deps

README.md

@@ -11,6 +11,7 @@ persistence.
 - Real-time collaboration with Server-Sent Events
 - Item locking mechanism to prevent conflicts
 - Hierarchical items (parent-child relationships)
+- **Item dependencies: Define prerequisites for completing items**
 - SQLite database for data persistence
 - **Modern web frontend with React and TypeScript**
 - **Real-time updates across multiple browser tabs/windows**
@@ -293,7 +294,8 @@ All API endpoints return JSON responses with a consistent format:
       "content": "New item",
       "checked": false,
       "parent_id": null,
-      "checklist_uuid": "123e4567-e89b-12d3-a456-426614174000"
+      "checklist_uuid": "123e4567-e89b-12d3-a456-426614174000",
+      "dependencies": []
    }
 }
 ```
@@ -309,7 +311,8 @@ All API endpoints return JSON responses with a consistent format:
       "content": "Updated content",
       "checked": true,
       "parent_id": null,
-      "checklist_uuid": "123e4567-e89b-12d3-a456-426614174000"
+      "checklist_uuid": "123e4567-e89b-12d3-a456-426614174000",
+      "dependencies": [2, 3]
    }
 }
 ```
@@ -348,7 +351,16 @@ All API endpoints return JSON responses with a consistent format:
          "content": "Item 1",
          "checked": false,
          "parent_id": null,
-         "checklist_uuid": "123e4567-e89b-12d3-a456-426614174000"
+         "checklist_uuid": "123e4567-e89b-12d3-a456-426614174000",
+         "dependencies": []
+      },
+      {
+         "id": 2,
+         "content": "Item 2",
+         "checked": true,
+         "parent_id": null,
+         "checklist_uuid": "123e4567-e89b-12d3-a456-426614174000",
+         "dependencies": [1]
       }
    ]
 }
@@ -363,8 +375,9 @@ All API endpoints return JSON responses with a consistent format:
 
 The application uses SQLite with the following schema:
 
-- `checklists` table: Stores checklist metadata
+- `checklist_info` table: Stores checklist metadata (uuid, name)
 - `items` table: Stores checklist items with hierarchical relationships
+- `dependencies` table: Stores item dependencies (item_id, dependency_id)
 
 ## Real-time Features
 
@@ -374,6 +387,41 @@ The application uses SQLite with the following schema:
 - **Broadcast updates to all connected clients**
 - **Immediate UI updates**: Changes appear instantly across all browsers
 
+## Item Dependencies
+
+The application supports item dependencies, allowing you to define prerequisites
+that must be completed before an item can be marked as done.
+
+### How Dependencies Work
+
+- **Prerequisites**: Items can depend on other items being completed first
+- **Visual Indicators**: Items with unmet dependencies show warning indicators
+- **Prevention**: Items cannot be completed until all dependencies are satisfied
+- **Circular Prevention**: The system prevents circular dependencies
+- **Real-time Updates**: Dependency status updates in real-time across all
+  clients
+
+### Managing Dependencies
+
+1. **Add Dependencies**: Click the dependency icon (⚡) on any item to open the
+   dependency manager
+2. **Select Prerequisites**: Choose which items must be completed first
+3. **Visual Feedback**: Items show dependency status with color-coded
+   indicators:
+   - 🟠 Orange: Dependencies not met (shows count)
+   - 🟢 Green: All dependencies met (shows "Ready")
+4. **Completion Prevention**: Items with unmet dependencies cannot be checked
+   off
+
+### Dependency Features
+
+- **Flexible Dependencies**: Items can depend on any number of other items
+- **Hierarchical Support**: Dependencies work with parent-child relationships
+- **Real-time Validation**: Dependency status updates immediately when items are
+  completed
+- **Clear Feedback**: Users see exactly which items need to be completed first
+- **Error Prevention**: System prevents circular dependencies automatically
+
 ## Development
 
 ### Local Development
@@ -383,7 +431,8 @@ To run in development mode with automatic reloading, you can use tools like
 
 #### Using the Development Script
 
-The project includes a development script that runs both backend and frontend with hot reloading:
+The project includes a development script that runs both backend and frontend
+with hot reloading:
 
 ```bash
 # Start development environment
@@ -391,6 +440,7 @@ The project includes a development script that runs both backend and frontend wi
 ```
 
 This will:
+
 - Start the Go backend with Air for hot reloading
 - Start the React frontend with Vite for hot reloading
 - Proxy API requests from frontend to backend
@@ -413,6 +463,7 @@ For a consistent development environment using Docker with hot reloading:
 ```
 
 This will:
+
 - Build a development container with all dependencies
 - Mount your source code for hot reloading
 - Start both backend (Air) and frontend (Vite) with hot reloading
@@ -440,8 +491,10 @@ docker-compose -f docker-compose.dev.yml up --build --force-recreate
 
 The Docker development environment includes:
 
-- **Hot Reloading**: Both Go backend and React frontend reload automatically on code changes
-- **Volume Mounts**: Your local code is mounted into the container for live editing
+- **Hot Reloading**: Both Go backend and React frontend reload automatically on
+  code changes
+- **Volume Mounts**: Your local code is mounted into the container for live
+  editing
 - **Dependency Management**: All dependencies are pre-installed in the container
 - **Consistent Environment**: Same environment across all developers
 - **Easy Cleanup**: Simple commands to start/stop the development environment
@@ -449,6 +502,7 @@ The Docker development environment includes:
 #### File Watching
 
 The development container uses:
+
 - **Air** for Go backend hot reloading (watches `.go` files)
 - **Vite** for React frontend hot reloading (watches all frontend files)
 - **inotify-tools** for efficient file system watching
@@ -459,5 +513,7 @@ If you encounter issues:
 
 1. **Port conflicts**: Ensure ports 8080 and 5173 are not in use
 2. **Permission issues**: The container runs with appropriate permissions
-3. **Hot reload not working**: Check that your files are being watched by the respective tools
-4. **Container won't start**: Check Docker logs with `docker-compose -f docker-compose.dev.yml logs`
+3. **Hot reload not working**: Check that your files are being watched by the
+   respective tools
+4. **Container won't start**: Check Docker logs with
+   `docker-compose -f docker-compose.dev.yml logs`

frontend/src/components/ChecklistItem.tsx

@@ -1,5 +1,6 @@
 import { useState, useRef, useEffect } from 'react'
 import type { ChecklistItem as ChecklistItemType } from '../types'
+import DependencyManager from './DependencyManager'
 
 interface ChecklistItemProps {
   item: ChecklistItemType
@@ -8,6 +9,7 @@ interface ChecklistItemProps {
   onLock: (id: number, user: string) => Promise<void>
   depth?: number
   children?: ChecklistItemType[]
+  allItems?: ChecklistItemType[]
 }
 
 export default function ChecklistItem({ 
@@ -16,16 +18,32 @@ export default function ChecklistItem({
   onDelete, 
   onLock, 
   depth = 0,
-  children = []
+  children = [],
+  allItems = []
 }: ChecklistItemProps) {
   const [isEditing, setIsEditing] = useState(false)
   const [isDeleting, setIsDeleting] = useState(false)
+  const [isDependencyModalOpen, setIsDependencyModalOpen] = useState(false)
   const [userName, setUserName] = useState('')
   const contentRef = useRef<HTMLSpanElement>(null)
 
   const isLocked = item.locked_by && item.lock_until && new Date(item.lock_until) > new Date()
   const isLockedByMe = isLocked && item.locked_by === userName
 
+  // Check if all dependencies are completed
+  const dependenciesCompleted = item.dependencies?.every(depId => {
+    const depItem = allItems.find(i => i.id === depId)
+    return depItem?.checked
+  }) ?? true
+
+  // Check if item can be completed (all dependencies met)
+  const canComplete = dependenciesCompleted || item.checked
+
+  // Get dependency items for display
+  const dependencyItems = item.dependencies?.map(depId => 
+    allItems.find(i => i.id === depId)
+  ).filter(Boolean) ?? []
+
   useEffect(() => {
     // Generate a random user name if not set
     if (!userName) {
@@ -97,10 +115,29 @@ export default function ChecklistItem({
   }
 
   const handleToggleCheck = async () => {
+    // Don't allow unchecking if already checked
+    if (item.checked) {
+      try {
+        await onUpdate(item.id, { checked: false })
+      } catch (error) {
+        console.error('Failed to uncheck item:', error)
+      }
+      return
+    }
+
+    // Check if dependencies are met before allowing completion
+    if (!dependenciesCompleted) {
+      alert(`Cannot complete this item. The following dependencies must be completed first:\n\n${dependencyItems.map(dep => `• ${dep?.content}`).join('\n')}`)
+      return
+    }
+
     try {
-      await onUpdate(item.id, { checked: !item.checked })
+      await onUpdate(item.id, { checked: true })
     } catch (error) {
       console.error('Failed to toggle item:', error)
+      if (error instanceof Error && error.message.includes('dependency')) {
+        alert(error.message)
+      }
     }
   }
 
@@ -132,8 +169,11 @@ export default function ChecklistItem({
             type="checkbox"
             checked={item.checked}
             onChange={handleToggleCheck}
-            disabled={Boolean(isLocked && !isLockedByMe)}
-            className="w-5 h-5 text-blue-600 bg-white dark:bg-gray-800 border-2 border-gray-300 dark:border-gray-600 rounded-md focus:ring-2 focus:ring-blue-500 focus:ring-offset-2 dark:focus:ring-offset-gray-900 disabled:opacity-50 disabled:cursor-not-allowed transition-all duration-200 hover:border-blue-400 dark:hover:border-blue-500"
+            disabled={Boolean(isLocked && !isLockedByMe) || (!item.checked && !canComplete)}
+            className={`w-5 h-5 text-blue-600 bg-white dark:bg-gray-800 border-2 border-gray-300 dark:border-gray-600 rounded-md focus:ring-2 focus:ring-blue-500 focus:ring-offset-2 dark:focus:ring-offset-gray-900 disabled:opacity-50 disabled:cursor-not-allowed transition-all duration-200 hover:border-blue-400 dark:hover:border-blue-500 ${
+              !item.checked && !canComplete ? 'cursor-not-allowed' : ''
+            }`}
+            title={!item.checked && !canComplete ? 'Complete dependencies first' : ''}
           />
         </div>
         
@@ -151,6 +191,8 @@ export default function ChecklistItem({
               item.checked 
                 ? 'line-through text-gray-500 dark:text-gray-500 opacity-75' 
                 : 'text-gray-900 dark:text-gray-100'
+            } ${
+              !item.checked && !canComplete ? 'opacity-60' : ''
             }`}
             onClick={!isEditing ? handleEdit : undefined}
             onKeyDown={isEditing ? handleKeyDown : undefined}
@@ -158,10 +200,33 @@ export default function ChecklistItem({
           >
             {item.content}
           </span>
+          
+          {/* Dependency warning */}
+          {!item.checked && !canComplete && dependencyItems.length > 0 && (
+            <div className="mt-1 text-xs text-orange-600 dark:text-orange-400">
+              ⚠️ Depends on: {dependencyItems.map(dep => dep?.content).join(', ')}
+            </div>
+          )}
         </div>
 
         {/* Actions */}
         <div className="flex items-center gap-2 flex-shrink-0 opacity-0 group-hover:opacity-100 transition-opacity duration-200">
+          {/* Dependency indicators */}
+          {item.dependencies && item.dependencies.length > 0 && (
+            <div className="flex items-center gap-1">
+              <span className={`inline-flex items-center gap-1 text-xs font-medium px-2 py-1 rounded-full whitespace-nowrap border ${
+                dependenciesCompleted 
+                  ? 'text-green-600 dark:text-green-400 bg-green-50 dark:bg-green-900/20 border-green-200 dark:border-green-800'
+                  : 'text-orange-600 dark:text-orange-400 bg-orange-50 dark:bg-orange-900/20 border-orange-200 dark:border-orange-800'
+              }`}>
+                <svg className="w-3 h-3" fill="currentColor" viewBox="0 0 20 20">
+                  <path fillRule="evenodd" d="M3 4a1 1 0 011-1h12a1 1 0 110 2H4a1 1 0 01-1-1zm0 4a1 1 0 011-1h12a1 1 0 110 2H4a1 1 0 01-1-1zm0 4a1 1 0 011-1h12a1 1 0 110 2H4a1 1 0 01-1-1z" clipRule="evenodd" />
+                </svg>
+                {dependenciesCompleted ? 'Ready' : `${item.dependencies.length} deps`}
+              </span>
+            </div>
+          )}
+          
           {isLocked && !isLockedByMe && (
             <span className="inline-flex items-center gap-1 text-xs font-medium text-red-600 dark:text-red-400 bg-red-50 dark:bg-red-900/20 px-2 py-1 rounded-full whitespace-nowrap border border-red-200 dark:border-red-800">
               <svg className="w-3 h-3" fill="currentColor" viewBox="0 0 20 20">
@@ -172,16 +237,27 @@ export default function ChecklistItem({
           )}
           
           {!isEditing && (
-            <button 
-              onClick={handleDelete}
-              disabled={isDeleting}
-              className="p-1.5 text-gray-400 hover:text-red-600 dark:hover:text-red-400 hover:bg-red-50 dark:hover:bg-red-900/20 rounded-md transition-all duration-200 disabled:opacity-30 disabled:cursor-not-allowed group/delete"
-              title="Delete item"
-            >
-              <svg className="w-4 h-4 group-hover/delete:scale-110 transition-transform duration-200" fill="none" stroke="currentColor" viewBox="0 0 24 24">
-                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M19 7l-.867 12.142A2 2 0 0116.138 21H7.862a2 2 0 01-1.995-1.858L5 7m5 4v6m4-6v6m1-10V4a1 1 0 00-1-1h-4a1 1 0 00-1 1v3M4 7h16" />
-              </svg>
-            </button>
+            <>
+              <button 
+                onClick={() => setIsDependencyModalOpen(true)}
+                className="p-1.5 text-gray-400 hover:text-blue-600 dark:hover:text-blue-400 hover:bg-blue-50 dark:hover:bg-blue-900/20 rounded-md transition-all duration-200 group/deps"
+                title="Manage dependencies"
+              >
+                <svg className="w-4 h-4 group-hover/deps:scale-110 transition-transform duration-200" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M13 10V3L4 14h7v7l9-11h-7z" />
+                </svg>
+              </button>
+              <button 
+                onClick={handleDelete}
+                disabled={isDeleting}
+                className="p-1.5 text-gray-400 hover:text-red-600 dark:hover:text-red-400 hover:bg-red-50 dark:hover:bg-red-900/20 rounded-md transition-all duration-200 disabled:opacity-30 disabled:cursor-not-allowed group/delete"
+                title="Delete item"
+              >
+                <svg className="w-4 h-4 group-hover/delete:scale-110 transition-transform duration-200" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                  <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M19 7l-.867 12.142A2 2 0 0116.138 21H7.862a2 2 0 01-1.995-1.858L5 7m5 4v6m4-6v6m1-10V4a1 1 0 00-1-1h-4a1 1 0 00-1 1v3M4 7h16" />
+                </svg>
+              </button>
+            </>
           )}
         </div>
       </div>
@@ -197,10 +273,20 @@ export default function ChecklistItem({
               onDelete={onDelete}
               onLock={onLock}
               depth={depth + 1}
+              allItems={allItems}
             />
           ))}
         </div>
       )}
+
+      {/* Dependency Manager Modal */}
+      <DependencyManager
+        item={item}
+        allItems={allItems}
+        onUpdate={onUpdate}
+        onClose={() => setIsDependencyModalOpen(false)}
+        isOpen={isDependencyModalOpen}
+      />
     </li>
   )
 } 

frontend/src/components/DependencyManager.tsx

@@ -0,0 +1,134 @@
+import { useState, useEffect } from 'react'
+import type { ChecklistItem } from '../types'
+
+interface DependencyManagerProps {
+  item: ChecklistItem
+  allItems: ChecklistItem[]
+  onUpdate: (id: number, updates: Partial<ChecklistItem>) => Promise<void>
+  onClose: () => void
+  isOpen: boolean
+}
+
+export default function DependencyManager({ 
+  item, 
+  allItems, 
+  onUpdate, 
+  onClose, 
+  isOpen 
+}: DependencyManagerProps) {
+  const [selectedDependencies, setSelectedDependencies] = useState<number[]>([])
+  const [isUpdating, setIsUpdating] = useState(false)
+
+  useEffect(() => {
+    if (isOpen) {
+      setSelectedDependencies(item.dependencies || [])
+    }
+  }, [isOpen, item.dependencies])
+
+  const handleSave = async () => {
+    setIsUpdating(true)
+    try {
+      await onUpdate(item.id, { dependencies: selectedDependencies })
+      onClose()
+    } catch (error) {
+      console.error('Failed to update dependencies:', error)
+    } finally {
+      setIsUpdating(false)
+    }
+  }
+
+  const toggleDependency = (depId: number) => {
+    setSelectedDependencies(prev => 
+      prev.includes(depId) 
+        ? prev.filter(id => id !== depId)
+        : [...prev, depId]
+    )
+  }
+
+  const availableItems = allItems.filter(otherItem => 
+    otherItem.id !== item.id && 
+    !otherItem.dependencies?.includes(item.id) // Prevent circular dependencies
+  )
+
+  if (!isOpen) return null
+
+  return (
+    <div className="fixed inset-0 bg-black bg-opacity-50 flex items-center justify-center z-50">
+      <div className="bg-white dark:bg-gray-800 rounded-lg shadow-xl max-w-md w-full mx-4 max-h-[80vh] overflow-hidden">
+        <div className="p-6">
+          <div className="flex items-center justify-between mb-4">
+            <h3 className="text-lg font-semibold text-gray-900 dark:text-white">
+              Manage Dependencies
+            </h3>
+            <button
+              onClick={onClose}
+              className="text-gray-400 hover:text-gray-600 dark:hover:text-gray-300"
+            >
+              <svg className="w-6 h-6" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M6 18L18 6M6 6l12 12" />
+              </svg>
+            </button>
+          </div>
+
+          <div className="mb-4">
