fix: code review — security fixes, dedup, cleanup

- setup: validate roles against users.VALID_ROLES (Supervisor was missing)
- files: fix path traversal prefix-match edge case (is_relative_to),
  dedupe path validation into resolve_upload_path(), use logging not print
- measurements: extract shared _build_measurement_filters() helper
- client app: prevent open redirect via Referer on /set-language
- maker: guard resp.json() in parse-technical-sheet proxy
- measure/maker: extract shared file proxy into services/file_proxy.py
- measure: localize supervisor validation error messages
- annotation-editor: remove global keydown listener in destroy()

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/frontend/flask_app/app.py

@@ -1,6 +1,7 @@
 """TieMeasureFlow Client - Flask Entry Point."""
 import json
 import os
+from urllib.parse import urlparse
 
 from flask import Flask, redirect, url_for, session, request
 from flask_babel import Babel
@@ -63,7 +64,14 @@ def create_app() -> Flask:
         """Set user's preferred language and store in session."""
         if lang in Config.LANGUAGES:
             session["language"] = lang
-        return redirect(request.referrer or url_for("auth.login"))
+        # Only follow the referrer if it points back to this host
+        # (prevents open redirect via a forged Referer header).
+        referrer = request.referrer
+        if referrer:
+            parsed = urlparse(referrer)
+            if parsed.netloc and parsed.netloc != request.host:
+                referrer = None
+        return redirect(referrer or url_for("auth.login"))
 
     @app.template_filter("tojson_attr")
     def tojson_attr_filter(value):

src/frontend/flask_app/blueprints/maker.py

@@ -1,12 +1,13 @@
 """Maker blueprint - recipe creation and editing."""
 import requests as http_requests
 
-from flask import Blueprint, Response, flash, jsonify, redirect, render_template, request, session, url_for
+from flask import Blueprint, flash, jsonify, redirect, render_template, request, session, url_for
 from flask_babel import gettext as _
 
 from blueprints.auth import login_required, role_required
 from config import Config
 from services.api_client import api_client
+from services.file_proxy import proxy_file
 
 maker_bp = Blueprint("maker", __name__, url_prefix="/maker")
 
@@ -380,19 +381,7 @@ def api_upload_file():
 @login_required
 def api_get_file(file_path: str):
     """Proxy: Serve file from API server (browser can't send X-API-Key)."""
-    api_key = session.get("api_key", "")
-    base_url = Config.API_SERVER_URL.rstrip("/")
-    resp = http_requests.get(
-        f"{base_url}/api/files/{file_path}",
-        headers={"X-API-Key": api_key},
-        timeout=30,
-    )
-    if resp.status_code != 200:
-        return Response(resp.text, status=resp.status_code)
-    return Response(
-        resp.content,
-        content_type=resp.headers.get("content-type", "application/octet-stream"),
-    )
+    return proxy_file(file_path)
 
 
 @maker_bp.route("/api/files/<path:file_path>", methods=["DELETE"])
@@ -444,4 +433,11 @@ def api_parse_technical_sheet(recipe_id: int):
         timeout=90,
     )
 
-    return jsonify(resp.json()), resp.status_code
+    try:
+        payload = resp.json()
+    except ValueError:
+        payload = {
+            "error": True,
+            "detail": resp.text or f"HTTP {resp.status_code}",
+        }
+    return jsonify(payload), resp.status_code

src/frontend/flask_app/blueprints/measure.py

@@ -1,8 +1,6 @@
 """MeasurementTec blueprint - recipe selection and measurement execution."""
-import requests as http_requests
-
 from flask import (
-    Blueprint, Response, flash, jsonify, redirect, render_template,
+    Blueprint, flash, jsonify, redirect, render_template,
     request, session, url_for,
 )
 from flask_babel import gettext as _
@@ -10,6 +8,7 @@ from flask_babel import gettext as _
 from blueprints.auth import login_required, role_required
 from config import Config
 from services.api_client import api_client
+from services.file_proxy import proxy_file
 
 measure_bp = Blueprint("measure", __name__)
 
