Automatic Retry Scheduler for FAILED Events (Complement to Staleness Monitor)

Feature Request: Automatic Retry Scheduler for FAILED Events

Requested: Add configurable automatic retry scheduler that leverages the new v2 schema infrastructure (completion_attempts, explicit states, multi-instance safety).

Context

Spring Modulith 2.0 M1 introduced:

• Staleness monitor (detects stuck events, marks as FAILED) ✅
• Completion attempts tracking ✅
• Multi-instance safety ✅

Missing piece: Automatic retry of FAILED events

Current Behavior

1. Event fails or gets stuck → Staleness monitor marks as FAILED ✅
2. Event remains in FAILED state forever ❌
3. Manual intervention required to retry ❌

Requested Feature

Add configurable retry scheduler:

spring:
  modulith:
    events:
      staleness:
        enabled: true
        processing-timeout: 5m
      
      # NEW: Automatic retry configuration
      retry:
        enabled: true
        fixed-delay: 60s
        max-attempts: 10              # ← Uses completion_attempts
        max-age: 7d                   # ← Age-based limit
        batch-size: 100
        states-to-retry:
          - FAILED                    # ← Retry events marked by staleness monitor
          - PUBLISHED                 # ← Retry immediate failures

How It Would Work

1. External system fails → Event marked FAILED by staleness monitor
2. Retry scheduler (every 60s):
   • Queries events in FAILED state
   • Filters by completion_attempts < 10
   • Filters by age < 7 days
   • Changes state to RESUBMITTED
   • Republishes events
3. If successful → State changes to COMPLETED
4. If fails again → completion_attempts++, back to FAILED
5. After 10 attempts or 7 days → Marked as BLOCKED

Propoesed state diagram-

Start with the existing staleness monitor, completion_attempts tracking, explicit event states, and multi-instance safety described in the issue; no source files or tests are named. Done means a configurable scheduler retries eligible FAILED or PUBLISHED events, enforces attempt and age limits, republishes them safely, and marks exhausted events BLOCKED.