feat: 大屏后端（FastAPI+MQTT+sim_engine）

- REST :10085 / MQTT 控制 / SSE 回退 / AI+语音
- 数据源规划：接核心服务端 + 算力引擎真实数据

backend/app/storage.py

@@ -0,0 +1,115 @@
+# -*- coding: utf-8 -*-
+"""JSON 持久化：设置 / 播放列表 / URL 媒体（对齐原 Rust storage 语义）"""
+
+import json
+import threading
+import time
+from pathlib import Path
+
+from .config import settings
+
+DEFAULT_SETTINGS = {
+    "username": "admin",
+    "password": "123456",
+    "volume": 80,
+    "sfx_volume": 60,
+    "auto_play": True,
+    "play_mode": "sequential",
+    "image_duration": 5,
+    "fullscreen": True,
+    "autostart": False,
+}
+
+
+class Storage:
+    def __init__(self, data_file: Path):
+        self.data_file = data_file
+        self._lock = threading.RLock()
+        self._data = self._load()
+
+    # ---------- 底层 ----------
+    def _load(self):
+        if self.data_file.exists():
+            try:
+                data = json.loads(self.data_file.read_text("utf-8"))
+                # 规范化：URL 来源自动标记（兼容旧数据 source=None 的 URL 条目）
+                for it in data.setdefault("playlist", []):
+                    p = it.get("path", "")
+                    if p.startswith(("http://", "https://")) and not it.get("source"):
+                        it["source"] = "url"
+                return data
+            except Exception:
+                pass
+        return {"settings": dict(DEFAULT_SETTINGS), "playlist": [], "url_media": []}
+
+    def _save(self):
+        self.data_file.parent.mkdir(parents=True, exist_ok=True)
+        tmp = self.data_file.with_suffix(".tmp")
+        tmp.write_text(json.dumps(self._data, ensure_ascii=False, indent=2), "utf-8")
+        tmp.replace(self.data_file)
+
+    # ---------- 设置 ----------
+    def get_settings(self):
+        with self._lock:
+            s = dict(DEFAULT_SETTINGS)
+            s.update(self._data.get("settings", {}))
+            return s
+
+    def update_settings(self, **kw):
+        with self._lock:
+            s = dict(DEFAULT_SETTINGS)
+            s.update(self._data.get("settings", {}))
+            for k, v in kw.items():
+                if v is not None and k in s:
+                    s[k] = v
+            self._data["settings"] = s
+            self._save()
+
+    # ---------- 播放列表 ----------
+    def get_playlist(self):
+        with self._lock:
+            return list(self._data.get("playlist", []))
+
+    def add_to_playlist(self, path):
+        with self._lock:
+            items = self._data.setdefault("playlist", [])
+            if not any(it.get("path") == path for it in items):
+                # URL 来源自动标记，避免被当作本地文件过滤
+                source = "url" if path.startswith(("http://", "https://")) else None
+                items.append({"path": path, "source": source, "name": None})
+            self._save()
+
+    def remove_from_playlist(self, path):
+        with self._lock:
+            self._data.setdefault("playlist", [])
+            self._data["playlist"] = [it for it in self._data["playlist"] if it.get("path") != path]
+            self._save()
+
+    # ---------- URL 媒体 ----------
+    def get_url_media(self):
+        with self._lock:
+            return list(self._data.get("url_media", []))
+
+    def add_url_media(self, url, name, media_type):
+        """返回 True 表示新增，False 表示已存在（重复）"""
+        with self._lock:
+            items = self._data.setdefault("url_media", [])
+            if any(it.get("url") == url for it in items):
+                return False
+            items.append({
+                "url": url, "name": name, "type": media_type,
+                "added_at": time.strftime("%Y-%m-%d %H:%M:%S"),
+            })
+            self._save()
+            return True
+
+    def delete_media(self, path):
+        with self._lock:
+            self._data.setdefault("url_media", [])
+            self._data["url_media"] = [it for it in self._data["url_media"] if it.get("url") != path]
+            self._data.setdefault("playlist", [])
+            self._data["playlist"] = [it for it in self._data["playlist"] if it.get("path") != path]
+            self._save()
+
+
+storage = Storage(settings.DATA_FILE)