# Auto-Heal & Watchdog

Exaplay 3 includes a built-in crash recovery system designed for unattended operation in permanent installations, trade-show booths, and touring productions that run 24/7.

## Components

| Component            | Description                                                                             |
| -------------------- | --------------------------------------------------------------------------------------- |
| **Watchdog Service** | A Windows Service (`exaplay3-service.exe`) that monitors the main application           |
| **Auto-Heal**        | Logic inside the engine that saves playback state so it can be restored after a restart |

## How It Works

```
1. Exaplay 3 writes a periodic "heartbeat" + playback state to disk
        ↓
2. Watchdog monitors the heartbeat
        ↓
3. If heartbeat stops (crash / hang detected), Watchdog:
   a. Terminates the hung process if still running
   b. Waits a configurable delay
   c. Restarts Exaplay 3 with the -autoheal-restore flag
        ↓
4. Exaplay 3 reads the saved state and resumes playback
   at (approximately) the timecode where it stopped
```

## Enabling Auto-Heal

Auto-Heal is enabled by default. To disable it for a session, launch Exaplay 3 with the `-fresh` flag.

## Watchdog Service

The Watchdog is installed as a Windows Service and starts automatically with Windows. You do not need to interact with it directly.

To check its status:

```powershell
Get-Service -Name "Exaplay3Watchdog"
```

To restart it manually:

```powershell
Restart-Service -Name "Exaplay3Watchdog"
```

## Auto-Heal Configuration

| Setting                | Description                                                 | Default |
| ---------------------- | ----------------------------------------------------------- | ------- |
| **Heartbeat interval** | How often the engine writes its heartbeat (ms)              | `500`   |
| **Miss threshold**     | Number of missed heartbeats before restart is triggered     | `10`    |
| **Restart delay**      | Seconds to wait before restarting after a crash             | `5`     |
| **Max restarts**       | Maximum automatic restarts within a rolling 5-minute window | `3`     |

Configure these in **Config → System → Auto-Heal**.

## Manual Recovery

If the system does not recover automatically:

1. Check the Watchdog Service status (see above).
2. Look at the log file in `Documents\Exaplay3\logs\` for the error.
3. Start Exaplay 3 manually; Auto-Heal will still restore the last saved state.

## Skipping Auto-Heal Restore

To start with a clean state (ignoring any saved auto-heal data), launch Exaplay 3 with:

```
exaplay3.exe -fresh
```

This is useful after a major project change or when debugging.


---

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