refactor: registry pattern for audio and image provider factories

Add internal/registry generic Registry[K,T] for keyed factory registration.
Wire audio.NewProvider via registered per-provider constructors; GUI and
processor newImageSearcher use registries of *Orchestrator/*Processor methods.
Export image.ImageProviderOpenAI and ImageProviderNanoBanana from search.go
and use them across gui to avoid duplicate string constants.

Made-with: Cursor

5 files changed, 57 insertions, 46 deletions

diff --git a/internal/gui/app.go b/internal/gui/app.go
index f7a7d51..6c1cf21 100644
--- a/internal/gui/app.go
+++ b/internal/gui/app.go
@@ -146,11 +146,6 @@ type Config struct {
 	Translator      *translation.Translator
 }
 
-const (
-	imageProviderOpenAI     = "openai"
-	imageProviderNanoBanana = "nanobanana"
-)
-
 // DefaultConfig returns default GUI configuration
 func DefaultConfig() *Config {
 	homeDir, err := appconfig.HomeDir()
@@ -168,7 +163,7 @@ func DefaultConfig() *Config {
 		NanoBananaModel:     image.DefaultNanoBananaModel,
 		NanoBananaTextModel: image.DefaultNanoBananaTextModel,
 		GeminiTTSModel:      audioDefaults.GeminiTTSModel,
-		ImageProvider:       imageProviderNanoBanana,
+		ImageProvider:       image.ImageProviderNanoBanana,
 		TranslationProvider: translation.ProviderGemini,
 		PhoneticProvider:    phonetic.ProviderGemini,
 		AutoPlay:            true, // Auto-play enabled by default
diff --git a/internal/gui/app_test.go b/internal/gui/app_test.go
index 9ac0125..86e8ec2 100644
--- a/internal/gui/app_test.go
+++ b/internal/gui/app_test.go
@@ -19,8 +19,8 @@ func TestDefaultConfigUsesGeminiLanguageProviders(t *testing.T) {
 	if config.PhoneticProvider != phonetic.ProviderGemini {
 		t.Fatalf("DefaultConfig() phonetic provider = %q, want %q", config.PhoneticProvider, phonetic.ProviderGemini)
 	}
-	if config.ImageProvider != imageProviderNanoBanana {
-		t.Fatalf("DefaultConfig() image provider = %q, want %q", config.ImageProvider, imageProviderNanoBanana)
+	if config.ImageProvider != image.ImageProviderNanoBanana {
+		t.Fatalf("DefaultConfig() image provider = %q, want %q", config.ImageProvider, image.ImageProviderNanoBanana)
 	}
 	if config.AudioProvider != audioDefaults.Provider {
 		t.Fatalf("DefaultConfig() audio provider = %q, want %q", config.AudioProvider, audioDefaults.Provider)
diff --git a/internal/gui/card_service.go b/internal/gui/card_service.go
index 395c741..cd4d549 100644
--- a/internal/gui/card_service.go
+++ b/internal/gui/card_service.go
@@ -9,6 +9,7 @@ import (
 
 	"codeberg.org/snonux/totalrecall/internal"
 	"codeberg.org/snonux/totalrecall/internal/anki"
+	"codeberg.org/snonux/totalrecall/internal/image"
 	"codeberg.org/snonux/totalrecall/internal/store"
 )
 
@@ -249,7 +250,7 @@ func (cs *CardService) loadImageFile(wordDir string, cf *CardFiles) {
 
 	// Try to load the image prompt from the attribution file as a fallback
 	// when the image provider is AI-based (OpenAI DALL-E or Nano Banana).
-	if cs.config.ImageProvider == imageProviderOpenAI || cs.config.ImageProvider == imageProviderNanoBanana {
+	if cs.config.ImageProvider == image.ImageProviderOpenAI || cs.config.ImageProvider == image.ImageProviderNanoBanana {
 		cs.loadPromptFromAttribution(cf)
 	}
 }
diff --git a/internal/gui/generator_test.go b/internal/gui/generator_test.go
index 40c0e2c..5ee238b 100644
--- a/internal/gui/generator_test.go
+++ b/internal/gui/generator_test.go
@@ -34,7 +34,7 @@ func (f *fakePromptAwareImageClient) Search(_ context.Context, opts *image.Searc
 			Height:       1,
 			Description:  "fake result",
 			Attribution:  "fake attribution",
-			Source:       imageProviderNanoBanana,
+			Source:       image.ImageProviderNanoBanana,
 		},
 	}, nil
 }
@@ -48,7 +48,7 @@ func (f *fakePromptAwareImageClient) GetAttribution(*image.SearchResult) string
 }
 
 func (f *fakePromptAwareImageClient) Name() string {
-	return imageProviderNanoBanana
+	return image.ImageProviderNanoBanana
 }
 
 func (f *fakePromptAwareImageClient) SetPromptCallback(callback func(prompt string)) {
@@ -99,7 +99,7 @@ func TestGenerateImagesWithPromptUsesNanoBananaProvider(t *testing.T) {
 	tempDir := t.TempDir()
 	app := &Application{
 		config: &Config{
-			ImageProvider:       imageProviderNanoBanana,
+			ImageProvider:       image.ImageProviderNanoBanana,
 			GoogleAPIKey:        "google-key",
 			NanoBananaModel:     "custom-image-model",
 			NanoBananaTextModel: "custom-text-model",
diff --git a/internal/gui/orchestrator.go b/internal/gui/orchestrator.go
index 191e919..ef4a167 100644
--- a/internal/gui/orchestrator.go
+++ b/internal/gui/orchestrator.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 	"time"
 
