Add assignment regrade update flow

README.md

@@ -25,6 +25,7 @@ docker compose up -d --build
 
 - `GET /api/assignments?username=xxx`
 - `POST /api/assignments` `multipart/form-data`：`username`、`title`、`images`（可多张，按上传顺序）
+- `PUT /api/assignments/{id}` `multipart/form-data`：`username`、`title`、`images`（重新上传并重新批改）
 - `GET /api/assignments/{id}?username=xxx`
 - `DELETE /api/assignments/{id}?username=xxx`
 

backend/main.go

@@ -123,6 +123,7 @@ func main() {
 		r.Get("/assignments/{id}", handleGetAssignment(db))
 		r.Get("/assignments/{id}/image", handleGetAssignmentImage(db, cfg.UploadDir))
 		r.Post("/assignments", handleCreateAssignment(db, llmClient, cfg.UploadDir))
+		r.Put("/assignments/{id}", handleUpdateAssignment(db, llmClient, cfg.UploadDir))
 		r.Delete("/assignments/{id}", handleDeleteAssignment(db))
 	})
 
@@ -396,6 +397,153 @@ func handleCreateAssignment(db *sql.DB, llm *LLMClient, uploadDir string) http.H
 	}
 }
 
+func handleUpdateAssignment(db *sql.DB, llm *LLMClient, uploadDir string) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		contentType := r.Header.Get("Content-Type")
+		if !strings.HasPrefix(contentType, "multipart/form-data") {
+			writeError(w, http.StatusBadRequest, "multipart form required")
+			return
+		}
+
+		r.Body = http.MaxBytesReader(w, r.Body, 50<<20)
+		if err := r.ParseMultipartForm(60 << 20); err != nil {
+			writeError(w, http.StatusBadRequest, "invalid multipart form")
+			return
+		}
+
+		username := strings.TrimSpace(r.FormValue("username"))
+		if username == "" {
+			username = strings.TrimSpace(r.URL.Query().Get("username"))
+		}
+		if username == "" {
+			writeError(w, http.StatusBadRequest, "username is required")
+			return
+		}
+
+		id, err := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
+		if err != nil {
+			writeError(w, http.StatusBadRequest, "invalid assignment id")
+			return
+		}
+
+		var existingTitle string
+		var createdAt time.Time
+		var existingImagePath sql.NullString
+		row := db.QueryRow(`
+      SELECT title, created_at, image_path
+      FROM assignments
+      WHERE id = ? AND username = ?
+      LIMIT 1
+    `, id, username)
+		if err := row.Scan(&existingTitle, &createdAt, &existingImagePath); err != nil {
+			if errors.Is(err, sql.ErrNoRows) {
+				writeError(w, http.StatusNotFound, "assignment not found")
+				return
+			}
+			writeError(w, http.StatusInternalServerError, "failed to query assignment")
+			return
+		}
+
+		title := strings.TrimSpace(r.FormValue("title"))
+		if title == "" {
+			title = existingTitle
+		}
+		if title == "" {
+			title = fmt.Sprintf("%s %s", defaultTitlePrefix, time.Now().Format("2006-01-02 15:04"))
+		}
+
+		files := r.MultipartForm.File["images"]
+		if len(files) == 0 {
+			files = r.MultipartForm.File["image"]
+		}
+		if len(files) == 0 {
+			writeError(w, http.StatusBadRequest, "image is required")
+			return
+		}
+
+		if err := os.MkdirAll(uploadDir, 0o755); err != nil {
+			writeError(w, http.StatusInternalServerError, "failed to prepare upload dir")
+			return
+		}
+
+		imagePaths := make([]string, 0, len(files))
+		images := make([]LLMImage, 0, len(files))
+		for _, header := range files {
+			file, err := header.Open()
+			if err != nil {
+				writeError(w, http.StatusBadRequest, "failed to read image")
+				return
+			}
+
+			data, err := io.ReadAll(file)
+			file.Close()
+			if err != nil || len(data) == 0 {
+				writeError(w, http.StatusBadRequest, "failed to read image")
+				return
+			}
+
+			mimeType := header.Header.Get("Content-Type")
+			if mimeType == "" {
+				mimeType = http.DetectContentType(data)
+			}
+			if !strings.HasPrefix(mimeType, "image/") {
+				writeError(w, http.StatusBadRequest, "invalid image type")
+				return
+			}
+
+			filename := fmt.Sprintf("%s_%s%s", time.Now().Format("20060102_150405"), randomToken(6), extFromMime(mimeType))
+			imagePath := filepath.Join(uploadDir, filename)
+			if err := os.WriteFile(imagePath, data, 0o644); err != nil {
+				writeError(w, http.StatusInternalServerError, "failed to save image")
+				return
+			}
+
+			imagePaths = append(imagePaths, imagePath)
+			images = append(images, LLMImage{
+				MimeType: mimeType,
+				Base64:   base64.StdEncoding.EncodeToString(data),
+			})
+		}
+
+		markdown, feedback, score, err := llm.FormatAndGradeFromImages(r.Context(), title, images)
+		if err != nil {
+			writeError(w, http.StatusBadGateway, fmt.Sprintf("llm failed: %v", err))
+			return
+		}
+
+		imagePathsJSON, _ := json.Marshal(imagePaths)
+
+		_, err = db.Exec(`
+      UPDATE assignments
+      SET title = ?, ocr_text = ?, markdown = ?, feedback = ?, score = ?, image_path = ?
+      WHERE id = ? AND username = ?
+    `, title, "", markdown, feedback, score, string(imagePathsJSON), id, username)
+		if err != nil {
+			writeError(w, http.StatusInternalServerError, "failed to update assignment")
+			return
+		}
+
+		if existingImagePath.Valid {
+			cleanupImages(uploadDir, existingImagePath.String)
+		}
+
+		assignment := Assignment{
+			ID:         id,
+			Username:   username,
+			Title:      title,
+			OCRText:    "",
+			Markdown:   markdown,
+			Feedback:   feedback,
+			Score:      score,
+			ImagePath:  firstPath(imagePaths),
+			ImagePaths: imagePaths,
+			CreatedAt:  createdAt,
+		}
+
+		writeJSON(w, http.StatusOK, assignment)
+	}
+}
+
 func handleCreateAssignmentWithImage(db *sql.DB, llm *LLMClient, uploadDir string, w http.ResponseWriter, r *http.Request) {
 	r.Body = http.MaxBytesReader(w, r.Body, 50<<20)
 	if err := r.ParseMultipartForm(60 << 20); err != nil {
@@ -566,7 +714,7 @@ func (c *LLMClient) FormatAndGrade(ctx context.Context, title, ocrText string) (
 		return "", "", 0, errors.New("LLM_BASE_URL or LLM_API_KEY missing")
 	}
 
