task 00o: split ImageSearcher into ImageSearcher + AttributionProvider (ISP)

Introduce AttributionProvider interface with GetAttribution() separate from
ImageSearcher so callers only needing search/download don't carry attribution.
ImageClient composes both. Downloader.searcher and NewDownloader now take
ImageClient since attribution is needed when saving downloaded files.
Compile-time assertions updated to ImageClient.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

4 files changed, 31 insertions, 13 deletions

diff --git a/internal/image/download.go b/internal/image/download.go
index 2f04359..5c9b020 100644
--- a/internal/image/download.go
+++ b/internal/image/download.go
@@ -29,14 +29,16 @@ func DefaultDownloadOptions() *DownloadOptions {
 	}
 }
 
-// Downloader handles image downloads from search results
+// Downloader handles image downloads from search results.
+// It requires ImageClient (ImageSearcher + AttributionProvider) because it
+// both downloads images and embeds attribution text in saved files.
 type Downloader struct {
-	searcher ImageSearcher
+	searcher ImageClient
 	options  *DownloadOptions
 }
 
 // NewDownloader creates a new image downloader
-func NewDownloader(searcher ImageSearcher, options *DownloadOptions) *Downloader {
+func NewDownloader(searcher ImageClient, options *DownloadOptions) *Downloader {
 	if options == nil {
 		options = DefaultDownloadOptions()
 	}
diff --git a/internal/image/nanobanana.go b/internal/image/nanobanana.go
index 1a3d6ad..4e99dfa 100644
--- a/internal/image/nanobanana.go
+++ b/internal/image/nanobanana.go
@@ -48,7 +48,9 @@ type NanoBananaClient struct {
 	PromptCallback func(prompt string)
 }
 
-var _ ImageSearcher = (*NanoBananaClient)(nil)
+// Compile-time check that NanoBananaClient implements the full ImageClient interface
+// (ImageSearcher + AttributionProvider).
+var _ ImageClient = (*NanoBananaClient)(nil)
 
 var newNanoBananaClient = genai.NewClient
 var nanoBananaGenerateText = func(ctx context.Context, c *NanoBananaClient, model, systemPrompt, userPrompt string, temperature float32, maxOutputTokens int32) (string, error) {
diff --git a/internal/image/openai.go b/internal/image/openai.go
index 8623fcd..c277406 100644
--- a/internal/image/openai.go
+++ b/internal/image/openai.go
@@ -13,8 +13,9 @@ import (
 	"github.com/sashabaranov/go-openai"
 )
 
-// Compile-time check that OpenAIClient implements the ImageSearcher interface.
-var _ ImageSearcher = (*OpenAIClient)(nil)
+// Compile-time check that OpenAIClient implements the full ImageClient interface
+// (ImageSearcher + AttributionProvider).
+var _ ImageClient = (*OpenAIClient)(nil)
 
 // imageHTTPClient is a shared HTTP client with a generous timeout for image
 // downloads. http.DefaultClient has no timeout, which can block goroutines
diff --git a/internal/image/search.go b/internal/image/search.go
index 9be72ed..be20731 100644
--- a/internal/image/search.go
+++ b/internal/image/search.go
@@ -43,21 +43,34 @@ func DefaultSearchOptions(query string) *SearchOptions {
 	}
 }
 
-// ImageSearcher defines the interface for image search providers
+// AttributionProvider returns required attribution text for a search result.
+// Kept separate from ImageSearcher so callers that only need attribution
+// do not depend on Search/Download/Name.
+type AttributionProvider interface {
+	GetAttribution(result *SearchResult) string
+}
+
+// ImageSearcher defines the interface for image search providers.
+// Providers that also carry attribution text implement AttributionProvider
+// in addition to this interface.
 type ImageSearcher interface {
-	// Search performs an image search with the given options
+	// Search performs an image search with the given options.
 	Search(ctx context.Context, opts *SearchOptions) ([]SearchResult, error)
 
-	// Download downloads an image from the given URL
+	// Download downloads an image from the given URL.
 	Download(ctx context.Context, url string) (io.ReadCloser, error)
 
-	// GetAttribution returns the required attribution text for an image
-	GetAttribution(result *SearchResult) string
-
-	// Name returns the name of the search provider
+	// Name returns the name of the search provider.
 	Name() string
 }
 
+// ImageClient combines ImageSearcher and AttributionProvider for callers
+// that need full provider capabilities (search, download, attribution).
+type ImageClient interface {
+	ImageSearcher
+	AttributionProvider
+}
+
 // SearchError represents an error from an image search provider
 type SearchError struct {
 	Provider string