+            <p className="text-sm text-gray-600 dark:text-gray-300 mb-3">
+              Select items that must be completed before "{item.content}" can be completed:
+            </p>
+          </div>
+
+          <div className="max-h-64 overflow-y-auto border border-gray-200 dark:border-gray-700 rounded-lg">
+            {availableItems.length === 0 ? (
+              <div className="p-4 text-center text-gray-500 dark:text-gray-400">
+                No available items to depend on
+              </div>
+            ) : (
+              <div className="divide-y divide-gray-200 dark:divide-gray-700">
+                {availableItems.map(otherItem => (
+                  <label
+                    key={otherItem.id}
+                    className="flex items-center p-3 hover:bg-gray-50 dark:hover:bg-gray-700 cursor-pointer"
+                  >
+                    <input
+                      type="checkbox"
+                      checked={selectedDependencies.includes(otherItem.id)}
+                      onChange={() => toggleDependency(otherItem.id)}
+                      className="w-4 h-4 text-blue-600 bg-white dark:bg-gray-800 border-2 border-gray-300 dark:border-gray-600 rounded focus:ring-2 focus:ring-blue-500 focus:ring-offset-2 dark:focus:ring-offset-gray-800"
+                    />
+                    <span className={`ml-3 text-sm ${
+                      otherItem.checked 
+                        ? 'line-through text-gray-500 dark:text-gray-500' 
+                        : 'text-gray-900 dark:text-gray-100'
+                    }`}>
+                      {otherItem.content}
+                    </span>
+                    {otherItem.checked && (
+                      <span className="ml-2 text-xs text-green-600 dark:text-green-400 bg-green-50 dark:bg-green-900/20 px-2 py-1 rounded-full">
+                        ✓ Done
+                      </span>
+                    )}
+                  </label>
+                ))}
+              </div>
+            )}
+          </div>
+
+          <div className="flex justify-end gap-3 mt-6">
+            <button
+              onClick={onClose}
+              className="px-4 py-2 text-gray-700 dark:text-gray-300 bg-gray-100 dark:bg-gray-700 rounded-lg hover:bg-gray-200 dark:hover:bg-gray-600 transition-colors duration-200"
+            >
+              Cancel
+            </button>
+            <button
+              onClick={handleSave}
+              disabled={isUpdating}
+              className="px-4 py-2 bg-blue-600 dark:bg-blue-500 text-white rounded-lg hover:bg-blue-700 dark:hover:bg-blue-600 disabled:opacity-50 disabled:cursor-not-allowed transition-colors duration-200"
+            >
+              {isUpdating ? 'Saving...' : 'Save'}
+            </button>
+          </div>
+        </div>
+      </div>
+    </div>
+  )
+} 

frontend/src/pages/Checklist.tsx

@@ -133,8 +133,8 @@ export default function Checklist() {
     }
   }
 
-  const renderItems = (items: ChecklistItemType[]) => {
-    return items.map(item => (
+  const renderItems = (treeItems: ChecklistItemType[], allItems: ChecklistItemType[]) => {
+    return treeItems.map(item => (
       <ChecklistItem
         key={item.id}
         item={item}
@@ -142,6 +142,7 @@ export default function Checklist() {
         onDelete={deleteItem}
         onLock={lockItem}
         children={item.children || []}
+        allItems={allItems}
       />
     ))
   }
@@ -236,7 +237,7 @@ export default function Checklist() {
             </div>
           ) : (
             <ul>
-              {renderItems(itemTree)}
+              {renderItems(itemTree, items)}
             </ul>
           )}
         </div>

frontend/src/types.ts

@@ -7,6 +7,7 @@ export interface ChecklistItem {
   lock_until?: string
   checklist_uuid: string
   children?: ChecklistItem[]
+  dependencies?: number[]
 }
 
 export interface SavedChecklist {

main.go

@@ -29,13 +29,14 @@ type Checklist struct {
 }
 
 type ChecklistItem struct {
-	ID        int        `json:"id"`
-	Content   string     `json:"content"`
-	Checked   bool       `json:"checked"`
-	ParentID  *int       `json:"parent_id"`
-	LockedBy  *string    `json:"locked_by,omitempty"`
-	LockUntil *time.Time `json:"lock_until,omitempty"`
-	Checklist string     `json:"checklist_uuid"`
+	ID           int        `json:"id"`
+	Content      string     `json:"content"`
+	Checked      bool       `json:"checked"`
+	ParentID     *int       `json:"parent_id"`
+	LockedBy     *string    `json:"locked_by,omitempty"`
+	LockUntil    *time.Time `json:"lock_until,omitempty"`
+	Checklist    string     `json:"checklist_uuid"`
+	Dependencies []int      `json:"dependencies,omitempty"`
 }
 
 type ItemLock struct {
@@ -79,6 +80,14 @@ func getChecklistDB(uuid string) (*sql.DB, error) {
 			parent_id INTEGER,
 			FOREIGN KEY(parent_id) REFERENCES items(id)
 		);`,
+		`CREATE TABLE IF NOT EXISTS dependencies (
+			item_id INTEGER NOT NULL,
+			dependency_id INTEGER NOT NULL,
+			PRIMARY KEY (item_id, dependency_id),
+			FOREIGN KEY(item_id) REFERENCES items(id) ON DELETE CASCADE,
+			FOREIGN KEY(dependency_id) REFERENCES items(id) ON DELETE CASCADE,
+			CHECK(item_id != dependency_id)
+		);`,
 	}
 	for _, q := range queries {
 		if _, err := db.Exec(q); err != nil {
@@ -89,6 +98,25 @@ func getChecklistDB(uuid string) (*sql.DB, error) {
 	return db, nil
 }
 
+func loadItemDependencies(db *sql.DB, itemID int) ([]int, error) {
+	rows, err := db.Query(`SELECT dependency_id FROM dependencies WHERE item_id = ?`, itemID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var deps []int
+	for rows.Next() {
+		var depID int
+		err = rows.Scan(&depID)
+		if err != nil {
+			return nil, err
+		}
+		deps = append(deps, depID)
+	}
+	return deps, nil
+}
+
 // ensureChecklistExists creates a checklist if it doesn't exist
 func ensureChecklistExists(uuid string) error {
 	db, err := getChecklistDB(uuid)
@@ -166,6 +194,13 @@ func loadChecklistItems(uuid string) ([]ChecklistItem, error) {
 		}
 		it.Checklist = uuid
 
+		// Load dependencies for this item
+		deps, err := loadItemDependencies(db, it.ID)
+		if err != nil {
+			return nil, err
+		}
+		it.Dependencies = deps
+
 		// Attach lock info if present
 		itemLocksMutex.Lock()
 		if lock, ok := itemLocks[it.ID]; ok && lock.Expires.After(time.Now()) {
@@ -214,16 +249,72 @@ func addItem(uuid, content string, parentID *int) (ChecklistItem, error) {
 	}, nil
 }
 
-func updateItem(uuid string, id int, content *string, checked *bool, parentID *int) (ChecklistItem, error) {
+func updateItem(uuid string, id int, content *string, checked *bool, parentID *int, dependencies *[]int) (ChecklistItem, error) {
+	log.Printf("updateItem called with uuid: %s, id: %d", uuid, id)
+	log.Printf("Parameters: content=%v, checked=%v, parentID=%v, dependencies=%v", content, checked, parentID, dependencies)
+
 	db, err := getChecklistDB(uuid)
 	if err != nil {
+		log.Printf("Failed to get database: %v", err)
 		return ChecklistItem{}, err
 	}
 	defer db.Close()
 
-	q := "UPDATE items SET "
-	args := []interface{}{}
+	log.Printf("Database connection successful for uuid: %s", uuid)
+
+	// If trying to check an item, validate dependencies first
+	if checked != nil && *checked {
+		log.Printf("Validating dependencies for item %d", id)
+		deps, err := loadItemDependencies(db, id)
+		if err != nil {
+			log.Printf("Failed to load dependencies: %v", err)
+			return ChecklistItem{}, err
+		}
+
+		// Check if all dependencies are completed
+		for _, depID := range deps {
+			var depChecked int
+			err = db.QueryRow(`SELECT checked FROM items WHERE id = ?`, depID).Scan(&depChecked)
+			if err != nil {
+				log.Printf("Failed to check dependency %d: %v", depID, err)
+				return ChecklistItem{}, err
+			}
+			if depChecked == 0 {
+				return ChecklistItem{}, fmt.Errorf("cannot complete item: dependency %d is not completed", depID)
+			}
+		}
+	} else {
+		log.Printf("Skipping dependency validation - checked is %v", checked)
+	}
+
+	log.Printf("About to check dependencies parameter")
+	// Update dependencies if provided
+	if dependencies != nil {
+		log.Printf("Updating dependencies for item %d: %v", id, *dependencies)
+		// Delete existing dependencies
+		_, err = db.Exec(`DELETE FROM dependencies WHERE item_id = ?`, id)
+		if err != nil {
+			log.Printf("Failed to delete existing dependencies: %v", err)
+			return ChecklistItem{}, err
+		}
+
+		// Add new dependencies
+		for _, depID := range *dependencies {
+			log.Printf("Adding dependency %d for item %d", depID, id)
+			_, err = db.Exec(`INSERT INTO dependencies (item_id, dependency_id) VALUES (?, ?)`, id, depID)
+			if err != nil {
+				log.Printf("Failed to add dependency %d: %v", depID, err)
+				return ChecklistItem{}, err
+			}
+		}
+		log.Printf("Dependencies updated successfully")
+	} else {
+		log.Printf("No dependencies to update")
+	}
+
+	log.Printf("About to build SQL update query")
 	set := []string{}
+	args := []interface{}{}
 	if content != nil {
 		set = append(set, "content = ?")
 		args = append(args, *content)
@@ -240,24 +331,36 @@ func updateItem(uuid string, id int, content *string, checked *bool, parentID *i
 		set = append(set, "parent_id = ?")
 		args = append(args, *parentID)
 	}
-	q += strings.Join(set, ", ") + " WHERE id = ?"
-	args = append(args, id)
-	_, err = db.Exec(q, args...)
-	if err != nil {
-		return ChecklistItem{}, err
+	if len(set) > 0 {
+		q := "UPDATE items SET " + strings.Join(set, ", ") + " WHERE id = ?"
+		args = append(args, id)
+		log.Printf("SQL query: %s with args: %v", q, args)
+		_, err = db.Exec(q, args...)
+		if err != nil {
+			log.Printf("Failed to execute SQL update: %v", err)
+			return ChecklistItem{}, err
+		}
+		log.Printf("SQL update executed successfully")
+	} else {
+		log.Printf("No fields to update in SQL, skipping update query")
 	}
+
 	// Return updated item
+	log.Printf("Querying updated item %d", id)
 	rows, err := db.Query(`SELECT id, content, checked, parent_id FROM items WHERE id = ?`, id)
 	if err != nil {
+		log.Printf("Failed to query updated item: %v", err)
 		return ChecklistItem{}, err
 	}
 	defer rows.Close()
 	if rows.Next() {
+		log.Printf("Found item %d in database", id)
 		var it ChecklistItem
 		var checkedInt int
 		var parentID sql.NullInt64
 		err = rows.Scan(&it.ID, &it.Content, &checkedInt, &parentID)
 		if err != nil {
+			log.Printf("Failed to scan updated item: %v", err)
 			return ChecklistItem{}, err
 		}
 		it.Checked = checkedInt != 0
@@ -266,8 +369,19 @@ func updateItem(uuid string, id int, content *string, checked *bool, parentID *i
 			it.ParentID = &v
 		}
 		it.Checklist = uuid
+
+		// Load dependencies
+		deps, err := loadItemDependencies(db, it.ID)
+		if err != nil {
+			log.Printf("Failed to load dependencies for return: %v", err)
+			return ChecklistItem{}, err
+		}
+		it.Dependencies = deps
+
+		log.Printf("Successfully updated item %d", id)
 		return it, nil
 	}
+	log.Printf("Item %d not found in database", id)
 	return ChecklistItem{}, fmt.Errorf("not found")
 }
 
@@ -278,6 +392,13 @@ func deleteItem(uuid string, id int) error {
 	}
 	defer db.Close()
 
+	// Delete dependencies that reference this item
+	_, err = db.Exec(`DELETE FROM dependencies WHERE dependency_id = ?`, id)
+	if err != nil {
+		return err
+	}
+
+	// Delete the item itself
 	_, err = db.Exec(`DELETE FROM items WHERE id = ?`, id)
 	return err
 }
@@ -381,7 +502,14 @@ func handleAddItem(w http.ResponseWriter, r *http.Request) {
 }
 
 func handleUpdateItem(w http.ResponseWriter, r *http.Request) {
+	log.Printf("handleUpdateItem called with path: %s", r.URL.Path)
 	parts := strings.Split(r.URL.Path, "/")
+
+	if len(parts) < 6 {
+		http.Error(w, "Invalid path", 400)
+		return
+	}
+
 	uuid := parts[3]
 	id := 0
 	fmt.Sscanf(parts[5], "%d", &id)
@@ -393,18 +521,23 @@ func handleUpdateItem(w http.ResponseWriter, r *http.Request) {
 	}
 
 	type Req struct {
-		Content  *string `json:"content"`
-		Checked  *bool   `json:"checked"`
-		ParentID *int    `json:"parent_id"`
+		Content      *string `json:"content"`
+		Checked      *bool   `json:"checked"`
+		ParentID     *int    `json:"parent_id"`
+		Dependencies *[]int  `json:"dependencies"`
 	}
 	var req Req
 	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
