Decoupling work continues

src/app/applicationcommands.cpp

@@ -61,11 +61,21 @@ int runOnce(QGuiApplication &app, const AppConfig &config, double seconds)
 {
     AudioRecorder recorder(config.audio);
     const std::shared_ptr<const TranscriptionEngine> transcriptionEngine = createTranscriptionEngine(config.transcriber);
-    std::unique_ptr<TranscriptionSession> transcriber = transcriptionEngine->createSession();
+    RuntimeError runtimeError;
+    const std::shared_ptr<const TranscriptionModelHandle> model = transcriptionEngine->loadModel(&runtimeError);
+    if (model == nullptr) {
+        qCCritical(appLog) << "Failed to load transcription model:" << runtimeError.message;
+        return 1;
+    }
+
+    std::unique_ptr<TranscriptionSession> transcriber = transcriptionEngine->createSession(model);
+    if (transcriber == nullptr) {
+        qCCritical(appLog) << "Failed to create transcription session";
+        return 1;
+    }
     ClipboardWriter clipboardWriter(QGuiApplication::clipboard());
 
     if (config.transcriber.warmupOnStart) {
-        RuntimeError runtimeError;
         if (!transcriber->warmup(&runtimeError)) {
             qCCritical(appLog) << "Failed to warm up transcriber:" << runtimeError.message;
             return 1;

src/service.cpp

@@ -80,6 +80,8 @@ QJsonObject MutterkeyService::diagnostics() const
     object.insert(QStringLiteral("transcriptions_completed"), m_transcriptionsCompleted);
     object.insert(QStringLiteral("transcriber_backend"),
                   m_transcriptionWorker != nullptr ? m_transcriptionWorker->backendName() : QStringLiteral("unconfigured"));
+    object.insert(QStringLiteral("transcriber_model"),
+                  m_transcriptionWorker != nullptr ? m_transcriptionWorker->loadedModelDescription() : QString());
     const BackendCapabilities capabilities =
         m_transcriptionWorker != nullptr ? m_transcriptionWorker->capabilities() : m_transcriptionEngine->capabilities();
     object.insert(QStringLiteral("transcriber_runtime"), capabilities.runtimeDescription);

src/transcription/transcriptionengine.cpp

@@ -19,9 +19,15 @@ class WhisperCppTranscriptionEngine final : public TranscriptionEngine
         return WhisperCppTranscriber::capabilitiesStatic();
     }
 
-    [[nodiscard]] std::unique_ptr<TranscriptionSession> createSession() const override
+    [[nodiscard]] std::shared_ptr<const TranscriptionModelHandle> loadModel(RuntimeError *error) const override
     {
-        return std::make_unique<WhisperCppTranscriber>(m_config);
+        return WhisperCppTranscriber::loadModelHandle(m_config, error);
+    }
+
+    [[nodiscard]] std::unique_ptr<TranscriptionSession>
+    createSession(std::shared_ptr<const TranscriptionModelHandle> model) const override
+    {
+        return WhisperCppTranscriber::createSession(m_config, std::move(model));
     }
 
 private:

src/transcription/transcriptionengine.h

@@ -12,6 +12,37 @@ struct Recording;
  * @brief Stable engine/session boundary for embedded transcription backends.
  */
 
+/**
+ * @brief Immutable loaded-model interface created by a transcription engine.
+ *
+ * Handles own validated backend assets and may be shared across multiple
+ * independent sessions without exposing backend-specific state to app code.
+ */
+class TranscriptionModelHandle
+{
+public:
+    virtual ~TranscriptionModelHandle() = default;
+    TranscriptionModelHandle(const TranscriptionModelHandle &) = delete;
+    TranscriptionModelHandle &operator=(const TranscriptionModelHandle &) = delete;
+    TranscriptionModelHandle(TranscriptionModelHandle &&) = delete;
+    TranscriptionModelHandle &operator=(TranscriptionModelHandle &&) = delete;
+
+    /**
+     * @brief Returns the backend identifier for this loaded model.
+     * @return Short backend name used in diagnostics.
+     */
+    [[nodiscard]] virtual QString backendName() const = 0;
+
+    /**
+     * @brief Returns a human-readable description of the loaded model.
+     * @return Diagnostic model description such as the resolved model path.
+     */
+    [[nodiscard]] virtual QString modelDescription() const = 0;
+
+protected:
+    TranscriptionModelHandle() = default;
+};
+
 /**
  * @brief Mutable per-session transcription interface.
  *
@@ -47,6 +78,14 @@ class TranscriptionSession
      */
     [[nodiscard]] virtual TranscriptionResult transcribe(const Recording &recording) = 0;
 
+    /**
+     * @brief Requests cooperative cancellation of any active decode.
+     *
+     * Implementations should stop in-flight backend work best-effort without
+     * using thread interruption.
+     */
+    virtual void cancel() = 0;
+
 protected:
     TranscriptionSession() = default;
 };
@@ -73,10 +112,19 @@ class TranscriptionEngine
     [[nodiscard]] virtual BackendCapabilities capabilities() const = 0;
 
