developer-guide.md

# MatGUI Developer Guide

This comprehensive guide covers everything developers need to know to integrate, customize, and extend MatGUI (formerly *Yasgui*).

> **Backwards compatibility:** MatGUI keeps the `@matdata/yasgui`, `@matdata/yasqe` and `@matdata/yasr` package names, the `Yasgui`/`Yasqe`/`Yasr` global variables and class names, the `yasgui`/`yasqe`/`yasr` CSS classes and the existing localStorage keys unchanged. Existing integrations continue to work without code changes.

> The Yasgui project has been renamed Matgui. But this is a brand rename only. The technical name still remains Yasgui for backwards compatibility. Whenever you read 'Matgui' in this document, you can likely read 'yasgui' as well. Since this is a technical document for developers and since the package names are kept the same, this document still largely talks about yasgui due to the reference to the still-kept package name.

## Table of Contents

- [Table of Contents](#table-of-contents)
- [Architecture Overview](#architecture-overview)
  - [Package Structure](#package-structure)
  - [Architecture Diagram](#architecture-diagram)
  - [Package Details](#package-details)
    - [@matdata/yasgui-utils](#matdatayasgui-utils)
    - [@matdata/yasqe (SPARQL Query Editor)](#matdatayasqe-sparql-query-editor)
    - [@matdata/yasr (SPARQL Results Viewer)](#matdatayasr-sparql-results-viewer)
    - [@matdata/yasgui (Main Package)](#matdatayasgui-main-package)
- [Installation](#installation)
  - [npm](#npm)
  - [Yarn](#yarn)
  - [CDN](#cdn)
  - [Source](#source)
- [Usage Examples](#usage-examples)
  - [Plain HTML](#plain-html)
  - [Node.js / ES Modules](#nodejs--es-modules)
  - [CommonJS](#commonjs)
  - [React](#react)
  - [Vue](#vue)
  - [Angular](#angular)
  - [Using YASQE and YASR Separately](#using-yasqe-and-yasr-separately)
- [Configuration](#configuration)
  - [Matgui Configuration](#matgui-configuration)
    - [Example Configuration](#example-configuration)
  - [YASQE Configuration](#yasqe-configuration)
    - [YASQE Example](#yasqe-example)
    - [Code Snippets](#code-snippets)
    - [Share Configuration](#share-configuration)
  - [YASR Configuration](#yasr-configuration)
    - [YASR Example](#yasr-example)
    - [Disabling Response Cache](#disabling-response-cache)
  - [Request Configuration](#request-configuration)
    - [Request Configuration Example](#request-configuration-example)
  - [Authentication](#authentication)
    - [Authentication Types](#authentication-types)
    - [Basic Authentication](#basic-authentication)
    - [Bearer Token Authentication](#bearer-token-authentication)
    - [API Key Authentication](#api-key-authentication)
    - [Managing Endpoint Configurations](#managing-endpoint-configurations)
    - [OAuth 2.0 Provider Examples](#oauth-20-provider-examples)
    - [Dynamic Authentication](#dynamic-authentication)
    - [Disabling Authentication](#disabling-authentication)
    - [TypeScript Support](#typescript-support)
    - [Authentication Priority](#authentication-priority)
    - [Examples](#examples)
    - [Security Best Practices](#security-best-practices)
  - [Endpoint Buttons Configuration](#endpoint-buttons-configuration)
  - [Endpoint Describe Configuration](#endpoint-describe-configuration)
  - [AI Assistant Configuration](#ai-assistant-configuration)
  - [Theme Configuration](#theme-configuration)
- [API Reference](#api-reference)
  - [Yasgui Class](#yasgui-class)
    - [Constructor](#constructor)
    - [Methods](#methods)
      - [`getTab(tabId?: string): Tab | undefined`](#gettabtabid-string-tab--undefined)
      - [`addTab(select?: boolean, config?: PartialTabConfig): Tab`](#addtabselect-boolean-config-partialtabconfig-tab)
      - [`selectTabId(tabId: string): void`](#selecttabidtabid-string-void)
      - [`closeTab(tab: Tab): void`](#closetabtab-tab-void)
      - [`getTabs(): { [tabId: string]: Tab }`](#gettabs--tabid-string-tab-)
      - [`setTheme(theme: 'light' | 'dark'): void`](#setthemetheme-light--dark-void)
      - [`getTheme(): 'light' | 'dark'`](#gettheme-light--dark)
      - [`toggleTheme(): 'light' | 'dark'`](#toggletheme-light--dark)
      - [`endpointDescribe: EndpointDescribePanel | undefined`](#endpointdescribe-endpointdescribepanel--undefined)
      - [`aiAssistant: AiAssistant | undefined`](#aiassistant-aiassistant--undefined)
  - [Tab Class](#tab-class)
    - [Methods](#methods-1)
      - [`getName(): string`](#getname-string)
      - [`setName(name: string): void`](#setnamename-string-void)
      - [`getId(): string`](#getid-string)
      - [`getYasqe(): Yasqe`](#getyasqe-yasqe)
      - [`getYasr(): Yasr`](#getyasr-yasr)
      - [`query(): Promise<void>`](#query-promisevoid)
      - [`setQuery(query: string): void`](#setqueryquery-string-void)
      - [`getQuery(): string`](#getquery-string)
      - [`runBackgroundQuery(query: string, options?): Promise<any>`](#runbackgroundqueryquery-string-options-promiseany)
      - [`getRequestInit(): Promise<{ headers, withCredentials } | undefined>`](#getrequestinit-promise-headers-withcredentials---undefined)
  - [Yasqe Class](#yasqe-class)
    - [Methods](#methods-2)
      - [`getValue(): string`](#getvalue-string)
      - [`setValue(value: string): void`](#setvaluevalue-string-void)
      - [`query(): Promise<any>`](#query-promiseany)
      - [`abortQuery(): void`](#abortquery-void)
      - [`format(): void`](#format-void)
      - [`getPrefixes(): Prefixes`](#getprefixes-prefixes)
      - [`addPrefixes(prefixes: Prefixes): void`](#addprefixesprefixes-prefixes-void)
      - [`removePrefixes(): void`](#removeprefixes-void)
  - [Yasr Class](#yasr-class)
    - [Methods](#methods-3)
      - [`setResponse(response: any, duration?: number): void`](#setresponseresponse-any-duration-number-void)
      - [`draw(): void`](#draw-void)
      - [`selectPlugin(pluginName: string): void`](#selectpluginpluginname-string-void)
      - [`getPlugins(): { [name: string]: Plugin }`](#getplugins--name-string-plugin-)
      - [`executeQuery(query: string, options?: PluginQueryOptions): Promise<any>`](#executequeryquery-string-options-pluginqueryoptions-promiseany)
      - [`download(filename?: string): void`](#downloadfilename-string-void)
- [Events](#events)
  - [YASGUI Events](#yasgui-events)
  - [YASQE Events](#yasqe-events)
  - [YASR Events](#yasr-events)
  - [Event Example: Query Tracking](#event-example-query-tracking)
  - [Event Example: Custom Query Logging](#event-example-custom-query-logging)
- [Plugin Development](#plugin-development)
  - [Plugin Interface](#plugin-interface)
  - [Step-by-Step Plugin Development Guide](#step-by-step-plugin-development-guide)
    - [Step 1: Create Plugin Class](#step-1-create-plugin-class)
    - [Step 2: Register Plugin](#step-2-register-plugin)
    - [Step 3: Configure Plugin](#step-3-configure-plugin)
    - [Step 4: Add Styling](#step-4-add-styling)
  - [Plugin Example: Chart Plugin](#plugin-example-chart-plugin)
  - [Plugin Best Practices](#plugin-best-practices)
  - [Theme Support for Plugins](#theme-support-for-plugins)
    - [Implementation Steps](#implementation-steps)
  - [Distributing Your Plugin](#distributing-your-plugin)
- [Using the Graph Plugin](#using-the-graph-plugin)
  - [Installation](#installation-1)
  - [Key Features](#key-features)
  - [Configuration Options](#configuration-options)
  - [Color Scheme](#color-scheme)
  - [Node Icons and Images](#node-icons-and-images)
  - [Predicate Icons](#predicate-icons)
  - [API Reference](#api-reference-1)
  - [Theme Integration](#theme-integration)
  - [Performance Considerations](#performance-considerations)
  - [Browser Requirements](#browser-requirements)
  - [Example Queries](#example-queries)
  - [Troubleshooting](#troubleshooting)
  - [Repository](#repository)
- [Using the Geo Plugin](#using-the-geo-plugin)
  - [Installation](#installation-2)
  - [Registering the Plugin](#registering-the-plugin)
  - [Quick Configuration](#quick-configuration)
  - [Key Features](#key-features-1)
  - [Options Reference](#options-reference)
  - [Convention-Based Per-Feature Bindings](#convention-based-per-feature-bindings)
  - [Supported Geometry Types](#supported-geometry-types)
  - [CRS and Coordinate Transformations](#crs-and-coordinate-transformations)
  - [Drawing Spatial Filters](#drawing-spatial-filters)
  - [Export Capabilities](#export-capabilities)
  - [Temporal Filtering](#temporal-filtering)
  - [Clustering and Heatmap](#clustering-and-heatmap)
  - [Permalink Support](#permalink-support)
  - [TypeScript Support](#typescript-support-1)
  - [Example Queries](#example-queries-1)
  - [Troubleshooting](#troubleshooting-1)
  - [Repository](#repository-1)
- [Using the Table Plugin](#using-the-table-plugin)
  - [Installation](#installation-3)
  - [Key Features](#key-features-2)
  - [Configuration Options](#configuration-options-1)
  - [Event API](#event-api)
  - [More Information](#more-information)
- [Using the Chart Plugin](#using-the-chart-plugin)
- [Contributing](#contributing)
  - [Getting Started](#getting-started)
  - [Project Structure](#project-structure)
  - [Development Workflow](#development-workflow)
    - [Making Changes](#making-changes)
    - [Building](#building)
    - [Pull Requests](#pull-requests)
  - [Code Guidelines](#code-guidelines)
    - [TypeScript](#typescript)
    - [CSS](#css)
    - [Documentation](#documentation)
  - [Reporting Issues](#reporting-issues)
  - [Feature Requests](#feature-requests)
  - [Release Process](#release-process)
  - [Community](#community)
  - [Code of Conduct](#code-of-conduct)
- [Additional Resources](#additional-resources)


---

## Architecture Overview

YASGUI is built as a monorepo with four main packages, each serving a specific purpose in the SPARQL querying workflow.

### Package Structure

```
@matdata/yasgui (root)
├── @matdata/yasgui-utils     - Shared utilities
├── @matdata/yasqe            - SPARQL Query Editor
├── @matdata/yasr             - SPARQL Results Viewer
└── @matdata/yasgui           - Main integration package
```

### Architecture Diagram

```
┌─────────────────────────────────────────────────────────┐
│                          YASGUI                         │
│  ┌───────────────────────────────────────────────────┐  │
│  │              Tab Management Layer                 │  │
│  │  - Multiple query tabs                            │  │
│  │  - Tab persistence                                │  │
│  │  - Theme management                               │  │
│  │  - Settings & configuration                       │  │
│  └───────────────────────────────────────────────────┘  │
│                                                         │
│  ┌────────────────────┐         ┌────────────────────┐  │
│  │      YASQE         │         │       YASR         │  │
│  │  (Query Editor)    │         │  (Results Viewer)  │  │
│  │                    │         │                    │  │
│  │  ┌──────────────┐  │         │  ┌──────────────┐  │  │
│  │  │ CodeMirror   │  │         │  │  Plugins     │  │  │
│  │  │ - Syntax     │  │         │  │  - Table     │  │  │
│  │  │ - Validation │  │         │  │  - Graph     │  │  │
│  │  │ - Autocomplete│ │         │  │  - Geo       │  │  │
│  │  └──────────────┘  │         │  │  - Boolean   │  │  │
│  │                    │         │  │  - Response  │  │  │
│  │  ┌──────────────┐  │         │  │  - Error     │  │  │
│  │  │ SPARQL       │  │         │  └──────────────┘  │  │
│  │  │ Execution    │  ├───────▶│                    │  │
│  │  └──────────────┘  │         │  ┌──────────────┐  │  │
│  │                    │         │  │ Parser       │  │  │
│  │  ┌──────────────┐  │         │  │ - JSON       │  │  │
│  │  │ Prefixes     │  │         │  │ - XML        │  │  │
│  │  │ Management   │  │         │  │ - CSV        │  │  │
│  │  └──────────────┘  │         │  │ - Turtle     │  │  │
│  └────────────────────┘         │  └──────────────┘  │  │
│                                 └────────────────────┘  │
└─────────────────────────────────────────────────────────┘
                              │
                              │ Uses
                              ▼
                    ┌──────────────────┐
                    │  YASGUI-UTILS    │
                    │  - DOM helpers   │
                    │  - Storage       │
                    │  - Utilities     │
                    └──────────────────┘
```

### Package Details

#### @matdata/yasgui-utils

**Purpose**: Shared utility functions and helpers used across all packages.

**Key Features:**
- DOM manipulation utilities
- Local storage abstraction
- Common helper functions
- DOMPurify integration for XSS protection

**Exports:**
- `Storage`: localStorage abstraction with namespacing
- `addClass`, `removeClass`, `hasClass`: DOM class utilities

#### @matdata/yasqe (SPARQL Query Editor)

**Purpose**: Rich SPARQL query editor built on CodeMirror 6.

**Key Features:**
- SPARQL syntax highlighting
- Auto-completion (keywords, prefixes, properties, classes)
- Query validation with error highlighting
- Prefix management and auto-completion
- Query execution
- Query formatting (sparql-formatter integration)
- Persistent storage
- Keyboard shortcuts

**Core Components:**
- CodeMirror 6 `EditorView` wrapped by a CodeMirror 5-compatible facade (`packages/yasqe/src/editor/`)
- SPARQL tokenizer/grammar exposed as a `StreamLanguage` (`packages/yasqe/grammar/tokenizer.ts`)
- Autocomplete system (extensible, bridged to `@codemirror/autocomplete`)
- HTTP request handler
- Prefix utilities

**Editor architecture (CodeMirror 6):**

`Yasqe` no longer extends the CodeMirror class. It owns a CodeMirror 6 `EditorView` and exposes the familiar
CodeMirror 5-style API (`getValue`, `setValue`, `getCursor`, `setCursor`, `getTokenAt`, `getDoc`, `markText`,
`on('change'|'cursorActivity'|...)`, `addKeyMap`, etc.) through the `EditorFacade`/`DocFacade` classes. The
`editor/` folder contains the CM6 building blocks:

- `facade.ts` / `doc.ts` – CM5-compatible editor and document API on top of `EditorView`/`EditorState`
- `language.ts` / `tokenizerRunner.ts` – `StreamLanguage` for the SPARQL grammar emitting `cm-<style>` classes, plus `getTokenAt` emulation
- `autocompletion.ts` – bridges Yasqe completers (`HintFn`) to `@codemirror/autocomplete`, rendering into a `.CodeMirror-hints` list
- `gutters.ts` – line-number gutter and error/warning marker gutter
- `folding.ts` – brace and PREFIX-block folding via a `foldService`
- `keymap.ts` – converts CM5 key names (`Ctrl-Enter`, `Shift-Ctrl-K`, ...) to CM6 keymaps

Themes are applied as `CodeMirror cm-s-<theme>` classes on the editor root, so existing `.cm-s-*` stylesheets and
`.CodeMirror`-based selectors keep working. Token classes follow the CM5 naming (`cm-keyword`, `cm-variable-3`, ...).

#### @matdata/yasr (SPARQL Results Viewer)

**Purpose**: Flexible results visualization with plugin system.

**Key Features:**
- Plugin-based architecture
- Multiple built-in visualization plugins
- Result parsing (JSON, XML, CSV, Turtle)
- Export functionality
- Persistent plugin selection
- Theme support

**Core Components:**
- Plugin manager
- Result parsers
- Plugin API
- Header controls
- Download manager

#### @matdata/yasgui (Main Package)

**Purpose**: Integrates YASQE and YASR into a complete SPARQL IDE.

**Key Features:**
- Tab management (multiple queries)
- Endpoint management and quick-switch buttons
- Theme system (light/dark)
- Layout orientation (vertical/horizontal)
- Settings modal
- Tab persistence
- Event system
- URL-based query sharing

**Core Components:**
- Tab manager
- Theme manager
- Persistent configuration
- Settings modal
- Endpoint selector
- Tab context menu
- AI assistant (`src/ai/`): OpenAI-compatible client, prompts, endpoint context, check queries, the AI view of the side panel and the AI settings

---

## Installation

### npm

Install the main package (includes all components):

```bash
npm install @matdata/yasgui
```

Install individual packages:

```bash
npm install @matdata/yasqe    # Query editor only
npm install @matdata/yasr     # Results viewer only
npm install @matdata/yasgui-utils  # Utilities only
```

### Yarn

```bash
yarn add @matdata/yasgui
```

### CDN

Include YASGUI directly from a CDN (replace `VERSION` with the desired version):

```html
<!-- CSS -->
<link rel="stylesheet" href="https://unpkg.com/@matdata/yasgui@VERSION/build/yasgui.min.css" />

<!-- JavaScript -->
<script src="https://unpkg.com/@matdata/yasgui@VERSION/build/yasgui.min.js"></script>
```

**Latest version:**
```html
<link rel="stylesheet" href="https://unpkg.com/@matdata/yasgui/build/yasgui.min.css" />
<script src="https://unpkg.com/@matdata/yasgui/build/yasgui.min.js"></script>
```

### Source

Clone and build from source:

```bash
git clone https://github.com/Matdata-eu/Matgui.git
cd Yasgui
npm install
npm run build
```

Build output is in the `build/` directory.

---

## Usage Examples

### Plain HTML

Basic integration in a static HTML page:

```html
<!DOCTYPE html>
<html>
<head>
  <link rel="stylesheet" href="https://unpkg.com/@matdata/yasgui/build/yasgui.min.css" />
</head>
<body>
  <div id="yasgui"></div>
  
  <script src="https://unpkg.com/@matdata/yasgui/build/yasgui.min.js"></script>
  <script>
    const yasgui = new Yasgui(document.getElementById("yasgui"), {
      requestConfig: {
        endpoint: "https://dbpedia.org/sparql"
      }
    });
  </script>
</body>
</html>
```

> **Important:** If you want Matgui to fill the entire page, you **must** set `height: 100%` on all parent elements, including `html` and `body`:
>
> ```css
> html, body {
>   height: 100%;
>   margin: 0;
>   padding: 0;
> }
> 
> #yasgui {
>   height: 100%;
> }
> ```
>
> Using `height: 100%` ensures proper scaling when users zoom in/out in the browser. Avoid using viewport units like `100vh` on the container as they don't scale correctly with browser zoom. 

