Let session owners reassign their session to another user

Previously a session could only be reassigned to another user via a
manual DB UPDATE. This adds it to the session edit UI for every owner of
a session (not just admins) - the ownership check in HandleUpdate
(existing.UserId == userId) already guarantees the caller owns the
session, so handing over one's own session is safe.

Backend:
- ProfileEndpoint: new GET /api/users returning a minimal user directory
  (userId/username/displayName only) for any logged-in user. The
  admin-gated /api/admin/users stays the source for sensitive fields
  (defaultPath/canUseCli/isAdmin).
- SessionEndpoint.HandleUpdate: validate the target user exists (400 if
  not) and pass allowUserReassign: true to UpdateSession.
- DatabaseService.UpdateSession: new allowUserReassign flag; only then is
  a non-empty userId applied as user_id (empty/null is ignored - a
  session must always have an owner).

Frontend:
- index.html: hidden #sessionOwnerRow with a user picker card in the
  session edit form (existing sessions only).
- cards.js: buildUserCard helper for the picker.
- session-page.js: initSessionUserPicker loads users via apiGetUsers(),
  preselects the current owner, and on an actual owner change asks for
  confirmation (irreversible - the session leaves the user's own list).
- api.js: apiGetUsers() -> /api/users.
- ARCHITECTURE.md: document /api/users.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ARCHITECTURE.md

@@ -488,6 +488,7 @@ Alle Endpoints folgen dem **Minimal API**-Pattern mit Extension Methods (`MapXxx
 | **Krea**      | `/api/images/`             | `POST generate`, `GET list`, `GET file/{name}`, `GET file/{name}/thumb`, `GET status` |
 | **Skills**    | `/api/skills`              | `GET list`, `GET/PUT agent skills`, Output-Files + Thumbnails |
 | **Profile**   | `/api/profile`             | `GET`, `PUT`, `PUT password`                |
+| **Users**     | `/api/users`               | `GET` (minimales User-Verzeichnis: id/username/displayName – für jeden eingeloggten User, z. B. Session-Zuweisung) |
 | **Settings**  | `/api/settings`            | `GET`, `PUT`                                |
 | **Backup**    | `/api/backup`              | `POST` (Admin only, tar.gz Download)        |
 | **Shared**    | `/api/shared/`, `/api/messages/{id}/share` | Share erstellen, öffentlich abrufen, auflisten, löschen |

Endpoints/ProfileEndpoint.cs

@@ -1,3 +1,4 @@
+using System.Linq;
 using System.Text.Json;
 using Gott.Extensions;
 using Gott.Services;
@@ -14,6 +15,24 @@ public static class ProfileEndpoint
         app.MapGet("/api/profile", HandleGet);
         app.MapPut("/api/profile", HandleUpdate);
         app.MapPut("/api/profile/password", HandlePasswordChange);
+        app.MapGet("/api/users", HandleListDirectory);
+    }
+
+    /// <summary>
+    /// Minimales User-Verzeichnis für jeden eingeloggten Nutzer (z. B. um eine Session
+    /// einem anderen Benutzer zuzuweisen). Gibt bewusst NUR id/username/displayName zurück –
+    /// keine sensiblen Felder wie defaultPath/canUseCli/isAdmin (dafür gibt es /api/admin/users).
+    /// </summary>
+    private static async System.Threading.Tasks.Task HandleListDirectory(HttpContext ctx, DatabaseService db)
+    {
+        var users = await db.GetUsers();
+        var result = users.Select(u => new
+        {
+            userId = u.UserId,
+            username = u.Username,
+            displayName = u.DisplayName
+        });
+        await ctx.Response.WriteAsJsonAsync(result);
     }
 
     private static async System.Threading.Tasks.Task HandleGet(HttpContext ctx, DatabaseService db)

Endpoints/SessionEndpoint.cs

@@ -186,7 +186,23 @@ public static class SessionEndpoint
             }
         }
 
-        await db.UpdateSession(sessionId, body, imageService);
+        // Session einem anderen Benutzer zuweisen. Jeder Besitzer darf seine EIGENE Session
+        // übergeben – die Ownership-Prüfung oben (existing.UserId == userId) stellt bereits sicher,
+        // dass der Aufrufer der Besitzer ist. Der Ziel-User muss existieren.
+        if (body.TryGetProperty("userId", out var newUid)
+            && newUid.ValueKind == JsonValueKind.String
+            && !string.IsNullOrWhiteSpace(newUid.GetString()))
+        {
+            var targetUser = await db.GetUser(newUid.GetString());
+            if (targetUser == null)
+            {
+                ctx.Response.StatusCode = 400;
+                await ctx.Response.WriteAsJsonAsync(new { error = "Zielbenutzer nicht gefunden" });
+                return;
+            }
+        }
+
+        await db.UpdateSession(sessionId, body, imageService, allowUserReassign: true);
 
         var session = await db.GetSession(sessionId);
         await ctx.Response.WriteAsJsonAsync(session);

Services/DatabaseService.Sessions.cs

@@ -112,7 +112,7 @@ public partial class DatabaseService
             new { sessionId, now = DateTime.UtcNow.ToString("o") });
     }
 
-    public async Task UpdateSession(string sessionId, System.Text.Json.JsonElement body, ImageService imageService = null)
+    public async Task UpdateSession(string sessionId, System.Text.Json.JsonElement body, ImageService imageService = null, bool allowUserReassign = false)
     {
         using var conn = CreateConnection();
         var sets = new List<string> { "updated_at = @now" };
@@ -120,6 +120,16 @@ public partial class DatabaseService
         p.Add("sessionId", sessionId);
         p.Add("now", DateTime.UtcNow.ToString("o"));
 
+        // Session einem anderen Benutzer zuweisen – nur wenn explizit erlaubt (Admin).
+        // Leerer/null userId wird ignoriert (eine Session muss immer einen Besitzer haben).
+        if (allowUserReassign && body.TryGetProperty("userId", out var uid)
+            && uid.ValueKind == System.Text.Json.JsonValueKind.String
+            && !string.IsNullOrWhiteSpace(uid.GetString()))
+        {
+            sets.Add("user_id = @newUserId");
+            p.Add("newUserId", uid.GetString());
+        }
+
         if (body.TryGetProperty("name", out var n)) { sets.Add("name = @name"); p.Add("name", n.GetString()); }
         if (body.TryGetProperty("description", out var d)) { sets.Add("description = @desc"); p.Add("desc", d.GetString()); }
         if (body.TryGetProperty("image", out var img))

wwwroot/index.html

@@ -174,6 +174,14 @@
               <button type="button" id="sessionTelegramUnlink" class="icon-btn danger-btn" title="Verknüpfung lösen"><i class="fa fa-chain-broken"></i></button>
             </div>
             <small class="form-hint">Wird automatisch gesetzt wenn jemand /start an den Bot sendet.</small>
+            <div id="sessionOwnerRow" hidden>
+              <label>Zugewiesener Benutzer</label>
+              <div id="sessionUserSelectCard" class="agent-select-card">
+                <div class="agent-select-empty"><i class="fa fa-user"></i> Kein Benutzer</div>
+              </div>
+              <input type="hidden" id="sessionUserSelect" value="">
+              <small class="form-hint">Weist diese Session einem anderen Benutzer zu. Nach dem Speichern verschwindet sie aus deiner Übersicht.</small>
+            </div>
           </div>
         </div>
         <div class="form-actions">

wwwroot/js/api.js

@@ -211,6 +211,9 @@ function apiShareMessage(id, includeContext) { return _post('/api/messages/' + i
 function apiGetShared(token) { return _get('/api/shared/' + token); }
 function apiDeleteShare(token) { return fetch('/api/shared/' + token, { method: 'DELETE' }); }
 
+// Minimales User-Verzeichnis (jeder eingeloggte User) – z. B. um eine Session zuzuweisen.
+function apiGetUsers() { return _get('/api/users'); }
+
 // ── Admin User API ──
 
 function apiAdminGetUsers() { return _get('/api/admin/users'); }

wwwroot/js/cards.js

@@ -87,6 +87,35 @@ function buildTelegramBotCard(bot) {
 }
 
 
+// ── User Card Helper ──
+// Erzeugt ein kompaktes .card-Element für einen Benutzer (für den Zuweisungs-Picker).
+function buildUserCard(user) {
+  const card = document.createElement('div');
+  card.className = 'card card-compact';
+
+  const badges = [];
+  if (user.isAdmin) {
+    badges.push('<span class="badge badge-feature"><i class="fa fa-shield"></i> Admin</span>');
+  }
+
+  const metaParts = [];
+  metaParts.push(`<span class="card-meta-item"><i class="fa fa-at"></i> ${esc(user.username)}</span>`);
+
+  const title = user.displayName || user.username;
+  card.innerHTML = `
+    <div class="card-body">
+      <div class="card-title-row">
+        <span class="card-title"><i class="fa fa-user"></i> ${esc(title)}</span>
+        ${badges.join('')}
+      </div>
+      ${metaParts.length ? `<div class="card-meta">${metaParts.join('')}</div>` : ''}
+    </div>
+  `;
+
+  return card;
+}
+
+
 // ── Agent Card Helper ──
 // Erzeugt ein .card-Element für einen Agent (wiederverwendbar für Dashboard + Picker).
 

wwwroot/js/pages/session-page.js

@@ -37,6 +37,9 @@ registerPage('session', {
     const addCommandBtn = document.getElementById('addCommandBtn');
     const unityMcpUrlEl = document.getElementById('sessionUnityMcpUrl');
     const unityMcpTokenEl = document.getElementById('sessionUnityMcpToken');
+    const ownerRow = document.getElementById('sessionOwnerRow');
+    const userSelectCard = document.getElementById('sessionUserSelectCard');
+    const userSelect = document.getElementById('sessionUserSelect');
     const more = document.querySelector('.more');
 
     // Avatar Editor initialisieren
@@ -123,6 +126,11 @@ registerPage('session', {
     updateReviewVisibility();
     setupAgentPicker(finalizerAgentSelectCard, finalizerAgentSelect, session && session.finalizerAgentId, 'fa-flag-checkered', 'Kein Finalizer-Agent');
 
+    // User-Zuweisung (jeder Besitzer, nur für bestehende Sessions)
+    if (!isNew) {
+      initSessionUserPicker(ownerRow, userSelectCard, userSelect, session && session.userId);
+    }
+
     initMoreButton(more);
 
     // Workspace Browse
@@ -179,6 +187,16 @@ registerPage('session', {
         unityMcpToken: unityMcpTokenEl.value.trim() || null
       };
 
+      // Session einem anderen Benutzer zuweisen. Wechselt der Besitzer tatsächlich,
+      // erst rückfragen – die Session verschwindet danach aus der eigenen Übersicht.
+      if (!isNew && userSelect.value && userSelect.value !== (session && session.userId)) {
+        var targetLabel = userSelect.dataset.userLabel || 'einem anderen Benutzer';
+        if (!confirm('Diese Session an "' + targetLabel + '" zuweisen? Sie verschwindet danach aus deiner Übersicht.')) {
+          return;
+        }
+        data.userId = userSelect.value;
+      }
+
       if (isNew) {
         await apiCreateSession(data);
       } else {
@@ -284,4 +302,53 @@ async function initTelegramBotPicker(cardEl, selectEl, currentBotId) {
   });
 }
 
+// Session einem anderen Benutzer zuweisen (jeder Besitzer seiner eigenen Session).
+async function initSessionUserPicker(rowEl, cardEl, selectEl, currentOwnerId) {
+  var users = [];
+  try {
+    var result = await apiGetUsers();
+    if (Array.isArray(result)) users = result;
+  } catch (e) {
+    // Fehler beim Laden → Zuweisung bleibt versteckt
+    return;
+  }
+  var userMap = {};
+  for (var i = 0; i < users.length; i++) userMap[users[i].userId] = users[i];
+
+  function userLabel(user) {
+    return user ? (user.displayName || user.username || '') : '';
+  }
+
+  function renderUserInCard(user) {
+    var inner = user ? buildUserCard(user) : null;
+    _renderCardPreview(cardEl, inner, 'fa-user', 'Kein Benutzer', 'agent-select-change');
+    selectEl.dataset.userLabel = userLabel(user);
+  }
+
+  selectEl.value = currentOwnerId || '';
+  renderUserInCard(userMap[currentOwnerId] || null);
+  rowEl.hidden = false;
+
+  cardEl.addEventListener('click', function() {
+    openUserPickerModal(users, selectEl.value, function(selectedUserId) {
+      // "Keine Änderung" (null) ignorieren – eine Session muss immer einen Besitzer haben.
+      if (!selectedUserId) return;
+      selectEl.value = selectedUserId;
+      renderUserInCard(userMap[selectedUserId] || null);
+    });
+  });
+}
+
+function openUserPickerModal(users, currentId, onSelect) {
+  var items = users.map(function(u) {
+    u._pickerId = u.userId;
+    return u;
+  });
+  _openPickerModal('Benutzer auswählen', items, currentId, onSelect, {
+    noneLabel: 'Keine Änderung',
+    noneIcon: 'fa-user',
+    buildCard: function(u) { return buildUserCard(u); }
+  });
+}
+