# Plugins

> Extend Fenmark with Rhai script plugins for custom import and export formats. Covers the plugins folder, writing your first plugin, and API helpers.

Source: https://fenmark.app/docs/plugins/

## What Are Plugins?

Fenmark supports custom import and export formats through Rhai script plugins. Rhai is a simple, sandboxed scripting language that runs inside the app. You can write a plugin to handle any file format that the built-in options do not cover.

Plugins appear in the Import and Export overlay dropdowns alongside the built-in formats.

![Export Entries dialog with a custom plugin format, "Plain Text Timeline", selected in the Format dropdown](https://fenmark.app/assets/docs/plugins-01-export-dropdown.webp "A Rhai plugin listed alongside the built-in export formats")

## Where Is the Plugins Folder?

The `plugins/` folder is shared across all journals and lives in the app data directory (this location is fixed and does not change when you configure a different journal path in Preferences):

- **Windows**: `%APPDATA%\com.minidiarium\plugins\`
- **macOS**: `~/Library/Application Support/com.minidiarium/plugins/`
- **Linux**: `~/.local/share/com.minidiarium/plugins/`

A `README.md` file with templates and API documentation is auto-generated in the plugins folder on first launch. If you previously had `.rhai` scripts in a per-journal `plugins/` folder, they are automatically copied to this central location on first launch after upgrading.

## Writing a Plugin

Each plugin is a single `.rhai` file with a metadata comment header and one entry-point function.

### Import Plugin

```rhai
// @name: My Custom Format
// @type: import
// @extensions: json

fn parse(content) {
    let data = parse_json(content);
    let entries = [];
    for item in data {
        entries += #{
            date: item.date,       // must be YYYY-MM-DD
            title: item.title,
            text: item.body,       // should be HTML
        };
    }
    entries
}
```

### Export Plugin

```rhai
// @name: Plain Text
// @type: export
// @extensions: txt

fn format_entries(entries) {
    let output = "";
    for entry in entries {
        output += entry.date + " - " + entry.title + "\n";
        output += html_to_markdown(entry.text) + "\n\n";
    }
    output
}
```

## Available Helper Functions

| Function | Description |
|----------|-------------|
| `parse_json(string)` | Parse a JSON string into a map or array |
| `count_words(string)` | Count words in a string |
| `now_rfc3339()` | Current timestamp in RFC 3339 format |
| `html_to_markdown(string)` | Convert HTML to Markdown |

## Rules and Limitations

![Diagram of the plugin sandbox boundary: a Rhai script has no file system or network access, and can only exchange plain text with the Import and Export dialogs](https://fenmark.app/assets/docs/diagrams/plugins-sandbox-boundary.svg "The plugin sandbox boundary")

- Import scripts must define `fn parse(content)` returning an array of entry maps.
- Export scripts must define `fn format_entries(entries)` returning a string. (`export` is a reserved word in Rhai, so the function is named `format_entries`.)
- The `date` field must be in `YYYY-MM-DD` format.
- The `text` field should contain HTML (the editor uses HTML internally).
- Scripts run in a sandbox: no file system access, no network access.
- Scripts are limited to 1,000,000 operations to prevent infinite loops.
- **Tags are not currently passed to Rhai export scripts.** Each entry map contains `date`, `title`, `text`, `word_count`, `date_created`, and `date_updated`. Tag support for Rhai plugins will be added in a future release.

## Official Example

An official example plugin is included in the repository at `docs/user-plugins/plain-text-timeline.rhai`.