# Tasks: Add Concurrency Handling and Reliability Improvements

## 1. Optimistic Locking
- [x] 1.1 Add `version` integer field to Task model with default=1
- [x] 1.2 Create database migration for version field
- [x] 1.3 Include version in TaskResponse schema
- [x] 1.4 Modify update_task to accept and validate version
- [x] 1.5 Return 409 Conflict when version mismatch detected
- [x] 1.6 Auto-increment version on successful update
- [x] 1.7 Update frontend to send version with update requests
- [x] 1.8 Handle 409 Conflict in frontend with user notification

## 2. Trigger Retry Mechanism
- [x] 2.1 Add retry configuration (max_retries=3, base_delay=1s)
- [x] 2.2 Implement exponential backoff (1s, 2s, 4s)
- [x] 2.3 Log each retry attempt with attempt number
- [x] 2.4 Mark trigger as permanently failed after max retries
- [x] 2.5 Send alert notification when trigger exhausts retries

## 3. Soft Delete Cascade Restore
- [x] 3.1 Modify restore_task to find all child tasks deleted at same time
- [x] 3.2 Recursively restore child tasks with matching deleted_at timestamp
- [x] 3.3 Add option to restore only parent vs cascade restore
- [x] 3.4 Log restore operations in audit trail

## 4. Testing
- [x] 4.1 Test concurrent updates with version conflict
- [x] 4.2 Test trigger retry on transient failure
- [x] 4.3 Test cascade restore of parent with children