新增作文区与 AI 解读开关，修复 CSV 导出。

系统设置可关闭成绩复盘 AI；学生详情增加作文区（OCR/手动题目、方案与范文、历史与 MD 下载）；导出改用 UTF-8 文件名响应。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/services/llm.py

@@ -306,4 +306,81 @@ async def generate_review_insight(
         careless_hint=careless_hint,
         subject_hints=subject_hints,
     )
-    return await generate_text(prompt, cfg, temperature=0.2)
+    return await generate_text(prompt, cfg, temperature=0.2)
+
+
+CURRICULUM_CHINESE_JUNIOR = """初中作文：记叙文、写人记事、简单议论文为主，通常 600-800 字。
+语言平实，素材来自课内与日常生活，禁止成人化腔调与超纲典故堆砌。"""
+
+CURRICULUM_CHINESE_SENIOR = """高中作文：记叙、议论、材料作文为主，通常 800-1000 字。
+可适度展开论证，仍须符合课内要求，禁止大学论文式写法与超纲理论。"""
+
+COMPOSITION_PROMPT = """你是一位{stage}语文老师，正在辅导{grade_text}学生完成作文。
+
+【学段年级 — 严禁超纲】
+{curriculum}
+
+作文题目：
+{topic}
+
+请严格按以下 Markdown 结构输出（不要增加其他一级标题）：
+
+## 写作方案
+（审题、立意、结构提纲、段落安排、可用素材方向，分条列出，贴合{grade_text}水平）
+
+## 范文
+（完整作文一篇，字数与语言风格必须符合{grade_text}课内要求，禁止超纲）
+
+注意：范文必须是可直接参考的学生习作水准，不要写成评论或教案。
+"""
+
+
+def _chinese_curriculum(level, grade: str | None) -> str:
+    is_senior = level == SchoolLevel.senior_high or level == "senior_high"
+    return CURRICULUM_CHINESE_SENIOR if is_senior else CURRICULUM_CHINESE_JUNIOR
+
+
+def _grade_text(grade: str | None) -> str:
+    if grade and grade.strip():
+        return grade.strip()
+    return "该学段学生"
+
+
+def split_composition_sections(text: str) -> tuple[str, str]:
+    import re
+
+    text = text.strip()
+    if "## 范文" not in text:
+        return text.replace("## 写作方案", "").strip(), ""
+    parts = re.split(r"\n##\s*范文\s*\n", text, maxsplit=1)
+    plan = parts[0].replace("## 写作方案", "").strip()
+    essay = parts[1].strip() if len(parts) > 1 else ""
+    return plan, essay
+
+
+async def generate_composition(
+    cfg: AIConfig,
+    topic: str,
+    school_level=None,
+    grade: str | None = None,
+) -> tuple[str, str]:
+    stage = school_level_label(school_level)
+    grade_text = _grade_text(grade)
+    curriculum = _chinese_curriculum(school_level, grade)
+    prompt = COMPOSITION_PROMPT.format(
+        stage=stage,
+        grade_text=grade_text,
+        curriculum=curriculum,
+        topic=topic.strip(),
+    )
+    full = await generate_text(prompt, cfg, temperature=0.35)
+    return split_composition_sections(full)
+
+
+def composition_markdown(topic: str, writing_plan: str | None, sample_essay: str | None) -> str:
+    parts = [f"# 作文题目\n\n{topic.strip()}", ""]
+    if writing_plan:
+        parts.extend(["## 写作方案", "", writing_plan.strip(), ""])
+    if sample_essay:
+        parts.extend(["## 范文", "", sample_essay.strip(), ""])
+    return "\n".join(parts).strip() + "\n"

backend/app/services/migrate.py

@@ -91,3 +91,13 @@ def run_migrations() -> None:
         if "review_statuses_json" not in ss_columns:
             with engine.begin() as conn:
                 conn.execute(text("ALTER TABLE subject_scores ADD COLUMN review_statuses_json TEXT"))
+
+    if "system_settings" in tables:
+        ss_columns = {col["name"] for col in inspector.get_columns("system_settings")}
+        if "ai_review_enabled" not in ss_columns:
+            with engine.begin() as conn:
+                conn.execute(
+                    text(
+                        "ALTER TABLE system_settings ADD COLUMN ai_review_enabled BOOLEAN NOT NULL DEFAULT TRUE"
+                    )
+                )