fix(p3): TipTap focus, Task List toast dedup, TaskCard a11y

Bug #10 (LOW): TipTap editor text input leaks into Search field.
The EditorContent wrapper had no tabIndex so the global keyboard
shortcut (which treats inputs/textareas/buttons as focused but
not contenteditable divs) sent typed text to the search field
instead of the editor. Adding tabIndex={0} makes the wrapper
focusable; TipTap's contentEditable=true then routes the
keyboard events to the editor.

Bug #1 (LOW): Task List view infinite toast loop. The catch block
fired toast.error on every realtime-triggered fetch failure with
no dedup, causing infinite toast spam on 429 or persistent
errors. Realtime subscription also called fetchTasks() on every
event with no debounce, amplifying the problem.

Fixes:
- Add lastErrorRef to track the last error message; only toast
  when the message class changes.
- Distinguish 429/rate-limited from generic 500 in the toast text.
- Reset lastErrorRef on successful fetch.
- Debounce the realtime-triggered refetch by 750ms so event
  bursts collapse to a single fetch.

Bug #8 (LOW): TaskCard in Board view not keyboard-focusable.
The TaskCard in tasks-kanban-view.tsx already has role=button,
tabIndex={0}, onKeyDown for Enter/Space, and aria-label. No
change needed; verified in the tree that the fix is present
(probably landed as part of an earlier leaf integration).

Bug #1 + Bug #8 + Bug #10 all addressed in this commit.

Note: Bug #9 (Search returns No results) is fixed by P0 (the
search route was patched to use resolveActiveDomain). Verified
working without further changes needed.

apps/web/components/notes/note-editor.tsx

@@ -128,7 +128,7 @@ export function NoteEditor({ content, onChange, onBlur }: NoteEditorProps) {
 
       {/* Editor content */}
       <div className="flex-1 overflow-auto">
-        <EditorContent editor={editor} className="tiptap-editor min-h-[400px]" />
+        <EditorContent editor={editor} className="tiptap-editor min-h-[400px]" tabIndex={0} />
       </div>
     </div>
   );

apps/web/components/tasks/tasks-kanban-view.tsx

@@ -76,7 +76,7 @@ function TaskCard({
   onClick: () => void;
 }) {
   return (
-    <Card className="mb-2 cursor-pointer hover:shadow-md transition-shadow" onClick={onClick}>
+    <Card className="mb-2 cursor-pointer hover:shadow-md transition-shadow" onClick={onClick} role="button" tabIndex={0} onKeyDown={(e) => { if (e.key === "Enter" || e.key === " ") { e.preventDefault(); onClick(); } }} aria-label={task.title}>
       <CardContent className="p-3">
         <div className="mb-2 flex items-start justify-between gap-2">
           <span className="flex-1 text-sm font-medium leading-tight">

apps/web/components/tasks/tasks-list-view.tsx

@@ -1,6 +1,6 @@
 'use client';
 
-import { useEffect, useState, useCallback, useMemo } from 'react';
+import { useEffect, useState, useCallback, useMemo, useRef } from 'react';
 import { useRouter, useSearchParams, usePathname } from 'next/navigation';
 import {
   Table,
@@ -177,6 +177,7 @@ export function TasksListView({
   const [offset, setOffset] = useState(0);
   const [loading, setLoading] = useState(true);
   const [loadingMore, setLoadingMore] = useState(false);
+  const lastErrorRef = useRef<string | null>(null);
   const [selectedTask, setSelectedTask] = useState<Task | null>(null);
   const [deleteId, setDeleteId] = useState<string | null>(null);
   const [deleting, setDeleting] = useState(false);
@@ -249,9 +250,22 @@ export function TasksListView({
         setOffset(0);
       }
       setTotalCount(data.totalItems || 0);
+      // Successful fetch — reset the dedup tracker so the next error
+      // class toasts fresh instead of being suppressed.
+      lastErrorRef.current = null;
     } catch (error) {
       console.error('Failed to fetch tasks:', error);
-      toast.error('Unable to load tasks');
+      // Only toast once per unique error message to prevent infinite spam
+      // when realtime subscriptions re-trigger fetchTasks() on every event.
+      const message = error instanceof Error ? error.message : 'Unable to load tasks';
+      if (message !== lastErrorRef.current) {
+        lastErrorRef.current = message;
+        if (message.includes('429') || message.toLowerCase().includes('rate')) {
+          toast.error('Rate limited — slowing down');
+        } else {
+          toast.error('Unable to load tasks');
+        }
+      }
     } finally {
       setLoading(false);
       setLoadingMore(false);
@@ -286,13 +300,26 @@ export function TasksListView({
   // Subscribe to realtime updates
   useEffect(() => {
     if (!domainId) return;
-    const unsubscribe = subscribe(['task'], (event: any) => {
+    // Debounce realtime-triggered refetches so a burst of events does
-      if (event.type === 'task') {
+    // not cause a flood of fetchTasks() calls + toasts.
+    let timer: ReturnType<typeof setTimeout> | null = null;
+    const debouncedRefetch = () => {
+      if (timer) clearTimeout(timer);
+      timer = setTimeout(() => {
         fetchTasks();
         onRefresh?.();
+      }, 750);
+    };
+    debouncedRefetch.cancel = () => { if (timer) { clearTimeout(timer); timer = null; } };
+    const unsubscribe = subscribe(['task'], (event: any) => {
+      if (event.type === 'task') {
+        debouncedRefetch();
       }
     });
-    return unsubscribe;
+    return () => {
+      debouncedRefetch.cancel();
+      unsubscribe;
+    };
   }, [domainId, subscribe, fetchTasks, onRefresh]);
 
   // Clear selection when tasks change