### Node.js / ES Modules

Using Matgui in a Node.js application or with module bundlers:

```javascript
import Yasgui from '@matdata/yasgui';
import '@matdata/yasgui/build/yasgui.min.css';

const yasgui = new Yasgui(document.getElementById('yasgui'), {
  requestConfig: {
    endpoint: 'https://query.wikidata.org/sparql'
  },
  theme: 'dark',
  orientation: 'horizontal'
});
```

### CommonJS

```javascript
const Yasgui = require('@matdata/yasgui').default;
require('@matdata/yasgui/build/yasgui.min.css');

const yasgui = new Yasgui(document.getElementById('yasgui'));
```

### React

Integration with React:

```jsx
import React, { useEffect, useRef } from 'react';
import Yasgui from '@matdata/yasgui';
import '@matdata/yasgui/build/yasgui.min.css';

function YasguiComponent() {
  const containerRef = useRef(null);
  const yasguiRef = useRef(null);

  useEffect(() => {
    if (containerRef.current && !yasguiRef.current) {
      yasguiRef.current = new Yasgui(containerRef.current, {
        requestConfig: {
          endpoint: 'https://dbpedia.org/sparql'
        }
      });

      // Listen to events
      yasguiRef.current.on('query', (instance, tab) => {
        console.log('Query executed on tab:', tab.getName());
      });
    }

    // Cleanup
    return () => {
      // Yasgui doesn't require explicit cleanup
      // but you can add custom cleanup logic here
    };
  }, []);

  return <div ref={containerRef} style={{ height: '100vh' }} />;
}

export default YasguiComponent;
```

### Vue

Integration with Vue 3:

```vue
<template>
  <div ref="yasguiContainer" class="yasgui-container"></div>
</template>

<script>
import { ref, onMounted, onUnmounted } from 'vue';
import Yasgui from '@matdata/yasgui';
import '@matdata/yasgui/build/yasgui.min.css';

export default {
  name: 'YasguiComponent',
  setup() {
    const yasguiContainer = ref(null);
    let yasgui = null;

    onMounted(() => {
      yasgui = new Yasgui(yasguiContainer.value, {
        requestConfig: {
          endpoint: 'https://dbpedia.org/sparql'
        },
        theme: 'dark'
      });

      yasgui.on('queryResponse', (instance, tab) => {
        console.log('Query completed:', tab.getName());
      });
    });

    onUnmounted(() => {
      // Cleanup if needed
      yasgui = null;
    });

    return {
      yasguiContainer
    };
  }
};
</script>

<style scoped>
.yasgui-container {
  height: 100vh;
  width: 100%;
}
</style>
```

### Angular

Integration with Angular:

```typescript
// yasgui.component.ts
import { Component, OnInit, ElementRef, ViewChild } from '@angular/core';
import Yasgui from '@matdata/yasgui';
import '@matdata/yasgui/build/yasgui.min.css';

@Component({
  selector: 'app-yasgui',
  template: '<div #yasguiContainer style="height: 100vh"></div>',
  styleUrls: ['./yasgui.component.css']
})
export class YasguiComponent implements OnInit {
  @ViewChild('yasguiContainer', { static: true }) 
  yasguiContainer!: ElementRef;
  
  private yasgui: any;

  ngOnInit(): void {
    this.yasgui = new Yasgui(this.yasguiContainer.nativeElement, {
      requestConfig: {
        endpoint: 'https://dbpedia.org/sparql'
      }
    });

    this.yasgui.on('query', (instance: any, tab: any) => {
      console.log('Query executed:', tab.getName());
    });
  }

  ngOnDestroy(): void {
    // Cleanup
    this.yasgui = null;
  }
}
```

### Using YASQE and YASR Separately

You can use the query editor and results viewer independently:

```javascript
import Yasqe from '@matdata/yasqe';
import Yasr from '@matdata/yasr';
import '@matdata/yasqe/build/yasqe.min.css';
import '@matdata/yasr/build/yasr.min.css';

// Create query editor
const yasqe = new Yasqe(document.getElementById('yasqe'), {
  value: 'SELECT * WHERE { ?s ?p ?o } LIMIT 10',
  requestConfig: {
    endpoint: 'https://dbpedia.org/sparql'
  }
});

// Create results viewer
const yasr = new Yasr(document.getElementById('yasr'), {
  prefixes: yasqe.getPrefixes()
});

// Connect them
yasqe.on('queryResponse', (yasqe, response, duration) => {
  yasr.setResponse(response, duration);
});

// Execute query
yasqe.query();
```

---

## Configuration

YASGUI offers extensive configuration options to customize behavior and appearance.

### Matgui Configuration

Complete configuration object with all available options:

```typescript
interface Config {
  // Auto-focus editor on load or tab switch
  autofocus: boolean;  // default: true

  // Custom endpoint info renderer
  endpointInfo?: (tab?: Tab) => Element;

  // Copy endpoint to new tabs
  copyEndpointOnNewTab: boolean;  // default: true

  // Default tab name
  tabName: string;  // default: "Query"

  // Endpoint catalogue configuration
  endpointCatalogueOptions: EndpointSelectConfig;

  // Quick-switch endpoint buttons
  endpointButtons?: EndpointButton[];

  // Populate config from URL parameters
  populateFromUrl: boolean | ((config: TabJson) => TabJson);  // default: true

  // Auto-create first tab on init
  autoAddOnInit: boolean;  // default: true

  // Persistence ID for localStorage
  persistenceId: string | ((yasgui: Yasgui) => string) | null;

  // Persistence labels
  persistenceLabelConfig: string;  // default: "config"
  persistenceLabelResponse: string;  // default: "response"

  // Persistence expiry (seconds)
  persistencyExpire: number;  // default: 2592000 (30 days)

  // YASQE configuration
  yasqe: Partial<YasqeConfig>;

  // YASR configuration
  yasr: YasrConfig;

  // Request configuration
  requestConfig: RequestConfig;

  // Context menu container element
  contextMenuContainer?: HTMLElement;

  // Theme: 'light' or 'dark'
  theme?: 'light' | 'dark';

  // Show theme toggle button
  showThemeToggle?: boolean;  // default: true

  // Show the MatGUI glyph and name at the start of the top bar
  showBrand?: boolean;  // default: true

  // Search for saved queries, commands and settings in the top bar, also opened with Ctrl+K / Cmd+K
  showCommandPalette?: boolean;  // default: true

  // Layout orientation: 'vertical' or 'horizontal'
  orientation?: 'vertical' | 'horizontal';  // default: 'vertical'

  // "Describe endpoint" panel (see Endpoint Describe Configuration)
  endpointDescribe: EndpointDescribeConfig;

  // Show the snippets bar above the editor. The snippets are always available
  // in the Insert menu of the editor and in the Ctrl+K search
  showSnippetsBar?: boolean;  // default: false

  // Tooltip with the label, description and type of an IRI hovered in the editor,
  // fetched from the tab's endpoint. Users can also switch it off in Settings → Editor
  iriHover?: boolean;  // default: true

  // Look up IRIs the endpoint doesn't describe in LOV (lov.linkeddata.es)
  iriHoverLovFallback?: boolean;  // default: true

  // Page opened by the help button of the top bar; false hides the button
  helpUrl?: string | false;  // default: 'https://matgui-doc.matdata.eu/docs/user-guide'

  // AI assistant (see AI Assistant Configuration); { enabled: false } removes it
  ai: Partial<AiConfig>;
}
```

#### Example Configuration

```javascript
const yasgui = new Yasgui(document.getElementById('yasgui'), {
  // Basic settings
  autofocus: true,
  tabName: 'My Query',
  theme: 'dark',
  orientation: 'horizontal',
  
  // Endpoint configuration
  requestConfig: {
    endpoint: 'https://dbpedia.org/sparql',
    method: 'POST'
  },
  
  // Quick-switch buttons
  endpointButtons: [
    { endpoint: 'https://dbpedia.org/sparql', label: 'DBpedia' },
    { endpoint: 'https://query.wikidata.org/sparql', label: 'Wikidata' }
  ],
  
  // Persistence
  persistenceId: 'my-yasgui-instance',
  persistencyExpire: 60 * 60 * 24 * 7,  // 7 days
  
  // YASQE config
  yasqe: {
    value: 'SELECT * WHERE { ?s ?p ?o } LIMIT 10',
    lineNumbers: true,
    showQueryButton: true
  },
  
  // YASR config
  yasr: {
    defaultPlugin: 'table',
    maxPersistentResponseSize: 500000
  }
});
```

### YASQE Configuration

YASQE (editor) specific configuration options:

```typescript
interface YasqeConfig {
  // Initial query value
  value?: string;

  // CodeMirror mode
  mode: string;  // default: 'sparql11'

  // Theme
  theme: string;  // default: 'default'

  // Line numbers
  lineNumbers: boolean;  // default: true

  // Line wrapping
  lineWrapping: boolean;  // default: false

  // Tab size
  tabSize: number;  // default: 2

  // Indent unit
  indentUnit: number;  // default: 2

  // Auto close brackets
  autoCloseBrackets: boolean;  // default: true

  // Match brackets
  matchBrackets: boolean;  // default: true

  // Fold gutter (code folding)
  foldGutter: boolean;  // default: true

  // Show query button
  showQueryButton: boolean;  // default: true. Yasgui hides the editor's own button and
                             // shows Run in its query bar; `yasqe: { showQueryButton: false }`
                             // in the Yasgui config hides that Run button too

  // Show share button
  showShareButton: boolean;  // default: false

  // Persistent storage ID
  persistenceId?: string | ((yasqe: Yasqe) => string);

  // Request configuration
  requestConfig: RequestConfig;

  // Autocomplete configuration
  autocomplete: {
    enabled: boolean;
    completerConfigs: CompleterConfig[];
  };

  // Editor height
  editorHeight: string;  // default: '300px'

  // Resizable editor
  resizeable: boolean;  // default: true
}
```

#### YASQE Example

```javascript
import Yasqe from '@matdata/yasqe';

const yasqe = new Yasqe(document.getElementById('yasqe'), {
  value: `PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>

SELECT ?label WHERE {
  ?s rdfs:label ?label
} LIMIT 10`,
  
  theme: 'github-dark',
  lineNumbers: true,
  lineWrapping: false,
  showQueryButton: true,
  editorHeight: '400px',
  
  requestConfig: {
    endpoint: 'https://dbpedia.org/sparql',
    method: 'POST',
    headers: {
      'Accept': 'application/sparql-results+json'
    }
  },
  
  autocomplete: {
    enabled: true,
    completerConfigs: [
      { name: 'prefixes', enabled: true },
      { name: 'properties', enabled: true },
      { name: 'classes', enabled: true }
    ]
  }
});
```

#### Code Snippets

Configure reusable code snippets that users can quickly insert into their queries.

**Configuration Options:**

```typescript
interface Snippet {
  label: string;      // Button label
  code: string;       // Code to insert
  group?: string;     // Optional group name (for dropdowns when >10 snippets)
}

interface YasqeConfig {
  // ... other config options
  
  // Code snippets
  snippets: Snippet[];           // default: 5 SPARQL snippets
  showSnippetsBar: boolean;      // default: true (standalone Yasqe)

  // Tooltip content for an IRI or prefixed name hovered in the editor (Yasgui sets this to
  // show its label, description and type). Return nothing to show no tooltip.
  iriHover: ((yasqe: Yasqe, iri: IriAtPosition) => HTMLElement | null | undefined) | undefined;
  iriHoverDelay: number;         // default: 500 (ms)
}
```

> In Yasgui the snippets are offered in the **Insert** menu of the query bar and the snippets bar is hidden by default (Yasgui option `showSnippetsBar`, default `false`). Set `showSnippetsBar: true` in the Yasgui configuration to show the bar as before.

```typescript
```

**Basic Example:**

```javascript
import Yasqe from '@matdata/yasqe';

const yasqe = new Yasqe(document.getElementById('yasqe'), {
  snippets: [
    {
      label: 'SELECT',
      code: 'SELECT * WHERE {\n  ?s ?p ?o .\n} LIMIT 10'
    },
    {
      label: 'FILTER',
      code: 'FILTER (?var > 100)'
    },
    {
      label: 'OPTIONAL',
      code: 'OPTIONAL {\n  ?s ?p ?o .\n}'
    }
  ]
});
```

**Grouped Snippets (Dropdown):**

When you have more than 10 snippets, use the `group` property to organize them into dropdown menus:

```javascript
const yasqe = new Yasqe(document.getElementById('yasqe'), {
  snippets: [
    // Query Types group
    {
      label: 'SELECT',
      code: 'SELECT * WHERE {\n  ?s ?p ?o .\n} LIMIT 10',
      group: 'Query Types'
    },
    {
      label: 'CONSTRUCT',
      code: 'CONSTRUCT {\n  ?s ?p ?o .\n} WHERE {\n  ?s ?p ?o .\n}',
      group: 'Query Types'
    },
    {
      label: 'ASK',
      code: 'ASK {\n  ?s ?p ?o .\n}',
      group: 'Query Types'
    },
    
    // Patterns group
    {
      label: 'FILTER',
      code: 'FILTER (?var > 100)',
      group: 'Patterns'
    },
    {
      label: 'OPTIONAL',
      code: 'OPTIONAL {\n  ?s ?p ?o .\n}',
      group: 'Patterns'
    },
    {
      label: 'UNION',
      code: '{ ?s ?p ?o . } UNION { ?s ?p2 ?o2 . }',
      group: 'Patterns'
    },
    
    // Modifiers group
    {
      label: 'ORDER BY',
      code: 'ORDER BY ?var',
      group: 'Modifiers'
    },
    {
      label: 'LIMIT',
      code: 'LIMIT 10',
      group: 'Modifiers'
    }
    // ... more snippets
  ]
});
```

**API Methods:**

```javascript
// Hide the snippets bar
yasqe.setSnippetsBarVisible(false);

// Show the snippets bar
yasqe.setSnippetsBarVisible(true);

// Check if snippets bar is visible
const isVisible = yasqe.getSnippetsBarVisible();
```

**Behavior:**
- When 10 or fewer snippets: All displayed as individual buttons
- When more than 10 snippets: Grouped into dropdown menus by the `group` property
- Snippets without a group appear as individual buttons
- User visibility preference is saved in localStorage
- Snippets bar is hidden automatically when `snippets` array is empty
- Code is inserted at the current cursor position

**Default Snippets:**

YASQE includes 5 default SPARQL snippets:
1. SELECT query template
2. CONSTRUCT query template
3. ASK query template
4. FILTER pattern
5. OPTIONAL pattern

**Disabling Snippets:**

```javascript
// Disable snippets bar
const yasqe = new Yasqe(document.getElementById('yasqe'), {
  showSnippetsBar: false
});

// Or provide empty array
const yasqe = new Yasqe(document.getElementById('yasqe'), {
  snippets: []
});
```

#### Endpoint Terms for Autocompletion

The class and property autocompleters list terms used in the endpoint before the Linked Open Vocabularies suggestions. MatGUI fills them from its Endpoint overview. A standalone Yasqe (or an embedding page that wants its own source) can provide them with `endpointTerms`:

```typescript
interface EndpointTerm {
  iri: string;
  count?: number;      // shown next to the suggestion
  prefix?: string;     // with namespace: insert a prefixed name and declare the prefix
  namespace?: string;
}

const yasqe = new Yasqe(element, {
  endpointTerms: async (yasqe, type /* "class" | "property" */) => {
    return [{ iri: "http://data.europa.eu/949/OperationalPoint", count: 52311, prefix: "era", namespace: "http://data.europa.eu/949/" }];
  },
});
```

Return the terms most used first; Yasqe filters them on what the user typed and shows at most 50. Setting `yasqe.endpointTerms` in the MatGUI config replaces the Endpoint overview as the source.

#### Linked Open Vocabularies Terms

The LOV suggestions come from `packages/yasqe/src/lov-terms.json`, which is bundled with Yasqe: no request is made to the LOV API at runtime. The file holds the classes and properties of the most used LOV vocabularies (ranked by the number of vocabularies that use them, up to about 600 KB) and is generated from the LOV N-Quads dump. The namespaces in `ALWAYS_INCLUDED` in `fetchLovData.js` (the ERA ontology, railML 3 and RailTopoModel) are added first, whatever their rank or the size budget, and their terms are read from the vocabulary's own source when the dump has none:

```bash
npm run util:fetchLov                      # downloads https://lov.linkeddata.es/lov.nq.gz
node fetchLovData.js path/to/lov.nq.gz     # or use a downloaded dump
```

The **Refresh LOV terms** GitHub workflow runs the same script monthly (or on demand) and opens a pull request when the list changed. Pass your own list with the `lovTerms` option (`{ namespaces: [[namespace, prefix, "ClassA ClassB", "propA propB"], ...] }`), or set it to `null` to leave out LOV suggestions.

#### Share Configuration

Configure how users can share their SPARQL queries with multiple output formats including URLs, cURL, PowerShell, and wget commands.

