Add private Jellystat viewing stats to Magent beta

backend/app/services/jellyfin_identity.py

@@ -0,0 +1,35 @@
+"""Stable Jellyfin identities for private, user-scoped integrations."""
+
+import hashlib
+from contextlib import closing
+
+from .. import db
+
+
+def source_key(base_url: str | None) -> str:
+    return hashlib.sha256(str(base_url or "").strip().rstrip("/").encode()).hexdigest()
+
+
+def linked_user_id(username: str, base_url: str | None) -> str | None:
+    user = db.get_user_by_username(username)
+    if not user or not base_url:
+        return None
+    with closing(db._connect()) as conn, conn:
+        row = conn.execute(
+            "SELECT jellyfin_user_id FROM jellyfin_user_links WHERE source = ? AND local_user_id = ?",
+            (source_key(base_url), user["id"]),
+        ).fetchone()
+    return row[0] if row else None
+
+
+def link_user(username: str, jellyfin_user_id: str, base_url: str | None) -> None:
+    """Use only verified login or canonical Jellyfin user sync, never playback names."""
+    user = db.get_user_by_username(username)
+    if not user or not jellyfin_user_id or not base_url:
+        return
+    with closing(db._connect()) as conn, conn:
+        # A renamed or re-created account must not silently take over an existing identity.
+        conn.execute(
+            "INSERT OR IGNORE INTO jellyfin_user_links (source, local_user_id, jellyfin_user_id) VALUES (?, ?, ?)",
+            (source_key(base_url), user["id"], str(jellyfin_user_id)),
+        )