# Story 5.5: Scheduler and Background Jobs System

## Metadata
- **Story ID**: 5.5
- **Title**: Scheduler and Background Jobs System
- **Epic**: 5 - Infrastructure Adapters
- **Status**: Pending
- **Priority**: High
- **Estimated Time**: 6-8 hours
- **Dependencies**: 1.1, 5.1

## Goal
Implement a complete scheduler and background job system with cron jobs, job queues, retries, and job status tracking.

## Description
This story implements a scheduler system using Asynq (Redis-backed) that supports cron jobs for periodic tasks and job queues for background processing. Jobs can be registered from modules and tracked.

## Deliverables

### 1. Scheduler Interface (`pkg/scheduler/scheduler.go`)
- `Scheduler` interface with:
  - `Cron(spec string, job JobFunc) error` - Schedule cron job
  - `Enqueue(queue string, payload any) error` - Enqueue job
  - `RegisterJob(name string, handler JobHandler) error` - Register job handler

### 2. Asynq Implementation (`internal/infra/scheduler/asynq_scheduler.go`)
- Redis-backed job queue
- Cron jobs for periodic tasks
- Job retries and backoff
- Job status tracking
- Job result storage

### 3. Job Registry (`internal/infra/scheduler/job_registry.go`)
- Register jobs from modules
- Start job processor on app startup
- Job lifecycle management

### 4. Example Jobs
- Cleanup expired tokens (daily)
- Send digest emails (weekly)
- Database cleanup tasks

### 5. Job Monitoring API
- `GET /api/v1/jobs/status` - Job status endpoint
- Job history and statistics

### 6. Configuration
- Scheduler config in `config/default.yaml`:
  - Redis connection (shared with cache)
  - Concurrency settings
  - Retry settings

### 7. DI Integration
- Provider function for Scheduler
- Register in DI container

## Acceptance Criteria
- [ ] Scheduler interface is defined
- [ ] Cron jobs can be scheduled
- [ ] Jobs can be enqueued
- [ ] Jobs are processed correctly
- [ ] Job retries work
- [ ] Job status is tracked
- [ ] Example jobs run on schedule
- [ ] Job monitoring API works

## Files to Create/Modify
- `pkg/scheduler/scheduler.go` - Scheduler interface
- `internal/infra/scheduler/asynq_scheduler.go` - Asynq implementation
- `internal/infra/scheduler/job_registry.go` - Job registry
- `internal/infra/scheduler/jobs.go` - Example jobs
- `internal/di/providers.go` - Add scheduler provider
- `config/default.yaml` - Add scheduler config