diff --git a/internal/httpapi/openai/file_inline_upload_test.go b/internal/httpapi/openai/file_inline_upload_test.go
index 4ea2445..fa399b8 100644
--- a/internal/httpapi/openai/file_inline_upload_test.go
+++ b/internal/httpapi/openai/file_inline_upload_test.go
@@ -216,6 +216,45 @@ func TestChatCompletionsInlineUploadFailureReturnsBadRequest(t *testing.T) {
 	}
 }
 
+func TestChatCompletionsInlineUploadLimitReturnsBadRequest(t *testing.T) {
+	ds := &inlineUploadDSStub{}
+	h := &openAITestSurface{Store: mockOpenAIConfig{wideInput: true}, Auth: streamStatusAuthStub{}, DS: ds}
+	content := []any{map[string]any{"type": "input_text", "text": "hi"}}
+	for i := 0; i < 51; i++ {
+		content = append(content, map[string]any{
+			"type":      "image_url",
+			"image_url": map[string]any{"url": "data:image/png;base64,QUJDRA=="},
+		})
+	}
+	body, err := json.Marshal(map[string]any{
+		"model": "deepseek-v4-flash",
+		"messages": []any{map[string]any{
+			"role":    "user",
+			"content": content,
+		}},
+		"stream": false,
+	})
+	if err != nil {
+		t.Fatalf("marshal request: %v", err)
+	}
+	req := httptest.NewRequest(http.MethodPost, "/v1/chat/completions", strings.NewReader(string(body)))
+	req.Header.Set("Authorization", "Bearer direct-token")
+	req.Header.Set("Content-Type", "application/json")
+	rec := httptest.NewRecorder()
+
+	h.ChatCompletions(rec, req)
+
+	if rec.Code != http.StatusBadRequest {
+		t.Fatalf("expected 400, got %d body=%s", rec.Code, rec.Body.String())
+	}
+	if !strings.Contains(rec.Body.String(), "exceeded maximum of 50 inline files per request") {
+		t.Fatalf("expected inline file limit error, got body=%s", rec.Body.String())
+	}
+	if ds.completionReq != nil {
+		t.Fatalf("did not expect completion call after inline file limit error")
+	}
+}
+
 func TestResponsesInlineUploadFailureReturnsInternalServerError(t *testing.T) {
 	ds := &inlineUploadDSStub{uploadErr: errors.New("boom")}
 	h := &openAITestSurface{Store: mockOpenAIConfig{wideInput: true}, Auth: streamStatusAuthStub{}, DS: ds}
diff --git a/internal/httpapi/openai/files/file_inline_upload.go b/internal/httpapi/openai/files/file_inline_upload.go
index c8d59a9..e12267c 100644
--- a/internal/httpapi/openai/files/file_inline_upload.go
+++ b/internal/httpapi/openai/files/file_inline_upload.go
@@ -135,7 +135,8 @@ func (s *inlineUploadState) tryUploadBlock(block map[string]any) (map[string]any
 		return nil, false, nil
 	}
 	if s.uploadCount >= maxInlineFilesPerRequest {
-		return nil, true, fmt.Errorf("exceeded maximum of %d inline files per request", maxInlineFilesPerRequest)
+		err := fmt.Errorf("exceeded maximum of %d inline files per request", maxInlineFilesPerRequest)
+		return nil, true, &inlineFileUploadError{status: http.StatusBadRequest, message: err.Error(), err: err}
 	}
 	fileID, err := s.uploadInlineFile(decoded)
 	if err != nil {