-	systemPrompt := "你是一位细致的老师。请把 OCR 文字整理成清晰的 Markdown，保持原有题号、分点、段落与格式。然后给出作业批改意见。只输出 JSON，包含 markdown、feedback、score(0-100整数)。不要加代码块或多余文字。"
+	systemPrompt := "你是一位严谨的阅卷老师。请把 OCR 文字整理成清晰的 Markdown，保持原有题号、分点、段落与格式。然后进行详细批改：对每一道题给出参考答案、解题过程拆解、学生答案摘录、正确性判定（正确/部分正确/错误）、正确答案对比说明、考察知识点说明。最后给出整体评价与改进建议。仅输出 JSON，字段为 markdown、feedback、score(0-100整数)。不要加代码块或多余文字。"
 	userPrompt := fmt.Sprintf("标题: %s\n\nOCR文本:\n%s", title, ocrText)
 
 	payload := map[string]any{
@@ -614,7 +762,7 @@ func (c *LLMClient) FormatAndGradeFromImages(ctx context.Context, title string,
 		return "", "", 0, errors.New("no images provided")
 	}
 
-	systemPrompt := "你是一位细致的老师。请根据作业图片识别内容，整理为清晰的 Markdown，保持题号、分点、段落与格式。然后给出作业批改意见。只输出 JSON，包含 markdown、feedback、score(0-100整数)。不要加代码块或多余文字。"
+	systemPrompt := "你是一位严谨的阅卷老师。请根据作业图片识别内容，整理为清晰的 Markdown，保持题号、分点、段落与格式。然后进行详细批改：对每一道题给出参考答案、解题过程拆解、学生答案摘录、正确性判定（正确/部分正确/错误）、正确答案对比说明、考察知识点说明。最后给出整体评价与改进建议。若题目或答案无法识别，请明确标注“无法辨识”。仅输出 JSON，字段为 markdown、feedback、score(0-100整数)。不要加代码块或多余文字。"
 	userText := fmt.Sprintf("标题: %s\n以下图片按上传顺序依次为第1页、第2页……请综合批改。", title)
 
 	contentParts := make([]map[string]any, 0, len(images)+1)
@@ -801,6 +949,29 @@ func firstPath(paths []string) string {
 	return paths[0]
 }
 
+func cleanupImages(uploadDir, raw string) {
+	paths := parseImagePaths(raw)
+	if len(paths) == 0 {
+		return
+	}
+
+	absUpload, err := filepath.Abs(uploadDir)
+	if err != nil {
+		return
+	}
+
+	for _, path := range paths {
+		absImage, err := filepath.Abs(path)
+		if err != nil {
+			continue
+		}
+		if !strings.HasPrefix(absImage, absUpload+string(os.PathSeparator)) && absImage != absUpload {
+			continue
+		}
+		_ = os.Remove(absImage)
+	}
+}
+
 func randomToken(length int) string {
 	const charset = "abcdefghijklmnopqrstuvwxyz0123456789"
 	buf := make([]byte, length)
@@ -845,7 +1016,7 @@ func basicAuth(user, pass string) func(http.Handler) http.Handler {
 func corsMiddleware(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Access-Control-Allow-Origin", "*")
-		w.Header().Set("Access-Control-Allow-Methods", "GET, POST, DELETE, OPTIONS")
+		w.Header().Set("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")
 		w.Header().Set("Access-Control-Allow-Headers", "Content-Type, Authorization")
 		if r.Method == http.MethodOptions {
 			w.WriteHeader(http.StatusNoContent)

frontend/app/globals.css

@@ -210,6 +210,17 @@ textarea.input {
   background: rgba(255, 255, 255, 0.7);
 }
 
