Capacitor ML Kit GenAI Rewriting Plugin

Unofficial Capacitor plugin for ML Kit GenAI Rewriting.[^1]

[!WARNING] The ML Kit GenAI APIs are currently in beta. The API surface and behavior may change in future releases.

Use Cases

The GenAI Rewriting plugin is typically used to reword short messages in different tones and styles on-device using Gemini Nano, for example:

• Tone adjustments: Rewrite a message to sound more friendly or more professional before sending it.
• Length adjustments: Shorten or elaborate a draft to fit the situation.
• Expressive messaging: Add emojis or rephrase text to give it a fresh look.

Requirements

This plugin uses Gemini Nano, which runs entirely on-device. It is only available on Android and has the following device requirements:

• The device must support Gemini Nano (see supported devices).
• The device must run Android API level 26 or higher.
• The device must not have an unlocked bootloader.

Use the checkFeatureStatus(...) method to check whether the feature is available on the device.

Compatibility

| Plugin Version | Capacitor Version | Status | | -------------- | ----------------- | -------------- | | 8.x.x | >=8.x.x | Active support |

Installation

You can use our AI-Assisted Setup to install the plugin. Add the Capawesome Skills to your AI tool using the following command:

npx skills add capawesome-team/skills --skill capacitor-plugins

Then use the following prompt:

Use the `capacitor-plugins` skill from `capawesome-team/skills` to install the `@capacitor-mlkit/genai-rewriting` plugin in my project.

If you prefer Manual Setup, install the plugin by running the following commands and follow the platform-specific instructions below:

npm install @capacitor-mlkit/genai-rewriting
npx cap sync

Android

API level

This plugin requires a minimum API level of 26. Make sure to set the minSdkVersion in your variables.gradle file to at least 26.

Variables

This plugin will use the following project variables (defined in your app’s variables.gradle file):

• $mlkitGenaiRewritingVersion version of com.google.mlkit:genai-rewriting (default: 1.0.0-beta1)

Usage

The following example shows how to check the feature status, download the feature and rewrite a text.

Check the feature status

Before using the rewriting feature, check whether it is available on the device. The feature availability depends on the configured output type and language:

import {
  FeatureStatus,
  GenAiRewriting,
  Language,
  OutputType,
} from '@capacitor-mlkit/genai-rewriting';

const checkFeatureStatus = async () => {
  const { featureStatus } = await GenAiRewriting.checkFeatureStatus({
    language: Language.English,
    outputType: OutputType.Elaborate,
  });
  return featureStatus === FeatureStatus.Available;
};

Download the feature

If the feature status is DOWNLOADABLE, download the feature before using it. Add a listener for the downloadProgress event to get notified about the download progress:

import { GenAiRewriting, Language, OutputType } from '@capacitor-mlkit/genai-rewriting';

const downloadFeature = async () => {
  await GenAiRewriting.addListener('downloadProgress', event => {
    console.log('Total bytes downloaded:', event.totalBytesDownloaded);
  });
  await GenAiRewriting.downloadFeature({
    language: Language.English,
    outputType: OutputType.Elaborate,
  });
};

Rewrite a text

Pass the text to rewrite(...) to generate the rewritten suggestions. Add a listener for the inferenceProgress event to receive partial results as they are generated:

import { GenAiRewriting, Language, OutputType } from '@capacitor-mlkit/genai-rewriting';

const rewrite = async () => {
  await GenAiRewriting.addListener('inferenceProgress', event => {
    console.log('Partial result:', event.text);
  });
  const { results } = await GenAiRewriting.rewrite({
    text: 'Capacitor is an open source native runtime for building Web Native apps.',
    language: Language.English,
    outputType: OutputType.Elaborate,
  });
  return results;
};

API

• checkFeatureStatus(...)
• downloadFeature(...)
• rewrite(...)
• addListener('downloadProgress', ...)
• addListener('inferenceProgress', ...)
• removeAllListeners()
• Interfaces
• Enums

checkFeatureStatus(...)

checkFeatureStatus(options?: FeatureOptions | undefined) => Promise<CheckFeatureStatusResult>

Check the current availability status of the rewriting feature.

If the status is DOWNLOADABLE, you can download the feature using downloadFeature(...).

Only available on Android.

| Param | Type | | ------------- | --------------------------------------------------------- | | options | FeatureOptions |

Returns: Promise<CheckFeatureStatusResult>

Since: 8.2.0

downloadFeature(...)

downloadFeature(options?: FeatureOptions | undefined) => Promise<void>

Download the rewriting feature.

The downloadProgress event listener will notify you about the download progress. The returned promise resolves when the download is complete or the feature is already available.

Only available on Android.

| Param | Type | | ------------- | --------------------------------------------------------- | | options | FeatureOptions |

Since: 8.2.0

rewrite(...)

rewrite(options: RewriteOptions) => Promise<RewriteResult>

Rewrite the given text in the configured style.

The inferenceProgress event listener will notify you about partial results as they are generated. The returned promise resolves with the full result.

Only available on Android.

| Param | Type | | ------------- | --------------------------------------------------------- | | options | RewriteOptions |

Returns: Promise<RewriteResult>

Since: 8.2.0

addListener('downloadProgress', ...)

addListener(eventName: 'downloadProgress', listenerFunc: (event: DownloadProgressEvent) => void) => Promise<PluginListenerHandle>

Called while the rewriting feature is being downloaded.

Only available on Android.

| Param | Type | | ------------------ | ------------------------------------------------------------------------------------------- | | eventName | 'downloadProgress' | | listenerFunc | (event: DownloadProgressEvent) => void |

Returns: Promise<PluginListenerHandle>

Since: 8.2.0

addListener('inferenceProgress', ...)

addListener(eventName: 'inferenceProgress', listenerFunc: (event: InferenceProgressEvent) => void) => Promise<PluginListenerHandle>

Called when a new partial result is available during inference.

Only available on Android.

| Param | Type | | ------------------ | --------------------------------------------------------------------------------------------- | | eventName | 'inferenceProgress' | | listenerFunc | (event: InferenceProgressEvent) => void |

Returns: Promise<PluginListenerHandle>

Since: 8.2.0

removeAllListeners()

removeAllListeners() => Promise<void>

Remove all listeners for this plugin.

Since: 8.2.0

Interfaces

CheckFeatureStatusResult

| Prop | Type | Description | Since | | ------------------- | ------------------------------------------------------- | --------------------------------------------------------- | ----- | | featureStatus | FeatureStatus | The current availability status of the rewriting feature. | 8.2.0 |

FeatureOptions

The feature availability depends on the configured output type and language. Therefore, checkFeatureStatus(...) and downloadFeature(...) take the same base options as rewrite(...).

| Prop | Type | Description | Default | Since | | ---------------- | ------------------------------------------------- | ------------------------------------------------------ | --------------------------------- | ----- | | language | Language | The language of the input text. | Language.English | 8.2.0 | | outputType | OutputType | The style in which the input text should be rewritten. | OutputType.Elaborate | 8.2.0 |

RewriteResult

| Prop | Type | Description | Since | | ------------- | --------------------- | ------------------------------------------------------------------------- | ----- | | results | string[] | The rewritten text suggestions, sorted in descending order of confidence. | 8.2.0 |

RewriteOptions

| Prop | Type | Description | Since | | ---------- | ------------------- | -------------------------------------------------------- | ----- | | text | string | The text to rewrite. The input must be under 256 tokens. | 8.2.0 |

PluginListenerHandle

| Prop | Type | | ------------ | ----------------------------------------- | | remove | () => Promise<void> |

DownloadProgressEvent

| Prop | Type | Description | Since | | -------------------------- | ------------------- | -------------------------------------------- | ----- | | totalBytesDownloaded | number | The total number of bytes downloaded so far. | 8.2.0 |

InferenceProgressEvent

| Prop | Type | Description | Since | | ---------- | ------------------- | ----------------------------------- | ----- | | text | string | The new text of the partial result. | 8.2.0 |

Enums

FeatureStatus

| Members | Value | Description | Since | | ------------------ | --------------------------- | ----------------------------------------------------------- | ----- | | Available | 'AVAILABLE' | The feature is available to use. | 8.2.0 | | Downloadable | 'DOWNLOADABLE' | The feature can be downloaded using downloadFeature(...). | 8.2.0 | | Downloading | 'DOWNLOADING' | The feature is currently being downloaded. | 8.2.0 | | Unavailable | 'UNAVAILABLE' | The feature is not available on this device. | 8.2.0 |

Language

| Members | Value | Since | | -------------- | ----------------------- | ----- | | English | 'ENGLISH' | 8.2.0 | | French | 'FRENCH' | 8.2.0 | | German | 'GERMAN' | 8.2.0 | | Italian | 'ITALIAN' | 8.2.0 | | Japanese | 'JAPANESE' | 8.2.0 | | Korean | 'KOREAN' | 8.2.0 | | Spanish | 'SPANISH' | 8.2.0 |

OutputType

| Members | Value | Description | Since | | ------------------ | --------------------------- | ---------------------------------------------- | ----- | | Elaborate | 'ELABORATE' | Elaborate the input text. | 8.2.0 | | Emojify | 'EMOJIFY' | Insert appropriate emojis into the input text. | 8.2.0 | | Shorten | 'SHORTEN' | Shorten the input text. | 8.2.0 | | Friendly | 'FRIENDLY' | Make the input text more friendly. | 8.2.0 | | Professional | 'PROFESSIONAL' | Make the input text more professional. | 8.2.0 | | Rephrase | 'REPHRASE' | Rephrase the input text. | 8.2.0 |

FAQ

What are the requirements to use this plugin?

The rewriting is performed on-device by Gemini Nano. This requires a device that supports Gemini Nano, Android API level 26 or higher and a locked bootloader (see Requirements). Use the checkFeatureStatus(...) method to check whether the feature is available on the device.

Why is this plugin only available on Android?

The ML Kit GenAI APIs are based on Gemini Nano and AICore, which are currently only available on Android. On iOS and Web, all methods reject with an appropriate error.

How large can the input text be?

The input must be under 256 tokens.

Why does rewrite(...) return multiple results?

The model may return more than one suggestion. The suggestions are sorted in descending order of confidence, so the first result is the most confident one.

How do I get the rewritten text as a stream?

Add a listener for the inferenceProgress event before calling rewrite(...). The listener is called with each partial result as it is generated. The promise returned by rewrite(...) resolves with the full result.

Can I use this plugin with Ionic, React, Vue or Angular?

Yes, the plugin is framework-agnostic. It works in any Capacitor app regardless of the web framework, including Ionic with Angular, React, or Vue, as well as plain JavaScript projects.

Related Plugins

• Translation: Unofficial Capacitor plugin for ML Kit Translation.
• Smart Reply: Unofficial Capacitor plugin for ML Kit Smart Reply.

Terms & Privacy

This plugin uses the Google ML Kit:

• Terms & Privacy
• Android Data Disclosure
• iOS Data Disclosure

Newsletter

Stay up to date with the latest news and updates about the Capawesome, Capacitor, and Ionic ecosystem by subscribing to our Capawesome Newsletter.

Changelog

See CHANGELOG.md.

License

See LICENSE.

[^1]: This project is not affiliated with, endorsed by, sponsored by, or approved by Google LLC or any of their affiliates or subsidiaries.