 	"fyne.io/fyne/v2"
@@ -12,6 +13,7 @@ import (
 	"codeberg.org/snonux/totalrecall/internal/audio"
 	"codeberg.org/snonux/totalrecall/internal/image"
 	"codeberg.org/snonux/totalrecall/internal/phonetic"
+	"codeberg.org/snonux/totalrecall/internal/registry"
 	"codeberg.org/snonux/totalrecall/internal/translation"
 )
 
@@ -410,48 +412,61 @@ func (o *GenerationOrchestrator) imagePromptCallback(cardDir, word string) func(
 	}
 }
 
-// newImageSearcher constructs the appropriate image client based on the
-// configured image provider. Returns image.PromptAwareClient so callers can
-// call SetPromptCallback directly without a type-assertion. The factory
-// functions are sourced from imageFactories (the shared image.ClientFactories
-// value) to avoid duplicating the factory signatures in this package.
-func (o *GenerationOrchestrator) newImageSearcher() (image.PromptAwareClient, error) {
-	switch o.config.ImageProvider {
-	case imageProviderOpenAI:
-		if o.config.OpenAIKey == "" {
-			return nil, fmt.Errorf("OpenAI API key is required for image generation")
-		}
+// guiImageClientFactories maps provider name to image client builder. Add new
+// providers by registering here instead of extending a switch in newImageSearcher.
+var guiImageClientFactories = func() *registry.Registry[string, func(*GenerationOrchestrator) (image.PromptAwareClient, error)] {
+	r := registry.New[string, func(*GenerationOrchestrator) (image.PromptAwareClient, error)]()
+	r.Register(image.ImageProviderOpenAI, (*GenerationOrchestrator).buildOpenAIImageClient)
+	r.Register(image.ImageProviderNanoBanana, (*GenerationOrchestrator).buildNanoBananaImageClient)
+	return r
+}()
 
-		openaiConfig := &image.OpenAIConfig{
-			APIKey:  o.config.OpenAIKey,
-			Model:   "dall-e-2", // DALL-E 2 supports 512×512
-			Size:    "512x512",
-			Quality: "standard",
-			Style:   "natural",
-		}
+func (o *GenerationOrchestrator) buildOpenAIImageClient() (image.PromptAwareClient, error) {
+	if o.config.OpenAIKey == "" {
+		return nil, fmt.Errorf("OpenAI API key is required for image generation")
+	}
 
-		return o.imageFactories.NewOpenAIClient(openaiConfig), nil
+	openaiConfig := &image.OpenAIConfig{
+		APIKey:  o.config.OpenAIKey,
+		Model:   "dall-e-2", // DALL-E 2 supports 512×512
+		Size:    "512x512",
+		Quality: "standard",
+		Style:   "natural",
+	}
 
-	case imageProviderNanoBanana:
-		cfg := o.config
-		if cfg == nil {
-			cfg = DefaultConfig()
-		}
-		if cfg.GoogleAPIKey == "" {
-			return nil, fmt.Errorf("google API key is required for image generation")
-		}
+	return o.imageFactories.NewOpenAIClient(openaiConfig), nil
+}
 
-		nanoBananaConfig := &image.NanoBananaConfig{
-			APIKey:    cfg.GoogleAPIKey,
-			Model:     cfg.NanoBananaModel,
-			TextModel: cfg.NanoBananaTextModel,
-		}
+func (o *GenerationOrchestrator) buildNanoBananaImageClient() (image.PromptAwareClient, error) {
+	cfg := o.config
+	if cfg == nil {
+		cfg = DefaultConfig()
+	}
+	if cfg.GoogleAPIKey == "" {
+		return nil, fmt.Errorf("google API key is required for image generation")
+	}
 
-		return o.imageFactories.NewNanoBananaClient(nanoBananaConfig), nil
+	nanoBananaConfig := &image.NanoBananaConfig{
+		APIKey:    cfg.GoogleAPIKey,
+		Model:     cfg.NanoBananaModel,
+		TextModel: cfg.NanoBananaTextModel,
+	}
+
+	return o.imageFactories.NewNanoBananaClient(nanoBananaConfig), nil
+}
 
-	default:
+// newImageSearcher constructs the appropriate image client based on the
+// configured image provider. Returns image.PromptAwareClient so callers can
+// call SetPromptCallback directly without a type-assertion. The factory
+// functions are sourced from imageFactories (the shared image.ClientFactories
+// value) to avoid duplicating the factory signatures in this package.
+func (o *GenerationOrchestrator) newImageSearcher() (image.PromptAwareClient, error) {
+	key := strings.ToLower(strings.TrimSpace(o.config.ImageProvider))
+	fn, ok := guiImageClientFactories.Get(key)
+	if !ok {
 		return nil, fmt.Errorf("unknown image provider: %s", o.config.ImageProvider)
 	}
+	return fn(o)
 }
 
 // --- Phonetics ---