fix: Add debounced Undo/Redo system to avoid character-by-character history

- Add debounced state updates for title and content (500ms delay)
- Immediate UI updates with delayed history saving
- Prevent one-letter-per-undo issue
- Add cleanup for debounce timers on unmount

keep-notes/app/api/notes/[id]/route.ts

@@ -0,0 +1,100 @@
+import { NextRequest, NextResponse } from 'next/server'
+import prisma from '@/lib/prisma'
+
+// Helper to parse JSON fields
+function parseNote(dbNote: any) {
+  return {
+    ...dbNote,
+    checkItems: dbNote.checkItems ? JSON.parse(dbNote.checkItems) : null,
+    labels: dbNote.labels ? JSON.parse(dbNote.labels) : null,
+  }
+}
+
+// GET /api/notes/[id] - Get a single note
+export async function GET(
+  request: NextRequest,
+  { params }: { params: { id: string } }
+) {
+  try {
+    const note = await prisma.note.findUnique({
+      where: { id: params.id }
+    })
+
+    if (!note) {
+      return NextResponse.json(
+        { success: false, error: 'Note not found' },
+        { status: 404 }
+      )
+    }
+
+    return NextResponse.json({
+      success: true,
+      data: parseNote(note)
+    })
+  } catch (error) {
+    console.error('GET /api/notes/[id] error:', error)
+    return NextResponse.json(
+      { success: false, error: 'Failed to fetch note' },
+      { status: 500 }
+    )
+  }
+}
+
+// PUT /api/notes/[id] - Update a note
+export async function PUT(
+  request: NextRequest,
+  { params }: { params: { id: string } }
+) {
+  try {
+    const body = await request.json()
+    const updateData: any = { ...body }
+
+    // Stringify JSON fields if they exist
+    if ('checkItems' in body) {
+      updateData.checkItems = body.checkItems ? JSON.stringify(body.checkItems) : null
+    }
+    if ('labels' in body) {
+      updateData.labels = body.labels ? JSON.stringify(body.labels) : null
+    }
+    updateData.updatedAt = new Date()
+
+    const note = await prisma.note.update({
+      where: { id: params.id },
+      data: updateData
+    })
+
+    return NextResponse.json({
+      success: true,
+      data: parseNote(note)
+    })
+  } catch (error) {
+    console.error('PUT /api/notes/[id] error:', error)
+    return NextResponse.json(
+      { success: false, error: 'Failed to update note' },
+      { status: 500 }
+    )
+  }
+}
+
+// DELETE /api/notes/[id] - Delete a note
+export async function DELETE(
+  request: NextRequest,
+  { params }: { params: { id: string } }
+) {
+  try {
+    await prisma.note.delete({
+      where: { id: params.id }
+    })
+
+    return NextResponse.json({
+      success: true,
+      message: 'Note deleted successfully'
+    })
+  } catch (error) {
+    console.error('DELETE /api/notes/[id] error:', error)
+    return NextResponse.json(
+      { success: false, error: 'Failed to delete note' },
+      { status: 500 }
+    )
+  }
+}