**Configuration Options:**

```typescript
interface YasqeConfig {
  // ... other config options
  
  // Function to create a shareable link (required to show share button)
  createShareableLink?: (yasqe: Yasqe) => string;
  
  // Optional URL shortener function
  createShortLink?: (yasqe: Yasqe, longUrl: string) => Promise<string>;
  
  // Function to consume/parse shared links
  consumeShareLink?: (yasqe: Yasqe) => void;
}
```

**Basic Share Configuration:**

```javascript
import Yasqe from '@matdata/yasqe';

const yasqe = new Yasqe(document.getElementById('yasqe'), {
  requestConfig: {
    endpoint: 'https://dbpedia.org/sparql',
    method: 'POST'
  },
  
  // Enable share button with URL generation
  createShareableLink: (yasqe) => {
    const query = yasqe.getValue();
    const endpoint = yasqe.getRequestConfig().endpoint;
    
    // Create shareable URL with query parameters
    const params = new URLSearchParams({
      query: query,
      endpoint: endpoint
    });
    
    return `${window.location.origin}${window.location.pathname}?${params.toString()}`;
  },
  
  // Parse shared URLs on page load
  consumeShareLink: (yasqe) => {
    const params = new URLSearchParams(window.location.search);
    const query = params.get('query');
    const endpoint = params.get('endpoint');
    
    if (query) yasqe.setValue(query);
    if (endpoint) {
      yasqe.setRequestConfig({
        ...yasqe.getRequestConfig(),
        endpoint: endpoint
      });
    }
  }
});
```

**URL Shortener Configuration (Kutt Example):**

Configure a URL shortener service to create shorter, more shareable links. This example shows integration with [Kutt](https://kutt.it), but any URL shortener API can be used.

```javascript
import Yasqe from '@matdata/yasqe';

const yasqe = new Yasqe(document.getElementById('yasqe'), {
  requestConfig: {
    endpoint: 'https://dbpedia.org/sparql'
  },
  
  // Basic shareable link creation
  createShareableLink: (yasqe) => {
    const query = yasqe.getValue();
    const config = yasqe.getRequestConfig();
    
    const params = new URLSearchParams({
      query: query,
      endpoint: config.endpoint || ''
    });
    
    return `${window.location.origin}${window.location.pathname}?${params.toString()}`;
  },
  
  // URL shortener integration (Kutt example)
  createShortLink: async (yasqe, longUrl) => {
    const KUTT_API_URL = 'https://kutt.it/api/v2/links';
    // Important: Load API key from a secure config or environment variable
    // Never hardcode real API keys in source code!
    // Example: Load from window.__CONFIG__ set by server-rendered template
    const KUTT_API_KEY = window.__CONFIG__?.KUTT_API_KEY;
    
    if (!KUTT_API_KEY) {
      throw new Error('Kutt API key not configured. Load it from a secure config or environment variable.');
    }
    
    try {
      const response = await fetch(KUTT_API_URL, {
        method: 'POST',
        headers: {
          'Content-Type': 'application/json',
          'X-API-Key': KUTT_API_KEY
        },
        body: JSON.stringify({
          target: longUrl,
          // Optional: custom short code
          // customurl: 'my-custom-code',
          // Optional: domain (if using custom domain)
          // domain: 'example.com',
          // Optional: expiration
          // expire_in: '2 hours'
        })
      });
      
      if (!response.ok) {
        const error = await response.json();
        throw new Error(error.message || 'Failed to shorten URL');
      }
      
      const data = await response.json();
      return data.link; // Returns shortened URL
      
    } catch (error) {
      console.error('URL shortening error:', error);
      throw error; // Error will be displayed to user
    }
  },
  
  consumeShareLink: (yasqe) => {
    const params = new URLSearchParams(window.location.search);
    const query = params.get('query');
    if (query) yasqe.setValue(query);
  }
});
```

**Other URL Shortener Examples:**

*YOURLS (Your Own URL Shortener):*
```javascript
createShortLink: async (yasqe, longUrl) => {
  const YOURLS_API_URL = 'https://your-domain.com/yourls-api.php'; // Your YOURLS instance
  const YOURLS_SIGNATURE = 'your-signature-token'; // Found in YOURLS admin > Tools
  
  try {
    const params = new URLSearchParams({
      signature: YOURLS_SIGNATURE,
      action: 'shorturl',
      url: longUrl,
      format: 'json',
      // Optional: custom keyword
      // keyword: 'my-custom-keyword'
    });
    
    const response = await fetch(`${YOURLS_API_URL}?${params.toString()}`, {
      method: 'GET'
    });
    
    if (!response.ok) {
      throw new Error(`HTTP error! status: ${response.status}`);
    }
    
    const data = await response.json();
    
    if (data.status === 'fail') {
      throw new Error(data.message || 'Failed to shorten URL');
    }
    
    return data.shorturl; // Returns shortened URL
    
  } catch (error) {
    console.error('YOURLS shortening error:', error);
    throw error;
  }
}
```

**Note:** YOURLS can authenticate using either a signature token (recommended) or username/password. The signature token is more secure and can be found in your YOURLS admin panel under Tools > Signature Token.

*TinyURL:*
```javascript
createShortLink: async (yasqe, longUrl) => {
  try {
    const response = await fetch(
      `https://tinyurl.com/api-create.php?url=${encodeURIComponent(longUrl)}`
    );

    if (!response.ok) {
      throw new Error(`TinyURL request failed with status ${response.status}`);
    }

    const shortUrl = await response.text();

    // Basic validation: ensure the response is a valid TinyURL link
    let parsedUrl;
    try {
      parsedUrl = new URL(shortUrl);
    } catch {
      throw new Error('TinyURL response was not a valid URL');
    }

    if (!/^https?:\/\/(www\.)?tinyurl\.com\//.test(parsedUrl.href)) {
      throw new Error('TinyURL response did not contain a TinyURL link');
    }

    return parsedUrl.href;
  } catch (error) {
    console.error('TinyURL shortening error:', error);
    throw error;
  }
}
```

*Bitly:*
```javascript
createShortLink: async (yasqe, longUrl) => {
  // Load token from secure config
  const BITLY_TOKEN = window.__CONFIG__?.BITLY_TOKEN;
  
  if (!BITLY_TOKEN) {
    throw new Error('Bitly token not configured');
  }
  
  try {
    const response = await fetch('https://api-ssl.bitly.com/v4/shorten', {
      method: 'POST',
      headers: {
        'Authorization': `Bearer ${BITLY_TOKEN}`,
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({ long_url: longUrl })
    });

    if (!response.ok) {
      throw new Error(`Bitly API request failed with status ${response.status}`);
    }

    const data = await response.json();

    if (!data || typeof data.link !== 'string') {
      throw new Error('Bitly API response missing expected "link" property');
    }

    return data.link;
  } catch (error) {
    console.error('Failed to create Bitly short link:', error);
    throw error;
  }
}
```

*Custom Backend:*
```javascript
createShortLink: async (yasqe, longUrl) => {
  const response = await fetch('/api/shorten', {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify({ url: longUrl })
  });
  
  const data = await response.json();
  return data.shortUrl;
}
```

**Share Button Features:**

When the share button is enabled (by configuring `createShareableLink`), users can:

1. **Copy URL** - Copies the shareable URL to clipboard
2. **Shorten URL** - Creates and copies a shortened URL (only shown if `createShortLink` is configured)
3. **Copy cURL** - Generates a cURL command with all headers and authentication
4. **Copy PowerShell** - Generates a PowerShell `Invoke-WebRequest` command
5. **Copy wget** - Generates a wget command

All command formats include:
- Complete SPARQL query
- Endpoint URL
- HTTP method (GET/POST)
- All configured headers
- Accept header (based on query type: JSON for SELECT/ASK, text/turtle for CONSTRUCT/DESCRIBE)
- Authentication credentials (with security warning)
- Output file specification (PowerShell only, with appropriate extension based on Accept header)

**Security Considerations:**

⚠️ When users copy command-line formats (cURL, PowerShell, wget) that include authentication credentials, YASQE displays a warning toast notification. This helps prevent accidental sharing of sensitive credentials.

**Best Practices:**

1. **Store API keys securely** - Never commit API keys to version control
2. **Use environment variables** - Load API keys from environment or configuration
3. **Implement rate limiting** - Prevent abuse of URL shortener services
4. **Handle errors gracefully** - Provide user-friendly error messages
5. **Consider privacy** - Be transparent about what data is included in shared URLs

**Troubleshooting:**

- If the share button doesn't appear, ensure `createShareableLink` is configured
- If "Shorten URL" doesn't appear, check that `createShortLink` is configured
- Check browser console for API errors when shortening fails
- Verify API keys and endpoints are correct
- Ensure CORS is properly configured for your URL shortener API

### YASR Configuration

YASR (results viewer) specific configuration options:

```typescript
interface YasrConfig {
  // Default plugin to use
  defaultPlugin?: string;

  // Plugin configurations
  plugins: {
    [pluginName: string]: {
      // Plugin-specific options
      // Priority for plugin selection (higher = preferred)
      priority?: number;
    };
  };

  // Prefixes for result display
  prefixes?: Prefixes;

  // Max response size to persist (bytes)
  maxPersistentResponseSize: number;  // default: 500000

  // Persistent storage ID
  persistenceId?: string | ((yasr: Yasr) => string);

  // Persistence labels
  persistenceLabelConfig: string;
  persistenceLabelResponse: string;

  // Download filename
  downloadFilename?: string | ((yasr: Yasr) => string);

  // Error renderers
  errorRenderers?: ErrorRenderer[];

  // Optional callback enabling plugins to execute background SPARQL queries
  executeQuery?: (query: string, options?: PluginQueryOptions) => Promise<any>;
}

interface PluginQueryOptions {
  // Custom Accept header for the request (e.g. "text/turtle", "application/sparql-results+json")
  acceptHeader?: string;
  // Abort signal for cancelling in-flight background queries
  signal?: AbortSignal;
}
```

When YASR is used inside a Yasgui `Tab`, the `executeQuery` callback is automatically
wired up. When using YASR standalone, you must provide your own implementation.

#### YASR Example

```javascript
import Yasr from '@matdata/yasr';

const yasr = new Yasr(document.getElementById('yasr'), {
  defaultPlugin: 'table',
  
  plugins: {
    table: {
      priority: 10,
      pageSize: 50
    },
    graph: {
      priority: 5
    },
    response: {
      priority: 1
    }
  },
  
  prefixes: {
    rdf: 'http://www.w3.org/1999/02/22-rdf-syntax-ns#',
    rdfs: 'http://www.w3.org/2000/01/rdf-schema#',
    foaf: 'http://xmlns.com/foaf/0.1/'
  },
  
  maxPersistentResponseSize: 1000000,  // 1MB
  
  downloadFilename: (yasr) => {
    return `results-${new Date().toISOString()}.csv`;
  }
});
```

#### Disabling Response Cache

To ensure YASR never shows a previously cached result, set:

- `maxPersistentResponseSize: 0`

Example:

```javascript
const yasr = new Yasr(document.getElementById("yasr"), {
  persistenceId: "my-yasr",
  maxPersistentResponseSize: 0,
});
```

Behavior details:

- `maxPersistentResponseSize <= 0` disables response persistence.
- On initialization, YASR does not restore a stored response.
- If a stored response exists for the same `persistenceId`, it is removed.
- New responses are not written to storage.

Important:

- `persistencyExpire: 0` does **not** mean "expire immediately". In current storage semantics, `0` acts as no expiry.

Regression coverage:

- Browser test: `test/run.ts` (`Yasr` suite, `does not restore previous response when response persistence is disabled`).

### Request Configuration

HTTP request configuration for SPARQL queries:

```typescript
interface RequestConfig {
  // SPARQL endpoint URL
  endpoint: string;

  // HTTP method
  method: 'GET' | 'POST';  // default: 'POST'

  // Accept header
  acceptHeaderGraph?: string;
  acceptHeaderSelect?: string;
  acceptHeaderUpdate?: string;

  // Named graphs
  namedGraphs?: string[];

  // Default graphs
  defaultGraphs?: string[];

  // Custom headers
  headers?: { [key: string]: string };

  // Custom arguments (URL parameters)
  args?: Array<{ name: string; value: string }>;

  // Adjust query before request
  adjustQueryBeforeRequest?: (query: string) => string;

  // Authentication
  basicAuth?: BasicAuthConfig | ((yasqe: Yasqe) => BasicAuthConfig | undefined);
  bearerAuth?: BearerAuthConfig | ((yasqe: Yasqe) => BearerAuthConfig | undefined);
  apiKeyAuth?: ApiKeyAuthConfig | ((yasqe: Yasqe) => ApiKeyAuthConfig | undefined);
  oauth2Auth?: OAuth2AuthConfig | ((yasqe: Yasqe) => OAuth2AuthConfig | undefined);
}

interface BasicAuthConfig {
  username: string;
  password: string;
}

interface BearerAuthConfig {
  token: string;
}

interface ApiKeyAuthConfig {
  headerName: string;
  apiKey: string;
}

interface OAuth2AuthConfig {
  accessToken: string;
  idToken?: string;
}
```

#### Request Configuration Example

```javascript
const config = {
  requestConfig: {
    endpoint: 'https://dbpedia.org/sparql',
    method: 'POST',
    
    acceptHeaderSelect: 'application/sparql-results+json',
    acceptHeaderGraph: 'text/turtle',
    
    namedGraphs: ['http://dbpedia.org'],
    
    headers: {
      'User-Agent': 'MyApp/1.0'
    },
    
    args: [
      { name: 'timeout', value: '30000' },
      { name: 'debug', value: 'on' }
    ],
    
    adjustQueryBeforeRequest: (query) => {
      // Add timestamp comment
      return `# Query executed at ${new Date().toISOString()}\n${query}`;
    }
  }
};
```

### Authentication

YASGUI supports multiple authentication methods for SPARQL endpoints: Basic Authentication, Bearer Token, and API Key (custom headers). **Authentication is stored per-endpoint**, meaning all tabs using the same endpoint share the same credentials.

#### Authentication Types

YASGUI supports four authentication types:

1. **Basic Authentication**: Username and password sent as HTTP Basic Auth
2. **Bearer Token**: Token sent in the `Authorization: Bearer <token>` header
3. **API Key**: Custom header with an API key (e.g., `X-API-Key: <key>`)
4. **OAuth 2.0**: Industry-standard OAuth 2.0 with automatic token refresh

#### Basic Authentication

Configure basic authentication programmatically when initializing YASGUI. Note that this sets the initial credentials, but users can also configure them via the UI.

```javascript
const yasgui = new Yasgui(document.getElementById("yasgui"), {
  requestConfig: {
    endpoint: "https://example.com/sparql",
    basicAuth: {
      username: "myuser",
      password: "mypassword"
    }
  }
});
```

#### Bearer Token Authentication

Use Bearer Token authentication for endpoints that require OAuth2 or JWT tokens:

```javascript
const yasgui = new Yasgui(document.getElementById("yasgui"), {
  requestConfig: {
    endpoint: "https://api.example.com/sparql",
    bearerAuth: {
      token: "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..."
    }
  }
});
```

#### API Key Authentication

Use API Key authentication for endpoints that require a custom header:

```javascript
const yasgui = new Yasgui(document.getElementById("yasgui"), {
  requestConfig: {
    endpoint: "https://api.example.com/sparql",
    apiKeyAuth: {
      headerName: "X-API-Key",
      apiKey: "your-api-key-here"
    }
  }
});
```

**Important:** When using programmatic configuration, the credentials will be used for that initial request, but YASGUI will store them in the endpoint-based configuration. Any subsequent tab that uses the same endpoint will automatically use these credentials.

#### Managing Endpoint Configurations

Use the PersistentConfig API to manage endpoint configurations programmatically:

```javascript
// Add or update an endpoint with Basic Authentication
yasgui.persistentConfig.addOrUpdateEndpoint("https://example.com/sparql", {
  label: "My Secure Endpoint",
  showAsButton: true,
  authentication: {
    type: 'basic',
    username: "myuser",
    password: "mypassword"
  }
});

// Add or update an endpoint with Bearer Token
yasgui.persistentConfig.addOrUpdateEndpoint("https://api.example.com/sparql", {
  label: "API with Bearer Token",
  showAsButton: true,
  authentication: {
    type: 'bearer',
    token: "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..."
  }
});

// Add or update an endpoint with API Key
yasgui.persistentConfig.addOrUpdateEndpoint("https://api.example.com/sparql", {
  label: "API with Custom Header",
  showAsButton: true,
  authentication: {
    type: 'apiKey',
    headerName: 'X-API-Key',
    apiKey: 'your-api-key-here'
  }
});

// Add or update an endpoint with OAuth 2.0
yasgui.persistentConfig.addOrUpdateEndpoint("https://oauth.example.com/sparql", {
  label: "OAuth Protected Endpoint",
  showAsButton: true,
  authentication: {
    type: 'oauth2',
    clientId: 'your-client-id',
    authorizationEndpoint: 'https://auth.example.com/oauth/authorize',
    tokenEndpoint: 'https://auth.example.com/oauth/token',
    redirectUri: 'https://yourapp.com/oauth2-callback', // optional
    scope: 'read write', // optional
    // The following are automatically populated after authentication:
    // accessToken: '...',
    // refreshToken: '...',
    // tokenExpiry: 1234567890
  }
});

// Get endpoint configuration
const config = yasgui.persistentConfig.getEndpointConfig("https://example.com/sparql");

// Remove authentication from an endpoint
yasgui.persistentConfig.addOrUpdateEndpoint("https://example.com/sparql", {
  authentication: undefined
});

// Delete an endpoint completely
yasgui.persistentConfig.deleteEndpointConfig("https://example.com/sparql");
```

#### OAuth 2.0 Provider Examples

**⚠️ Important Prerequisite:**
Before OAuth 2.0 authentication can work, the **OAuth administrator must register the redirect URI** (callback URL) in the OAuth provider's application configuration. YASGUI uses the current page URL as the redirect URI by default (e.g., `https://yasgui.example.com/`). This URL must be added to the list of allowed redirect URIs in your OAuth application settings.

**Microsoft Azure (Entra ID)**

```javascript
yasgui.persistentConfig.addOrUpdateEndpoint("https://your-sparql-endpoint.com/sparql", {
  label: "Azure Protected Endpoint",
  authentication: {
    type: 'oauth2',
    clientId: 'your-azure-client-id',
    authorizationEndpoint: 'https://login.microsoftonline.com/{tenant-id}/oauth2/v2.0/authorize',
    tokenEndpoint: 'https://login.microsoftonline.com/{tenant-id}/oauth2/v2.0/token',
    scope: 'api://your-app-id/.default', // or specific scopes like 'openid profile'
    redirectUri: window.location.origin + window.location.pathname // optional
  }
});
```

**Redirect URI Registration:** In Azure AD app registration, add your YASGUI URL to "Redirect URIs" under Authentication settings.

