fix: fix gemini models list

backend/internal/ai/gemini.go

@@ -74,11 +74,43 @@ func (p *geminiProvider) Summarize(ctx context.Context, prompt string, _ GenOpti
 	return result.Candidates[0].Content.Parts[0].Text, nil
 }
 
-func (p *geminiProvider) ListModels(_ context.Context) ([]string, error) {
-	return []string{
-		"gemini-2.0-flash",
-		"gemini-2.0-flash-lite",
-		"gemini-1.5-pro",
-		"gemini-1.5-flash",
-	}, nil
+func (p *geminiProvider) ListModels(ctx context.Context) ([]string, error) {
+	url := fmt.Sprintf("https://generativelanguage.googleapis.com/v1beta/models?key=%s", p.apiKey)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, err
+	}
+	resp, err := p.client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+	raw, _ := io.ReadAll(resp.Body)
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("gemini list models error %d: %s", resp.StatusCode, raw)
+	}
+	var result struct {
+		Models []struct {
+			Name               string   `json:"name"`
+			SupportedMethods   []string `json:"supportedGenerationMethods"`
+		} `json:"models"`
+	}
+	if err := json.Unmarshal(raw, &result); err != nil {
+		return nil, err
+	}
+	var names []string
+	for _, m := range result.Models {
+		for _, method := range m.SupportedMethods {
+			if method == "generateContent" {
+				// name is "models/gemini-xxx", strip prefix
+				id := m.Name
+				if len(id) > 7 {
+					id = id[7:] // strip "models/"
+				}
+				names = append(names, id)
+				break
+			}
+		}
+	}
+	return names, nil
 }