diff --git a/internal/provider/provider.go b/internal/provider/provider.go
index 8590192..89b1c82 100644
--- a/internal/provider/provider.go
+++ b/internal/provider/provider.go
@@ -434,7 +434,7 @@ func (p *Provider) probeModels(ctx context.Context) (bool, string) {
 	case resp.StatusCode == 404 || resp.StatusCode == 405:
 		return false, ""
 	default:
-		return false, fmt.Sprintf("api error %d: %s", resp.StatusCode, truncate(string(raw), 300))
+		return false, shortAPIError(resp.StatusCode, string(raw))
 	}
 }
 
@@ -471,7 +471,7 @@ func (p *Provider) probeChat(ctx context.Context) (bool, string) {
 			} else if status == 200 {
 				ok = true
 			} else {
-				msg = fmt.Sprintf("api error %d: %s", status, truncate(raw, 500))
+				msg = shortAPIError(status, raw)
 			}
 		} else {
 			msg = err.Error()
@@ -717,7 +717,7 @@ func (p *Provider) Chat(ctx context.Context, req *types.ChatRequest) (*types.Uni
 	}
 	if status != 200 {
 		p.ReportStatus(model, status)
-		return nil, fmt.Errorf("api error %d: %s", status, truncate(raw, 500))
+		return nil, fmt.Errorf("%s", shortAPIError(status, raw))
 	}
 	unified, err := p.vm.Transform(p.adapter, "transform_response", raw)
 	if err != nil {
@@ -793,7 +793,7 @@ func (p *Provider) ChatStream(ctx context.Context, req *types.ChatRequest) (<-ch
 		sel.resp.Body.Close()
 		p.ReportStatus(model, sel.resp.StatusCode)
 		p.Release()
-		return nil, fmt.Errorf("api error %d: %s", sel.resp.StatusCode, truncate(string(raw), 500))
+		return nil, fmt.Errorf("%s", shortAPIError(sel.resp.StatusCode, string(raw)))
 	}
 	go func() {
 		defer p.Release()
@@ -928,6 +928,56 @@ func errorOnlyChunk(ck types.UnifiedChunk) bool {
 		ck.ReasoningContent == "" && ck.Usage == nil
 }
 
+// shortAPIError condenses an upstream error response into its human reason:
+// JSON envelopes contribute their error/message field, HTML pages (WAF
+// blocklists) collapse to a marker, anything else is capped as-is. Raw
+// bodies must not leak through errors to clients.
+func shortAPIError(status int, body string) string {
+	b := strings.TrimSpace(body)
+	low := strings.ToLower(b)
+	if strings.HasPrefix(low, "<!doctype") || strings.Contains(low, "<html") {
+		return fmt.Sprintf("api error %d: upstream returned an HTML error page", status)
+	}
+	var env struct {
+		Error   json.RawMessage `json:"error"`
+		Message string          `json:"message"`
+		Msg     string          `json:"msg"`
+	}
+	if err := json.Unmarshal([]byte(b), &env); err == nil {
+		msg := ""
+		switch {
+		case len(env.Error) > 0:
+			var es string
+			if json.Unmarshal(env.Error, &es) == nil {
+				msg = es
+			} else {
+				var obj struct {
+					Message string `json:"message"`
+				}
+				if json.Unmarshal(env.Error, &obj) == nil {
+					msg = obj.Message
+				}
+			}
+		case env.Message != "":
+			msg = env.Message
+		case env.Msg != "":
+			msg = env.Msg
+		}
+		if msg != "" {
+			return fmt.Sprintf("api error %d: %s", status, oneLineStr(msg, 160))
+		}
+	}
+	return fmt.Sprintf("api error %d: %s", status, oneLineStr(b, 160))
+}
+
+func oneLineStr(s string, n int) string {
+	s = strings.Join(strings.Fields(s), " ")
+	if len(s) > n {
+		s = s[:n] + "..."
+	}
+	return s
+}
+
 // Image generates images via /v1/images/generations. Same scheduling-state
 // accounting as Chat: fail fast on busy, record per (source, model).
 func (p *Provider) Image(ctx context.Context, req *types.ImageGenRequest) (*types.UnifiedResponse, error) {
diff --git a/internal/provider/provider_test.go b/internal/provider/provider_test.go
index 66b9d66..d24a342 100644
--- a/internal/provider/provider_test.go
+++ b/internal/provider/provider_test.go
@@ -538,3 +538,30 @@ func TestStandardSSEChunkFinishReason(t *testing.T) {
 		t.Fatalf("empty-string finish reason is not a finish signal: %s", out)
 	}
 }
+
+func TestShortAPIError(t *testing.T) {
+	cases := []struct{ name, body, want string }{
+		{"openai-style envelope", `{"error":{"message":"Allocated quota exceeded","type":"invalid_request_error","code":"insufficient_quota"}}`, "api error 429: Allocated quota exceeded"},
+		{"nested console envelope", `{"error":{"type":"server_error","message":"Error from provider (Console): Upstream request failed: Endpoint is unavailable."}}`, "api error 503: Error from provider (Console): Upstream request failed: Endpoint is unavailable."},
+		{"string error", `{"error":"boom"}`, "api error 500: boom"},
+		{"html waf page", "<!doctypehtml><html lang=\"zh-cn\"><title>405</title></html>", "api error 405: upstream returned an HTML error page"},
+		{"plain text body", "service unavailable", "api error 503: service unavailable"},
+	}
+	for _, c := range cases {
+		if got := shortAPIError(statusFor(c.want), c.body); got != c.want {
+			t.Fatalf("%s: got %q want %q", c.name, got, c.want)
+		}
+	}
+}
+
+func statusFor(want string) int {
+	switch {
+	case strings.Contains(want, "429"):
+		return 429
+	case strings.Contains(want, "503"):
+		return 503
+	case strings.Contains(want, "405"):
+		return 405
+	}
+	return 500
+}