**AWS Cognito**

```javascript
yasgui.persistentConfig.addOrUpdateEndpoint("https://your-sparql-endpoint.com/sparql", {
  label: "AWS Cognito Protected Endpoint",
  authentication: {
    type: 'oauth2',
    clientId: 'your-cognito-app-client-id',
    authorizationEndpoint: 'https://your-domain.auth.region.amazoncognito.com/oauth2/authorize',
    tokenEndpoint: 'https://your-domain.auth.region.amazoncognito.com/oauth2/token',
    scope: 'openid profile', // adjust based on your needs
    redirectUri: window.location.origin + window.location.pathname // optional
  }
});
```

**Redirect URI Registration:** In Cognito app client settings, add your YASGUI URL to "Allowed callback URLs".

**Keycloak**

```javascript
yasgui.persistentConfig.addOrUpdateEndpoint("https://your-sparql-endpoint.com/sparql", {
  label: "Keycloak Protected Endpoint",
  authentication: {
    type: 'oauth2',
    clientId: 'your-keycloak-client-id',
    authorizationEndpoint: 'https://your-keycloak-domain.com/realms/{realm-name}/protocol/openid-connect/auth',
    tokenEndpoint: 'https://your-keycloak-domain.com/realms/{realm-name}/protocol/openid-connect/token',
    scope: 'openid profile', // adjust based on your client configuration
    redirectUri: window.location.origin + window.location.pathname // optional
  }
});
```

**Redirect URI Registration:** In Keycloak client configuration, add your YASGUI URL to "Valid Redirect URIs".

**Important Notes:**
- Replace placeholders like `{tenant-id}`, `{realm-name}`, `region`, etc. with your actual values
- **The OAuth administrator must register the redirect URI** in the OAuth provider before authentication will work
- For Azure, the client must be registered in Azure AD with public client flow enabled
- For AWS Cognito, the app client should have "Authorization code grant" flow enabled
- For Keycloak, the client should have "Standard Flow" enabled and "Access Type" set to "public"

#### Dynamic Authentication

Use a function to dynamically provide credentials:

```javascript
const yasgui = new Yasgui(document.getElementById("yasgui"), {
  requestConfig: {
    endpoint: "https://example.com/sparql",
    // Dynamic Basic Auth
    basicAuth: (yasqe) => {
      return {
        username: getCurrentUsername(),
        password: getCurrentPassword()
      };
    },
    // Dynamic Bearer Token
    bearerAuth: (yasqe) => {
      return {
        token: getAccessToken()
      };
    },
    // Dynamic API Key
    apiKeyAuth: (yasqe) => {
      return {
        headerName: "X-API-Key",
        apiKey: getApiKey()
      };
    }
  }
});
```

#### Disabling Authentication

To disable authentication:

```javascript
tab.setRequestConfig({
  basicAuth: undefined,
  bearerAuth: undefined,
  apiKeyAuth: undefined
});
```

#### TypeScript Support

```typescript
import { BasicAuthConfig, BearerAuthConfig, ApiKeyAuthConfig } from "@matdata/yasqe";

// Basic Auth
const basicAuthConfig: BasicAuthConfig = {
  username: "myuser",
  password: "mypassword"
};

// Bearer Token
const bearerAuthConfig: BearerAuthConfig = {
  token: "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9..."
};

// API Key
const apiKeyAuthConfig: ApiKeyAuthConfig = {
  headerName: "X-API-Key",
  apiKey: "your-api-key-here"
};

const yasgui = new Yasgui(element, {
  requestConfig: {
    endpoint: "https://secure-endpoint.com/sparql",
    basicAuth: basicAuthConfig,
    // or
    bearerAuth: bearerAuthConfig,
    // or
    apiKeyAuth: apiKeyAuthConfig
  }
});
```

#### Authentication Priority

When multiple authentication methods are configured:
1. Bearer Token is applied first (if configured)
2. API Key is applied (if configured and doesn't conflict)
3. Basic Authentication is applied last (if no Authorization header exists)

Note: Bearer Token and Basic Authentication both use the `Authorization` header, so only one will be applied. API Key uses a custom header and can coexist with Authorization headers.

#### Examples

**Example 1: Simple Authentication**

```javascript
const yasgui = new Yasgui(document.getElementById("yasgui"), {
  requestConfig: {
    endpoint: "https://secure-endpoint.example.com/sparql",
    basicAuth: {
      username: "user",
      password: "pass"
    }
  }
});
```

**Example 2: Multiple Endpoints with Different Credentials**

Authentication is stored **per-endpoint**, not per-tab. All tabs using the same endpoint will share the same credentials.

```javascript
const yasgui = new Yasgui(document.getElementById("yasgui"));

// Configure authentication for first endpoint
yasgui.persistentConfig.addOrUpdateEndpoint("https://dbpedia.org/sparql", {
  // No authentication needed for public endpoint
});

// Configure authentication for second endpoint
yasgui.persistentConfig.addOrUpdateEndpoint("https://private.example.com/sparql", {
  authentication: {
    type: "basic",
    username: "admin",
    password: "secret"
  }
});

// Create tabs - they will automatically use endpoint-based auth
const tab1 = yasgui.addTab();
tab1.setRequestConfig({ endpoint: "https://dbpedia.org/sparql" });

const tab2 = yasgui.addTab();
tab2.setRequestConfig({ endpoint: "https://private.example.com/sparql" });

// Both tabs pointing to the same endpoint will share credentials
const tab3 = yasgui.addTab();
tab3.setRequestConfig({ endpoint: "https://private.example.com/sparql" }); // Uses same auth as tab2
```

**Example 3: Prompt User for Credentials**

⚠️ **Security Warning**: Storing credentials in localStorage exposes them to any script running on the same origin (e.g., XSS attacks or malicious third-party scripts). For production use:
- Use session-based authentication with short-lived tokens
- Consider OAuth 2.0 or other secure authentication flows
- Avoid storing reusable passwords in browser storage
- Only use HTTPS endpoints

```javascript
const yasgui = new Yasgui(document.getElementById("yasgui"), {
  requestConfig: {
    endpoint: "https://secure-endpoint.example.com/sparql",
    basicAuth: (yasqe) => {
      // WARNING: This example stores credentials in localStorage for demonstration only.
      // In production, use more secure alternatives (session tokens, OAuth, etc.)
      
      const username = prompt("Enter username:");
      const password = prompt("Enter password:");
      
      if (username && password) {
        return { username, password };
      }
      
      return undefined;
    }
  }
});
```

**Recommended Approach**: Use endpoint-based authentication via the UI or configure it once programmatically:

```javascript
// Configure authentication securely
yasgui.persistentConfig.addOrUpdateEndpoint("https://secure-endpoint.example.com/sparql", {
  authentication: {
    type: "basic",
    username: "user",
    password: "pass"  // Consider using environment variables or secure credential management
  }
});
```

#### Security Best Practices

1. **Use HTTPS Only**: Never use basic authentication with HTTP endpoints
2. **Secure Storage**: Consider implementing additional encryption for stored credentials
3. **Token-Based Auth**: For production applications, consider using token-based authentication instead of basic auth
4. **Clear on Logout**: Implement a logout mechanism that clears stored credentials
5. **Environment Variables**: Store credentials in environment variables for server-side applications

### Endpoint Buttons Configuration

The endpoint quick switch buttons feature allows you to configure a list of predefined SPARQL endpoints that users can quickly switch between with a single click.

**Interface:**

```typescript
interface EndpointButton {
  endpoint: string;  // SPARQL endpoint URL (required)
  label: string;     // Button text displayed to user (required)
}
```

**Configuration:**

```javascript
const yasgui = new Yasgui(document.getElementById("yasgui"), {
  endpointButtons: [
    { endpoint: "https://dbpedia.org/sparql", label: "DBpedia" },
    { endpoint: "https://query.wikidata.org/sparql", label: "Wikidata" },
    { endpoint: "https://example.com/sparql", label: "Custom" }
  ]
});
```

**Complete Example:**

```javascript
const yasgui = new Yasgui(document.getElementById("yasgui"), {
  requestConfig: {
    endpoint: "https://dbpedia.org/sparql"
  },
  endpointButtons: [
    { endpoint: "https://dbpedia.org/sparql", label: "DBpedia" },
    { endpoint: "https://query.wikidata.org/bigdata/namespace/wdq/sparql", label: "Wikidata" },
    { endpoint: "https://graph.data.era.europa.eu/repositories/rinf-plus", label: "ERA" }
  ]
});
```

**Features:**

- **Predefined Buttons**: Configure endpoint buttons during YASGUI initialization
- **User-Defined Buttons**: Users can add their own custom buttons through the Settings modal
- **One-Click Switching**: Instantly switch to a different SPARQL endpoint with a single click
- **Persistent Storage**: User-defined buttons are saved in local storage
- **Accessible**: Buttons include ARIA labels for accessibility

**Behavior:**

- The endpoints are listed in the **Quick switch** group of the endpoint dropdown of the query bar (they were shown as buttons next to the endpoint field before; the configuration is unchanged)
- Clicking one immediately updates the endpoint of the tab
- The endpoint change triggers the same behavior as manually entering an endpoint
- Buttons are fully accessible with ARIA labels

**User-Defined Custom Buttons:**

Users can add their own custom endpoint buttons through the Settings menu:
1. Click the Settings button (⚙) in the controlbar
2. Navigate to the "Endpoint Buttons" tab
3. Enter a button label and endpoint URL
4. Click "+ Add Button"
5. Click "Save" to apply changes

Custom buttons are persisted in local storage and will appear alongside the configured buttons.

**CSS Customization:**

These variables are still defined for backwards compatibility, but the quick switch entries now follow the theme tokens (`--yasgui-brand`, `--yasgui-surface-sunken`, ...) described under [Theme Configuration](#theme-configuration):

```css
:root {
  --yasgui-endpoint-button-bg: #f0f0f0;
  --yasgui-endpoint-button-border: #ccc;
  --yasgui-endpoint-button-text: #333;
  --yasgui-endpoint-button-hover-bg: #e0e0e0;
  --yasgui-endpoint-button-hover-border: #999;
  --yasgui-endpoint-button-focus: #0066cc;
}
```

### Endpoint Describe Configuration

The **Endpoint overview** panel shows the SPARQL service description and VoID description of the current endpoint, and a set of predefined overview queries (classes, properties, named graphs, languages, links, time and geo). Results are cached per endpoint under their own localStorage key (`<persistenceId>_endpointDescribe`), separately from the main configuration.

```typescript
interface EndpointDescribeConfig {
  // Show the "Describe endpoint" button and panel
  enabled: boolean;  // default: true

  // Replace or extend the default describe queries
  queries?: DescribeQuery[] | ((defaults: DescribeQuery[]) => DescribeQuery[]);

  // Replace or extend the default categories
  categories?: DescribeCategory[] | ((defaults: DescribeCategory[]) => DescribeCategory[]);

  // Timeout of a single describe query, in milliseconds
  timeoutMs: number;  // default: 60000

  // Maximum number of describe queries running at the same time
  maxConcurrentQueries: number;  // default: 2

  // Fetch the service description and VoID when the panel opens
  fetchMetadata: boolean;  // default: true

  // Suggest the classes and properties used in the endpoint in the editor's autocomplete.
  // Users can still switch this off per endpoint in the panel.
  autocomplete: boolean;  // default: true
}

interface DescribeQuery {
  id: string;
  category: string;  // id of a DescribeCategory
  label: string;
  description?: string;
  // SPARQL SELECT query, or a function that builds it (use ctx.limit and ctx.offset for paginated queries)
  query: string | ((ctx: { limit: number; offset: number; getResult: (queryId: string) => any }) => string);
  paginated?: boolean;  // show "Load more"
  pageSize?: number;  // default: 25
  expensive?: boolean;  // show a "may be slow" hint
  dependsOn?: string;  // id of a query whose results are needed to build this one
}

interface DescribeCategory {
  id: string;
  label: string;
  icon: string;  // Font Awesome icon class, e.g. "fa-train"
}
```

**Example**: add a category with endpoint specific queries:

```javascript
const yasgui = new Yasgui(document.getElementById("yasgui"), {
  endpointDescribe: {
    categories: (defaults) => [
      ...defaults,
      { id: "railway", label: "Railway infrastructure", icon: "fa-train" },
    ],
    queries: (defaults) => [
      ...defaults,
      {
        id: "operational-points",
        category: "railway",
        label: "Operational points per country",
        query: `PREFIX era: <http://data.europa.eu/949/>
SELECT ?country (COUNT(?op) AS ?operationalPoints) WHERE {
  ?op a era:OperationalPoint ; era:inCountry ?country .
}
GROUP BY ?country
ORDER BY DESC(?operationalPoints)
LIMIT 50`,
      },
    ],
  },
});
```

Disable the panel with `endpointDescribe: { enabled: false }`. The panel can also be controlled programmatically through `yasgui.endpointDescribe` (`open()`, `close()`, `toggle()`, `collapse()`, `setPinned(pinned)`, `runQuery(queryId)`).

### AI Assistant Configuration

The AI assistant writes queries from questions in natural language, explains and fixes queries, and explains results (see the [user guide](user-guide.md#ai-assistant)). It talks to any **OpenAI-compatible chat completions API** (`POST <baseUrl>/chat/completions`), in one of two ways:

- **Bring your own key**: users add one or more services (base URL, API key, model) in **Settings → AI**, and pick a default. Requests go straight from the browser to that service, so it must allow CORS. The Base URL field suggests popular providers (`src/ai/providers.ts`).
- **Proxy of the embedding site**: set `ai.proxy` (one proxy, or a list, for example one per model or region). Requests go to your proxy, which holds the provider key server side and can add authentication, quotas, logging, or a fixed model and provider (for example one hosted in the EU).

Without either, the assistant still works as **Copy for AI**: its actions copy a ready-made prompt to the clipboard.

```typescript
interface AiConfig {
  // Show the AI features. false removes the AI view, buttons, commands, settings and "Copy for AI"
  enabled: boolean; // default: true

  // AI service of the embedding site, or a list of them. When set, the first one is the default for users
  // who didn't pick another default; users switch between these and their own services in the AI view
  proxy?: AiProxyConfig | AiProxyConfig[];

  // Let users enter their own base URL and API key
  allowOwnKey: boolean; // default: true

  // Base URL and model suggested to users who bring their own key
  defaultBaseUrl: string; // default: "https://api.openai.com/v1"
  defaultModel?: string;

  // Maximum number of result rows sent by "Explain results"
  maxResultRows: number; // default: 50

  // Let the model run small read-only check queries (SELECT/ASK, at most 20 rows) on the endpoint
  // before answering. Users can switch this off in Settings → AI
  allowCheckQueries: boolean; // default: true
  maxCheckQueries: number; // per question, default: 5

  // Maximum number of classes and of properties of the endpoint sent as context
  maxSchemaTerms: number; // default: 150

  // Timeout of one request to the AI service, in milliseconds
  timeoutMs: number; // default: 90000
}

interface AiProxyConfig {
  url: string; // OpenAI-compatible base URL, e.g. "https://example.org/ai/v1"
  label?: string; // shown in the privacy notice, settings and AI view, e.g. "ERA AI service"
  model?: string; // sent as "model"; leave unset when the proxy picks the model
  headers?: Record<string, string> | (() => Record<string, string> | Promise<Record<string, string>>);
  withCredentials?: boolean; // send cookies (fetch credentials: "include")
  privacyUrl?: string; // linked from the privacy notice
}
```

**Examples**

```javascript
// Only the site's own AI service, no user keys
new Yasgui(el, {
  ai: {
    allowOwnKey: false,
    proxy: {
      url: "https://data.example.org/ai/v1",
      label: "Example AI service",
      privacyUrl: "https://data.example.org/privacy#ai",
      headers: async () => ({ Authorization: `Bearer ${await getSessionToken()}` }),
    },
  },
});

// Users bring their own key, suggest Mistral
new Yasgui(el, { ai: { defaultBaseUrl: "https://api.mistral.ai/v1", defaultModel: "mistral-small-latest" } });

// No AI at all
new Yasgui(el, { ai: { enabled: false } });
```

**Writing a proxy**

The proxy only has to accept the OpenAI chat completions request and return the OpenAI response format. MatGUI sends `messages`, `model` (when known) and, for check queries, `tools` with one function named `run_sparql`; it expects `choices[0].message` back, with `content` and optionally `tool_calls`. Responses are not streamed. `GET <url>/models` is optional. If the provider or model has no tool support, answer with a 4xx error whose body mentions "tools": MatGUI then retries without check queries.

A minimal proxy for Node 18+ (Express), forwarding to OpenAI with a server-side key:

```javascript
import express from "express";

const app = express();
app.use(express.json({ limit: "1mb" }));
app.use((req, res, next) => {
  res.set("Access-Control-Allow-Origin", "https://matgui.example.org");
  res.set("Access-Control-Allow-Headers", "Content-Type, Authorization");
  if (req.method === "OPTIONS") return res.sendStatus(204);
  next();
});

app.post("/ai/v1/chat/completions", async (req, res) => {
  // Authenticate the user and apply quotas here
  const { messages, tools } = req.body;
  const upstream = await fetch("https://api.openai.com/v1/chat/completions", {
    method: "POST",
    headers: { "Content-Type": "application/json", Authorization: `Bearer ${process.env.OPENAI_API_KEY}` },
    body: JSON.stringify({ model: "gpt-4.1-mini", messages, tools }), // the proxy picks the model
  });
  res
    .status(upstream.status)
    .type("application/json")
    .send(await upstream.text());
});

app.listen(8080);
```

**Privacy and security**

- Nothing is sent until the user clicks an action. Before the first request to a host, the AI view lists what is sent and where, and asks for confirmation (users can skip it per host). Every answer has a "What was sent" section with the exact request.
- The user's settings, including the API key, are stored under their own localStorage key (`<persistenceId>_ai`, namespace `yasgui-ai`). They are not part of the persisted Yasgui configuration, so configuration export and share links never contain the key. Each key is only sent to the base URL of its service: as `Authorization: Bearer`, plus `x-api-key` for Anthropic, or as `api-key` for Azure OpenAI.
- Endpoint credentials are never part of a prompt. Check queries run in the browser through `tab.runBackgroundQuery()`, with the tab's endpoint and authentication; only their (at most 20) result rows go to the model. Updates and CONSTRUCT/DESCRIBE queries are refused, and a LIMIT of at most 20 is enforced.
- Generated queries are never run automatically.
- Model answers are rendered as Markdown by building DOM nodes, never as HTML, so an answer can't inject markup.

**Endpoint context**

For "Ask" and "Fix", the system message contains the endpoint URL, the prefixes in use, and the most used classes and properties of the endpoint with their counts (up to `maxSchemaTerms` of each). They come from `yasgui.endpointDescribe.getAutocompleteTerms()`, the same source as the class and property autocomplete (VoID, overview results, or one bounded background query). "Explain query" and "Explain results" don't send it.

**Programmatic use**

`yasgui.aiAssistant` is undefined when `ai.enabled` is false. Otherwise:

```javascript
const ai = yasgui.aiAssistant;
ai.isConnected(); // false: actions copy a prompt
ai.panel.open(); // show the AI view of the side panel
ai.panel.focusQuestion();
await ai.run(ai.createTask("ask", { question: "Which tunnels are longer than 5 km?" }));
await ai.run(ai.createTask("explainQuery")); // also "fix" and "explainResults"
const prompt = await ai.getCopyPrompt(ai.createTask("fix")); // the "Copy for AI" text
ai.newConversation();
```

### Theme Configuration

YASGUI supports both light and dark themes with comprehensive customization options.

