make translation api public to fetch on first app start

api/app_questionnaires.php

@@ -4,33 +4,34 @@
  *
  * GET (no params)                -> ordered questionnaire list with conditions
  * GET ?id=<questionnaireID>      -> single questionnaire in app JSON format
- * GET ?translations=1            -> global app UI strings only (not questionnaire content)
+ * GET ?translations=1            -> global app UI strings only; **no auth** (login screen).
  *
  * POST (coach interview upload) is handled by api/index.php -> handlers/app_questionnaires.php
  */
 require_once __DIR__ . '/../common.php';
 require_once __DIR__ . '/../db_init.php';
+require_once __DIR__ . '/../lib/response.php';
 
 header('Content-Type: application/json; charset=UTF-8');
 
+$method = $_SERVER['REQUEST_METHOD'];
+
+if ($method === 'GET' && !empty($_GET['translations'])) {
+    [$pdo, $tmpDb, $lockFp] = qdb_open(false);
+    json_success(['translations' => qdb_build_app_translations_map($pdo)]);
+    qdb_discard($tmpDb, $lockFp);
+    exit;
+}
+
 $tokenRec = require_valid_token();
 
-if ($_SERVER['REQUEST_METHOD'] !== 'GET') {
+if ($method !== 'GET') {
-    http_response_code(405);
+    json_error('METHOD_NOT_ALLOWED', 'Method not allowed', 405);
-    echo json_encode(["error" => "Method not allowed"]);
-    exit;
 }
 
 [$pdo, $tmpDb, $lockFp] = qdb_open(false);
 
-$qnID        = $_GET['id'] ?? '';
+$qnID = $_GET['id'] ?? '';
-$translations = $_GET['translations'] ?? '';
-
-if ($translations) {
-    qdb_discard($tmpDb, $lockFp);
-    echo json_encode(['success' => true, 'translations' => qdb_build_app_translations_map($pdo)]);
-    exit;
-}
 
 if ($qnID) {
     // Single questionnaire in app JSON format

docs/android-questionnaire-api.md

@@ -265,6 +265,8 @@ Common failures:
 
