feat: 新增参考材料后端支持

- 新增 SessionMaterial 模型
- 新增 builder_session_materials 表自动迁移
- BuilderSession 增加 Materials 字段
- CreateBuilderSession/UpdateBuilderSession 支持保存材料
- GetBuilderSession 支持加载材料
- DeleteBuilderSession 支持级联删除材料
- AssemblePrompt 支持组装材料内容到 Prompt

internal/db/db.go

@@ -102,6 +102,16 @@ func AutoMigrate() error {
 			PRIMARY KEY (id),
 			KEY idx_session_id (builder_session_id)
 		) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4`,
+
+		`CREATE TABLE IF NOT EXISTS builder_session_materials (
+			id bigint NOT NULL AUTO_INCREMENT,
+			builder_session_id bigint NOT NULL,
+			title varchar(255) NOT NULL DEFAULT '',
+			content text NOT NULL,
+			sort_order int NOT NULL DEFAULT 0,
+			PRIMARY KEY (id),
+			KEY idx_session_id (builder_session_id)
+		) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4`,
 	}
 
 	for _, ddl := range tables {

internal/handlers/builder.go

@@ -47,6 +47,11 @@ func CreateBuilderSession(w http.ResponseWriter, r *http.Request) {
 			SnippetID int64 `json:"snippet_id"`
 			SortOrder int   `json:"sort_order"`
 		} `json:"snippet_ids"`
+		Materials []struct {
+			Title    string `json:"title"`
+			Content  string `json:"content"`
+			SortOrder int   `json:"sort_order"`
+		} `json:"materials"`
 	}
 	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
 		fail(w, 400, "请求格式错误")
@@ -79,6 +84,12 @@ func CreateBuilderSession(w http.ResponseWriter, r *http.Request) {
 			sessionID, s.SnippetID, s.SortOrder)
 	}
 
+	// Insert materials
+	for _, m := range req.Materials {
+		db.DB.Exec("INSERT INTO builder_session_materials (builder_session_id, title, content, sort_order) VALUES (?, ?, ?, ?)",
+			sessionID, m.Title, m.Content, m.SortOrder)
+	}
+
 	success(w, map[string]int64{"id": sessionID})
 }
 
@@ -121,12 +132,27 @@ func GetBuilderSession(w http.ResponseWriter, r *http.Request) {
 		snippetRows.Close()
 	}
 
+	// Load materials
+	materialRows, err := db.DB.Query("SELECT id, builder_session_id, title, content, sort_order FROM builder_session_materials WHERE builder_session_id=? ORDER BY sort_order", id)
+	if err == nil {
+		for materialRows.Next() {
+			var m models.SessionMaterial
+			if err := materialRows.Scan(&m.ID, &m.BuilderSessionID, &m.Title, &m.Content, &m.SortOrder); err == nil {
+				s.Materials = append(s.Materials, m)
+			}
+		}
+		materialRows.Close()
+	}
+
 	if s.Tags == nil {
 		s.Tags = []models.SessionTag{}
 	}
 	if s.Snippets == nil {
 		s.Snippets = []models.SessionSnippet{}
 	}
+	if s.Materials == nil {
+		s.Materials = []models.SessionMaterial{}
+	}
 
 	success(w, s)
 }
@@ -151,6 +177,11 @@ func UpdateBuilderSession(w http.ResponseWriter, r *http.Request) {
 			SnippetID int64 `json:"snippet_id"`
 			SortOrder int   `json:"sort_order"`
 		} `json:"snippet_ids"`
+		Materials []struct {
+			Title    string `json:"title"`
+			Content  string `json:"content"`
+			SortOrder int   `json:"sort_order"`
+		} `json:"materials"`
 	}
 	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
 		fail(w, 400, "请求格式错误")
@@ -183,6 +214,13 @@ func UpdateBuilderSession(w http.ResponseWriter, r *http.Request) {
 			id, s.SnippetID, s.SortOrder)
 	}
 
+	// Replace materials
+	db.DB.Exec("DELETE FROM builder_session_materials WHERE builder_session_id=?", id)
+	for _, m := range req.Materials {
+		db.DB.Exec("INSERT INTO builder_session_materials (builder_session_id, title, content, sort_order) VALUES (?, ?, ?, ?)",
+			id, m.Title, m.Content, m.SortOrder)
+	}
+
 	success(w, nil)
 }
 
@@ -195,12 +233,13 @@ func DeleteBuilderSession(w http.ResponseWriter, r *http.Request) {
 
 	db.DB.Exec("DELETE FROM builder_session_tags WHERE builder_session_id=?", id)
 	db.DB.Exec("DELETE FROM builder_session_snippets WHERE builder_session_id=?", id)
+	db.DB.Exec("DELETE FROM builder_session_materials WHERE builder_session_id=?", id)
 	db.DB.Exec("DELETE FROM builder_sessions WHERE id=?", id)
 	success(w, nil)
 }
 
 // AssemblePrompt 组装最终 Prompt
-func AssemblePrompt(projectName string, customContent string, tagOptions []models.TagOption, snippets []models.Snippet, suggestions []string) string {
+func AssemblePrompt(projectName string, customContent string, tagOptions []models.TagOption, snippets []models.Snippet, suggestions []string, materials []models.SessionMaterial) string {
 	var parts []string
 
 	// Project context
@@ -231,6 +270,19 @@ func AssemblePrompt(projectName string, customContent string, tagOptions []model
 		parts = append(parts, fmt.Sprintf("## 参考片段\n\n%s", strings.Join(snippetParts, "\n\n")))
 	}
 
+	// Materials
+	if len(materials) > 0 {
+		var materialParts []string
+		for i, m := range materials {
+			title := m.Title
+			if title == "" {
+				title = fmt.Sprintf("参考材料%d", i+1)
+			}
+			materialParts = append(materialParts, fmt.Sprintf("--- %s ---\n%s", title, m.Content))
+		}
+		parts = append(parts, fmt.Sprintf("## 参考材料\n\n%s", strings.Join(materialParts, "\n\n")))
+	}
+
 	// Suggestions
 	if len(suggestions) > 0 {
 		parts = append(parts, fmt.Sprintf("## 补充建议\n\n%s", strings.Join(suggestions, "\n")))

internal/models/models.go

@@ -43,6 +43,7 @@ type BuilderSession struct {
 	UpdatedAt       time.Time `json:"updated_at"`
 	Tags            []SessionTag     `json:"tags,omitempty"`
 	Snippets        []SessionSnippet `json:"snippets,omitempty"`
+	Materials       []SessionMaterial `json:"materials,omitempty"`
 }
 
 // SessionTag 构建会话标签关联
@@ -61,6 +62,15 @@ type SessionSnippet struct {
 	SortOrder       int   `json:"sort_order"`
 }
 
+// SessionMaterial 构建会话参考材料
+type SessionMaterial struct {
+	ID              int64  `json:"id"`
+	BuilderSessionID int64 `json:"builder_session_id"`
+	Title           string `json:"title"`
+	Content         string `json:"content"`
+	SortOrder       int    `json:"sort_order"`
+}
+
 // Prompt prompts 表记录（只读）
 type Prompt struct {
 	ID          int64     `json:"id"`