationPreset().trimmed(),
+        settings->customInstructions(),
     };
 
     if (!config.baseUrl.isValid() || config.baseUrl.scheme().isEmpty() || config.baseUrl.host().isEmpty()) {
@@ -235,11 +247,13 @@ QCoro::Task<> TranslationService::run(QUrl videoUrl, QVariantMap track)
         co_return;
     }
 
-    // Same subtitles, model and language give the same file, so it is translated once.
+    // Same subtitles, model, language, and prompt settings give the same file, so it is translated once.
     QCryptographicHash hash(QCryptographicHash::Sha1);
     hash.addData(CacheVersion);
     hash.addData(config.model.toUtf8());
     hash.addData(config.targetLanguage.toUtf8());
+    hash.addData(config.translationPreset.toUtf8());
+    hash.addData(config.customInstructions.toUtf8());
     hash.addData(Subtitles::toSrt(cues).toUtf8());
     const QString outputPath = cachePath(videoUrl, QString::fromLatin1(hash.result().toHex().left(12)), config.targetLanguage);