 		http.Error(w, "Bad body", 400)
 		return
 	}
-	item, err := updateItem(uuid, id, req.Content, req.Checked, req.ParentID)
+	item, err := updateItem(uuid, id, req.Content, req.Checked, req.ParentID, req.Dependencies)
 	if err != nil {
-		http.Error(w, "Not found", 404)
+		if strings.Contains(err.Error(), "cannot complete item: dependency") {
+			http.Error(w, err.Error(), 400)
+		} else {
+			http.Error(w, "Not found", 404)
+		}
 		return
 	}
 	broadcast(uuid, map[string]interface{}{"type": "item_updated", "item": item})
@@ -587,7 +720,45 @@ func main() {
 
 	go lockExpiryDaemon()
 
-	// Serve static files from embedded filesystem
+	// Register API handlers first
+	http.HandleFunc("/api/checklists", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == "POST" {
+			handleCreateChecklist(w, r)
+		} else {
+			http.NotFound(w, r)
+		}
+	})
+
+	http.HandleFunc("/api/checklists/", func(w http.ResponseWriter, r *http.Request) {
+		path := r.URL.Path
+		log.Printf("API request: %s %s", r.Method, path)
+
+		switch {
+		case strings.HasSuffix(path, "/items") && r.Method == "GET":
+			log.Printf("Handling GET items")
+			handleGetItems(w, r)
+		case strings.HasSuffix(path, "/items") && r.Method == "POST":
+			log.Printf("Handling POST items")
+			handleAddItem(w, r)
+		case strings.Contains(path, "/items/") && strings.HasSuffix(path, "/lock") && r.Method == "POST":
+			log.Printf("Handling lock item")
+			handleLockItem(w, r)
+		case strings.Contains(path, "/items/") && r.Method == "PATCH":
+			log.Printf("Handling PATCH item")
+			handleUpdateItem(w, r)
+		case strings.Contains(path, "/items/") && r.Method == "DELETE":
+			log.Printf("Handling DELETE item")
+			handleDeleteItem(w, r)
+		case strings.HasSuffix(path, "/sse") && r.Method == "GET":
+			log.Printf("Handling SSE")
+			handleSSE(w, r)
+		default:
+			log.Printf("No handler found for %s %s", r.Method, path)
+			http.NotFound(w, r)
+		}
+	})
+
+	// Serve static files from embedded filesystem (register last)
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		// Check if this is a UUID path (starts with / followed by 36 characters)
 		isUUIDPath := len(r.URL.Path) == 37 && r.URL.Path[0] == '/' &&
@@ -613,34 +784,6 @@ func main() {
 		}
 	})
 
-	http.HandleFunc("/api/checklists", func(w http.ResponseWriter, r *http.Request) {
-		if r.Method == "POST" {
-			handleCreateChecklist(w, r)
-		} else {
-			http.NotFound(w, r)
-		}
-	})
-
-	http.HandleFunc("/api/checklists/", func(w http.ResponseWriter, r *http.Request) {
-		path := r.URL.Path
-		switch {
-		case strings.HasSuffix(path, "/items") && r.Method == "GET":
-			handleGetItems(w, r)
-		case strings.HasSuffix(path, "/items") && r.Method == "POST":
-			handleAddItem(w, r)
-		case strings.Contains(path, "/items/") && strings.HasSuffix(path, "/lock") && r.Method == "POST":
-			handleLockItem(w, r)
-		case strings.Contains(path, "/items/") && r.Method == "PATCH":
-			handleUpdateItem(w, r)
-		case strings.Contains(path, "/items/") && r.Method == "DELETE":
-			handleDeleteItem(w, r)
-		case strings.HasSuffix(path, "/sse") && r.Method == "GET":
-			handleSSE(w, r)
-		default:
-			http.NotFound(w, r)
-		}
-	})
-
 	port := strings.TrimSpace(os.Getenv("PORT"))
 	if port == "" {
 		port = "8080"