feat(backend): 扩展 Gemini OAuth Repository 层

- 更新 gemini_oauth_client.go: 支持 AI Studio OAuth 客户端
- 更新 geminicli_codeassist_client.go: 适配新的认证流程

backend/internal/repository/gemini_oauth_client.go

@@ -28,10 +28,20 @@ func NewGeminiOAuthClient(cfg *config.Config) ports.GeminiOAuthClient {
 func (c *geminiOAuthClient) ExchangeCode(ctx context.Context, code, codeVerifier, redirectURI, proxyURL string) (*geminicli.TokenResponse, error) {
 	client := createGeminiReqClient(proxyURL)
 
+	// Both Code Assist and AI Studio OAuth use the same token endpoint and OAuth client.
+	oauthCfg, err := geminicli.EffectiveOAuthConfig(geminicli.OAuthConfig{
+		ClientID:     c.cfg.Gemini.OAuth.ClientID,
+		ClientSecret: c.cfg.Gemini.OAuth.ClientSecret,
+		Scopes:       c.cfg.Gemini.OAuth.Scopes,
+	}, "code_assist")
+	if err != nil {
+		return nil, err
+	}
+
 	formData := url.Values{}
 	formData.Set("grant_type", "authorization_code")
-	formData.Set("client_id", c.cfg.Gemini.OAuth.ClientID)
-	formData.Set("client_secret", c.cfg.Gemini.OAuth.ClientSecret)
+	formData.Set("client_id", oauthCfg.ClientID)
+	formData.Set("client_secret", oauthCfg.ClientSecret)
 	formData.Set("code", code)
 	formData.Set("code_verifier", codeVerifier)
 	formData.Set("redirect_uri", redirectURI)
@@ -54,11 +64,21 @@ func (c *geminiOAuthClient) ExchangeCode(ctx context.Context, code, codeVerifier
 func (c *geminiOAuthClient) RefreshToken(ctx context.Context, refreshToken, proxyURL string) (*geminicli.TokenResponse, error) {
 	client := createGeminiReqClient(proxyURL)
 
+	// Both Code Assist and AI Studio OAuth use the same token endpoint and OAuth client.
+	oauthCfg, err := geminicli.EffectiveOAuthConfig(geminicli.OAuthConfig{
+		ClientID:     c.cfg.Gemini.OAuth.ClientID,
+		ClientSecret: c.cfg.Gemini.OAuth.ClientSecret,
+		Scopes:       c.cfg.Gemini.OAuth.Scopes,
+	}, "code_assist")
+	if err != nil {
+		return nil, err
+	}
+
 	formData := url.Values{}
 	formData.Set("grant_type", "refresh_token")
 	formData.Set("refresh_token", refreshToken)
-	formData.Set("client_id", c.cfg.Gemini.OAuth.ClientID)
-	formData.Set("client_secret", c.cfg.Gemini.OAuth.ClientSecret)
+	formData.Set("client_id", oauthCfg.ClientID)
+	formData.Set("client_secret", oauthCfg.ClientSecret)
 
 	var tokenResp geminicli.TokenResponse
 	resp, err := client.R().

backend/internal/repository/geminicli_codeassist_client.go

@@ -34,11 +34,15 @@ func (c *geminiCliCodeAssistClient) LoadCodeAssist(ctx context.Context, accessTo
 		SetSuccessResult(&out).
 		Post(c.baseURL + "/v1internal:loadCodeAssist")
 	if err != nil {
+		fmt.Printf("[CodeAssist] LoadCodeAssist request error: %v\n", err)
 		return nil, fmt.Errorf("request failed: %w", err)
 	}
 	if !resp.IsSuccessState() {
-		return nil, fmt.Errorf("loadCodeAssist failed: status %d, body: %s", resp.StatusCode, geminicli.SanitizeBodyForLogs(resp.String()))
+		body := geminicli.SanitizeBodyForLogs(resp.String())
+		fmt.Printf("[CodeAssist] LoadCodeAssist failed: status %d, body: %s\n", resp.StatusCode, body)
+		return nil, fmt.Errorf("loadCodeAssist failed: status %d, body: %s", resp.StatusCode, body)
 	}
+	fmt.Printf("[CodeAssist] LoadCodeAssist success: status %d, response: %+v\n", resp.StatusCode, out)
 	return &out, nil
 }
 
@@ -47,6 +51,8 @@ func (c *geminiCliCodeAssistClient) OnboardUser(ctx context.Context, accessToken
 		reqBody = defaultOnboardUserRequest()
 	}
 
+	fmt.Printf("[CodeAssist] OnboardUser request body: %+v\n", reqBody)
+
 	var out geminicli.OnboardUserResponse
 	resp, err := createGeminiCliReqClient(proxyURL).R().
 		SetContext(ctx).
@@ -57,11 +63,15 @@ func (c *geminiCliCodeAssistClient) OnboardUser(ctx context.Context, accessToken
 		SetSuccessResult(&out).
 		Post(c.baseURL + "/v1internal:onboardUser")
 	if err != nil {
+		fmt.Printf("[CodeAssist] OnboardUser request error: %v\n", err)
 		return nil, fmt.Errorf("request failed: %w", err)
 	}
 	if !resp.IsSuccessState() {
-		return nil, fmt.Errorf("onboardUser failed: status %d, body: %s", resp.StatusCode, geminicli.SanitizeBodyForLogs(resp.String()))
+		body := geminicli.SanitizeBodyForLogs(resp.String())
+		fmt.Printf("[CodeAssist] OnboardUser failed: status %d, body: %s\n", resp.StatusCode, body)
+		return nil, fmt.Errorf("onboardUser failed: status %d, body: %s", resp.StatusCode, body)
 	}
+	fmt.Printf("[CodeAssist] OnboardUser success: status %d, response: %+v\n", resp.StatusCode, out)
 	return &out, nil
 }