Task 70 — Backend-профили и деградация

Phase: 4 Initiative: 30 Status: done Owner: — Slug: backend-profiles-degradation

Goal

Профили развёртывания объявляют, какой mesh используется: только локальный SQLite, Redis/Valkey, NATS, PostgreSQL или комбинации. Если бэкенд становится недоступен, агенты деградируют в local-only режим или прекращают приём новых делегаций по policy, а не падают молча. Состояние деградации наблюдаемо.

Acceptance criteria

Sub-tasks

• Mesh/Profiles/MeshProfile.cs — types: MeshBackendProfile enum (Local, Redis, Nats, Postgres, Hybrid), MeshProfileDefinition (name, description, backends map, constraints, degradationPolicy), MeshBackendConfig (kind, connectionString/hosts, enabled, healthCheckIntervalSec, timeoutSec, maxRetries), DegradationPolicy (mode: FailSilent/DegradeToLocal/RefuseDelegations, alertWebhook, maxDegradedSeconds before full-stop)
• Mesh/Profiles/MeshProfileLoader.cs — reads profiles from config section; resolves effective profile by name; validates required backends are available; logs profile activation
• Mesh/Backend/IMeshBackendHealthMonitor.cs — interface: GetBackendStatuses(), SubscribeToChanges(Func<BackendHealthChangedEvent, Task>), BackendHealthChangedEvent record
• Mesh/Backend/MeshBackendHealthMonitor.cs — BackgroundService; periodically calls IMeshBus.IsHealthyAsync, ITaskQueue.IsHealthyAsync, IMeshStateStore.IsHealthyAsync; transitions states (Healthy → Degraded → Unavailable); calls registered callbacks; emits OTel metrics
• Config/AppConfig.cs — add MeshProfilesConfig with ActiveProfile, ProfilesDir, HealthCheckIntervalSec, EnableDegradationAlerts
• Config/AppConfig.cs — add MeshProfiles property to MeshConfig
• Mesh/MeshServiceExtensions.cs — register MeshProfilesConfig and IMeshBackendHealthMonitor in DI; log active profile at startup
• Program.cs — register MeshProfilesConfig and IMeshBackendHealthMonitor in DI
• Hercules.WebApi/Controllers/MeshProfileController.cs — endpoints: GET /api/mesh/profiles, GET /api/mesh/profiles/{name}, GET /api/mesh/profiles/{name}/backends, GET /api/mesh/backend-status (live health), GET /api/mesh/backend-status/{backend} (per-backend health)
• tests/.../Mesh/Profiles/MeshProfileLoaderTests.cs — unit tests: load valid profile, local default profile, profile not found, effective backends resolution
• tests/.../Mesh/Backend/MeshBackendHealthMonitorTests.cs — unit tests: all healthy → Degraded → Unavailable transitions, callback invoked, metrics recorded
• dotnet build + dotnet test pass

Scope / Likely files

src/agent/Mesh/Profiles/, src/agent/Mesh/Profiles/MeshProfileLoader.cs, src/agent/Mesh/Degradation/HealthMonitor.cs

Dependencies

• блокирует / опирается на: task_066 — mesh-backends-abstraction
• блокирует / опирается на: task_065 — mesh-observability
• блокирует / опирается на: task_067 — redis-coordination-backend
• блокирует / опирается на: task_068 — nats-jetstream-transport
• блокирует / опирается на: task_069 — postgres-shared-state

Risks / Rollback

Тихое падение в degraded-режим без видимости; явный mode flag + alerting + policy-driven refuse-when-stale.

Links

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

Implementation notes

src/agent/Mesh/Profiles/MeshProfile.cs — 13 types: MeshBackendProfile enum (Local/Redis/Nats/Postgres/Hybrid), MeshBackendConfig, DegradationPolicy, DegradationMode, MeshProfileDefinition, MeshProfileConstraints, MeshBackendHealthStatus, BackendHealthState, BackendHealthChangedEvent.

src/agent/Mesh/Profiles/MeshProfileLoader.cs — loads profiles from config + .meshprofile.json files; built-in “local” profile always available; GetActiveProfile(), GetEffectiveBackend() for per-role resolution.

src/agent/Mesh/Backend/IMeshBackendHealthMonitor.cs — interface: GetBackendStatuses(), SubscribeToChanges(), CheckAllAsync().

src/agent/Mesh/Backend/MeshBackendHealthMonitor.cs — BackgroundService; in-process backends always Healthy (no external calls); external backends monitored on interval; transitions: Healthy→Degraded→Unavailable with consecutive failure tracking; OTel metrics via IMeshObservabilityService; subscriber callbacks fire on background thread.

Config/AppConfig.cs — added MeshProfilesConfig and AppConfig.MeshProfiles property.

Config/AppConfig.cs — added using Hercules.Mesh.Profiles; (added to Profiles dict property).

Mesh/MeshServiceExtensions.cs — registered MeshProfilesConfig and IMeshBackendHealthMonitor in DI.

Program.cs — registered appConfig.MeshProfiles.

Hercules.WebApi/Controllers/MeshProfileController.cs — 5 endpoints: GET /api/mesh/profiles, GET /api/mesh/profiles/{name}, GET /api/mesh/profiles/{name}/backends, GET /api/mesh/backend-status, GET /api/mesh/backend-status/{role}.

Tests (tests/.../Mesh/Profiles/MeshProfileLoaderTests.cs, tests/.../Mesh/Backend/MeshBackendHealthMonitorTests.cs): 24 unit tests covering profile loading, effective backend resolution, state transitions, callbacks, timeout handling, and subscription lifecycle.

Validation

• dotnet build Hercules.csproj -c Release — 0 new errors (pre-existing warnings unchanged)
• dotnet build Hercules.WebApi.csproj -c Release — 0 new errors
• dotnet build Hercules.Agent.Tests.csproj -c Release — 0 new errors
• dotnet test --filter MeshProfileLoader — 10/10 passed
• dotnet test --filter MeshBackendHealthMonitor — 14/14 passed
• Full suite: 1646/1655 (9 pre-existing failures: OtelService×5, BudgetGuard×1, NumericValidator×2, WasmTool×1)