id: CORE-001D3B
title: Alert History Degraded State Handling
status: done
priority: P2
effort: S
depends_on:
  - CORE-001D3A
tags:
  - core
  - alerts
  - persistence
  - ux
summary: Corrupt or unreadable alert-history storage now surfaces as an explicit degraded state instead of silently appearing as empty history.
completed_notes:
  - Added `AlertHistoryLoadError` in `app/models/alerts.py` so corrupt or unreadable alert-history storage is an explicit failure mode.
  - `AlertService.evaluate(...)` now logs history load failures and returns `history_unavailable` / `history_notice` metadata instead of silently treating corruption as an empty history list.
  - `/overview` and `/{workspace_id}/settings` now render a visible degraded-history notice when alert history storage is unavailable.
  - Added focused regression coverage in `tests/test_alerts.py` for corrupt-history load failures in both persisted and preview paths.
  - Validated with focused pytest coverage, local Docker, and browser-driven checks on overview and settings with an intentionally corrupted `/app/data/alert_history.json`.