diff --git a/pkg/agent/loop.go b/pkg/agent/loop.go
index 364e67b..08c3597 100644
--- a/pkg/agent/loop.go
+++ b/pkg/agent/loop.go
@@ -1898,6 +1898,10 @@ func isModelProviderSelectionError(err error) bool {
 		"invalid model",
 		"does not exist",
 		"not available for model",
+		"not allowed to use this model",
+		"model is not available to your account",
+		"access to this model is denied",
+		"you do not have permission to use this model",
 	}
 
 	for _, keyword := range keywords {
@@ -1908,8 +1912,32 @@ func isModelProviderSelectionError(err error) bool {
 	return false
 }
 
+func isForbiddenModelPermissionError(err error) bool {
+	if err == nil {
+		return false
+	}
+	msg := strings.ToLower(err.Error())
+	if !strings.Contains(msg, "status 403") && !strings.Contains(msg, "403 forbidden") {
+		return false
+	}
+	keywords := []string{
+		"model",
+		"permission",
+		"forbidden",
+		"access denied",
+		"not allowed",
+		"insufficient permissions",
+	}
+	for _, keyword := range keywords {
+		if strings.Contains(msg, keyword) {
+			return true
+		}
+	}
+	return false
+}
+
 func shouldRetryWithFallbackModel(err error) bool {
-	return isQuotaOrRateLimitError(err) || isModelProviderSelectionError(err) || isGatewayTransientError(err) || isUpstreamAuthRoutingError(err)
+	return isQuotaOrRateLimitError(err) || isModelProviderSelectionError(err) || isForbiddenModelPermissionError(err) || isGatewayTransientError(err) || isUpstreamAuthRoutingError(err)
 }
 
 func isGatewayTransientError(err error) bool {
diff --git a/pkg/providers/openai_provider.go b/pkg/providers/openai_provider.go
index f223a35..4959261 100644
--- a/pkg/providers/openai_provider.go
+++ b/pkg/providers/openai_provider.go
@@ -11,6 +11,7 @@ import (
 	"clawgo/pkg/logger"
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net/http"
 	"net/url"
@@ -31,7 +32,7 @@ const (
 	ProtocolResponses       = "responses"
 )
 
-type HTTPProvider struct {
+type OpenAIProvider struct {
 	apiKey                   string
 	apiBase                  string
 	protocol                 string
@@ -43,7 +44,7 @@ type HTTPProvider struct {
 	client                   openai.Client
 }
 
-func NewHTTPProvider(apiKey, apiBase, protocol, defaultModel string, supportsResponsesCompact bool, authMode string, timeout time.Duration) *HTTPProvider {
+func NewOpenAIProvider(apiKey, apiBase, protocol, defaultModel string, supportsResponsesCompact bool, authMode string, timeout time.Duration) *OpenAIProvider {
 	normalizedBase := normalizeAPIBase(apiBase)
 	resolvedProtocol := normalizeProtocol(protocol)
 	resolvedDefaultModel := strings.TrimSpace(defaultModel)
@@ -64,7 +65,7 @@ func NewHTTPProvider(apiKey, apiBase, protocol, defaultModel string, supportsRes
 		}
 	}
 
-	return &HTTPProvider{
+	return &OpenAIProvider{
 		apiKey:                   apiKey,
 		apiBase:                  normalizedBase,
 		protocol:                 resolvedProtocol,
@@ -77,7 +78,7 @@ func NewHTTPProvider(apiKey, apiBase, protocol, defaultModel string, supportsRes
 	}
 }
 
-func (p *HTTPProvider) Chat(ctx context.Context, messages []Message, tools []ToolDefinition, model string, options map[string]interface{}) (*LLMResponse, error) {
+func (p *OpenAIProvider) Chat(ctx context.Context, messages []Message, tools []ToolDefinition, model string, options map[string]interface{}) (*LLMResponse, error) {
 	if p.apiBase == "" {
 		return nil, fmt.Errorf("API base not configured")
 	}
@@ -98,7 +99,7 @@ func (p *HTTPProvider) Chat(ctx context.Context, messages []Message, tools []Too
 		}
 		resp, err := p.client.Responses.New(ctx, params)
 		if err != nil {
-			return nil, fmt.Errorf("API error: %w", err)
+			return nil, wrapOpenAIAPIError(err)
 		}
 		return mapResponsesAPIResponse(resp), nil
 	}
@@ -109,7 +110,7 @@ func (p *HTTPProvider) Chat(ctx context.Context, messages []Message, tools []Too
 	}
 	resp, err := p.client.Chat.Completions.New(ctx, params)
 	if err != nil {
-		return nil, fmt.Errorf("API error: %w", err)
+		return nil, wrapOpenAIAPIError(err)
 	}
 	return mapChatCompletionResponse(resp), nil
 }
@@ -573,15 +574,15 @@ func extractTag(src string, tag string) string {
 	return strings.TrimSpace(m[1])
 }
 
-func (p *HTTPProvider) GetDefaultModel() string {
+func (p *OpenAIProvider) GetDefaultModel() string {
 	return p.defaultModel
 }
 
-func (p *HTTPProvider) SupportsResponsesCompact() bool {
+func (p *OpenAIProvider) SupportsResponsesCompact() bool {
 	return p != nil && p.supportsResponsesCompact && p.protocol == ProtocolResponses
 }
 
-func (p *HTTPProvider) BuildSummaryViaResponsesCompact(
+func (p *OpenAIProvider) BuildSummaryViaResponsesCompact(
 	ctx context.Context,
 	model string,
 	existingSummary string,
@@ -613,7 +614,7 @@ func (p *HTTPProvider) BuildSummaryViaResponsesCompact(
 		},
 	})
 	if err != nil {
-		return "", fmt.Errorf("responses compact request failed: %w", err)
+		return "", fmt.Errorf("responses compact request failed: %w", wrapOpenAIAPIError(err))
 	}
 
 	payload, err := json.Marshal(compacted.Output)
@@ -639,7 +640,7 @@ func (p *HTTPProvider) BuildSummaryViaResponsesCompact(
 		},
 	})
 	if err != nil {
-		return "", fmt.Errorf("responses summary request failed: %w", err)
+		return "", fmt.Errorf("responses summary request failed: %w", wrapOpenAIAPIError(err))
 	}
 	summary := strings.TrimSpace(summaryResp.OutputText())
 	if summary == "" {
@@ -674,7 +675,7 @@ func CreateProviderByName(cfg *config.Config, name string) (LLMProvider, error)
 	if len(pc.Models) > 0 {
 		defaultModel = pc.Models[0]
 	}
-	return NewHTTPProvider(
+	return NewOpenAIProvider(
 		pc.APIKey,
 		pc.APIBase,
 		pc.Protocol,
@@ -771,6 +772,39 @@ func containsStringTrimmed(values []string, target string) bool {
 	return false
 }
 
+func wrapOpenAIAPIError(err error) error {
+	if err == nil {
+		return nil
+	}
+
+	var apiErr *openai.Error
+	if errors.As(err, &apiErr) {
+		status := apiErr.StatusCode
+		msg := strings.TrimSpace(apiErr.Message)
+		if msg == "" {
+			msg = strings.TrimSpace(apiErr.RawJSON())
+		}
+		if msg == "" && apiErr.Response != nil {
+			dump := string(apiErr.DumpResponse(true))
+			if idx := strings.Index(dump, "\r\n\r\n"); idx >= 0 && idx+4 < len(dump) {
+				msg = strings.TrimSpace(dump[idx+4:])
+			} else if idx := strings.Index(dump, "\n\n"); idx >= 0 && idx+2 < len(dump) {
+				msg = strings.TrimSpace(dump[idx+2:])
+			}
+		}
+		msg = strings.Join(strings.Fields(msg), " ")
+		if len(msg) > 600 {
+			msg = msg[:600] + "..."
+		}
+		if msg != "" {
+			return fmt.Errorf("API error (status %d): %s", status, msg)
+		}
+		return fmt.Errorf("API error (status %d): %s", status, strings.TrimSpace(err.Error()))
+	}
+
+	return fmt.Errorf("API error: %w", err)
+}
+
 func getProviderConfigByName(cfg *config.Config, name string) (config.ProviderConfig, error) {
 	if cfg == nil {
 		return config.ProviderConfig{}, fmt.Errorf("nil config")