**Configuration Options:**

```javascript
// Set initial theme
const yasgui = new Yasgui(element, {
  theme: 'dark',           // 'light' or 'dark'
  showThemeToggle: true    // Show/hide theme toggle button (default: true)
});
```

**Programmatic Theme Control:**

```javascript
// Get current theme
const currentTheme = yasgui.getTheme(); // Returns 'light' or 'dark'

// Set theme
yasgui.setTheme('dark');  // Switch to dark theme
yasgui.setTheme('light'); // Switch to light theme

// Toggle theme
const newTheme = yasgui.toggleTheme(); // Switch and return new theme
```

**TypeScript Support:**

```typescript
import Yasgui, { Theme } from '@matdata/yasgui';

const theme: Theme = 'dark'; // Type-safe: only 'light' or 'dark' allowed
yasgui.setTheme(theme);
```

**Theme Persistence:**

The selected theme is automatically saved to localStorage under the key `yasgui_theme`:
- Theme preference persists across page reloads
- Each user's preference is independent
- No server-side configuration needed

**System Theme Detection:**

If no theme is explicitly set and no saved preference exists, YASGUI will:
1. Check the system's color scheme preference (`prefers-color-scheme` media query)
2. Apply dark theme if system prefers dark mode
3. Apply light theme otherwise
4. Automatically update if the user changes their system preference

**CSS Customization:**

You can customize theme colors by overriding CSS custom properties:

```css
/* Custom dark theme colors */
[data-theme="dark"] {
  --yasgui-bg-primary: #0d1117;
  --yasgui-accent-color: #58a6ff;
  /* Override other variables as needed */
}
```

**Design tokens:**

The MatData look is defined by a small set of tokens, in `:root` (light) and `[data-theme="dark"]`. New components and plugins use these, with a fallback value (`var(--yasgui-brand, #0563bb)`):

```css
--yasgui-surface          /* page background */
--yasgui-surface-raised   /* the query card, active tab, menus */
--yasgui-surface-sunken   /* hover backgrounds, inputs */
--yasgui-line             /* dividers */
--yasgui-line-strong      /* input borders */
--yasgui-ink              /* text */
--yasgui-ink-muted        /* secondary text, icons */
--yasgui-brand            /* primary actions (Run), links */
--yasgui-brand-strong     /* hover / pressed */
--yasgui-brand-soft       /* selected backgrounds */
--yasgui-on-brand         /* text on --yasgui-brand */
--yasgui-highlight        /* amber: active tab, unsaved marker */
--yasgui-highlight-ink
--yasgui-danger
--yasgui-focus            /* focus ring */
--yasgui-radius-sm / -md / -lg / -button
--yasgui-shadow-soft / --yasgui-shadow-raised
--yasgui-surface-selected /* selected rows */
--yasgui-line-soft        /* separators inside the query card */
--yasgui-line-grip        /* grip of the editor / results separator */
--yasgui-ink-subtle       /* breadcrumbs, status text */
--yasgui-brand-fill       /* background of the Run button */
--yasgui-success          /* "Saved" check */
--yasgui-shadow-raise / --yasgui-shadow-sheet / --yasgui-shadow-overlay
--yasgui-scrim            /* backdrop behind the Ctrl+K search */
--yasgui-font-family      /* Geist, then system sans-serif */
--yasgui-font-size        /* base text size, 13px */
--yasgui-font-mono        /* JetBrains Mono, then system monospace */
```

**Fonts:** Yasgui does not load web fonts itself, so embedding it never triggers an unexpected network request. Geist and JetBrains Mono are first in the font stacks and are used when the page provides them, for example:

```html
<link rel="stylesheet"
  href="https://fonts.googleapis.com/css2?family=Geist:wght@400;500;600;700&family=JetBrains+Mono:wght@400;500&display=swap">
```

**Available CSS Custom Properties (original names, still supported):**

```css
--yasgui-bg-primary       /* Primary background color */
--yasgui-bg-secondary     /* Secondary background (hover states, etc.) */
--yasgui-bg-tertiary      /* Tertiary background */
--yasgui-text-primary     /* Primary text color */
--yasgui-text-secondary   /* Secondary text color */
--yasgui-text-muted       /* Muted text color */
--yasgui-border-color     /* Primary border color */
--yasgui-link-color       /* Link color */
--yasgui-accent-color     /* Accent color for highlights */
--yasgui-error-color      /* Error message color */
/* ... and more */
```

**Browser Compatibility:**

Themes work in all modern browsers that support:
- CSS Custom Properties
- localStorage
- Media Queries (for system theme detection)

This includes all recent versions of Chrome, Firefox, Safari, and Edge.

---

## API Reference

### Yasgui Class

Main YASGUI instance.

#### Constructor

```typescript
new Yasgui(parent: HTMLElement, config?: PartialConfig)
```

**Parameters:**
- `parent`: DOM element to attach YASGUI to
- `config`: Optional configuration object

**Example:**
```javascript
const yasgui = new Yasgui(document.getElementById('yasgui'), {
  requestConfig: { endpoint: 'https://dbpedia.org/sparql' }
});
```

#### Methods

##### `getTab(tabId?: string): Tab | undefined`

Get a tab instance by ID. If no ID provided, returns current tab.

```javascript
const currentTab = yasgui.getTab();
const specificTab = yasgui.getTab('tab-123');
```

##### `addTab(select?: boolean, config?: PartialTabConfig): Tab`

Add a new query tab.

**Parameters:**
- `select`: Whether to select the new tab (default: false)
- `config`: Optional tab configuration

```javascript
const newTab = yasgui.addTab(true, {
  name: 'My Query',
  yasqe: {
    value: 'SELECT * WHERE { ?s ?p ?o } LIMIT 10'
  }
});
```

##### `selectTabId(tabId: string): void`

Select a tab by ID.

```javascript
yasgui.selectTabId('tab-123');
```

##### `closeTab(tab: Tab): void`

Close a tab.

```javascript
const tab = yasgui.getTab();
yasgui.closeTab(tab);
```

##### `getTabs(): { [tabId: string]: Tab }`

Get all tabs.

```javascript
const allTabs = yasgui.getTabs();
Object.keys(allTabs).forEach(id => {
  console.log('Tab:', allTabs[id].getName());
});
```

##### `setTheme(theme: 'light' | 'dark'): void`

Set the theme.

```javascript
yasgui.setTheme('dark');
```

##### `getTheme(): 'light' | 'dark'`

Get the current theme.

```javascript
const theme = yasgui.getTheme();
console.log('Current theme:', theme);
```

##### `toggleTheme(): 'light' | 'dark'`

Toggle between themes and return the new theme.

```javascript
const newTheme = yasgui.toggleTheme();
console.log('Switched to:', newTheme);
```

##### `endpointDescribe: EndpointDescribePanel | undefined`

The endpoint overview panel (see [Endpoint Describe Configuration](#endpoint-describe-configuration)). It is `undefined` when the panel is disabled with `endpointDescribe: { enabled: false }`.

```javascript
yasgui.endpointDescribe?.open();            // open (or expand) the panel
yasgui.endpointDescribe?.setPinned(true);   // keep it open, also after a reload
await yasgui.endpointDescribe?.runQuery("classes"); // run a describe query for the current endpoint
yasgui.endpointDescribe?.collapse();        // collapse it to a thin bar
yasgui.endpointDescribe?.close();
```

##### `aiAssistant: AiAssistant | undefined`

The AI assistant (see [AI Assistant Configuration](#ai-assistant-configuration)). It is `undefined` when AI is switched off with `ai: { enabled: false }`.

```javascript
yasgui.aiAssistant?.panel.open(); // show the AI view of the side panel
await yasgui.aiAssistant?.run(yasgui.aiAssistant.createTask("explainQuery"));
```

##### `sidePanel: SidePanel`

The left side panel of the redesigned interface. It hosts the query browser (view `"queries"`), the AI assistant (view `"assistant"`) and, when enabled, the endpoint overview (view `"endpoint"`). Its state (open, collapsed, pinned, view, width) is saved in the persistent configuration.

```javascript
yasgui.sidePanel.show("queries");     // open the panel on a view
yasgui.sidePanel.toggle("endpoint");  // what F8 does
yasgui.sidePanel.setPinned(true);     // keep it open, also after a reload
yasgui.sidePanel.collapse();          // shrink it to a rail
yasgui.sidePanel.close();
const off = yasgui.sidePanel.onChange((state) => console.log(state)); // returns an unsubscribe function
```

The older entry points keep working and now drive the side panel:

| Old API                                   | Now                                              |
| ----------------------------------------- | ------------------------------------------------ |
| `yasgui.queryBrowser.open/close/toggle()` | opens/closes the **Queries** view                |
| `yasgui.endpointDescribe.open/close/toggle()` | opens/closes the **Endpoint** view           |
| `yasgui.endpointDescribe.collapse()`      | collapses the side panel to its rail             |
| `yasgui.endpointDescribe.setPinned(b)`    | pins the side panel                              |
| `runQuery`, `runCategory`, `syncEndpoint` | unchanged                                        |

A pinned describe panel saved by an earlier version is restored as the pinned Endpoint view.

### Tab Class

Represents a query tab.

#### Methods

##### `getName(): string`

Get tab name.

```javascript
const name = tab.getName();
```

##### `setName(name: string): void`

Set tab name.

```javascript
tab.setName('My Query Tab');
```

##### `getId(): string`

Get tab ID.

```javascript
const id = tab.getId();
```

##### `openSettings(section?: string): void`

Open the settings modal of this tab, optionally on a section (for example `"endpoints"`).

```javascript
tab.openSettings("endpoints");
```

##### `getYasqe(): Yasqe`

Get YASQE instance for this tab.

```javascript
const yasqe = tab.getYasqe();
yasqe.setValue('SELECT * WHERE { ?s ?p ?o }');
```

##### `getYasr(): Yasr`

Get YASR instance for this tab.

```javascript
const yasr = tab.getYasr();
yasr.draw();
```

##### `query(): Promise<void>`

Execute the query in this tab.

```javascript
tab.query()
  .then(() => console.log('Query completed'))
  .catch(err => console.error('Query failed:', err));
```

##### `setQuery(query: string): void`

Set the query value.

```javascript
tab.setQuery('SELECT ?s ?p ?o WHERE { ?s ?p ?o } LIMIT 10');
```

##### `getQuery(): string`

Get the current query.

```javascript
const query = tab.getQuery();
console.log('Current query:', query);
```

##### `runBackgroundQuery(query: string, options?): Promise<any>`

Execute a SPARQL query against the tab's endpoint without changing the editor or the results view. The tab's request configuration and authentication are used (an expired OAuth 2.0 token is refreshed first) and no query events are emitted. Rejects on HTTP errors.

Options: `accept` (Accept header), `signal` (an `AbortSignal`) and `skipGraphArgs` (don't send the tab's default/named graphs).

```javascript
const response = await tab.runBackgroundQuery("SELECT (COUNT(*) AS ?n) WHERE { ?s ?p ?o }", {
  accept: "application/sparql-results+json",
  skipGraphArgs: true,
});
const count = JSON.parse(response.content).results.bindings[0].n.value;
```

##### `getRequestInit(): Promise<{ headers, withCredentials } | undefined>`

Get the request headers (including authentication headers) and credentials mode used for requests to the tab's endpoint, for example to fetch other resources from the same server.

```javascript
const init = await tab.getRequestInit();
const response = await fetch(tab.getEndpoint(), {
  headers: { ...init.headers, Accept: "text/turtle" },
  credentials: init.withCredentials ? "include" : "same-origin",
});
```

### Yasqe Class

SPARQL query editor.

#### Methods

##### `getValue(): string`

Get the query text.

```javascript
const query = yasqe.getValue();
```

##### `setValue(value: string): void`

Set the query text.

```javascript
yasqe.setValue('SELECT * WHERE { ?s ?p ?o } LIMIT 10');
```

##### `query(): Promise<any>`

Execute the query.

```javascript
yasqe.query()
  .then(response => console.log('Results:', response))
  .catch(err => console.error('Error:', err));
```

##### `isQueryRunning(): boolean`

Whether a query of this editor is running (used by the Run/Stop button of Yasgui).

##### `insertSnippet(code: string): void`

Insert a snippet at the cursor, as the snippets bar and the Insert menu of Yasgui do.

##### `abortQuery(): void`

Abort the current query.

```javascript
yasqe.abortQuery();
```

##### `format(): void`

Format the query using the selected formatter.

```javascript
yasqe.format();
```

##### `getPrefixes(): Prefixes`

Get defined prefixes in the query.

```javascript
const prefixes = yasqe.getPrefixes();
console.log('Prefixes:', prefixes);
```

##### `addPrefixes(prefixes: Prefixes): void`

Add prefixes to the query.

```javascript
yasqe.addPrefixes({
  foaf: 'http://xmlns.com/foaf/0.1/',
  dc: 'http://purl.org/dc/elements/1.1/'
});
```

##### `removePrefixes(): void`

Remove all PREFIX declarations from the query.

```javascript
yasqe.removePrefixes();
```

### Yasr Class

SPARQL results viewer.

#### Methods

##### `setResponse(response: any, duration?: number): void`

Set the query response to display.

```javascript
yasr.setResponse(response, 1234);  // duration in ms
```

##### `draw(): void`

Redraw the current plugin.

```javascript
yasr.draw();
```

##### `selectPlugin(pluginName: string): void`

Select a specific plugin.

```javascript
yasr.selectPlugin('table');
```

##### `getPlugins(): { [name: string]: Plugin }`

Get all registered plugins.

```javascript
const plugins = yasr.getPlugins();
console.log('Available plugins:', Object.keys(plugins));
```

##### `executeQuery(query: string, options?: PluginQueryOptions): Promise<any>`

Execute a background SPARQL query on behalf of a plugin. This delegates to the
`executeQuery` callback in the YASR configuration and returns the raw response
without replacing the currently displayed results.

The returned response object has the following shape:

```typescript
{
  ok: boolean;          // true if HTTP status is 2xx
  status: number;       // HTTP status code
  statusText: string;   // HTTP status text
  headers: Headers;     // Response headers
  content: string;      // Raw response body
  data: string;         // Alias for content
  json(): Promise<any>; // Parse content as JSON
  text(): Promise<string>; // Return content as string
}
```

Plugins can use this to fetch additional data (e.g. expanding a node in a graph
visualization) without interfering with the main query results.

```javascript
// Inside a plugin
const response = await this.yasr.executeQuery(
  'DESCRIBE <http://example.org/resource>',
  { acceptHeader: 'text/turtle' }
);
const turtle = await response.text();
```

If no `executeQuery` callback is configured, the returned Promise rejects with
an error.

##### `download(filename?: string): void`

Download results using current plugin's download method.

```javascript
yasr.download('my-results.csv');
```

---

## Events

YASGUI uses an event-driven architecture. All components extend EventEmitter and emit events for various actions.

### YASGUI Events

Listen to events on the main YASGUI instance:

```javascript
const yasgui = new Yasgui(element);

// Tab events
yasgui.on('tabSelect', (instance, tabId) => {
  console.log('Tab selected:', tabId);
});

yasgui.on('tabAdd', (instance, tabId) => {
  console.log('Tab added:', tabId);
});

yasgui.on('tabClose', (instance, tab) => {
  console.log('Tab closed:', tab.getName());
});

yasgui.on('tabChange', (instance, tab) => {
  console.log('Tab changed:', tab.getName());
});

yasgui.on('tabOrderChanged', (instance, tabList) => {
  console.log('Tab order changed:', tabList);
});

// Query events
yasgui.on('query', (instance, tab) => {
  console.log('Query started on tab:', tab.getName());
});

yasgui.on('queryBefore', (instance, tab) => {
  console.log('Query about to start on tab:', tab.getName());
});

yasgui.on('queryResponse', (instance, tab) => {
  console.log('Query completed on tab:', tab.getName());
});

yasgui.on('queryAbort', (instance, tab) => {
  console.log('Query aborted on tab:', tab.getName());
});

// Fullscreen events
yasgui.on('fullscreen-enter', (instance) => {
  console.log('Entered fullscreen');
});

yasgui.on('fullscreen-leave', (instance) => {
  console.log('Exited fullscreen');
});

// Autocomplete events
yasgui.on('autocompletionShown', (instance, tab, widget) => {
  console.log('Autocomplete shown on tab:', tab.getName());
});

yasgui.on('autocompletionClose', (instance, tab) => {
  console.log('Autocomplete closed on tab:', tab.getName());
});

// Endpoint events
yasgui.on('endpointHistoryChange', (instance, history) => {
  console.log('Endpoint history updated:', history);
});
```

### YASQE Events

Listen to events on YASQE instances:

```javascript
const yasqe = new Yasqe(element);

yasqe.on('query', (instance, request, abortController) => {
  console.log('Query started with endpoint:', request.url);
});

yasqe.on('queryBefore', (instance, config) => {
  console.log('Query about to start with config:', config);
  // Modify config here if needed
});

yasqe.on('queryResponse', (instance, response, duration) => {
  console.log('Query completed in', duration, 'ms');
});

yasqe.on('queryResults', (instance, results, duration) => {
  console.log('Results received:', results);
});

yasqe.on('queryAbort', (instance, request) => {
  console.log('Query aborted');
});

yasqe.on('error', (instance) => {
  console.log('Error occurred');
});

yasqe.on('blur', (instance) => {
  console.log('Editor lost focus');
});

yasqe.on('autocompletionShown', (instance, widget) => {
  console.log('Autocomplete widget shown');
});

yasqe.on('autocompletionClose', (instance) => {
  console.log('Autocomplete closed');
});

yasqe.on('resize', (instance, newSize) => {
  console.log('Editor resized to:', newSize);
});

// Editor events (Yasqe wraps a CodeMirror 6 EditorView and re-emits CodeMirror 5-style events)
yasqe.on('change', (instance, changeObj) => {
  console.log('Editor content changed');
});

yasqe.on('cursorActivity', (instance) => {
  console.log('Cursor moved');
});
```

### YASR Events

Listen to events on YASR instances:

```javascript
const yasr = new Yasr(element);

yasr.on('change', (instance) => {
  console.log('YASR state changed');
});

yasr.on('draw', (instance, plugin) => {
  console.log('Started drawing with plugin:', plugin.label);
});

yasr.on('drawn', (instance, plugin) => {
  console.log('Finished drawing with plugin:', plugin.label);
});

yasr.on('toggle-help', (instance) => {
  console.log('Help toggled');
});
```

### Event Example: Query Tracking

Track query execution time and results:

```javascript
const yasgui = new Yasgui(element);

yasgui.on('queryBefore', (instance, tab) => {
  tab.queryStartTime = Date.now();
  console.log('Query started:', tab.getQuery());
});

yasgui.on('queryResponse', (instance, tab) => {
  const duration = Date.now() - tab.queryStartTime;
  console.log('Query completed in', duration, 'ms');
  
  const yasr = tab.getYasr();
  if (yasr.results) {
    console.log('Result type:', yasr.results.getType());
    if (yasr.results.getType() === 'json') {
      const bindings = yasr.results.getBindings();
      console.log('Result count:', bindings?.length || 0);
    }
  }
});

yasgui.on('queryAbort', (instance, tab) => {
  console.log('Query aborted after', Date.now() - tab.queryStartTime, 'ms');
});
```

### Event Example: Custom Query Logging

Log all queries to a backend service:

```javascript
yasgui.on('query', async (instance, tab) => {
  const logData = {
    query: tab.getQuery(),
    endpoint: tab.getYasqe().config.requestConfig.endpoint,
    timestamp: new Date().toISOString(),
    tabName: tab.getName()
  };
  
  try {
    await fetch('/api/log-query', {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify(logData)
    });
  } catch (err) {
    console.error('Failed to log query:', err);
  }
});
```

---

## Plugin Development

YASR uses a plugin system for result visualization. You can create custom plugins to visualize results in new ways.

