Fix Bergamot model download: migrate from GitHub LFS/API to Google Cloud Storage

[Copilot]

mozilla/firefox-translations-models was archived in December 2025 and its GitHub LFS objects were deleted (LFS batch API returns 410 Gone), causing model downloads to fail.

Changes

• Model listing: Replace GitHub API (Repository.Content.GetAllContents) with GCS db/models.json (https://storage.googleapis.com/moz-fx-translations-data--303e-prod-translations-data/db/models.json). The index is fetched at runtime and cached, so the plugin automatically picks up new models without code changes.
• Model download: Use Google.Cloud.Storage.V1 (StorageClient.CreateUnauthenticated()) to stream model files directly from the GCS bucket. Both the JSON index fetch and binary downloads use the GCS library.
• Model selection: Prefer releaseStatus == "Release" models, with architecture fallback order base → base-memory → tiny.
• Removed dependencies: Octokit / IGitHubClient are no longer needed and have been removed from the plugin.
• Added dependency: Google.Cloud.Storage.V1 4.14.0.

// Before: GitHub API for listing + media.githubusercontent.com for LFS downloads
var contents = await client.Repository.Content.GetAllContents(owner, repo, $"models/base/{langPair}");

// After: GCS db/models.json for listing + StorageClient for downloads
private const string BucketName = "moz-fx-translations-data--303e-prod-translations-data";
private const string ModelsJsonObject = "db/models.json";

using var stream = new MemoryStream();
await StorageClient.DownloadObjectAsync(BucketName, ModelsJsonObject, stream);
_cachedModels = await JsonSerializer.DeserializeAsync<GcsModelsRoot>(stream);

Original prompt

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This section details on the original issue you should resolve

<issue_title>bergamot翻訳プラグインでモデルダウンロードに失敗する</issue_title>
<issue_description>ダウンロード先リポジトリを確認して、修正する</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes bergamot翻訳プラグインでモデルダウンロードに失敗する #600

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[Freeesia]

@copilot
そもそもモデル一覧の取得自体をGitHubではなくGCSから取得するようにして。
モデル一覧は以下のURLから取得可能。ランタイムでもこのURLを使って取得してモデルの更新に対応できるようにして。
https://storage.googleapis.com/moz-fx-translations-data--303e-prod-translations-data/db/models.json

可能であれば、GCSのライブラリ使って。

[Copilot]

@copilot
そもそもモデル一覧の取得自体をGitHubではなくGCSから取得するようにして。
モデル一覧は以下のURLから取得可能。ランタイム�...

対応しました（コミット 0f4f696）。

主な変更点：

• モデル一覧の取得: GitHub API (GetAllContents) から GCS の db/models.json (https://storage.googleapis.com/moz-fx-translations-data--303e-prod-translations-data/db/models.json) に変更。ランタイムで取得するためモデルの更新に自動追従します。
• GCS ライブラリ: Google.Cloud.Storage.V1 (StorageClient.CreateUnauthenticated()) を使用。db/models.json の取得とモデルバイナリのダウンロードの両方に利用。
• Octokit / IGitHubClient の削除: 完全に不要になったため除去。
• モデル選択: releaseStatus == "Release" を優先し、次いで base → base-memory → tiny の順でフォールバック。
• キャッシュ: db/models.json は volatile + ダブルチェックロックでスレッドセーフにキャッシュ。

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/repos/mozilla/firefox-translations-models/contents/tests
  • Triggering command: /usr/bin/curl curl -s REDACTED (http block)
• https://api.github.com/repos/mozilla/firefox-translations-models/contents/tests/remote_settings
  • Triggering command: /usr/bin/curl curl -s REDACTED (http block)
• https://api.github.com/repos/mozilla/firefox-translations-models/contents/tests/remote_settings/create
  • Triggering command: /usr/bin/curl curl -s REDACTED (http block)
• https://api.github.com/repos/mozilla/firefox-translations-models/git/trees/e7957fc407441a5e3e35bbcbf9d60d9b35764618
  • Triggering command: /usr/bin/curl curl -s REDACTED (http block)
• https://api.github.com/repos/mozilla/translations/contents/.github/workflows/github-pages.yml
  • Triggering command: /usr/bin/curl curl -s REDACTED (http block)
• https://api.github.com/repos/mozilla/translations/contents/docs
  • Triggering command: /usr/bin/curl curl -s REDACTED (http block)
• https://api.github.com/repos/mozilla/translations/contents/tracking
  • Triggering command: /usr/bin/curl curl -s REDACTED (http block)
• https://api.github.com/repos/mozilla/translations/contents/tracking/translations_parser
  • Triggering command: /usr/bin/curl curl -s REDACTED (http block)
• https://api.github.com/repos/mozilla/translations/git/trees/HEAD
  • Triggering command: /usr/bin/curl curl -s REDACTED (http block)
• https://api.github.com/search/code
  • Triggering command: /usr/bin/curl curl -s REDACTED (http block)
• https://storage.googleapis.com/moz-fx-translations-data--303e-prod-translations-data/db/models.json
  • Triggering command: /usr/bin/curl curl -s REDACTED (http block)
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)