 `GET /api/app_questionnaires?translations=1`
 
+**Authentication:** not required. The Android app calls this on the login screen before the coach signs in. All other `app_questionnaires` routes still require `Authorization: Bearer <token>`.
+
 Success:
 
 ```json
@@ -307,16 +309,30 @@ Android should apply this map while a questionnaire is open (overlay on top of a
 
 ## Recommended Android Sync Flow
 
-1. Login with `/api/auth/login` and store the returned token securely.
+1. On app start (login screen), fetch app UI translations with `GET /api/app_questionnaires?translations=1` (no token) and cache locally.
-2. Fetch the assigned client list with `GET /api/app_questionnaires?clients=1` (coach role only).
+2. Login with `/api/auth/login` and store the returned token securely (EncryptedSharedPreferences on Android).
-3. Fetch app UI translations with `GET /api/app_questionnaires?translations=1`.
+3. Fetch the assigned client list with `GET /api/app_questionnaires?clients=1` (coach role only).
-4. Fetch the active questionnaire list with `GET /api/app_questionnaires`.
+4. Re-fetch app UI translations optionally after login (same public endpoint, or authenticated refresh).
-5. For each list item, fetch details with `GET /api/app_questionnaires?id=<id>` (includes per-questionnaire `translations`).
+6. For each list item, fetch details with `GET /api/app_questionnaires?id=<id>` (includes per-questionnaire `translations`).
-6. Cache the client list, app translations, the questionnaire list, and questionnaire details (with embedded translations) locally for offline use.
+7. Cache the client list, app translations, the questionnaire list, and questionnaire details (with embedded translations) locally for offline use.
-7. When a questionnaire is completed, upload answers with `POST /api/app_questionnaires`.
+8. When a questionnaire is completed, upload answers with `POST /api/app_questionnaires` (plaintext JSON over HTTPS; server stores answers in the database — not the app's local ciphertext).
 
 There is currently no version or `updatedAt` field in the app fetch response, so the safest refresh strategy is to re-fetch translations, list, and details at login or app start when network is available.
 
+## Android local data security
+
+The Android app encrypts sensitive data **at rest on the device**:
+
+- **Answer text** and **client codes** in the local Room database use AES-256-GCM with keys in Android Keystore (ciphertext on disk; plaintext only inside the running app).
+- **Assigned client list** cache and **session token** use the same encryption / EncryptedSharedPreferences respectively.
+- **Questionnaire definitions** and UI translations cached from this API are not encrypted (no user answers).
+
+After a successful `POST /api/app_questionnaires`, answer data is readable on the **server** (normal database storage, RBAC-protected). The upload body is **decrypted plaintext** (AES-GCM applies only to the on-device Room database). The app keeps encrypted local copies so coaches can review, edit, and re-upload work offline.
+
+Re-uploading the same `clientCode` + `questionnaireID` updates server rows in place (see upload behavior below). This matches upcoming editable flows on web and mobile.
+
+Legacy full-database download endpoints (`downloadFull.php`, encrypted SQLite master file) are **not** used by the current Android app.
+
 ## Upload Questionnaire Data
 
 `POST /api/app_questionnaires`
@@ -377,7 +393,7 @@ Current upload behavior:
 - Unknown or empty `questionID` values are skipped.
 - Unknown `answerOptionKey` values are stored as no selected option for that question.
 - Re-uploading the same `clientCode` and `questionID` overwrites the previous answer.
-- Re-uploading the same `clientCode` and `questionnaireID` overwrites the completed questionnaire status and point sum.
+- Re-uploading the same `clientCode` and `questionnaireID` overwrites the completed questionnaire status and point sum (supports correction / re-edit workflows).
 - `sumPoints` is calculated from recognized `answerOptionKey` values.
 - The current database stores one selected answer option per question. If the Android UI allows multiple selections for a layout, coordinate a server change before uploading multiple option keys for one question.
 

handlers/app_questionnaires.php

@@ -3,11 +3,21 @@
  * Android app API endpoint.
  * GET (no params)           -> ordered questionnaire list with conditions
  * GET ?id=<questionnaireID> -> single questionnaire in app JSON format
- * GET ?translations=1       -> global app UI strings only (not questionnaire content)
+ * GET ?translations=1       -> global app UI strings only (not questionnaire content); **no auth** (login screen).
  * GET ?clients=1            -> list of clients assigned to the authenticated coach
- * POST                      -> submit interview answers for a client (coach / supervisor / admin)
+ * POST                      -> submit interview answers for a client (coach / supervisor / admin).
+ *                             Re-posting the same clientCode + questionnaireID updates answers in place (re-edit).
+ *                             Mobile clients encrypt answers at rest on device; POST body is plaintext JSON over HTTPS.
  */
 
+// Public app UI catalog for the login screen (no token, no PII).
+if ($method === 'GET' && !empty($_GET['translations'])) {
+    [$pdo, $tmpDb, $lockFp] = qdb_open(false);
+    json_success(['translations' => qdb_build_app_translations_map($pdo)]);
+    qdb_discard($tmpDb, $lockFp);
+    return;
+}
+
 $tokenRec = require_valid_token();
 
 if ($method === 'POST') {
@@ -252,11 +262,6 @@ if ($fetchClients) {
     json_success(['coachID' => $coachID, 'clients' => $clients]);
 }
 
-if ($translations) {
-    qdb_discard($tmpDb, $lockFp);
-    json_success(['translations' => qdb_build_app_translations_map($pdo)]);
-}
-
 if ($qnID) {
     $qn = $pdo->prepare("SELECT * FROM questionnaire WHERE questionnaireID = :id");
     $qn->execute([':id' => $qnID]);

website/css/style.css

@@ -602,6 +602,12 @@ th.sort-desc::after { content: ' \2193'; opacity: 1; }
     font-size: .9rem;
     margin-bottom: 24px;
 }
+.login-card .login-privacy-note {
+    color: var(--text-secondary);
+    font-size: .8rem;
+    line-height: 1.4;
+    margin: -12px 0 20px;
+}
 .error-text { color: var(--danger); font-size: .85rem; margin-top: 8px; }
 
 /* Toast */

website/js/pages/login.js

@@ -10,6 +10,7 @@ export function loginPage() {
             <div class="login-card card">
                 <h1>BW Sch&uuml;tzt</h1>
                 <p class="subtitle">Questionnaire Management</p>
+                <p class="login-privacy-note">Coach app stores interview answers encrypted on device; data shown here is loaded from the server after upload.</p>
                 <form id="loginForm">
                     <div class="form-group">
                         <label for="username">Username</label>