     /**
-     * @brief Creates a new isolated transcription session.
-     * @return Newly constructed session that owns its backend state.
+     * @brief Loads an immutable validated model handle for this engine.
+     * @param error Optional destination for a structured failure reason.
+     * @return Shared loaded-model handle suitable for multiple sessions.
+     */
+    [[nodiscard]] virtual std::shared_ptr<const TranscriptionModelHandle> loadModel(RuntimeError *error = nullptr) const = 0;
+
+    /**
+     * @brief Creates a new isolated transcription session from a loaded model.
+     * @param model Shared immutable model handle created by this engine.
+     * @return Newly constructed session that owns only mutable backend state.
      */
-    [[nodiscard]] virtual std::unique_ptr<TranscriptionSession> createSession() const = 0;
+    [[nodiscard]] virtual std::unique_ptr<TranscriptionSession>
+    createSession(std::shared_ptr<const TranscriptionModelHandle> model) const = 0;
 
 protected:
     TranscriptionEngine() = default;

src/transcription/transcriptiontypes.h

@@ -16,6 +16,7 @@
  */
 enum class RuntimeErrorCode : std::uint8_t {
     None,
+    Cancelled,
     InvalidConfig,
     ModelNotFound,
     ModelLoadFailed,

src/transcription/transcriptionworker.cpp

@@ -38,13 +38,27 @@ BackendCapabilities TranscriptionWorker::capabilities() const
     return m_capabilities;
 }
 
+QString TranscriptionWorker::loadedModelDescription() const
+{
+    if (m_model == nullptr) {
+        return {};
+    }
+
+    return m_model->modelDescription();
+}
+
 bool TranscriptionWorker::warmup(RuntimeError *error)
 {
     if (!ensureSession(error)) {
         return false;
     }
 
-    return m_transcriber->warmup(error);
+    const bool ready = m_transcriber->warmup(error);
+    if (!ready && (error == nullptr || shouldDiscardSession(*error))) {
+        m_transcriber.reset();
+    }
+
+    return ready;
 }
 
 void TranscriptionWorker::transcribe(const Recording &recording)
@@ -57,6 +71,9 @@ void TranscriptionWorker::transcribe(const Recording &recording)
 
     const TranscriptionResult result = m_transcriber->transcribe(recording);
     if (!result.success) {
+        if (shouldDiscardSession(result.error)) {
+            m_transcriber.reset();
+        }
         emit transcriptionFailed(result.error);
         return;
     }
@@ -70,6 +87,10 @@ bool TranscriptionWorker::ensureSession(RuntimeError *error)
         return true;
     }
 
+    if (!ensureModel(error)) {
+        return false;
+    }
+
     if (m_engine == nullptr) {
         if (error != nullptr) {
             *error = makeRuntimeError(RuntimeErrorCode::InternalRuntimeError,
@@ -78,7 +99,7 @@ bool TranscriptionWorker::ensureSession(RuntimeError *error)
         return false;
     }
 
-    m_transcriber = m_engine->createSession();
+    m_transcriber = m_engine->createSession(m_model);
     if (m_transcriber == nullptr) {
         if (error != nullptr) {
             *error = makeRuntimeError(RuntimeErrorCode::InternalRuntimeError,
@@ -88,3 +109,36 @@ bool TranscriptionWorker::ensureSession(RuntimeError *error)
     }
     return true;
 }
+
+bool TranscriptionWorker::ensureModel(RuntimeError *error)
+{
+    if (m_model != nullptr) {
+        return true;
+    }
+
+    if (m_engine == nullptr) {
+        return true;
+    }
+
+    m_model = m_engine->loadModel(error);
+    return m_model != nullptr;
+}
+
+bool TranscriptionWorker::shouldDiscardSession(const RuntimeError &error)
+{
+    switch (error.code) {
+    case RuntimeErrorCode::Cancelled:
+    case RuntimeErrorCode::ModelLoadFailed:
+    case RuntimeErrorCode::DecodeFailed:
+    case RuntimeErrorCode::InternalRuntimeError:
+        return true;
+    case RuntimeErrorCode::None:
+    case RuntimeErrorCode::InvalidConfig:
+    case RuntimeErrorCode::ModelNotFound:
+    case RuntimeErrorCode::AudioNormalizationFailed:
+    case RuntimeErrorCode::UnsupportedLanguage:
+        return false;
+    }
+
+    return true;
+}

src/transcription/transcriptionworker.h

@@ -51,6 +51,12 @@ class TranscriptionWorker final : public QObject
      */
     [[nodiscard]] BackendCapabilities capabilities() const;
 
+    /**
+     * @brief Returns the currently loaded model description, if available.
+     * @return Human-readable loaded model description or an empty string.
+     */
+    [[nodiscard]] QString loadedModelDescription() const;
+
     /**
      * @brief Eagerly initializes backend state before the first real transcription.
      * @param error Optional output for warmup failures.
@@ -78,10 +84,15 @@ class TranscriptionWorker final : public QObject
     void transcriptionFailed(const RuntimeError &error);
 
 private:
+    static bool shouldDiscardSession(const RuntimeError &error);
+
+    bool ensureModel(RuntimeError *error = nullptr);
     bool ensureSession(RuntimeError *error = nullptr);
 
     /// Shared immutable engine used to create the live session lazily on the worker thread.
     std::shared_ptr<const TranscriptionEngine> m_engine;
+    /// Shared immutable loaded model handle reused across session instances.
+    std::shared_ptr<const TranscriptionModelHandle> m_model;
     /// Capability snapshot reported even before the first session exists.
     BackendCapabilities m_capabilities;
     /// Owned transcription backend implementation.