@@ -339,17 +338,17 @@ def validate_supervisor():
     password = data.get("password", "")
 
     if not username or not password:
-        return jsonify({"error": True, "detail": "Username e password richiesti"}), 400
+        return jsonify({"error": True, "detail": _("Username e password richiesti")}), 400
 
     resp = api_client.post("/api/auth/login", data={"username": username, "password": password})
 
     if resp.get("error"):
-        return jsonify({"error": True, "detail": "Credenziali non valide"}), 401
+        return jsonify({"error": True, "detail": _("Credenziali non valide")}), 401
 
     user = resp.get("user", {})
     is_supervisor = "Supervisor" in (user.get("roles") or [])
     if not (is_supervisor or user.get("is_admin")):
-        return jsonify({"error": True, "detail": "Utente non autorizzato (richiesto capoturno)"}), 403
+        return jsonify({"error": True, "detail": _("Utente non autorizzato (richiesto capoturno)")}), 403
 
     return jsonify({"authorized": True, "supervisor": user.get("display_name", username)}), 200
 
@@ -361,16 +360,4 @@ def validate_supervisor():
 @login_required
 def api_get_file(file_path: str):
     """Proxy: Serve file from API server (browser can't send X-API-Key)."""
-    api_key = session.get("api_key", "")
-    base_url = Config.API_SERVER_URL.rstrip("/")
-    resp = http_requests.get(
-        f"{base_url}/api/files/{file_path}",
-        headers={"X-API-Key": api_key},
-        timeout=30,
-    )
-    if resp.status_code != 200:
-        return Response(resp.text, status=resp.status_code)
-    return Response(
-        resp.content,
-        content_type=resp.headers.get("content-type", "application/octet-stream"),
-    )
+    return proxy_file(file_path)

src/frontend/flask_app/services/file_proxy.py

@@ -0,0 +1,25 @@
+"""Shared file proxy: relay uploads from the FastAPI server to the browser.
+
+The browser can't send the X-API-Key header directly, so blueprints expose
+a proxy route and delegate here.
+"""
+import requests as http_requests
+from flask import Response, session
+
+from config import Config
+
+
+def proxy_file(file_path: str) -> Response:
+    """Fetch a file from the API server and relay it with its content type."""
+    base_url = Config.API_SERVER_URL.rstrip("/")
+    resp = http_requests.get(
+        f"{base_url}/api/files/{file_path}",
+        headers={"X-API-Key": session.get("api_key", "")},
+        timeout=30,
+    )
+    if resp.status_code != 200:
+        return Response(resp.text, status=resp.status_code)
+    return Response(
+        resp.content,
+        content_type=resp.headers.get("content-type", "application/octet-stream"),
+    )

src/frontend/flask_app/static/js/annotation-editor.js

@@ -956,7 +956,7 @@ function annotationEditor() {
     setupKeyboard() {
       var self = this;
 
-      document.addEventListener('keydown', function (e) {
+      this._onKeyDown = function (e) {
         // Skip when typing in form fields
         var tag = e.target.tagName;
         if (tag === 'INPUT' || tag === 'TEXTAREA' || tag === 'SELECT') return;
@@ -970,7 +970,8 @@ function annotationEditor() {
           self.canvas.discardActiveObject();
           self.canvas.renderAll();
         }
-      });
+      };
+      document.addEventListener('keydown', this._onKeyDown);
     },
 
     // ----------------------------------------------------------------
@@ -1289,6 +1290,9 @@ function annotationEditor() {
       if (this._onImageLoaded) {
         window.removeEventListener('image-loaded', this._onImageLoaded);
       }
+      if (this._onKeyDown) {
+        document.removeEventListener('keydown', this._onKeyDown);
+      }
       if (this.canvas) {
         this.canvas.dispose();
         this.canvas = null;