diff --git a/docs/core-checklist-status.md b/docs/core-checklist-status.md
index c937219..fc5166d 100644
--- a/docs/core-checklist-status.md
+++ b/docs/core-checklist-status.md
@@ -32,7 +32,7 @@ Legend:
 23. Groups - `PARTIAL` (create/add/remove/invite link; join-by-invite and invite permissions covered by integration tests; members API now returns profile fields (`username/name/avatar_url`) and web Chat Info consumes them to avoid extra per-member profile requests; add-member search also shows avatars; advanced moderation still partial)
 24. Roles - `DONE` (owner/admin/member)
 25. Admin Rights - `PARTIAL` (delete/pin/edit info + explicit ban APIs for groups/channels including ban list endpoint; web Chat Info now shows searchable `Banned users` with both inline and right-click `Unban` actions for owner/admin, member search, avatars in moderation lists, invite-link copy/regenerate actions, ban metadata (`who banned/when`), explicit member action button for touch/trackpad UX, `@username`-friendly moderation filters, and resilient profile hydration (`allSettled`) for partially missing users; integration tests cover channel member read-only, channel admin full-delete, channel message delete-for-all permissions, group profile edit permissions, owner-only role management rules, and admin-visible/member-forbidden ban-list access; remaining UX moderation tools limited)
-26. Channels - `PARTIAL` (create/post/edit/delete/subscribe/unsubscribe; integration tests now also cover invite-link permissions (member forbidden, admin allowed); web Chat Info now differentiates destructive actions by role for both groups/channels (`Delete ... for all` for owner/admin, `Leave` for members); app auto-join by invite token is now single-shot with toast errors (no retry spam on invalid/expired links); remaining UX edge-cases still polishing)
+26. Channels - `PARTIAL` (create/post/edit/delete/subscribe/unsubscribe; integration tests now also cover invite-link permissions (member forbidden, admin allowed); web Chat Info now differentiates destructive actions by role for both groups/channels (`Delete ... for all` for owner/admin, `Leave` for members) and blocks invalid owner-leave action when members remain; app auto-join by invite token is now single-shot with toast errors (no retry spam on invalid/expired links); remaining UX edge-cases still polishing)
 27. Channel Types - `DONE` (public/private)
 28. Notifications - `PARTIAL` (browser notifications + mute/settings; chat mute is propagated in chat list payload, honored by web realtime notifications with mention override, and mute toggle now syncs instantly in chat store; backend now emits `chat_updated` after notification mute/unmute for cross-tab consistency; no mobile push infra)
 29. Archive - `DONE`
diff --git a/web/src/components/ChatInfoPanel.tsx b/web/src/components/ChatInfoPanel.tsx
index 66ad5f3..66147f1 100644
--- a/web/src/components/ChatInfoPanel.tsx
+++ b/web/src/components/ChatInfoPanel.tsx
@@ -92,6 +92,16 @@ export function ChatInfoPanel({ chatId, open, onClose }: Props) {
   const canManageMembers = Boolean(isGroupLike && (myRoleNormalized === "owner" || myRoleNormalized === "admin"));
   const canEditTitle = Boolean(isGroupLike && (myRoleNormalized === "owner" || myRoleNormalized === "admin"));
   const canEditChatProfile = Boolean(isGroupLike && (myRoleNormalized === "owner" || myRoleNormalized === "admin"));
+  const canLeaveGroupLikeChat = useMemo(() => {
+    if (!chat || !isGroupLike) {
+      return false;
+    }
+    if (myRoleNormalized !== "owner") {
+      return true;
+    }
+    const count = chat.members_count ?? members.length;
+    return count <= 1;
+  }, [chat, isGroupLike, myRoleNormalized, members.length]);
   const photoAttachments = useMemo(() => attachments.filter((item) => item.file_type.startsWith("image/")).sort((a, b) => b.id - a.id), [attachments]);
   const videoAttachments = useMemo(() => attachments.filter((item) => item.file_type.startsWith("video/")).sort((a, b) => b.id - a.id), [attachments]);
   const voiceAttachments = useMemo(() => attachments.filter((item) => item.message_type === "voice").sort((a, b) => b.id - a.id), [attachments]);
@@ -983,8 +993,12 @@ export function ChatInfoPanel({ chatId, open, onClose }: Props) {
                   </button>
                 ) : null}
                 <button
-                  className="w-full rounded bg-slate-700 px-3 py-2 text-sm"
+                  className="w-full rounded bg-slate-700 px-3 py-2 text-sm disabled:cursor-not-allowed disabled:opacity-60"
+                  disabled={!canLeaveGroupLikeChat}
                   onClick={async () => {
+                    if (!canLeaveGroupLikeChat) {
+                      return;
+                    }
                     try {
                       await leaveChat(chatId);
                       await loadChats();
@@ -995,7 +1009,9 @@ export function ChatInfoPanel({ chatId, open, onClose }: Props) {
                     }
                   }}
                 >
-                  {chat.type === "channel" ? "Leave channel" : "Leave chat"}
+                  {canLeaveGroupLikeChat
+                    ? (chat.type === "channel" ? "Leave channel" : "Leave chat")
+                    : "Owner cannot leave while members remain"}
                 </button>
               </>
             ) : null}