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docs/ai/Common/DTS.CommonCore/Events/Database.md

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+---
+source_files:
+  - Common/DTS.CommonCore/Events/Database/DbStatusEvent.cs
+generated_at: "2026-04-17T16:40:13.623179+00:00"
+model: "zai-org/GLM-5-FP8"
+schema_version: 1
+sha256: "d12f546e7f17ce45"
+---
+
+# Documentation: DbStatusEvent.cs
+
+## 1. Purpose
+
+This module provides an event mechanism for broadcasting database status changes within the application, specifically related to database switch operations. It exists to decouple database operation outcomes from their consumers, allowing loosely-coupled components to react to database synchronization, backup, restore, and connection failures. The module implements the Prism event aggregation pattern via `CompositePresentationEvent<T>`.
+
+---
+
+## 2. Public Interface
+
+### `DbStatusEvent`
+**Signature:** `public class DbStatusEvent : CompositePresentationEvent<DbStatusArg>`
+
+A concrete event class that serves as a typed event carrier in the Prism event aggregation system. It carries `DbStatusArg` as its payload. This class has no additional members beyond its inherited functionality.
+
+---
+
+### `DbStatusArg`
+**Signature:** `public class DbStatusArg`
+
+An immutable payload class containing the details of a database status event.
+
+**Constructor:**
+```csharp
+public DbStatusArg(EventTypes error, Exception exception)
+```
+Constructs a new instance with the specified status type and optional exception.
+
+**Properties:**
+
+| Property | Type | Access | Description |
+|----------|------|--------|-------------|
+| `Status` | `EventTypes` | Get only | The type of status event that occurred |
+| `Exception` | `Exception` | Get only | An associated exception, if any |
+
+---
+
+### `DbStatusArg.EventTypes`
+**Signature:** `public enum EventTypes`
+
+Defines the possible database operation outcomes.
+
+| Value | Implied Meaning |
+|-------|-----------------|
+| `FailedToConnectToRemote` | Connection to remote database failed |
+| `FailedToBackupLocal` | Local database backup operation failed |
+| `FailedToCopy` | Copy operation failed |
+| `FailedToRestoreLocal` | Local database restore operation failed |
+| `FailedToBackupLocalFileNotFound` | Backup failed due to missing file |
+| `Complete` | Operation completed successfully |
+| `LegacyStatus` | Unclear from source alone |
+
+---
+
+## 3. Invariants
+
+- **Immutability:** `DbStatusArg` instances are immutable after construction. The `Status` and `Exception` properties have no setters.
+- **Non-null Status:** The `Status` property is always assigned via the constructor; it cannot be null since `EventTypes` is a value type enum.
+- **Event payload type:** `DbStatusEvent` always carries `DbStatusArg` as its payload type, enforced by the generic base class.
+
+---
+
+## 4. Dependencies
+
+**This module depends on:**
+- `System` (standard .NET namespace for `Exception` type)
+- `Microsoft.Practices.Prism.Events` (provides `CompositePresentationEvent<T>` for event aggregation)
+
+**What depends on this module:**
+- Cannot be