Task 60 — Offline resilience

Phase: 6 Initiative: 38 Status: done Owner: — Slug: offline-resilience

Goal

Edge-агент буферизует sensor logs, task results и outgoing alerts через bounded local queues; возобновляет sync с deduplication и ordering при восстановлении связи.

Acceptance criteria

• OfflineSyncConfig: bounded queue size (max items), TTL per item type, flush interval

• [x] OutboxItem model: Id, Type (sensor_log

  task_result

  alert), Payload (JSON), CreatedAt, Priority, Status (pending

  synced

  failed), RetryCount, LastError

• SqliteOutboxStore: persists items in outbox_items table; adds IF_NOT_EXISTS migration on startup
• OfflineSyncService:
  • Enqueue(item): adds to SQLite, respects bounded queue cap (drops oldest synced items first)
  • FlushAsync(): drains pending items to MeshBus (or direct endpoint); marks synced; handles failures with RetryCount
  • NetworkMonitor: polls connectivity (HTTP HEAD to mesh endpoint); raises OnReconnected event
  • BackgroundHostedService: flushes on OnReconnected + periodic interval (OfflineSyncConfig.FlushIntervalSeconds)
  • Deduplication: skip items already synced (by item Id) on re-connect
  • Ordering: items sorted by CreatedAt ASC within same priority
• Registration in Program.cs: AddSingleton, register NetworkMonitor
• Unit tests: Enqueue respects cap, Flush marks synced, deduplication works, periodic flush fires

Scope / Likely files

src/agent/Offline/

Dependencies

• блокирует / опирается на: task_003 — hybrid-storage
• блокирует / опирается на: task_018 — durable-task-lifecycle

Risks / Rollback

Buffer overflow; явные приоритеты и TTL.

Links

• Backlog: ../backlog.md
• Roadmap (EN): ../../ROADMAP-EN.md
• Roadmap (RU): ../../ROADMAP-RU.md

Implementation notes

• Implemented in src/agent/Offline/: OfflineSyncConfig, SyncItem, IOutboxStore, SqliteOutboxStore, INetworkMonitor, NetworkMonitor, OfflineSyncService
• SQLite co-located with SqliteSessionStore (outbox_items table, WAL mode)
• Items published to mesh bus topics: offline/sensor-log, offline/task-result, offline/alert
• Config section: OfflineSync in appsettings.json (enabled by default, max 1000 items, 30s flush interval, 15s network poll)
• TTL cleanup runs on startup; capped at 1440 min (sensor logs), 60 min (task results), 30 min (alerts)
• OfflineSyncConfig added to AppConfig.OfflineSync
• 19 unit tests in tests/Hercules.Agent.Tests/Offline/OfflineSyncTests.cs — all passing

Validation

• dotnet build src/agent/Hercules.csproj — 0 errors
• dotnet test tests/Hercules.Agent.Tests/Hercules.Agent.Tests.csproj --filter "FullyQualifiedName~Offline" — 19 passed
• Full suite: 1564 passed, 8 pre-existing failures (OtelService + BudgetGuard)