feat(tiktok): rehydration blob extractor

surfsense_backend/app/proprietary/platforms/tiktok/extraction/__init__.py

@@ -0,0 +1,7 @@
+"""Turn raw TikTok page/API payloads into normalized items."""
+
+from __future__ import annotations
+
+from .hydration import extract_rehydration_data
+
+__all__ = ["extract_rehydration_data"]

surfsense_backend/app/proprietary/platforms/tiktok/extraction/hydration.py

@@ -0,0 +1,28 @@
+"""Extract the ``__UNIVERSAL_DATA_FOR_REHYDRATION__`` JSON embedded in page HTML.
+
+TikTok server-renders the first page of data into a single script tag; parsing
+it yields page-one items (video/profile/hashtag) without any signed API call.
+"""
+
+from __future__ import annotations
+
+import json
+import re
+from typing import Any
+
+_BLOB_RE = re.compile(
+    r'<script[^>]*id="__UNIVERSAL_DATA_FOR_REHYDRATION__"[^>]*>(.*?)</script>',
+    re.DOTALL,
+)
+
+
+def extract_rehydration_data(html: str) -> dict[str, Any] | None:
+    """Return the parsed rehydration blob, or ``None`` if absent/unparseable."""
+    match = _BLOB_RE.search(html)
+    if not match:
+        return None
+    try:
+        data = json.loads(match.group(1))
+    except (json.JSONDecodeError, ValueError):
+        return None
+    return data if isinstance(data, dict) else None