diff --git a/api/src/routes/auth.js b/api/src/routes/auth.js
index aee64f2..c5c27fb 100644
--- a/api/src/routes/auth.js
+++ b/api/src/routes/auth.js
@@ -114,6 +114,17 @@ async function authRoutes(app) {
         return { status: 'not_implemented', provider, message: `${provider} OAuth coming soon. Configure at Settings > Connections.` };
     });
 
+    // Search users by name or email (for collaboration)
+    app.get('/auth/users/search', async (req) => {
+        const q = (req.query.q || '').trim();
+        if (q.length < 2) return { data: [] };
+        const { rows } = await app.db.query(
+            "SELECT id, name, email, avatar_url FROM users WHERE (name ILIKE $1 OR email ILIKE $1) ORDER BY name LIMIT 20",
+            ["%" + q + "%"]
+        );
+        return { data: rows };
+    });
+
 }
 
 module.exports = authRoutes;
diff --git a/apps/tasks/app/tasks/[id]/collaborate/page.tsx b/apps/tasks/app/tasks/[id]/collaborate/page.tsx
new file mode 100644
index 0000000..0f9d836
--- /dev/null
+++ b/apps/tasks/app/tasks/[id]/collaborate/page.tsx
@@ -0,0 +1,634 @@
+"use client";
+
+import { useEffect, useState, useCallback } from "react";
+import { useRouter, useParams } from "next/navigation";
+import { useAuth } from "@/lib/auth";
+import { useTranslation } from "@/lib/i18n";
+import {
+  getTask,
+  Task,
+  Subtask,
+  CollabRequest,
+  getSubtasks,
+  createSubtask,
+  updateSubtask,
+  deleteSubtask,
+  getCollaborationHistory,
+  sendCollabRequest,
+  searchUsers,
+} from "@/lib/api";
+
+interface UserResult {
+  id: string;
+  name: string;
+  email: string;
+  avatar_url: string | null;
+}
+
+function UserAvatar({ name, avatarUrl, size = "sm" }: { name: string; avatarUrl?: string | null; size?: "sm" | "md" }) {
+  const sz = size === "md" ? "w-10 h-10 text-sm" : "w-8 h-8 text-xs";
+  const initials = name
+    .split(" ")
+    .map((n) => n[0])
+    .join("")
+    .toUpperCase()
+    .slice(0, 2);
+  if (avatarUrl) {
+    return <img src={avatarUrl} alt={name} className={`${sz} rounded-full object-cover`} />;
+  }
+  const colors = ["bg-blue-500", "bg-green-500", "bg-purple-500", "bg-orange-500", "bg-pink-500", "bg-teal-500"];
+  const color = colors[name.charCodeAt(0) % colors.length];
+  return (
+    <div className={`${sz} rounded-full ${color} text-white flex items-center justify-center font-medium`}>
+      {initials}
+    </div>
+  );
+}
+
+function UserSearchDropdown({
+  token,
+  onSelect,
+  placeholder,
+}: {
+  token: string;
+  onSelect: (user: UserResult) => void;
+  placeholder: string;
+}) {
+  const [query, setQuery] = useState("");
+  const [results, setResults] = useState<UserResult[]>([]);
+  const [searching, setSearching] = useState(false);
+
+  useEffect(() => {
+    if (query.length < 2) {
+      setResults([]);
+      return;
+    }
+    const timer = setTimeout(async () => {
+      setSearching(true);
+      try {
+        const res = await searchUsers(token, query);
+        setResults(res.data || []);
+      } catch {
+        setResults([]);
+      } finally {
+        setSearching(false);
+      }
+    }, 300);
+    return () => clearTimeout(timer);
+  }, [query, token]);
+
+  return (
+    <div className="relative">
+      <input
+        type="text"
+        value={query}
+        onChange={(e) => setQuery(e.target.value)}
+        placeholder={placeholder}
+        className="w-full px-3 py-2 text-sm border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-gray-800 focus:ring-2 focus:ring-blue-500 focus:border-transparent"
+      />
+      {searching && (
+        <div className="absolute right-3 top-2.5">
+          <div className="animate-spin rounded-full h-4 w-4 border-b-2 border-blue-600" />
+        </div>
+      )}
+      {results.length > 0 && (
+        <div className="absolute z-10 w-full mt-1 bg-white dark:bg-gray-800 border border-gray-200 dark:border-gray-700 rounded-lg shadow-lg max-h-48 overflow-y-auto">
+          {results.map((user) => (
+            <button
+              key={user.id}
+              onClick={() => {
+                onSelect(user);
+                setQuery("");
+                setResults([]);
+              }}
+              className="w-full flex items-center gap-2 px-3 py-2 hover:bg-gray-100 dark:hover:bg-gray-700 text-left"
+            >
+              <UserAvatar name={user.name} avatarUrl={user.avatar_url} />
+              <div>
+                <div className="text-sm font-medium">{user.name}</div>
+                <div className="text-xs text-gray-500">{user.email}</div>
+              </div>
+            </button>
+          ))}
+        </div>
+      )}
+    </div>
+  );
+}
+
+export default function CollaboratePage() {
+  const { token, user } = useAuth();
+  const { t } = useTranslation();
+  const router = useRouter();
+  const params = useParams();
+  const id = params.id as string;
+
+  const [task, setTask] = useState<Task | null>(null);
+  const [subtasks, setSubtasks] = useState<Subtask[]>([]);
+  const [history, setHistory] = useState<CollabRequest[]>([]);
+  const [assignees, setAssignees] = useState<UserResult[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState("");
+
+  // Forms
+  const [showAssignSearch, setShowAssignSearch] = useState(false);
+  const [showTransferSearch, setShowTransferSearch] = useState(false);
+  const [transferMessage, setTransferMessage] = useState("");
+  const [newSubtaskTitle, setNewSubtaskTitle] = useState("");
+  const [showSubtaskForm, setShowSubtaskForm] = useState(false);
+  const [subtaskAssignee, setSubtaskAssignee] = useState<UserResult | null>(null);
+  const [actionLoading, setActionLoading] = useState(false);
+
+  const loadAll = useCallback(async () => {
+    if (!token || !id) return;
+    setLoading(true);
+    try {
+      const [taskData, subtasksData, historyData] = await Promise.all([
+        getTask(token, id),
+        getSubtasks(token, id),
+        getCollaborationHistory(token, id),
+      ]);
+      setTask(taskData);
+      setSubtasks(subtasksData.data || []);
+      setHistory(historyData.data || []);
+
+      // Load assignee details
+      const assignedIds: string[] = taskData.assigned_to || [];
+      if (assignedIds.length > 0) {
+        try {
+          const usersRes = await searchUsers(token, "");
+          // Filter by IDs — the workload endpoint returns all users, filter client-side
+          // For now just show what we can from collaboration history
+          const knownUsers = new Map<string, UserResult>();
+          (historyData.data || []).forEach((h: CollabRequest) => {
+            if (h.from_user_id && h.from_name) knownUsers.set(h.from_user_id, { id: h.from_user_id, name: h.from_name, email: "", avatar_url: null });
+            if (h.to_user_id && h.to_name) knownUsers.set(h.to_user_id, { id: h.to_user_id, name: h.to_name, email: "", avatar_url: null });
+          });
+          // Merge with any search results
+          (usersRes.data || []).forEach((u: UserResult) => knownUsers.set(u.id, u));
+          setAssignees(assignedIds.map((uid) => knownUsers.get(uid) || { id: uid, name: uid.slice(0, 8), email: "", avatar_url: null }));
+        } catch {
+          setAssignees(assignedIds.map((uid) => ({ id: uid, name: uid.slice(0, 8), email: "", avatar_url: null })));
+        }
+      } else {
+        setAssignees([]);
+      }
+    } catch (err) {
+      setError(err instanceof Error ? err.message : t("tasks.loadError"));
+    } finally {
+      setLoading(false);
+    }
+  }, [token, id, t]);
+
+  useEffect(() => {
+    if (!token) {
+      router.replace("/login");
+      return;
+    }
+    loadAll();
+  }, [token, router, loadAll]);
+
+  async function handleAssign(selectedUser: UserResult) {
+    if (!token || !id || !user) return;
+    setActionLoading(true);
+    try {
+      await sendCollabRequest(token, id, {
+        from_user_id: user.id,
+        to_user_id: selectedUser.id,
+        type: "assign",
+        message: "",
+      });
+      setShowAssignSearch(false);
+      await loadAll();
+    } catch (err) {
+      setError(err instanceof Error ? err.message : t("common.error"));
+    } finally {
+      setActionLoading(false);
+    }
+  }
+
+  async function handleTransfer(selectedUser: UserResult) {
+    if (!token || !id || !user) return;
+    setActionLoading(true);
+    try {
+      await sendCollabRequest(token, id, {
+        from_user_id: user.id,
+        to_user_id: selectedUser.id,
+        type: "transfer",
+        message: transferMessage,
+      });
+      setShowTransferSearch(false);
+      setTransferMessage("");
+      await loadAll();
+    } catch (err) {
+      setError(err instanceof Error ? err.message : t("common.error"));
+    } finally {
+      setActionLoading(false);
+    }
+  }
+
+  async function handleClaim() {
+    if (!token || !id || !user) return;
+    setActionLoading(true);
+    try {
+      await sendCollabRequest(token, id, {
+        from_user_id: user.id,
+        type: "claim",
+      });
+      await loadAll();
+    } catch (err) {
+      setError(err instanceof Error ? err.message : t("common.error"));
+    } finally {
+      setActionLoading(false);
+    }
+  }
+
+  async function handleAddSubtask() {
+    if (!token || !id || !newSubtaskTitle.trim()) return;
+    setActionLoading(true);
+    try {
+      await createSubtask(token, id, {
+        title: newSubtaskTitle.trim(),
+        assigned_to: subtaskAssignee?.id,
+      });
+      setNewSubtaskTitle("");
+      setSubtaskAssignee(null);
+      setShowSubtaskForm(false);
+      await loadAll();
+    } catch (err) {
+      setError(err instanceof Error ? err.message : t("common.error"));
+    } finally {
+      setActionLoading(false);
+    }
+  }
+
+  async function handleToggleSubtask(subtask: Subtask) {
+    if (!token || !id) return;
+    const newStatus = subtask.status === "done" || subtask.status === "completed" ? "pending" : "done";
+    try {
+      await updateSubtask(token, id, subtask.id, { status: newStatus });
+      await loadAll();
+    } catch (err) {
+      setError(err instanceof Error ? err.message : t("common.error"));
+    }
+  }
+
+  async function handleDeleteSubtask(subtaskId: string) {
+    if (!token || !id) return;
+    try {
+      await deleteSubtask(token, id, subtaskId);
+      await loadAll();
+    } catch (err) {
+      setError(err instanceof Error ? err.message : t("common.error"));
+    }
+  }
+
+  if (!token) return null;
+
+  if (loading) {
+    return (
+      <div className="flex justify-center py-12">
+        <div className="animate-spin rounded-full h-8 w-8 border-b-2 border-blue-600" />
+      </div>
+    );
+  }
+
+  if (error && !task) {
+    return (
+      <div className="text-center py-12">
+        <p className="text-red-500">{error}</p>
+        <button onClick={() => router.back()} className="mt-4 text-blue-600 hover:underline">
+          {t("common.back")}
+        </button>
+      </div>
+    );
+  }
+
+  const subtasksDone = subtasks.filter((s) => s.status === "done" || s.status === "completed").length;
+  const subtasksTotal = subtasks.length;
+  const progressPct = subtasksTotal > 0 ? Math.round((subtasksDone / subtasksTotal) * 100) : 0;
+
+  const collabTypeLabels: Record<string, { icon: string; label: string; color: string }> = {
+    assign: { icon: "+", label: t("collab.assigned"), color: "text-blue-600" },
+    transfer: { icon: "->", label: t("collab.transferred"), color: "text-orange-600" },
+    claim: { icon: "!", label: t("collab.claimed"), color: "text-green-600" },
+    collaborate: { icon: "&", label: t("collab.collaborated"), color: "text-purple-600" },
+  };
+
+  return (
+    <div className="max-w-lg mx-auto space-y-4 pb-20">
+      {/* Header */}
+      <div className="flex items-center gap-2">
+        <button
+          onClick={() => router.push(`/tasks/${id}`)}
+          className="inline-flex items-center gap-1.5 px-3 py-2 text-sm font-medium text-gray-700 dark:text-gray-300 bg-gray-100 dark:bg-gray-800 hover:bg-gray-200 dark:hover:bg-gray-700 rounded-lg transition-colors"
+        >
+          <svg className="w-4 h-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+            <path strokeLinecap="round" strokeLinejoin="round" d="M15 19l-7-7 7-7" />
+          </svg>
+          {t("common.back")}
+        </button>
+        <h1 className="text-lg font-bold flex-1 truncate">{t("collab.title")}</h1>
+      </div>
+
+      {/* Task title */}
+      {task && (
+        <div className="bg-white dark:bg-gray-900 border border-gray-200 dark:border-gray-700 rounded-xl p-4">
+          <h2 className="font-semibold text-base">{task.title}</h2>
+          {task.description && <p className="text-sm text-gray-500 mt-1 line-clamp-2">{task.description}</p>}
+        </div>
+      )}
+
+      {error && (
+        <div className="bg-red-50 dark:bg-red-900/20 border border-red-200 dark:border-red-800 rounded-lg p-3 text-sm text-red-600 dark:text-red-400">
+          {error}
+          <button onClick={() => setError("")} className="ml-2 underline">
+            OK
+          </button>
+        </div>
+      )}
+
+      {/* Assignees section */}
+      <div className="bg-white dark:bg-gray-900 border border-gray-200 dark:border-gray-700 rounded-xl p-4">
+        <h3 className="text-sm font-semibold text-gray-500 dark:text-gray-400 uppercase tracking-wider mb-3">
+          {t("collab.assignees")}
+        </h3>
+
+        {assignees.length > 0 ? (
+          <div className="flex flex-wrap gap-2 mb-3">
+            {assignees.map((a) => (
+              <div key={a.id} className="flex items-center gap-2 bg-gray-50 dark:bg-gray-800 rounded-full px-3 py-1.5">
+                <UserAvatar name={a.name} avatarUrl={a.avatar_url} />
+                <span className="text-sm font-medium">{a.name}</span>
+              </div>
+            ))}
+          </div>
+        ) : (
+          <p className="text-sm text-gray-400 mb-3">{t("collab.noAssignees")}</p>
+        )}
+
+        {/* Action buttons */}
+        <div className="flex flex-wrap gap-2">
+          <button
+            onClick={() => {
+              setShowAssignSearch(!showAssignSearch);
+              setShowTransferSearch(false);
+            }}
+            disabled={actionLoading}
+            className="inline-flex items-center gap-1.5 px-3 py-2 text-sm font-medium bg-blue-600 hover:bg-blue-700 text-white rounded-lg transition-colors disabled:opacity-50"
+          >
+            <svg className="w-4 h-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+              <path strokeLinecap="round" strokeLinejoin="round" d="M18 9v3m0 0v3m0-3h3m-3 0h-3m-2-5a4 4 0 11-8 0 4 4 0 018 0zM3 20a6 6 0 0112 0v1H3v-1z" />
+            </svg>
+            {t("collab.assign")}
+          </button>
+
+          <button
+            onClick={() => {
+              setShowTransferSearch(!showTransferSearch);
+              setShowAssignSearch(false);
+            }}
+            disabled={actionLoading}
+            className="inline-flex items-center gap-1.5 px-3 py-2 text-sm font-medium bg-orange-600 hover:bg-orange-700 text-white rounded-lg transition-colors disabled:opacity-50"
+          >
+            <svg className="w-4 h-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+              <path strokeLinecap="round" strokeLinejoin="round" d="M8 7h12m0 0l-4-4m4 4l-4 4m0 6H4m0 0l4 4m-4-4l4-4" />
+            </svg>
+            {t("collab.transfer")}
+          </button>
+
+          <button
+            onClick={handleClaim}
+            disabled={actionLoading}
+            className="inline-flex items-center gap-1.5 px-3 py-2 text-sm font-medium bg-green-600 hover:bg-green-700 text-white rounded-lg transition-colors disabled:opacity-50"
+          >
+            <svg className="w-4 h-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+              <path strokeLinecap="round" strokeLinejoin="round" d="M7 11.5V14m0 0V14m0 0h2.5M7 14H4.5m4.5 0a6 6 0 1012 0 6 6 0 00-12 0z" />
+            </svg>
+            {t("collab.claim")}
+          </button>
+        </div>
+
+        {/* Assign search dropdown */}
+        {showAssignSearch && (
+          <div className="mt-3">
+            <UserSearchDropdown
+              token={token!}
+              onSelect={handleAssign}
+              placeholder={t("collab.searchUser")}
+            />
+          </div>
+        )}
+
+        {/* Transfer search dropdown */}
+        {showTransferSearch && (
+          <div className="mt-3 space-y-2">
+            <UserSearchDropdown
+              token={token!}
+              onSelect={handleTransfer}
+              placeholder={t("collab.searchUser")}
+            />
+            <textarea
+              value={transferMessage}
+              onChange={(e) => setTransferMessage(e.target.value)}
+              placeholder={t("collab.transferMessage")}
+              rows={2}
+              className="w-full px-3 py-2 text-sm border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-gray-800 focus:ring-2 focus:ring-blue-500"
+            />
+          </div>
+        )}
+      </div>
+
+      {/* Subtasks section */}
+      <div className="bg-white dark:bg-gray-900 border border-gray-200 dark:border-gray-700 rounded-xl p-4">
+        <div className="flex items-center justify-between mb-3">
+          <h3 className="text-sm font-semibold text-gray-500 dark:text-gray-400 uppercase tracking-wider">
+            {t("collab.subtasks")}
+          </h3>
+          {subtasksTotal > 0 && (
+            <span className="text-xs text-gray-500">
+              {subtasksDone}/{subtasksTotal}
+            </span>
+          )}
+        </div>
+
+        {/* Progress bar */}
+        {subtasksTotal > 0 && (
+          <div className="w-full bg-gray-200 dark:bg-gray-700 rounded-full h-2 mb-3">
+            <div
+              className="bg-green-500 h-2 rounded-full transition-all duration-300"
+              style={{ width: `${progressPct}%` }}
+            />
+          </div>
+        )}
+
+        {/* Subtask list */}
+        <div className="space-y-2 mb-3">
+          {subtasks.map((sub) => {
+            const isDone = sub.status === "done" || sub.status === "completed";
+            return (
+              <div
+                key={sub.id}
+                className="flex items-center gap-2 group"
+              >
+                <button
+                  onClick={() => handleToggleSubtask(sub)}
+                  className={`flex-shrink-0 w-5 h-5 rounded border-2 flex items-center justify-center transition-colors ${
+                    isDone
+                      ? "bg-green-500 border-green-500 text-white"
+                      : "border-gray-300 dark:border-gray-600 hover:border-green-400"
+                  }`}
+                >
+                  {isDone && (
+                    <svg className="w-3 h-3" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={3}>
+                      <path strokeLinecap="round" strokeLinejoin="round" d="M5 13l4 4L19 7" />
+                    </svg>
+                  )}
+                </button>
+                <span className={`flex-1 text-sm ${isDone ? "line-through text-gray-400" : ""}`}>
+                  {sub.title}
+                </span>
+                {sub.assignee_name && (
+                  <span className="text-xs text-gray-400 bg-gray-100 dark:bg-gray-800 px-2 py-0.5 rounded-full">
+                    {sub.assignee_name}
+                  </span>
+                )}
+                <button
+                  onClick={() => handleDeleteSubtask(sub.id)}
+                  className="opacity-0 group-hover:opacity-100 text-red-400 hover:text-red-600 transition-opacity"
+                >
+                  <svg className="w-4 h-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+                    <path strokeLinecap="round" strokeLinejoin="round" d="M6 18L18 6M6 6l12 12" />
+                  </svg>
+                </button>
+              </div>
+            );
+          })}
+        </div>
+
+        {subtasks.length === 0 && (
+          <p className="text-sm text-gray-400 mb-3">{t("collab.noSubtasks")}</p>
+        )}
+
+        {/* Add subtask form */}
+        {showSubtaskForm ? (
+          <div className="space-y-2 border-t border-gray-100 dark:border-gray-700 pt-3">
+            <input
+              type="text"
+              value={newSubtaskTitle}
+              onChange={(e) => setNewSubtaskTitle(e.target.value)}
+              placeholder={t("collab.subtaskTitle")}
+              className="w-full px-3 py-2 text-sm border border-gray-300 dark:border-gray-600 rounded-lg bg-white dark:bg-gray-800 focus:ring-2 focus:ring-blue-500"
+              onKeyDown={(e) => {
+                if (e.key === "Enter" && newSubtaskTitle.trim()) handleAddSubtask();
+              }}
+              autoFocus
+            />
+            {subtaskAssignee && (
+              <div className="flex items-center gap-2 text-sm">
+                <UserAvatar name={subtaskAssignee.name} avatarUrl={subtaskAssignee.avatar_url} />
+                <span>{subtaskAssignee.name}</span>
+                <button onClick={() => setSubtaskAssignee(null)} className="text-gray-400 hover:text-red-500">
+                  <svg className="w-3 h-3" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+                    <path strokeLinecap="round" strokeLinejoin="round" d="M6 18L18 6M6 6l12 12" />
+                  </svg>
+                </button>
+              </div>
+            )}
+            {!subtaskAssignee && (
+              <UserSearchDropdown
+                token={token!}
+                onSelect={(user) => setSubtaskAssignee(user)}
+                placeholder={t("collab.assignSubtask")}
+              />
+            )}
+            <div className="flex gap-2">
+              <button
+                onClick={handleAddSubtask}
+                disabled={!newSubtaskTitle.trim() || actionLoading}
+                className="px-3 py-1.5 text-sm font-medium bg-blue-600 hover:bg-blue-700 text-white rounded-lg transition-colors disabled:opacity-50"
+              >
+                {t("collab.addBtn")}
+              </button>
+              <button
+                onClick={() => {
+                  setShowSubtaskForm(false);
+                  setNewSubtaskTitle("");
+                  setSubtaskAssignee(null);
+                }}
+                className="px-3 py-1.5 text-sm font-medium text-gray-600 hover:text-gray-800 dark:text-gray-400"
+              >
+                {t("tasks.form.cancel")}
+              </button>
+            </div>
+          </div>
+        ) : (
+          <button
+            onClick={() => setShowSubtaskForm(true)}
+            className="inline-flex items-center gap-1.5 text-sm text-blue-600 hover:text-blue-700 font-medium"
+          >
+            <svg className="w-4 h-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+              <path strokeLinecap="round" strokeLinejoin="round" d="M12 4v16m8-8H4" />
+            </svg>
+            {t("collab.addSubtask")}
+          </button>
+        )}
+      </div>
+
+      {/* Collaboration history */}
+      <div className="bg-white dark:bg-gray-900 border border-gray-200 dark:border-gray-700 rounded-xl p-4">
+        <h3 className="text-sm font-semibold text-gray-500 dark:text-gray-400 uppercase tracking-wider mb-3">
+          {t("collab.history")}
+        </h3>
+
+        {history.length > 0 ? (
+          <div className="space-y-3">
+            {history.map((h) => {
+              const info = collabTypeLabels[h.type] || collabTypeLabels.assign;
+              const date = new Date(h.created_at);
+              const dateStr = date.toLocaleDateString("cs-CZ", {
+                day: "numeric",
+                month: "numeric",
+                hour: "2-digit",
+                minute: "2-digit",
+              });
+              return (
+                <div key={h.id} className="flex items-start gap-3 text-sm">
+                  <div className={`flex-shrink-0 w-6 h-6 rounded-full flex items-center justify-center text-xs font-bold ${info.color} bg-gray-100 dark:bg-gray-800`}>
+                    {info.icon}
+                  </div>
+                  <div className="flex-1 min-w-0">
+                    <div>
+                      <span className="font-medium">{h.from_name || t("collab.system")}</span>
+                      <span className="text-gray-500"> {info.label} </span>
+                      {h.to_name && <span className="font-medium">{h.to_name}</span>}
+                    </div>
+                    {h.message && (
+                      <p className="text-gray-500 text-xs mt-0.5 italic">&quot;{h.message}&quot;</p>
+                    )}
+                    <div className="flex items-center gap-2 mt-0.5">
+                      <span className="text-xs text-gray-400">{dateStr}</span>
+                      <span
+                        className={`text-xs px-1.5 py-0.5 rounded-full ${
+                          h.status === "accepted"
+                            ? "bg-green-100 text-green-700 dark:bg-green-900/30 dark:text-green-400"
+                            : h.status === "rejected"
+                            ? "bg-red-100 text-red-700 dark:bg-red-900/30 dark:text-red-400"
+                            : "bg-yellow-100 text-yellow-700 dark:bg-yellow-900/30 dark:text-yellow-400"
+                        }`}
+                      >
+                        {h.status === "accepted" ? t("collab.statusAccepted") : h.status === "rejected" ? t("collab.statusRejected") : t("collab.statusPending")}
+                      </span>
+                    </div>
+                  </div>
+                </div>
+              );
+            })}
+          </div>
+        ) : (
+          <p className="text-sm text-gray-400">{t("collab.noHistory")}</p>
+        )}
+      </div>
+    </div>
+  );
+}
diff --git a/apps/tasks/app/tasks/[id]/page.tsx b/apps/tasks/app/tasks/[id]/page.tsx
index dc4a0d7..7e02f97 100644
--- a/apps/tasks/app/tasks/[id]/page.tsx
+++ b/apps/tasks/app/tasks/[id]/page.tsx
@@ -11,6 +11,9 @@ import {
   deleteTask,
   Task,
   Group,
+  Subtask,
+  getSubtasks,
+  searchUsers,
 } from "@/lib/api";
 import TaskForm from "@/components/TaskForm";
 import StatusBadge from "@/components/StatusBadge";
@@ -31,6 +34,8 @@ export default function TaskDetailPage() {
   const [editing, setEditing] = useState(false);
   const [deleting, setDeleting] = useState(false);
   const [error, setError] = useState("");
+  const [subtasks, setSubtasks] = useState<Subtask[]>([]);
+  const [assigneeNames, setAssigneeNames] = useState<Record<string, string>>({});
 
   const dateLocale = locale === "ua" ? "uk-UA" : locale === "cs" ? "cs-CZ" : locale === "he" ? "he-IL" : "ru-RU";
 
@@ -55,12 +60,26 @@ export default function TaskDetailPage() {
     if (!token || !id) return;
     setLoading(true);
     try {
-      const [taskData, groupsData] = await Promise.all([
+      const [taskData, groupsData, subtasksData] = await Promise.all([
         getTask(token, id),
         getGroups(token),
+        getSubtasks(token, id).catch(() => ({ data: [] })),
       ]);
       setTask(taskData);
       setGroups(groupsData.data || []);
+      setSubtasks(subtasksData.data || []);
+      // Load assignee names
+      const assigned: string[] = taskData.assigned_to || [];
+      if (assigned.length > 0) {
+        try {
+          const res = await searchUsers(token, "");
+          const nameMap: Record<string, string> = {};
+          (res.data || []).forEach((u: { id: string; name: string }) => {
+            if (assigned.includes(u.id)) nameMap[u.id] = u.name;
+          });
+          setAssigneeNames(nameMap);
+        } catch { /* ignore */ }
+      }
     } catch (err) {
       setError(
         err instanceof Error ? err.message : t("tasks.loadError")
@@ -292,6 +311,78 @@ export default function TaskDetailPage() {
           )}
         </div>
       </div>
+
+      {/* Collaboration summary */}
+      <div className="bg-white dark:bg-gray-900 border border-gray-200 dark:border-gray-700 rounded-2xl p-6">
+        <div className="flex items-center justify-between mb-3">
+          <h2 className="text-sm font-semibold text-gray-500 dark:text-gray-400 uppercase tracking-wider">
+            {t("collab.collaboration")}
+          </h2>
+          <button
+            onClick={() => router.push(`/tasks/${id}/collaborate`)}
+            className="inline-flex items-center gap-1.5 px-3 py-1.5 text-sm font-medium bg-purple-600 hover:bg-purple-700 text-white rounded-lg transition-colors"
+          >
+            <svg className="w-4 h-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
+              <path strokeLinecap="round" strokeLinejoin="round" d="M17 20h5v-2a3 3 0 00-5.356-1.857M17 20H7m10 0v-2c0-.656-.126-1.283-.356-1.857M7 20H2v-2a3 3 0 015.356-1.857M7 20v-2c0-.656.126-1.283.356-1.857m0 0a5.002 5.002 0 019.288 0M15 7a3 3 0 11-6 0 3 3 0 016 0zm6 3a2 2 0 11-4 0 2 2 0 014 0zM7 10a2 2 0 11-4 0 2 2 0 014 0z" />
+            </svg>
+            {t("collab.collaboration")}
+          </button>
+        </div>
+
+        {/* Assigned users */}
+        {task.assigned_to && task.assigned_to.length > 0 && (
+          <div className="flex items-center gap-2 mb-3">
+            <span className="text-sm text-gray-500">{t("collab.assignees")}:</span>
+            <div className="flex -space-x-2">
+              {task.assigned_to.slice(0, 5).map((uid: string) => {
+                const name = assigneeNames[uid] || uid.slice(0, 4);
+                const initials = name.split(" ").map((n: string) => n[0]).join("").toUpperCase().slice(0, 2);
+                const colors = ["bg-blue-500", "bg-green-500", "bg-purple-500", "bg-orange-500", "bg-pink-500"];
+                const color = colors[name.charCodeAt(0) % colors.length];
+                return (
+                  <div
+                    key={uid}
+                    title={assigneeNames[uid] || uid}
+                    className={`w-8 h-8 rounded-full ${color} text-white flex items-center justify-center text-xs font-medium border-2 border-white dark:border-gray-900`}
+                  >
+                    {initials}
+                  </div>
+                );
+              })}
+              {task.assigned_to.length > 5 && (
+                <div className="w-8 h-8 rounded-full bg-gray-400 text-white flex items-center justify-center text-xs font-medium border-2 border-white dark:border-gray-900">
+                  +{task.assigned_to.length - 5}
+                </div>
+              )}
+            </div>
+          </div>
+        )}
+
+        {/* Subtask progress */}
+        {subtasks.length > 0 && (() => {
+          const done = subtasks.filter(s => s.status === "done" || s.status === "completed").length;
+          const total = subtasks.length;
+          const pct = Math.round((done / total) * 100);
+          return (
+            <div>
+              <div className="flex items-center justify-between text-sm mb-1">
+                <span className="text-gray-500">{t("collab.subtasks")}</span>
+                <span className="font-medium">{done}/{total} {t("collab.subtasksDone")}</span>
+              </div>
+              <div className="w-full bg-gray-200 dark:bg-gray-700 rounded-full h-2">
+                <div
+                  className="bg-green-500 h-2 rounded-full transition-all duration-300"
+                  style={{ width: `${pct}%` }}
+                />
+              </div>
+            </div>
+          );
+        })()}
+
+        {(!task.assigned_to || task.assigned_to.length === 0) && subtasks.length === 0 && (
+          <p className="text-sm text-gray-400">{t("collab.noAssignees")}</p>
+        )}
+      </div>
     </div>
   );
 }
diff --git a/apps/tasks/lib/api.ts b/apps/tasks/lib/api.ts
index 85fb599..ced75b1 100644
--- a/apps/tasks/lib/api.ts
+++ b/apps/tasks/lib/api.ts
@@ -245,3 +245,61 @@ export function deleteProject(token: string, id: string) {
 export function inviteToProject(token: string, id: string, userId: string) {
   return apiFetch<{ data: Project; status: string }>("/api/v1/projects/" + id + "/invite", { method: "POST", body: { user_id: userId }, token });
 }
+
+// Subtasks
+export interface Subtask {
+  id: string;
+  parent_task_id: string;
+  title: string;
+  description: string;
+  status: "pending" | "in_progress" | "done" | "completed";
+  assigned_to: string | null;
+  assignee_name: string | null;
+  order_index: number;
+  completed_at: string | null;
+  created_at: string;
+  updated_at: string;
+}
+
+export interface CollabRequest {
+  id: string;
+  task_id: string;
+  from_user_id: string | null;
+  to_user_id: string;
+  type: "assign" | "transfer" | "collaborate" | "claim";
+  status: "pending" | "accepted" | "rejected";
+  message: string;
+  from_name: string | null;
+  to_name: string | null;
+  task_title?: string;
+  created_at: string;
+  responded_at: string | null;
+}
+
+export function getSubtasks(token: string, taskId: string) {
+  return apiFetch<{ data: Subtask[] }>(`/api/v1/tasks/${taskId}/subtasks`, { token });
+}
+
+export function createSubtask(token: string, taskId: string, data: { title: string; description?: string; assigned_to?: string }) {
+  return apiFetch<{ data: Subtask }>(`/api/v1/tasks/${taskId}/subtasks`, { method: "POST", body: data, token });
+}
+
+export function updateSubtask(token: string, taskId: string, subtaskId: string, data: Partial<Subtask>) {
+  return apiFetch<{ data: Subtask }>(`/api/v1/tasks/${taskId}/subtasks/${subtaskId}`, { method: "PUT", body: data, token });
+}
+
+export function deleteSubtask(token: string, taskId: string, subtaskId: string) {
+  return apiFetch<void>(`/api/v1/tasks/${taskId}/subtasks/${subtaskId}`, { method: "DELETE", token });
+}
+
+export function getCollaborationHistory(token: string, taskId: string) {
+  return apiFetch<{ data: CollabRequest[] }>(`/api/v1/tasks/${taskId}/collaboration`, { token });
+}
+
+export function sendCollabRequest(token: string, taskId: string, data: { to_user_id?: string; from_user_id?: string; type: string; message?: string }) {
+  return apiFetch<{ data?: CollabRequest; status: string }>(`/api/v1/tasks/${taskId}/collaborate`, { method: "POST", body: data, token });
+}
+
+export function searchUsers(token: string, query: string) {
+  return apiFetch<{ data: { id: string; name: string; email: string; avatar_url: string | null }[] }>(`/api/v1/auth/users/search?q=${encodeURIComponent(query)}`, { token });
+}
diff --git a/apps/tasks/messages/cs.json b/apps/tasks/messages/cs.json
index e645467..313c84d 100644
--- a/apps/tasks/messages/cs.json
+++ b/apps/tasks/messages/cs.json
@@ -152,5 +152,33 @@
   },
   "forgotPassword": {
     "description": "Obnova hesla bude brzy k dispozici."
+  },
+  "collab": {
+    "title": "Spoluprace",
+    "assignees": "Prirazeni uzivatele",
+    "noAssignees": "Nikdo neni prirazen",
+    "assign": "Priradit",
+    "transfer": "Predat",
+    "claim": "Prevzit",
+    "searchUser": "Hledat uzivatele...",
+    "transferMessage": "Zprava k predani...",
+    "subtasks": "Podukoly",
+    "noSubtasks": "Zadne podukoly",
+    "subtaskTitle": "Nazev podukolu...",
+    "assignSubtask": "Priradit podukol (volitelne)...",
+    "addSubtask": "Pridat podukol",
+    "addBtn": "Pridat",
+    "history": "Historie spoluprace",
+    "noHistory": "Zadna historie",
+    "assigned": "priradil/a",
+    "transferred": "predal/a",
+    "claimed": "prevzal/a",
+    "collaborated": "spolupracuje",
+    "system": "System",
+    "statusAccepted": "Prijato",
+    "statusRejected": "Odmitnuto",
+    "statusPending": "Ceka",
+    "subtasksDone": "podukolu hotovo",
+    "collaboration": "Spoluprace"
   }
-}
+}
\ No newline at end of file
diff --git a/apps/tasks/messages/he.json b/apps/tasks/messages/he.json
index d368c2c..5d9acf6 100644
--- a/apps/tasks/messages/he.json
+++ b/apps/tasks/messages/he.json
@@ -152,5 +152,33 @@
   },
   "forgotPassword": {
     "description": "שחזור סיסמה יהיה זמין בקרוב."
+  },
+  "collab": {
+    "title": "שיתוף פעולה",
+    "assignees": "משתמשים משויכים",
+    "noAssignees": "אף אחד לא משויך",
+    "assign": "שייך",
+    "transfer": "העבר",
+    "claim": "קח",
+    "searchUser": "חפש משתמש...",
+    "transferMessage": "הודעה להעברה...",
+    "subtasks": "משימות משנה",
+    "noSubtasks": "אין משימות משנה",
+    "subtaskTitle": "שם משימת משנה...",
+    "assignSubtask": "שייך משימת משנה...",
+    "addSubtask": "הוסף משימת משנה",
+    "addBtn": "הוסף",
+    "history": "היסטוריית שיתוף פעולה",
+    "noHistory": "אין היסטוריה",
+    "assigned": "שייך",
+    "transferred": "העביר",
+    "claimed": "לקח",
+    "collaborated": "שיתף פעולה",
+    "system": "מערכת",
+    "statusAccepted": "אושר",
+    "statusRejected": "נדחה",
+    "statusPending": "ממתין",
+    "subtasksDone": "משימות הושלמו",
+    "collaboration": "שיתוף פעולה"
   }
-}
+}
\ No newline at end of file
diff --git a/apps/tasks/messages/ru.json b/apps/tasks/messages/ru.json
index 8156cd8..f626174 100644
--- a/apps/tasks/messages/ru.json
+++ b/apps/tasks/messages/ru.json
@@ -152,5 +152,33 @@
   },
   "forgotPassword": {
     "description": "Восстановление пароля будет доступно в ближайшее время."
+  },
+  "collab": {
+    "title": "Сотрудничество",
+    "assignees": "Назначенные",
+    "noAssignees": "Никто не назначен",
+    "assign": "Назначить",
+    "transfer": "Передать",
+    "claim": "Взять",
+    "searchUser": "Поиск пользователя...",
+    "transferMessage": "Сообщение к передаче...",
+    "subtasks": "Подзадачи",
+    "noSubtasks": "Нет подзадач",
+    "subtaskTitle": "Название подзадачи...",
+    "assignSubtask": "Назначить подзадачу...",
+    "addSubtask": "Добавить подзадачу",
+    "addBtn": "Добавить",
+    "history": "История сотрудничества",
+    "noHistory": "Нет истории",
+    "assigned": "назначил",
+    "transferred": "передал",
+    "claimed": "взял",
+    "collaborated": "сотрудничает",
+    "system": "Система",
+    "statusAccepted": "Принято",
+    "statusRejected": "Отклонено",
+    "statusPending": "Ожидает",
+    "subtasksDone": "подзадач выполнено",
+    "collaboration": "Сотрудничество"
   }
-}
+}
\ No newline at end of file
diff --git a/apps/tasks/messages/ua.json b/apps/tasks/messages/ua.json
index e2e3e1c..b83dd0c 100644
--- a/apps/tasks/messages/ua.json
+++ b/apps/tasks/messages/ua.json
@@ -152,5 +152,33 @@
   },
   "forgotPassword": {
     "description": "Вiдновлення паролю буде доступне найближчим часом."
+  },
+  "collab": {
+    "title": "Співпраця",
+    "assignees": "Призначені",
+    "noAssignees": "Нікого не призначено",
+    "assign": "Призначити",
+    "transfer": "Передати",
+    "claim": "Взяти",
+    "searchUser": "Пошук користувача...",
+    "transferMessage": "Повідомлення до передачі...",
+    "subtasks": "Підзавдання",
+    "noSubtasks": "Немає підзавдань",
+    "subtaskTitle": "Назва підзавдання...",
+    "assignSubtask": "Призначити підзавдання...",
+    "addSubtask": "Додати підзавдання",
+    "addBtn": "Додати",
+    "history": "Історія співпраці",
+    "noHistory": "Немає історії",
+    "assigned": "призначив",
+    "transferred": "передав",
+    "claimed": "взяв",
+    "collaborated": "співпрацює",
+    "system": "Система",
+    "statusAccepted": "Прийнято",
+    "statusRejected": "Відхилено",
+    "statusPending": "Очікує",
+    "subtasksDone": "підзавдань виконано",
+    "collaboration": "Співпраця"
   }
-}
+}
\ No newline at end of file
diff --git a/mobile/eas.json b/mobile/eas.json
new file mode 100644
index 0000000..11bbc92
--- /dev/null
+++ b/mobile/eas.json
@@ -0,0 +1,23 @@
+{
+  "cli": { "version": ">= 14.0.0" },
+  "build": {
+    "development": {
+      "developmentClient": true,
+      "distribution": "internal"
+    },
+    "preview": {
+      "distribution": "internal",
+      "android": { "buildType": "apk" }
+    },
+    "production": {
+      "android": { "buildType": "app-bundle" },
+      "ios": { "autoIncrement": true }
+    }
+  },
+  "submit": {
+    "production": {
+      "android": { "serviceAccountKeyPath": "./google-service-account.json" },
+      "ios": { "appleId": "soft.it.enterprise@gmail.com", "ascAppId": "", "appleTeamId": "8U2KKLXVSN" }
+    }
+  }
+}