fix(antigravity): keep primary model list and backfill empty auths

internal/runtime/executor/antigravity_executor.go

@@ -54,8 +54,58 @@ const (
 var (
 	randSource      = rand.New(rand.NewSource(time.Now().UnixNano()))
 	randSourceMutex sync.Mutex
+	// antigravityPrimaryModelsCache keeps the latest non-empty model list fetched
+	// from any antigravity auth. Empty fetches never overwrite this cache.
+	antigravityPrimaryModelsCache struct {
+		mu     sync.RWMutex
+		models []*registry.ModelInfo
+	}
 )
 
+func cloneAntigravityModels(models []*registry.ModelInfo) []*registry.ModelInfo {
+	if len(models) == 0 {
+		return nil
+	}
+	out := make([]*registry.ModelInfo, 0, len(models))
+	for _, model := range models {
+		if model == nil || strings.TrimSpace(model.ID) == "" {
+			continue
+		}
+		clone := *model
+		out = append(out, &clone)
+	}
+	if len(out) == 0 {
+		return nil
+	}
+	return out
+}
+
+func storeAntigravityPrimaryModels(models []*registry.ModelInfo) bool {
+	cloned := cloneAntigravityModels(models)
+	if len(cloned) == 0 {
+		return false
+	}
+	antigravityPrimaryModelsCache.mu.Lock()
+	antigravityPrimaryModelsCache.models = cloned
+	antigravityPrimaryModelsCache.mu.Unlock()
+	return true
+}
+
+func loadAntigravityPrimaryModels() []*registry.ModelInfo {
+	antigravityPrimaryModelsCache.mu.RLock()
+	cloned := cloneAntigravityModels(antigravityPrimaryModelsCache.models)
+	antigravityPrimaryModelsCache.mu.RUnlock()
+	return cloned
+}
+
+func fallbackAntigravityPrimaryModels() []*registry.ModelInfo {
+	models := loadAntigravityPrimaryModels()
+	if len(models) > 0 {
+		log.Debugf("antigravity executor: using cached primary model list (%d models)", len(models))
+	}
+	return models
+}
+
 // AntigravityExecutor proxies requests to the antigravity upstream.
 type AntigravityExecutor struct {
 	cfg *config.Config
@@ -1007,7 +1057,7 @@ func FetchAntigravityModels(ctx context.Context, auth *cliproxyauth.Auth, cfg *c
 	exec := &AntigravityExecutor{cfg: cfg}
 	token, updatedAuth, errToken := exec.ensureAccessToken(ctx, auth)
 	if errToken != nil || token == "" {
-		return nil
+		return fallbackAntigravityPrimaryModels()
 	}
 	if updatedAuth != nil {
 		auth = updatedAuth
@@ -1020,7 +1070,7 @@ func FetchAntigravityModels(ctx context.Context, auth *cliproxyauth.Auth, cfg *c
 		modelsURL := baseURL + antigravityModelsPath
 		httpReq, errReq := http.NewRequestWithContext(ctx, http.MethodPost, modelsURL, bytes.NewReader([]byte(`{}`)))
 		if errReq != nil {
-			return nil
+			return fallbackAntigravityPrimaryModels()
 		}
 		httpReq.Header.Set("Content-Type", "application/json")
 		httpReq.Header.Set("Authorization", "Bearer "+token)
@@ -1032,13 +1082,13 @@ func FetchAntigravityModels(ctx context.Context, auth *cliproxyauth.Auth, cfg *c
 		httpResp, errDo := httpClient.Do(httpReq)
 		if errDo != nil {
 			if errors.Is(errDo, context.Canceled) || errors.Is(errDo, context.DeadlineExceeded) {
-				return nil
+				return fallbackAntigravityPrimaryModels()
 			}
 			if idx+1 < len(baseURLs) {
 				log.Debugf("antigravity executor: models request error on base url %s, retrying with fallback base url: %s", baseURL, baseURLs[idx+1])
 				continue
 			}
-			return nil
+			return fallbackAntigravityPrimaryModels()
 		}
 
 		bodyBytes, errRead := io.ReadAll(httpResp.Body)
@@ -1050,19 +1100,27 @@ func FetchAntigravityModels(ctx context.Context, auth *cliproxyauth.Auth, cfg *c
 				log.Debugf("antigravity executor: models read error on base url %s, retrying with fallback base url: %s", baseURL, baseURLs[idx+1])
 				continue
 			}
-			return nil
+			return fallbackAntigravityPrimaryModels()
 		}
 		if httpResp.StatusCode < http.StatusOK || httpResp.StatusCode >= http.StatusMultipleChoices {
 			if httpResp.StatusCode == http.StatusTooManyRequests && idx+1 < len(baseURLs) {
 				log.Debugf("antigravity executor: models request rate limited on base url %s, retrying with fallback base url: %s", baseURL, baseURLs[idx+1])
 				continue
 			}
-			return nil
+			if idx+1 < len(baseURLs) {
+				log.Debugf("antigravity executor: models request failed with status %d on base url %s, retrying with fallback base url: %s", httpResp.StatusCode, baseURL, baseURLs[idx+1])
+				continue
+			}
+			return fallbackAntigravityPrimaryModels()
 		}
 
 		result := gjson.GetBytes(bodyBytes, "models")
 		if !result.Exists() {
-			return nil
+			if idx+1 < len(baseURLs) {
+				log.Debugf("antigravity executor: models field missing on base url %s, retrying with fallback base url: %s", baseURL, baseURLs[idx+1])
+				continue
+			}
+			return fallbackAntigravityPrimaryModels()
 		}
 
 		now := time.Now().Unix()
@@ -1107,9 +1165,18 @@ func FetchAntigravityModels(ctx context.Context, auth *cliproxyauth.Auth, cfg *c
 			}
 			models = append(models, modelInfo)
 		}
+		if len(models) == 0 {
+			if idx+1 < len(baseURLs) {
+				log.Debugf("antigravity executor: empty models list on base url %s, retrying with fallback base url: %s", baseURL, baseURLs[idx+1])
+				continue
+			}
+			log.Debug("antigravity executor: fetched empty model list; retaining cached primary model list")
+			return fallbackAntigravityPrimaryModels()
+		}
+		storeAntigravityPrimaryModels(models)
 		return models
 	}
-	return nil
+	return fallbackAntigravityPrimaryModels()
 }
 
 func (e *AntigravityExecutor) ensureAccessToken(ctx context.Context, auth *cliproxyauth.Auth) (string, *cliproxyauth.Auth, error) {