+.edit-banner {
+  display: flex;
+  justify-content: space-between;
+  align-items: flex-start;
+  gap: 12px;
+  padding: 12px 14px;
+  border-radius: 14px;
+  border: 1px dashed rgba(31, 29, 26, 0.3);
+  background: rgba(15, 76, 92, 0.08);
+}
+
 .preview {
   width: 100%;
   border-radius: 16px;

frontend/app/page.tsx

@@ -40,6 +40,7 @@ export default function HomePage() {
   const [assignments, setAssignments] = useState<AssignmentSummary[]>([]);
   const [selectedId, setSelectedId] = useState<number | null>(null);
   const [selected, setSelected] = useState<AssignmentDetail | null>(null);
+  const [editingId, setEditingId] = useState<number | null>(null);
 
   const [title, setTitle] = useState("");
   const [images, setImages] = useState<ImageItem[]>([]);
@@ -255,6 +256,23 @@ export default function HomePage() {
     );
   };
 
+  const beginEdit = async (item: AssignmentSummary) => {
+    setError("");
+    clearImages();
+    setTitle(item.title);
+    setEditingId(item.id);
+    setSelectedId(item.id);
+    setInfo("已进入重新修改模式，请上传新的作业图片。");
+    await loadAssignmentDetail(item.id);
+  };
+
+  const cancelEdit = () => {
+    setEditingId(null);
+    setTitle("");
+    clearImages();
+    setInfo("");
+  };
+
   const startCamera = async () => {
     setError("");
     try {
@@ -308,6 +326,7 @@ export default function HomePage() {
     setIsSubmitting(true);
     setInfo("正在提交图片并调用 LLM 批改，请稍候...");
     try {
+      const isEditing = editingId !== null;
       const formData = new FormData();
       formData.append("username", savedUser);
       if (title.trim()) {
@@ -319,8 +338,11 @@ export default function HomePage() {
         formData.append("images", blob, name);
       });
 
-      const res = await fetch(`${apiBase}/assignments`, {
+      const endpoint = isEditing
-        method: "POST",
+        ? `${apiBase}/assignments/${editingId}`
+        : `${apiBase}/assignments`;
+      const res = await fetch(endpoint, {
+        method: isEditing ? "PUT" : "POST",
         body: formData,
       });
       if (!res.ok) {
@@ -328,12 +350,19 @@ export default function HomePage() {
         throw new Error(payload.error || "提交失败");
       }
       const created = (await res.json()) as AssignmentDetail;
+      if (isEditing) {
+        setAssignments((prev) =>
+          prev.map((item) => (item.id === created.id ? { ...item, ...created } : item))
+        );
+      } else {
         setAssignments((prev) => [created, ...prev]);
+      }
       setSelectedId(created.id);
       setSelected(created);
       setTitle("");
       clearImages();
-      setInfo("批改完成，可在右侧查看结果。");
+      setEditingId(null);
+      setInfo(isEditing ? "修改完成，已重新批改。" : "批改完成，可在右侧查看结果。");
     } catch (err) {
       setError(err instanceof Error ? err.message : "提交失败");
     } finally {
@@ -354,6 +383,9 @@ export default function HomePage() {
         setSelectedId(null);
         setSelected(null);
       }
+      if (editingId === id) {
+        cancelEdit();
+      }
     } catch (err) {
       setError(err instanceof Error ? err.message : "删除失败");
     }
@@ -414,6 +446,18 @@ export default function HomePage() {
               <span className="tag">IMAGE + LLM</span>
             </header>
             <div className="upload-area">
+              {editingId && (
+                <div className="edit-banner">
+                  <div>
+                    <strong>正在重新修改：</strong>
+                    {selected?.title || title || `作业 #${editingId}`}
+                    <div className="muted">请上传新的作业图片后重新批改。</div>
+                  </div>
+                  <button className="button ghost" onClick={cancelEdit}>
+                    取消修改
+                  </button>
+                </div>
+              )}
               <label className="muted">作业标题</label>
               <input
                 className="input"
@@ -486,7 +530,7 @@ export default function HomePage() {
                 onClick={handleSubmit}
                 disabled={isSubmitting}
               >
-                {isSubmitting ? "批改中..." : "提交批改"}
+                {isSubmitting ? "批改中..." : editingId ? "重新提交批改" : "提交批改"}
               </button>
 
               {error && <div className="feedback">{error}</div>}
@@ -530,6 +574,15 @@ export default function HomePage() {
                         保存图片{imageCountFor(item) > 1 ? ` (${imageCountFor(item)}张)` : ""}
                       </a>
                     )}
+                    <button
+                      className="button secondary"
+                      onClick={(event) => {
+                        event.stopPropagation();
+                        void beginEdit(item);
+                      }}
+                    >
+                      重新修改
+                    </button>
                     <button
                       className="button ghost"
                       onClick={(event) => {