### Plugin Interface

A YASR plugin must implement the `Plugin` interface:

```typescript
interface Plugin<Options = any> {
  // Priority for automatic plugin selection (higher = preferred)
  priority: number;

  // Label shown in plugin selector
  label?: string;

  // Plugin-specific options
  options?: Options;

  // Hide plugin from manual selection
  hideFromSelection?: boolean;

  // Help/documentation URL
  helpReference?: string;

  // Determine if this plugin can handle current results
  canHandleResults(): boolean;

  // Initialize plugin (async setup)
  initialize?(): Promise<void>;

  // Cleanup when plugin destroyed
  destroy?(): void;

  // Draw visualization
  draw(persistentConfig: any, runtimeConfig?: any): Promise<void> | void;

  // Return plugin icon for selector
  getIcon(): Element | undefined;

  // Provide download functionality
  download?(filename?: string): DownloadInfo | undefined;
}

#### Background Queries from Plugins

Plugins can execute additional SPARQL queries via `this.yasr.executeQuery()`
without overwriting the currently displayed results. This is useful for
interactive features like expanding a node in a graph visualization.

The query runs in **silent mode** — no YASQE lifecycle events (`queryBefore`,
`queryResponse`, etc.) are emitted and `yasr.setResponse()` is not called, so
the visible results remain unchanged.

```typescript
// Example: fetch additional data when a user interacts with a result
async expandNode(uri: string): Promise<void> {
  const controller = new AbortController();

  const response = await this.yasr.executeQuery(
    `DESCRIBE <${uri}>`,
    {
      acceptHeader: 'text/turtle',
      signal: controller.signal,
    }
  );

  const body = await response.text();
  // … parse and merge into the current visualization
}
```

**Response shape** — see [`executeQuery()` method](#executequeryquery-string-options-pluginqueryoptions-promiseany)
for the full response object description.

**Cancellation** — pass an `AbortSignal` via `options.signal` to cancel
in-flight requests (e.g. when the user navigates away or triggers a new
expansion before the previous one finishes).

```typescript
interface DownloadInfo {
  contentType: string;
  getData: () => string;
  filename: string;
  title: string;
}
```

### Step-by-Step Plugin Development Guide

#### Step 1: Create Plugin Class

Create a class implementing the Plugin interface:

```typescript
import { Plugin } from '@matdata/yasr';

export default class MyCustomPlugin implements Plugin {
  private yasr: Yasr;
  private container: HTMLElement;
  
  // Priority for auto-selection (higher = more likely to be auto-selected)
  public priority = 5;
  
  // Label shown in UI
  public label = 'My Visualization';
  
  // Help URL
  public helpReference = 'https://example.com/help';

  constructor(yasr: Yasr) {
    this.yasr = yasr;
    this.container = document.createElement('div');
    this.container.className = 'my-custom-plugin';
    yasr.resultsEl.appendChild(this.container);
  }

  // Determine if this plugin can visualize current results
  canHandleResults(): boolean {
    // Check if results exist and are of the right type
    if (!this.yasr.results) return false;
    
    // Example: only handle SELECT query results
    const results = this.yasr.results;
    if (results.getType() === 'json') {
      return true;
    }
    
    return false;
  }

  // Return icon for plugin selector
  getIcon(): Element | undefined {
    const icon = document.createElement('span');
    icon.textContent = '📊';  // Or use SVG
    return icon;
  }

  // Draw the visualization
  async draw(persistentConfig: any, runtimeConfig?: any): Promise<void> {
    if (!this.yasr.results) return;
    
    // Clear container
    this.container.innerHTML = '';
    
    // Get results
    const bindings = this.yasr.results.getBindings();
    if (!bindings) return;
    
    // Create your visualization
    const table = document.createElement('table');
    table.className = 'my-custom-table';
    
    // Add headers
    const thead = document.createElement('thead');
    const headerRow = document.createElement('tr');
    const vars = this.yasr.results.getVariables();
    vars?.forEach(varName => {
      const th = document.createElement('th');
      th.textContent = varName;
      headerRow.appendChild(th);
    });
    thead.appendChild(headerRow);
    table.appendChild(thead);
    
    // Add data rows
    const tbody = document.createElement('tbody');
    bindings.forEach(binding => {
      const row = document.createElement('tr');
      vars?.forEach(varName => {
        const td = document.createElement('td');
        const value = binding[varName];
        td.textContent = value?.value || '';
        row.appendChild(td);
      });
      tbody.appendChild(row);
    });
    table.appendChild(tbody);
    
    this.container.appendChild(table);
  }

  // Optional: Provide download functionality
  download(filename?: string): DownloadInfo | undefined {
    if (!this.yasr.results) return undefined;
    
    // Generate CSV
    const bindings = this.yasr.results.getBindings();
    const vars = this.yasr.results.getVariables();
    
    let csv = vars?.join(',') + '\n';
    bindings?.forEach(binding => {
      const row = vars?.map(v => {
        const val = binding[v]?.value || '';
        return `"${val.replace(/"/g, '""')}"`;
      }).join(',');
      csv += row + '\n';
    });
    
    return {
      contentType: 'text/csv',
      getData: () => csv,
      filename: filename || 'results.csv',
      title: 'Download as CSV'
    };
  }

  // Optional: Cleanup
  destroy(): void {
    this.container.remove();
  }
}
```

#### Step 2: Register Plugin

Register your plugin with YASR:

```javascript
import Yasr from '@matdata/yasr';
import MyCustomPlugin from './MyCustomPlugin';

// Register globally
Yasr.registerPlugin('MyCustomPlugin', MyCustomPlugin);

// Now use YASR as normal
const yasr = new Yasr(element);
```

Or register for a specific YASR instance:

```javascript
const yasr = new Yasr(element);
yasr.registerPlugin('MyCustomPlugin', MyCustomPlugin);
```

#### Step 3: Configure Plugin

Configure plugin-specific options:

```javascript
const yasr = new Yasr(element, {
  plugins: {
    MyCustomPlugin: {
      priority: 10,
      // Custom plugin options
      customOption: 'value'
    }
  }
});
```

#### Step 4: Add Styling

Create a CSS file for your plugin:

```css
.my-custom-plugin {
  padding: 20px;
  background: var(--yasgui-bg-primary);
  color: var(--yasgui-text-primary);
}

.my-custom-table {
  width: 100%;
  border-collapse: collapse;
}

.my-custom-table th,
.my-custom-table td {
  padding: 8px;
  border: 1px solid var(--yasgui-border-color);
  text-align: left;
}

.my-custom-table th {
  background: var(--yasgui-bg-secondary);
  font-weight: bold;
}

/* Dark theme support */
[data-theme="dark"] .my-custom-plugin {
  background: var(--yasgui-bg-primary);
}
```

### Plugin Example: Chart Plugin

Complete example of a chart visualization plugin:

```typescript
import { Plugin } from '@matdata/yasr';
import Chart from 'chart.js/auto';

export default class ChartPlugin implements Plugin {
  private yasr: Yasr;
  private container: HTMLElement;
  private canvas: HTMLCanvasElement;
  private chart: Chart | null = null;
  
  public priority = 7;
  public label = 'Chart';
  public helpReference = 'https://example.com/chart-help';

  constructor(yasr: Yasr) {
    this.yasr = yasr;
    this.container = document.createElement('div');
    this.container.className = 'yasr-chart-plugin';
    this.canvas = document.createElement('canvas');
    this.container.appendChild(this.canvas);
    yasr.resultsEl.appendChild(this.container);
  }

  canHandleResults(): boolean {
    if (!this.yasr.results) return false;
    
    // Only handle SELECT results with numeric values
    const results = this.yasr.results;
    if (results.getType() !== 'json') return false;
    
    const vars = results.getVariables();
    const bindings = results.getBindings();
    
    // Need at least 2 variables (label and value)
    if (!vars || vars.length < 2 || !bindings || bindings.length === 0) {
      return false;
    }
    
    // Check if second variable contains numbers
    const firstBinding = bindings[0];
    const valueVar = vars[1];
    const value = firstBinding[valueVar]?.value;
    
    return !isNaN(parseFloat(value));
  }

  getIcon(): Element | undefined {
    const icon = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
    icon.setAttribute('viewBox', '0 0 24 24');
    icon.setAttribute('width', '24');
    icon.setAttribute('height', '24');
    
    const path = document.createElementNS('http://www.w3.org/2000/svg', 'path');
    path.setAttribute('d', 'M3 13h2v8H3zm4-4h2v12H7zm4-4h2v16h-2zm4 2h2v14h-2zm4 4h2v10h-2z');
    path.setAttribute('fill', 'currentColor');
    
    icon.appendChild(path);
    return icon;
  }

  async draw(persistentConfig: any, runtimeConfig?: any): Promise<void> {
    if (!this.yasr.results) return;
    
    const results = this.yasr.results;
    const vars = results.getVariables();
    const bindings = results.getBindings();
    
    if (!vars || !bindings) return;
    
    // Extract data
    const labels: string[] = [];
    const data: number[] = [];
    
    bindings.forEach(binding => {
      const label = binding[vars[0]]?.value || '';
      const value = parseFloat(binding[vars[1]]?.value || '0');
      labels.push(label);
      data.push(value);
    });
    
    // Destroy previous chart
    if (this.chart) {
      this.chart.destroy();
    }
    
    // Create chart
    const ctx = this.canvas.getContext('2d');
    if (!ctx) return;
    
    this.chart = new Chart(ctx, {
      type: 'bar',
      data: {
        labels: labels,
        datasets: [{
          label: vars[1],
          data: data,
          backgroundColor: 'rgba(75, 192, 192, 0.6)',
          borderColor: 'rgba(75, 192, 192, 1)',
          borderWidth: 1
        }]
      },
      options: {
        responsive: true,
        maintainAspectRatio: false,
        scales: {
          y: {
            beginAtZero: true
          }
        }
      }
    });
  }

  destroy(): void {
    if (this.chart) {
      this.chart.destroy();
    }
    this.container.remove();
  }
}
```

### Host API for Result Plugins (yasr hostApi v2)

YASR exposes a small host API so plugins share one describe panel and one toolbar style. Feature-detect it with `yasr.hostApi`, never with version strings, and keep your own fallback for older hosts:

```js
const host = this.yasr?.hostApi;
if (host?.describe && typeof this.yasr.describe === "function") {
  this.yasr.describe(iri, { direction: "outgoing", source: "Map" }); // or "incoming"
} else {
  /* fall back to the plugin's own describe UI */
}
const bar = host?.toolbar && typeof this.yasr.getPluginToolbar === "function" ? this.yasr.getPluginToolbar() : null;
```

- `yasr.describe(iri, { direction?, source?, newHistory? }): Promise<void>` opens the shared describe panel. It runs a CONSTRUCT query through `yasr.executeQuery` with `Accept: text/turtle` and never rejects; errors show in the panel. `newHistory: false` adds to the panel's back/forward history instead of starting a new one. `yasr.closeDescribe()` closes it, `yasr.isDescribeOpen()` reports its state, and YASR emits `"describe"` with `(yasr, iri, direction)` each time a resource is shown.
- `yasr.getPluginToolbar()` returns `div.yasr_pluginToolbar`, a full-width bar under the YASR header. YASR empties it before every `draw()` and hides it while it is empty. A plugin that redraws itself must remove its own items first. Build controls inside it with `.yasr_toolbarButton` (toggle with `aria-pressed="true"` or `.is-active`), `.yasr_toolbarSelect` (`<label><span>Label</span><select>`), `.yasr_toolbarSearch` (`<input type="search">`), `.yasr_toolbarGroup` and `.yasr_toolbarSpacer` (a direct child of the slot). Put "View settings" last, as a `.yasr_toolbarButton` with the Lucide `sliders-horizontal` icon.
- Hosts can set the YASR config hook `openQueryInNewTab(query)` to enable the panel's "Open as query" button. YASGUI sets it to open a new tab on the same endpoint.
- `yasr.executeQuery(query, options)` runs a background request with the endpoint, method, headers and authentication of the tab and resolves with the raw response (`status`, `headers`, `content`). Since host API 2 (`hostApi.queryRequest`), `options.extraArgs` adds request parameters next to the query (for example `{ explain: "details" }`) and `options.endpoint` sends the request to another URL with the same settings (for example Stardog's `/{db}/explain`). Older hosts ignore both, so a plugin that needs them checks `hostApi.queryRequest` first.
- `yasr.hostApi.assistant` is true when the host has an AI assistant (MatGUI unless `ai.enabled` is false). A plugin can then hand a question to it with `yasr.askAssistant({ title, prompt, context? })`, for example "Explain this chart" with the chart settings as `context`. MatGUI opens its AI view and handles the service, privacy notice and "Copy for AI"; the context is shown to the user under "What was sent", so keep it small. `askAssistant()` returns false when there is no assistant, so hide your AI button in that case:

  ```js
  if (this.yasr?.hostApi?.assistant) {
    button.addEventListener("click", () =>
      this.yasr.askAssistant({
        title: "Explain this chart",
        prompt: "Explain what this chart shows.",
        context: summary,
      }),
    );
  }
  ```

- Hosts provide the assistant through the YASR config key `assistant` (`{ ask, fixError?, copyErrorPrompt?, isConnected? }`). With `fixError` or `copyErrorPrompt`, the error view shows **Fix with AI** and **Copy for AI**.
- Style with `var(--yasgui-…, fallback)`. Inside `.yasr`, the `--yasr-ui-*` shorthands (for example `--yasr-ui-brand`, `--yasr-ui-line`) already carry light and dark fallbacks.

### Plugin Best Practices

1. **Theme Support**: Use CSS custom properties for colors
2. **Responsive**: Make visualizations responsive to container size
3. **Error Handling**: Gracefully handle invalid or missing data
4. **Performance**: Optimize for large result sets
5. **Accessibility**: Include ARIA labels and keyboard navigation
6. **Documentation**: Provide clear documentation and examples
7. **TypeScript**: Use TypeScript for better type safety
8. **Testing**: Write unit tests for your plugin

### Theme Support for Plugins

YASGUI uses a centralized theme system that plugins should integrate with to provide a consistent user experience across light and dark modes.

#### Implementation Steps

**1. Detect the Current Theme**

Read the `data-theme` attribute on `document.documentElement`:

```javascript
const currentTheme = document.documentElement.getAttribute('data-theme');
// Returns: "light" or "dark"
```

**2. Use CSS Custom Properties**

Use YASGUI's CSS custom properties for consistent theming:

```css
/* Light mode (default) */
.my-plugin-container {
  background-color: var(--yasgui-bg-primary);
  color: var(--yasgui-text-primary);
  border: 1px solid var(--yasgui-border-color);
}

.my-plugin-element {
  fill: var(--yasgui-accent-color);
  stroke: var(--yasgui-border-color);
}

/* Dark mode overrides */
[data-theme="dark"] .my-plugin-tooltip {
  background-color: var(--yasgui-bg-secondary);
  color: var(--yasgui-text-primary);
  border-color: var(--yasgui-border-color);
}
```

**Available CSS Custom Properties:**

- **Background Colors**: `--yasgui-bg-primary`, `--yasgui-bg-secondary`, `--yasgui-bg-tertiary`
- **Text Colors**: `--yasgui-text-primary`, `--yasgui-text-secondary`
- **Accent Colors**: `--yasgui-accent-color`, `--yasgui-link-hover`
- **Border Colors**: `--yasgui-border-color`, `--yasgui-input-border`, `--yasgui-input-focus`
- **Button Colors**: `--yasgui-button-text`, `--yasgui-button-hover`
- **Other Colors**: `--yasgui-notification-bg`, `--yasgui-notification-text`

**3. Watch for Theme Changes**

Use a `MutationObserver` to detect theme changes:

```javascript
class MyPlugin {
  constructor(yasr) {
    this.yasr = yasr;
    this.initializeTheme();
    this.watchThemeChanges();
  }

  initializeTheme() {
    const theme = document.documentElement.getAttribute('data-theme') || 'light';
    this.applyTheme(theme);
  }

  watchThemeChanges() {
    const observer = new MutationObserver((mutations) => {
      mutations.forEach((mutation) => {
        if (mutation.attributeName === 'data-theme') {
          const theme = document.documentElement.getAttribute('data-theme');
          this.applyTheme(theme);
        }
      });
    });

    observer.observe(document.documentElement, {
      attributes: true,
      attributeFilter: ['data-theme']
    });
  }

  applyTheme(theme) {
    const styles = getComputedStyle(document.documentElement);
    
    // Extract colors from CSS custom properties
    this.config.colors = {
      background: styles.getPropertyValue('--yasgui-bg-primary').trim(),
      text: styles.getPropertyValue('--yasgui-text-primary').trim(),
      accent: styles.getPropertyValue('--yasgui-accent-color').trim(),
      border: styles.getPropertyValue('--yasgui-border-color').trim()
    };

    // Update your visualization
    this.redraw();
  }
}
```

**4. Add Smooth Transitions**

Include CSS transitions for smooth theme switching:

```css
.my-plugin-container,
.my-plugin-node,
.my-plugin-link,
.my-plugin-text {
  transition: fill 0.3s ease, stroke 0.3s ease, 
              background-color 0.3s ease, color 0.3s ease;
}
```

**Elements to Theme:**

Ensure you apply theme colors to all visual elements:
- Graph/Visualization backgrounds
- Nodes/Points and their borders
- Edges/Links between nodes
- Text labels and annotations
- Tooltips (background, text, and borders)
- Control buttons (zoom, pan, etc.)
- Legends and explanatory text
- Loading indicators and error messages
- Selection highlights

**Testing:**

Test your plugin in both themes:
1. **Light Mode**: Verify proper contrast and readability
2. **Dark Mode**: Ensure colors work well on dark backgrounds
3. **Theme Switching**: Verify smooth transitions without visual glitches
4. **Theme Persistence**: Check that the theme persists across page reloads

### Distributing Your Plugin

Package and distribute your plugin:

```json
{
  "name": "yasr-my-plugin",
  "version": "1.0.0",
  "main": "dist/index.js",
  "types": "dist/index.d.ts",
  "peerDependencies": {
    "@matdata/yasr": "^4.0.0"
  }
}
```

Users can install and use it:

```bash
npm install yasr-my-plugin
```

```javascript
import Yasr from '@matdata/yasr';
import MyPlugin from 'yasr-my-plugin';

Yasr.registerPlugin('MyPlugin', MyPlugin);
```

---

## Using the Graph Plugin

The Graph Plugin is a specialized YASR plugin for visualizing SPARQL CONSTRUCT and DESCRIBE query results as interactive, force-directed graphs with advanced customization capabilities.

### Installation

**NPM:**

```bash
npm install @matdata/yasgui-graph-plugin
```

```javascript
import Yasgui from '@matdata/yasgui';
import GraphPlugin from '@matdata/yasgui-graph-plugin';

Yasgui.Yasr.registerPlugin('Graph', GraphPlugin);

const yasgui = new Yasgui(document.getElementById('yasgui'));
```

**CDN (UMD):**

```html
<!-- YASGUI -->
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@matdata/yasgui/build/yasgui.min.css">
<script src="https://cdn.jsdelivr.net/npm/@matdata/yasgui/build/yasgui.min.js"></script>

<!-- Graph Plugin -->
<script src="https://cdn.jsdelivr.net/npm/@matdata/yasgui-graph-plugin/dist/yasgui-graph-plugin.min.js"></script>

<script>
  // Plugin auto-registers as 'graph'
  const yasgui = new Yasgui(document.getElementById('yasgui'));
</script>
```

### Key Features

- **🔷 Interactive Force-Directed Layout**: Automatic physics-based node positioning
- **🎨 Smart Color Coding**: Color-coded nodes by type (URIs, literals, blank nodes, classes)
- **🖼️ Node Icons & Images**: Support for `schema:image` and `schema:icon` properties
- **📦 Compact Mode**: Hide literal/class nodes and show info in tooltips
- **🔍 Advanced Navigation**: Zoom, pan, and "Zoom to Fit" functionality
- **✋ Drag & Drop**: Reorganize nodes with automatic pinning
- **💬 Rich HTML Tooltips**: Detailed node/edge information on hover  
- **🌓 Theme Support**: Automatic light/dark mode with dynamic color switching
- **♿ Accessibility**: WCAG AA color contrast and keyboard navigation

### Configuration Options

The plugin provides extensive configuration through a settings panel (⚙ button). All settings are automatically persisted to localStorage.

**Available Settings:**

```typescript
interface GraphPluginSettings {
  compactMode: boolean;        // Hide literals and classes (default: false)
  edgeStyle: 'curved' | 'straight';  // Edge appearance (default: 'curved')
  predicateDisplay: 'label' | 'icon' | 'hidden';  // Predicate visibility (default: 'icon')
  showLiterals: boolean;       // Include literal nodes (default: true)
  showClasses: boolean;        // Include rdf:type object nodes (default: true)
  showBlankNodes: boolean;     // Include blank nodes (default: true)
  showLabels: boolean;         // Display node labels (default: true)
  physics: boolean;            // Enable force-directed layout (default: true)
  nodeSize: 'small' | 'medium' | 'large';  // Node radius (default: 'medium')
}
```

**Programmatic Configuration:**

```javascript
class CustomGraphPlugin extends GraphPlugin {
  constructor(yasr) {
    super(yasr);
    // Override defaults
    this.settings.edgeStyle = 'straight';
    this.settings.predicateDisplay = 'label';
    this.settings.nodeSize = 'large';
    this.settings.compactMode = true;
  }
}

Yasgui.Yasr.registerPlugin('customGraph', CustomGraphPlugin);
```

### Color Scheme

The plugin uses a semantic color scheme:

| Color | Hex Code | Meaning | Example |
|-------|----------|---------|---------|
| Light Blue | #97C2FC | URI nodes | `ex:Person`, `ex:Alice` |
| Light Green | #a6c8a6ff | Literal values | `"Alice"`, `"30"^^xsd:integer` |
| Light Grey | #c5c5c5ff | Blank nodes | `_:b1`, `_:addr1` |
| Orange | #e15b13ff | rdf:type objects (classes) | `ex:Person` in `ex:Alice rdf:type ex:Person` |

Colors automatically adjust for dark mode with appropriate contrast ratios.

### Node Icons and Images

The plugin supports custom node visualization using standard Schema.org properties:

**`schema:image` (https://schema.org/image):**
- Accepts a URL literal or URI
- Renders the node as a circular image
- Image is loaded asynchronously

**`schema:icon` (https://schema.org/icon):**
- Accepts emoji or short text string
- Displays as the node's label
- Takes priority over `schema:image`

**Compact Mode Inheritance:**

In compact mode, when class nodes are hidden, resources inherit icons/images from their `rdf:type` class:

1. Direct property on resource (highest priority)
2. Property on `rdf:type` class
3. Property on `rdfs:subClassOf` superclass (one hop)

**Example:**

```sparql
CONSTRUCT {
  ex:alice  schema:image <https://example.com/alice.png> .
  ex:alice  rdf:type ex:Person .
  ex:Person schema:icon "👤" .
  ex:bob    rdf:type ex:Person .
}
WHERE {}
```

- `ex:alice`: Shows as circular image (direct `schema:image`)
- `ex:bob`: In compact mode, inherits "👤" from `ex:Person` class
- `ex:Person`: Hidden in compact mode

### Predicate Icons

When `predicateDisplay` is set to `'icon'`, common predicates display as compact symbols:

**RDF/RDFS:**
- `rdf:type` → `a`
- `rdfs:label` → `lbl`
- `rdfs:comment` → `cmt`
- `rdfs:subClassOf` → `⊂`
- `rdfs:subPropertyOf` → `⊆`

**OWL:**
- `owl:sameAs` → `≡`
- `owl:equivalentClass` → `≅`
- `owl:inverseOf` → `⇄`
- `owl:disjointWith` → `≠`

**SKOS:**
- `skos:prefLabel` → `★`
- `skos:altLabel` → `☆`
- `skos:broader` → `↑`
- `skos:narrower` → `↓`
- `skos:related` → `↔`

**Dublin Core / FOAF / Schema.org:**
- `dcterms:title` → `ttl`
- `dcterms:creator` → `by`
- `foaf:knows` → `⟷`
- `schema:name` → `nm`
- And many more...

See the [full list](https://github.com/Matdata-eu/yasgui-graph-plugin#predicate-icons) in the repository.

### API Reference

**Plugin Properties:**

```typescript
class GraphPlugin {
  // Settings object (auto-persisted to localStorage)
  settings: GraphPluginSettings;
  
  // vis-network instance
  network: Network;
  
  // Current theme ('light' | 'dark')
  theme: string;
}
```

**Plugin Methods:**

```typescript
// Inherited from Plugin interface
canHandleResults(): boolean;  // Returns true for CONSTRUCT/DESCRIBE
draw(): Promise<void>;        // Renders the graph
destroy(): void;              // Cleanup

// Graph-specific
updateColors(): void;         // Apply theme colors
resetView(): void;            // Reset zoom/pan to fit all nodes
```

### Theme Integration

The Graph Plugin fully integrates with YASGUI's theme system:

1. **Automatic Detection**: Reads `data-theme` attribute from `document.documentElement`
2. **Dynamic Updates**: Uses `MutationObserver` to detect theme changes
3. **Smooth Transitions**: All color changes are animated
4. **CSS Variables**: Leverages YASGUI's CSS custom properties

**Theme-Aware Elements:**
- Background canvas
- Node fill and border colors
- Edge colors
- Tooltip backgrounds and text
- Control button styling
- Settings panel

### Performance Considerations

**Benchmarks:**
- **< 500 nodes**: Excellent performance, smooth interactions
- **500-1,000 nodes**: Good performance, slight delay on initial render
- **> 1,000 nodes**: May experience lag; consider limiting results

**Optimization Tips:**

1. **Use LIMIT in Queries**: Restrict result size
   ```sparql
   CONSTRUCT { ?s ?p ?o }
   WHERE { ?s ?p ?o }
   LIMIT 500
   ```

2. **Disable Physics**: Turn off physics after initial layout for faster interactions

3. **Use Compact Mode**: Reduces node count by hiding literals and classes

4. **Filter Node Types**: Use "Show literals", "Show classes", and "Show blank nodes" toggles

### Browser Requirements

- **ES2018+ Support**: Uses modern JavaScript features
- **Canvas API**: Required for vis-network rendering
- **localStorage**: For settings persistence

**Tested Browsers:**
- Chrome/Edge (latest 2 versions)
- Firefox (latest 2 versions)
- Safari (latest 2 versions)

### Example Queries

**Basic CONSTRUCT:**

```sparql
PREFIX ex: <http://example.org/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>

CONSTRUCT {
  ex:Alice rdf:type ex:Person .
  ex:Alice ex:knows ex:Bob .
  ex:Alice ex:name "Alice" .
  ex:Bob rdf:type ex:Person .
  ex:Bob ex:name "Bob" .
}
WHERE {}
```

**With Icons:**

```sparql
PREFIX ex: <http://example.org/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX schema: <https://schema.org/>

CONSTRUCT {
  ex:Alice rdf:type ex:Person .
  ex:Person schema:icon "👤" .
  ex:Alice ex:worksFor ex:Company .
  ex:Company rdf:type ex:Organization .
  ex:Organization schema:icon "🏢" .
}
WHERE {}
```

**DESCRIBE Query:**

```sparql
PREFIX ex: <http://example.org/>

DESCRIBE ex:Alice ex:Bob
```

### Troubleshooting

**Plugin tab not showing:**
- Verify CONSTRUCT or DESCRIBE query type
- Check browser console for errors
- Ensure plugin is properly registered

**Empty visualization:**
- Confirm query returns triples (check "Response" or "Table" tab)
- Verify RDF structure is valid
- Check that node filter settings aren't hiding all nodes

**Performance issues:**
- Reduce result size with LIMIT clause
- Disable physics simulation
- Enable compact mode
- Hide literal nodes if not needed

**Icons/images not displaying:**
- Verify `schema:image` URL is accessible (check CORS)
- Ensure `schema:icon` values are valid emoji or short strings
- Check browser console for image loading errors

### Repository

For complete documentation, examples, and source code, visit:
**[https://github.com/Matdata-eu/yasgui-graph-plugin](https://github.com/Matdata-eu/yasgui-graph-plugin)**

---

## Using the Geo Plugin

The Geo Plugin is a YASR plugin that renders geographic SPARQL results on an interactive [Leaflet](https://leafletjs.com/) map. It supports multiple geometry formats, on-the-fly CRS reprojection, drawing-based spatial filters, export, temporal animation, clustering, heatmap rendering, and more.

### Installation

**npm:**

```bash
npm install @matdata/yasgui-geo-plugin
```

```javascript
import Yasgui from '@matdata/yasgui';
import GeoPlugin from '@matdata/yasgui-geo-plugin';

Yasgui.Yasr.registerPlugin('geo', GeoPlugin);

const yasgui = new Yasgui(document.getElementById('yasgui'));
```

**CDN (IIFE bundle):**

The release ships a minified IIFE bundle. Include Leaflet first, then the bundle:

```html
<!doctype html>
<html>
<head>
  <!-- Leaflet -->
  <link rel="stylesheet" href="https://unpkg.com/leaflet@1.9.4/dist/leaflet.css" />
  <script src="https://unpkg.com/leaflet@1.9.4/dist/leaflet.js"></script>
  <!-- YASGUI -->
  <link rel="stylesheet" href="https://unpkg.com/@matdata/yasgui/build/yasgui.min.css" />
  <script src="https://unpkg.com/@matdata/yasgui/build/yasgui.min.js"></script>
  <!-- Geo Plugin -->
  <script src="https://unpkg.com/@matdata/yasgui-geo-plugin/dist/yasgui-geo-plugin.min.js"></script>
</head>
<body>
  <div id="yasgui" style="height:600px"></div>
  <script>
    const GeoPlugin = window.YasguiGeoPlugin?.default ?? window.YasguiGeoPlugin;
    Yasgui.Yasr.registerPlugin('geo', GeoPlugin);
    const yasgui = new Yasgui(document.getElementById('yasgui'), {
      requestConfig: { endpoint: 'https://dbpedia.org/sparql' },
      yasr: { pluginOrder: ['table', 'response', 'geo'], defaultPlugin: 'geo' },
    });
  </script>
</body>
</html>
```

### Registering the Plugin

Call `Yasr.registerPlugin` **before** constructing the `Yasgui` instance:

```javascript
import Yasgui from '@matdata/yasgui';
import GeoPlugin from '@matdata/yasgui-geo-plugin';

// Register under the name 'geo'
Yasgui.Yasr.registerPlugin('geo', GeoPlugin);

const yasgui = new Yasgui(document.getElementById('yasgui'), {
  yasr: {
    pluginOrder: ['table', 'response', 'geo'],
    defaultPlugin: 'geo',
  },
});
```

### Quick Configuration

Pass plugin options through Yasgui's `yasr.plugins.geo` slot:

```javascript
const yasgui = new Yasgui(document.getElementById('yasgui'), {
  yasr: {
    pluginOrder: ['table', 'response', 'geo'],
    defaultPlugin: 'geo',
    plugins: {
      geo: {
        defaultColor: '#ff5722',
        defaultBasemap: 'CartoDB Voyager',
        initialView: { center: [50.85, 4.35], zoom: 8 },
        maxZoom: 18,
        clustering: true,
        permalink: true,
      },
    },
  },
});
```

### Key Features

- **Multi-format geometry**: WKT, GeoJSON, GML, GeoHash, and DBpedia/WGS84 literals
- **On-the-fly reprojection**: 15+ embedded SRIDs plus automatic fetch from epsg.io for unknown ones
- **Lat/lon auto-detection**: Numeric `?lat`/`?lon` column pairs are recognized without WKT
- **Per-column layers**: One toggleable overlay per detected geometry column in the layers control
- **Style control**: Persisted default color, opacity, fill, stroke width and marker radius; per-feature `?wktColor` overrides color
- **Marker clustering**: Optional `leaflet.markercluster` integration for large point sets
- **Heatmap**: Optional `leaflet.heat` rendering mode
- **Drawing tools**: Rectangle/polygon drawing emits a ready-to-paste GeoSPARQL `sfWithin` filter
- **Geometry simplification**: turf-simplify with a live tolerance slider
- **Export**: GeoJSON, KML, CSV-with-WKT, PNG screenshot, clipboard copy
- **Temporal filtering**: Time slider with play/pause animation for `?time`/`?date` bindings
- **Permalink**: Map center, zoom, basemap and visible columns encoded in the URL hash
- **Coordinate readout** and **distance measure** tool
- **Dark-mode-aware** default basemap
- **Safe popups**: bindings rendered via DOM APIs (no XSS), IRI linkification, inline image previews
- **Accessibility**: keyboard-focusable popups, semantic buttons, ARIA-labeled plugin icon
- **TypeScript declarations** included

### Options Reference

| Option | Type | Default | Description |
|---|---|---|---|
| `defaultColor` | `string` (CSS color) | `#3388ff` | Color for features without a `?wktColor` binding. |
| `defaultBasemap` | `string` | `'openStreetMap'` | Name of the basemap to activate on startup. Must match a key in `basemaps`. |
| `initialView` | `{ center: [lat, lon], zoom: number }` | Belgium @ 5 | Map center and zoom when no features are present. |
| `maxZoom` | `number` | `14` | Upper bound applied when auto-fitting bounds to features. |
| `minHeight` | `number` (px) | `500` | Minimum height of the map container. |
| `latLonAutoDetect` | `boolean` | `true` | Auto-detect numeric lat/lon column pairs and synthesize a WKT POINT column. |
| `basemaps` | `{ [name]: L.TileLayer }` | built-in | Replace the bundled basemap dictionary entirely. |
| `clustering` | `boolean` | `false` | Enable marker clustering via `leaflet.markercluster`. |
| `clusteringThreshold` | `number` | `100` | Minimum feature count before clustering activates. |
| `heatmap` | `boolean` | `false` | Render points as a heatmap via `leaflet.heat` instead of markers. |
| `styleControl` | `boolean` | `true` | Show the compact style control panel. |
| `styleStorageKey` | `string \| null` | query hash | Override the localStorage key used to persist style-control values. |
| `simplifyTolerance` | `number` | `0` | Initial turf-simplify tolerance in degrees. |
| `simplifyControl` | `boolean` | `true` | Show the live simplification tolerance slider. |
| `simplifyMaxTolerance` | `number` | `0.05` | Maximum tolerance exposed by the slider. |
| `simplifyStep` | `number` | `0.0001` | Slider step size. |
| `timeSlider` | `boolean` | `true` | Show a temporal slider when rows contain time/date-like bindings. |
| `timeBindingNames` | `string[] \| null` | common names | Override recognized temporal binding names. Defaults: `time`, `date`, `datetime`, `timestamp`, `start`, `startDate`. |
| `timeMode` | `'cumulative' \| 'instant'` | `'cumulative'` | Show all features up to the selected time (`cumulative`) or only features at the exact selected time (`instant`). |
| `permalink` | `boolean` | `false` | Persist center, zoom, basemap and visible geometry columns in the URL hash. |
| `exportControl` | `boolean` | `true` | Show the Export control on the map. |
| `drawing` | `boolean` | `true` | Enable rectangle/polygon drawing tools and spatial filter output. |

### Convention-Based Per-Feature Bindings

The plugin reads the following SPARQL variable names from result rows:

| Binding | Effect |
|---|---|
| `?wktColor` | Override fill/stroke color for that feature (CSS color string). |
| `?wktLabel` | Plain-text popup content (replaces the default key/value table). |
| `?wktTooltip` | Hover tooltip text shown on mouse-over. |

### Supported Geometry Types

| Datatype URI | Parsed as |
|---|---|
| `geo:wktLiteral` (`http://www.opengis.net/ont/geosparql#wktLiteral`) | WKT / CRS-prefixed WKT / EWKT |
| `virtrdf:Geometry` (`http://www.openlinksw.com/schemas/virtrdf#Geometry`) | WKT |
| `wgs84:geometry` (`http://www.w3.org/2003/01/geo/wgs84_pos#geometry`) | WKT (DBpedia style) |
| `geo:geoJSONLiteral` | GeoJSON geometry |
| `geo:gmlLiteral` | GML 2/3 geometry |
| `geo:geoHashLiteral` | GeoHash — decoded to center point |

All major WKT geometry types are supported, including `GeometryCollection`.

### CRS and Coordinate Transformations

The plugin follows GeoSPARQL coordinate-order semantics:

- **No CRS specified**: lon/lat order (CRS84 / plain WKT convention)
- **`SRID=4326;` prefix (EWKT)**: lon/lat order
- **`<http://www.opengis.net/def/crs/EPSG/0/4326>` URI prefix**: authority lat/lon order — coordinates are automatically swapped before Leaflet rendering
- **`<http://www.opengis.net/def/crs/OGC/1.3/CRS84>` URI prefix**: lon/lat order

**Embedded SRIDs** (no network request required):
`4326`, `3857`, `31370`, `4258`, `3035`, `25831`, `25832`, `25833`, `2154`, `27700`, `28992`, `3006`, `2056`, `4269`, `3978`

**Auto-loading unknown SRIDs:**

For any SRID not embedded, the helper `ensureProjDef` fetches the proj4 definition from `https://epsg.io/<srid>.proj4` and registers it at runtime:

```javascript
import { ensureProjDef } from '@matdata/yasgui-geo-plugin';

await ensureProjDef('7855');  // GDA2020 / MGA zone 55
geoPlugin.draw();             // re-render after CRS is registered
```

### Drawing Spatial Filters

When `options.drawing` is `true` (default), the map gains rectangle and polygon drawing tools. After finishing a shape, a panel displays a ready-to-paste GeoSPARQL filter:

```sparql
FILTER(geof:sfWithin(?geom, "POLYGON((4.30 50.80, 4.40 50.80, 4.40 50.90, 4.30 50.80))"^^geo:wktLiteral))
```

A **Copy** button copies the snippet to the clipboard. The required prefixes are:

```sparql
PREFIX geo:  <http://www.opengis.net/ont/geosparql#>
PREFIX geof: <http://www.opengis.net/def/function/geosparql/>
```

### Export Capabilities

The **Export** control (top-right of the map, toggle via `exportControl` option) provides:

| Action | Output | Notes |
|---|---|---|
| GeoJSON download | `results.geojson` | Verbatim copy of the in-memory feature collection. |
| Clipboard copy | — | Formatted GeoJSON copied to clipboard. |
| PNG screenshot | `map.png` | Current viewport captured as an image. |
| KML download | `results.kml` | Supports Point, LineString, Polygon (incl. holes). |
| CSV download | `results.csv` | One row per feature with all binding variables plus a `wkt` column. |

### Temporal Filtering

When result rows contain a binding whose name matches `?time`, `?date`, `?datetime`, `?timestamp`, `?start`, or `?startDate`, the plugin displays a time slider with play/pause controls.

- **Cumulative mode** (default): Shows all features with a timestamp up to and including the selected value. Features without a timestamp remain visible at all times.
- **Instant mode**: Shows only features whose timestamp matches the exact selected value.

Configure via the `timeSlider`, `timeMode`, and `timeBindingNames` options.

### Clustering and Heatmap

**Marker clustering** groups nearby points into cluster markers at lower zoom levels, reducing visual clutter for large point datasets:

```javascript
const yasgui = new Yasgui(el, {
  yasr: {
    plugins: {
      geo: {
        clustering: true,
        clusteringThreshold: 50,  // activate when > 50 points
      },
    },
  },
});
```

**Heatmap** renders point intensity as a color gradient. Clustering and heatmap are mutually exclusive — heatmap takes precedence when both are enabled:

```javascript
geo: { heatmap: true }
```

### Permalink Support

When `permalink: true`, the plugin appends map state to the page URL hash on every map move. State encoded:

- Map center (lat/lon) and zoom level
- Active basemap name
- Visible geometry columns (layer visibility)

This lets users share a URL that reopens the map at the same view and layer configuration.

### TypeScript Support

The package ships `index.d.ts` declarations. Import the options type:

```typescript
import GeoPlugin from '@matdata/yasgui-geo-plugin';
import type { GeoPluginOptions } from '@matdata/yasgui-geo-plugin';

const options: GeoPluginOptions = {
  defaultColor: '#e91e63',
  clustering: true,
  permalink: true,
};
```

### Example Queries

**WKT points with custom colors and tooltips:**

```sparql
PREFIX geo: <http://www.opengis.net/ont/geosparql#>

SELECT * WHERE {
  VALUES (?name ?lat ?lon ?wktColor) {
    ("Brussels"  50.8503 4.3517  "blue")
    ("Antwerp"   51.2194 4.4025  "red")
    ("Ghent"     51.0543 3.7174  "green")
  }
  BIND(STRDT(CONCAT("POINT(", STR(?lon), " ", STR(?lat), ")"), geo:wktLiteral) AS ?wkt)
  BIND(?name AS ?wktTooltip)
}
```

**GeoSPARQL endpoint (e.g., GraphDB, Fuseki with GeoSPARQL):**

```sparql
PREFIX geo: <http://www.opengis.net/ont/geosparql#>

SELECT ?feature ?wkt WHERE {
  ?feature a geo:Feature ;
           geo:hasGeometry/geo:asWKT ?wkt .
}
LIMIT 500
```

**Lat/lon auto-detection (no WKT required):**

```sparql
SELECT ?name ?lat ?lon WHERE {
  ?city a <http://dbpedia.org/ontology/City> ;
        <http://www.w3.org/2000/01/rdf-schema#label>    ?name ;
        <http://www.w3.org/2003/01/geo/wgs84_pos#lat>   ?lat ;
        <http://www.w3.org/2003/01/geo/wgs84_pos#long>  ?lon .
  FILTER(LANG(?name) = 'en')
} LIMIT 100
```

When `latLonAutoDetect` is enabled (default), the plugin synthesizes a `POINT` geometry from `?lat` and `?lon` automatically.

**Temporal data:**

```sparql
PREFIX geo: <http://www.opengis.net/ont/geosparql#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>

SELECT ?name ?wkt ?date WHERE {
  # ... your query ...
  BIND("2024-03-15"^^xsd:date AS ?date)
}
```

### Troubleshooting

**Geo plugin tab not appearing:**
- Ensure `Yasgui.Yasr.registerPlugin('geo', GeoPlugin)` is called **before** creating the `Yasgui` instance.
- Verify the query returns at least one geometry binding (WKT literal, GeoJSON, etc.) or a `?lat`/`?lon` pair with `latLonAutoDetect: true`.
- Check the browser console for JavaScript errors.

**Map shows no features:**
- Check that geometry literals use a [supported datatype](#supported-geometry-types).
- For `geo:wktLiteral` with a CRS URI prefix, verify the coordinate order matches the CRS specification.
- Switch to the **Table** or **Response** tab to confirm the query returns data.

**CRS reprojection not working:**
- Verify the SRID number in your WKT CRS prefix is correct.
- For non-embedded SRIDs, call `ensureProjDef(srid)` before rendering (see [CRS section](#crs-and-coordinate-transformations)).
- Check the browser console — failed `epsg.io` fetches are logged as warnings.

**Clustering or heatmap not rendering:**
- Ensure `leaflet.markercluster` / `leaflet.heat` are available if you are using the IIFE bundle without a bundler (they are bundled in the npm package).
- Heatmap mode only applies to point geometries; lines and polygons render normally regardless.

**Drawing tools missing:**
- Confirm `options.drawing` is not set to `false`.
- `leaflet-draw` is included in the bundle; no separate installation is needed.

**Export PNG is blank or missing tiles:**
- Most basemap tile servers restrict cross-origin image use. The PNG export captures whatever the browser can render; third-party basemap tiles may be excluded due to CORS policy.
- Switch to a CORS-friendly basemap (e.g., the bundled OpenStreetMap layer) before exporting.

### Repository

For full source code, issue tracker, and additional documentation:
**[https://github.com/Matdata-eu/yasgui-geo-plugin](https://github.com/Matdata-eu/yasgui-geo-plugin)**

Npm package: [`@matdata/yasgui-geo-plugin`](https://www.npmjs.com/package/@matdata/yasgui-geo-plugin)

---

## Contributing

We welcome contributions to YASGUI! Here's how to get involved.

### Getting Started

1. **Fork the Repository**
   ```bash
   git clone https://github.com/Matdata-eu/Matgui.git
   cd Yasgui
   ```

2. **Install Dependencies**
   ```bash
   npm install
   ```

3. **Run Development Server**
   ```bash
   npm run dev
   ```
   
   Visit `http://localhost:5173/demo` to see Matgui in action.

4. **Make Changes**
   - Create a feature branch: `git checkout -b feature/my-feature`
   - Make your changes
   - Test locally

5. **Build**
   ```bash
   npm run build
   ```

6. **Run Tests**
   ```bash
   npm test
   ```

7. **Run Linter**
   ```bash
   npm run util:lint
   ```

### Project Structure

```
Yasgui/
├── packages/
│   ├── utils/           # Shared utilities
│   ├── yasqe/           # Query editor
│   ├── yasr/            # Results viewer
│   └── yasgui/          # Main package
├── dev/                 # Development pages
├── build/               # Build output
├── docs/                # Documentation
├── .github/             # GitHub workflows
└── test/                # Tests
```

### Development Workflow

#### Making Changes

1. **Code Style**: Follow the existing code style
   - Use TypeScript
   - Follow ESLint rules (`npm run util:lint`)
   - Use Prettier for formatting (`npm run util:prettify`)

2. **Commit Messages**: Use conventional commit format
   ```
   feat: add new plugin system
   fix: resolve query execution bug
   docs: update API documentation
   style: format code
   refactor: restructure plugin loading
   test: add unit tests for parser
   chore: update dependencies
   ```

3. **Testing**: Add tests for new features
   ```bash
   npm run unit-test        # Unit tests
   npm run puppeteer-test   # E2E tests
   ```

#### Building

```bash
npm run build    # Production build
npm run dev      # Development server
```

#### Pull Requests

1. **Create PR** with clear description
2. **Link Issues**: Reference related issues
3. **Tests**: Ensure all tests pass
4. **Documentation**: Update docs if needed
5. **Changelog**: Add entry if applicable

### Code Guidelines

#### TypeScript

- Use strict TypeScript settings
- Define interfaces for all public APIs
- Avoid `any` types when possible
- Export types for library consumers

```typescript
// Good
interface PluginConfig {
  priority: number;
  enabled: boolean;
}

function configurePlugin(config: PluginConfig): void {
  // Implementation
}

// Avoid
function configurePlugin(config: any) {
  // Implementation
}
```

#### CSS

- Use CSS custom properties for theming
- Follow BEM naming convention
- Support both light and dark themes

```css
/* Good */
.yasgui__header {
  background: var(--yasgui-bg-primary);
  color: var(--yasgui-text-primary);
}

.yasgui__header--collapsed {
  height: 0;
}

/* Avoid inline styles or theme-specific colors */
```

#### Documentation

- Document all public APIs
- Include code examples
- Keep README up to date
- Add JSDoc comments

```typescript
/**
 * Execute a SPARQL query against the configured endpoint.
 * 
 * @param query - The SPARQL query string
 * @param options - Optional request configuration
 * @returns Promise resolving to query results
 * @throws {Error} If query is invalid or network request fails
 * 
 * @example
 * ```typescript
 * const results = await yasqe.query(
 *   'SELECT * WHERE { ?s ?p ?o } LIMIT 10',
 *   { endpoint: 'https://dbpedia.org/sparql' }
 * );
 * ```
 */
async query(query: string, options?: RequestConfig): Promise<any> {
  // Implementation
}
```

### Reporting Issues

When reporting bugs:

1. **Search Existing Issues**: Check if already reported
2. **Provide Details**:
   - Matgui version
   - Browser and version
   - Steps to reproduce
   - Expected vs actual behavior
   - Error messages
   - Example query (if applicable)

3. **Use Issue Template**: Follow the provided template

### Feature Requests

When requesting features:

1. **Describe Use Case**: Explain the problem
2. **Propose Solution**: Suggest implementation
3. **Consider Alternatives**: Mention other approaches
4. **Provide Examples**: Show how it would work

### Release Process

Releases are managed using Changesets:

1. **Create Changeset**
   ```bash
   npx changeset
   ```

2. **Select Packages**: Choose affected packages
3. **Describe Changes**: Write changelog entry
4. **Commit**: Commit changeset file

5. **Release** (maintainers only)
   ```bash
   npm run release
   ```

### Community

- **GitHub Discussions**: Ask questions, share ideas
- **Issues**: Report bugs, request features
- **Pull Requests**: Contribute code

### Code of Conduct

- Be respectful and inclusive
- Welcome newcomers
- Focus on constructive feedback
- Follow GitHub's Community Guidelines

---

## Using the Table Plugin

The Table Plugin is a high-performance YASR plugin for rendering SPARQL SELECT results as an interactive table. It is included with Matgui and activates automatically for SELECT queries.

### Installation

The Table Plugin ships with `@matdata/yasgui`. If you are building a standalone integration, install it from npm:

```bash
npm install @matdata/yasgui-table-plugin
```

```javascript
import Yasgui from '@matdata/yasgui';
import TablePlugin from '@matdata/yasgui-table-plugin';

Yasgui.Yasr.registerPlugin('Table', TablePlugin);
```

### Key Features

- **Virtual Scrolling** - Efficiently handles 10,000+ rows
- **Search & Filter** - Real-time search with highlighted matches
- **Sortable & Resizable Columns** - Click headers to sort, drag borders to resize
- **Cell Selection** - Select cells or ranges and copy with `Ctrl+C`
- **Export** - Copy the full table as Markdown, CSV, or TSV; integrated with YASR's CSV download
- **Dynamic Themes** - Adapts automatically to Matgui light/dark themes
- **Smart Formatters** - Auto-render columns by variable name suffix:
  - `*stars` → star ratings (0–5)
  - `*percent` → progress bars (0–100%)
  - `*image` → images from a URL binding
  - `*color` / `*colour` → color swatches
  - `*description` → wrapping text block
- **Decimal Places** - Configure fixed fraction digits for `xsd:float`, `xsd:double`, and `xsd:decimal` literals via the Display dropdown or `displayConfig.decimalPlaces`
- **DESCRIBE Resource** - `Ctrl+click` (or `Cmd+click`) any URI, or right-click it and choose **Describe resource**, to run a background `DESCRIBE <uri>` query in a modal; choose **Describe resource (new query)** to replace the YASQE editor query
- **URI Link Prefix** - Toolbar control to set a custom URL prefix for all URI links
- **Quick Reference** - Toolbar help icon with a feature and keyboard-shortcut reference card

### Configuration Options

```javascript
const yasgui = new Yasgui(document.getElementById('yasgui'), {
  yasr: {
    pluginsOptions: {
      table: {
        displayConfig: {
          uriDisplayMode: 'abbreviated',   // 'full' or 'abbreviated'
          showDatatypes: true,             // Show datatype annotations
          ellipsisMode: true,              // Truncate long cell content
          smartFormatters: true,           // Apply suffix-based formatters
          decimalPlaces: 2,                // Fraction digits for float/double/decimal (omit for raw values)
        },
        persistenceEnabled: true,          // Save user preferences
        exportFormats: ['tsv', 'csv', 'markdown'],

        // Developer adapter: transform a URI into a custom href
        uriHrefAdapter: (uri) => `https://browser.example.org/?uri=${encodeURIComponent(uri)}`,

        // Developer adapter: transform an entire binding set before rendering
        bindingSetAdapter: (bindingSet) => bindingSet,
      }
    }
  }
});
```

### Event API

```javascript
const tablePlugin = yasgui.getTab().yasr.plugins.table;

tablePlugin.on('search', (data) => {
  console.log(`Filtered to ${data.filteredCount} of ${data.totalCount} rows`);
});

tablePlugin.on('columnSort', (data) => {
  console.log(`Sorted by ${data.column} ${data.dir}`);
});

tablePlugin.on('selectionChange', (data) => {
  console.log('Selection:', data.range);
});

tablePlugin.on('copy', (data) => {
  console.log(`Copied as ${data.format}`);
});

tablePlugin.on('linkPrefixChange', (data) => {
  console.log(`Link prefix set to: ${data.prefix}`);
});

tablePlugin.on('describeQuery', (data) => {
  console.log(`DESCRIBE ${data.uri}: ${data.success ? data.triples + ' triples' : 'failed'}`);
});
```

### More Information

See the [Table Plugin Repository](https://github.com/Matdata-eu/yasgui-table-plugin) for the full README, specification, and API reference.

---

## Using the Chart Plugin

The Chart Plugin ([`@matdata/yasgui-chart-plugin`](https://www.npmjs.com/package/@matdata/yasgui-chart-plugin)) renders SELECT results with at least one numeric column as bar, stacked bar, horizontal bar, line, area, pie, donut, scatter or histogram charts, built on [Apache ECharts](https://echarts.apache.org/). MatGUI registers it as `Chart`.

### Installation

```bash
npm install @matdata/yasgui-chart-plugin
```

```typescript
import Yasgui from '@matdata/yasgui';
import ChartPlugin from '@matdata/yasgui-chart-plugin';
import '@matdata/yasgui-chart-plugin/dist/yasgui-chart-plugin.min.css';

Yasgui.Yasr.registerPlugin('Chart', ChartPlugin);
```

Or load `dist/yasgui-chart-plugin.min.js` (and its CSS) from a CDN; the bundle registers itself as `Chart` when `window.Yasgui` exists.

### Behaviour

- `canHandleResults()` is true for SELECT results with at least one numeric column. Its priority (5) is below the Table plugin (10), so SELECT results keep opening in the table.
- The chart type and the category, value and series columns are chosen automatically and can be changed with the pickers the plugin puts in the shared toolbar (`yasr.getPluginToolbar()`); **Automatic chart** and the PNG/SVG downloads are in its **View settings** menu. The choice is stored with `yasr.storePluginConfig()`, so MatGUI saves it per tab, together with the result's variables; results with other variables fall back to the automatic choice.
- Ctrl+click on a bar, slice or point opens its IRI in the shared describe panel through `yasr.describe(iri, { direction, source: 'Chart' })` (Ctrl+Shift+click for incoming triples). Without the YASR host API the plugin falls back to its own toolbar and describe modal.
- `download()` returns a PNG of the chart; the View settings menu also exports SVG.

### Options

| Option | Default | Description |
| --- | --- | --- |
| `maxRows` | `5000` | Maximum number of result rows plotted |

```typescript
Yasgui.Yasr.defaults.plugins.Chart = { enabled: true, options: { maxRows: 10000 } };
```

### More Information

See the [Chart Plugin Repository](https://github.com/Matdata-eu/yasgui-chart-plugin) for the full README and the [online demo](https://matdata-eu.github.io/yasgui-chart-plugin/).

---

## Additional Resources

- **GitHub Repository**: [https://github.com/Matdata-eu/MatGUI](https://github.com/Matdata-eu/MatGUI)
- **Issue Tracker**: [https://github.com/Matdata-eu/MatGUI/issues](https://github.com/Matdata-eu/MatGUI/issues)
- **User Guide**: See `docs/user-guide.md`
- **SPARQL Specification**: [https://www.w3.org/TR/sparql11-query/](https://www.w3.org/TR/sparql11-query/)
- **CodeMirror 6 Documentation**: [https://codemirror.net/docs/](https://codemirror.net/docs/)
- **Table Plugin**: [https://github.com/Matdata-eu/yasgui-table-plugin](https://github.com/Matdata-eu/yasgui-table-plugin)
- **Graph Plugin**: [https://github.com/Matdata-eu/yasgui-graph-plugin](https://github.com/Matdata-eu/yasgui-graph-plugin)
- **Geo Plugin**: [https://github.com/Matdata-eu/yasgui-geo-plugin](https://github.com/Matdata-eu/yasgui-geo-plugin)
- **Chart Plugin**: [https://github.com/Matdata-eu/yasgui-chart-plugin](https://github.com/Matdata-eu/yasgui-chart-plugin)

---

*This developer guide is maintained as part of the Matgui project. For user-facing documentation, see the User Guide.*