열기 링크에 사용자 식별값 전달

- /go 리다이렉트 엔드포인트 추가: 로그인 시 email, 비로그인 시 IP를 쿼리에 부착
- ncue.net 및 하위 도메인 링크에만 적용(안전한 allowlist)
- script.js 및 index.html 폴백에서 열기 버튼을 /go 경유로 변경

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

flask_app.py

@@ -7,13 +7,14 @@ import time
 from dataclasses import dataclass
 from pathlib import Path
 from typing import Any, Dict, Optional, Tuple
+from urllib.parse import parse_qsl, urlencode, urlparse, urlunparse
 
 import jwt
 import psycopg2
 import psycopg2.pool
 import requests
 from dotenv import load_dotenv
-from flask import Flask, Response, jsonify, request, send_from_directory
+from flask import Flask, Response, jsonify, redirect, request, send_from_directory
 from flask_cors import CORS
 
 
@@ -248,6 +249,37 @@ ALLOWED_STATIC = {
 }
 
 
+def client_ip() -> str:
+    # Prefer proxy header (Apache ProxyPass sets this)
+    xff = str(request.headers.get("X-Forwarded-For", "")).strip()
+    if xff:
+        return xff.split(",")[0].strip()
+    return str(request.remote_addr or "").strip()
+
+
+def is_http_url(u: str) -> bool:
+    try:
+        p = urlparse(u)
+        return p.scheme in ("http", "https") and bool(p.netloc)
+    except Exception:
+        return False
+
+
+def is_ncue_host(host: str) -> bool:
+    h = str(host or "").strip().lower()
+    return h == "ncue.net" or h.endswith(".ncue.net")
+
+
+def add_ref_params(target_url: str, ref_type: str, ref_value: str) -> str:
+    p = urlparse(target_url)
+    q = dict(parse_qsl(p.query, keep_blank_values=True))
+    # Keep names short + explicit
+    q["ref_type"] = ref_type
+    q["ref"] = ref_value
+    new_query = urlencode(q, doseq=True)
+    return urlunparse((p.scheme, p.netloc, p.path, p.params, new_query, p.fragment))
+
+
 @app.get("/")
 def home() -> Response:
     return send_from_directory(ROOT_DIR, "index.html")
@@ -261,6 +293,35 @@ def static_files(filename: str) -> Response:
     return send_from_directory(ROOT_DIR, filename)
 
 
+@app.get("/go")
+def go() -> Response:
+    """
+    Redirect helper to pass identity to internal apps.
+    - Logged-in user: pass email (from query param)
+    - Anonymous user: pass client IP (server-side)
+
+    For safety, only redirects to ncue.net / *.ncue.net targets.
+    """
+    u = str(request.args.get("u", "")).strip()
+    if not u or not is_http_url(u):
+        return jsonify({"ok": False, "error": "invalid_url"}), 400
+
+    p = urlparse(u)
+    if not is_ncue_host(p.hostname or ""):
+        return jsonify({"ok": False, "error": "host_not_allowed"}), 400
+
+    email = str(request.args.get("e", "") or request.args.get("email", "")).strip().lower()
+    if email:
+        target = add_ref_params(u, "email", email)
+    else:
+        ip = client_ip()
+        target = add_ref_params(u, "ip", ip)
+
+    resp = redirect(target, code=302)
+    resp.headers["Cache-Control"] = "no-store"
+    return resp
+
+
 @app.get("/healthz")
 def healthz() -> Response:
     try: