On-Device LanguageDetector.availability() returns 'available', not 'readily' on macOS (Apple M4)

[Suraj Rana]

1. Description of the issue:

  The on-device LanguageDetector API model does not seem to become fully

   operational. Calling LanguageDetector.availability() consistently

  returns a status of 'available' instead of the expected 'readily'.

  This prevents the use of the API, as it never reaches a ready state.

  The issue occurs on compatible hardware (Apple M4) with all necessary

  feature flags enabled. Other on-device APIs like Summarizer and

  LanguageModel are working correctly, indicating the issue is specific

  to the LanguageDetector component's lifecycle.

  2. Steps to Reproduce:

   1. On a compatible macOS machine, enable the following flags:

      #optimization-guide-on-device-model, #prompt-api-for-gemini-nano,

      #summarization-api-for-gemini-nano, #translation-api, and

      #language-detection-api.

   2. Relaunch the browser and wait for components to download.

   3. Open the DevTools console.

   4. Execute the following JavaScript code:

   1    await LanguageDetector.availability();

  3. Expected Behavior:

  The await LanguageDetector.availability() call should eventually

  return the string 'readily'.

  4. Actual Behavior:

  The call consistently returns the string 'available', and never seems

  to progress to 'readily'.

  5. Environment:

   * Browser: Google Chrome v143

   * OS: macOS 26

   * Hardware: iMac with Apple M4 Chip

[Ezequiel Cicala]

The `availability` function returns `available`, `downloadable`, `downloading`  and `unavailable`, but not `readily`. I don't think the OS type makes any difference.

[Ezequiel Cicala]

From your screenshot, it seems you have a bug in your background.js, where although the translator is available, it displays a "not ready" error.

[Suraj Rana]

Hi Team,

  I've been investigating the issue where our on-device translation

  feature consistently fails and falls back to the cloud API.

  After some debugging, we've identified that the root cause is likely

  missing Origin Trial tokens for the Translator and LanguageDetector

  APIs in our manifest.json file.

  Currently, the manifest includes tokens for WriterAPI,

  SummarizationAPI, and RewriterAPI, which are working as expected.

  However, the absence of tokens for the translation-related APIs would

  cause the browser to block access to those on-device models,

  explaining the consistent fallback to the cloud.

  To fix this, we need to register our extension for the Translation API

   and/or Language Detection API origin trials and add the new tokens to

   the trial_tokens array in manifest.json.

  This should enable the on-device translation feature and allow it to

  function correctly.

  Best,

[Suraj Rana]

these are working on on-device-ai "

     *Writer API

   * Summarization API

   * Rewriter API

   * Proofreader API

   * Prompts API

but Translator , Language Detection is not Woorking.

[Ezequiel Cicala]

Summarize, Translator and Language Detector are available sin Chrome 138 and don't require Origin Trials access. See https://developer.chrome.com/docs/ai/built-in-apis.

El 12/10/25 a las 01:27, Suraj Rana escribió: