Support editor.formatOnSaveMode: modifications for all Prettier languages

[Copilot]

Description

VS Code's editor.formatOnSaveMode: "modifications" setting formats only modified lines by invoking the range formatter. The extension previously registered range formatting for only 7 languages (JavaScript, TypeScript, JSON, JSONC, GraphQL), causing the feature to fail for CSS, HTML, Markdown, and other Prettier-supported languages.

Changes:

• Removed hardcoded allRangeLanguages array limiting range formatting to 7 languages
• Register DocumentRangeFormattingEditProvider for all Prettier-supported languages via the existing allLanguages array
• Added test coverage for CSS, HTML, and Markdown range formatting

Result:
Users can now combine editor.formatOnSaveMode: "modifications" with editor.defaultFormatter: "esbenp.prettier-vscode" for any Prettier-supported file type.

Related Issue

Fixes #3506

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Refactoring (no functional changes)
• CI/Build changes

Checklist

• I have read the CONTRIBUTING guidelines
• My code follows the code style of this project (npm run lint passes)
• I have run npm run prettier to format my code
• I have added/updated tests that prove my fix or feature works
• All new and existing tests pass (npm test)
• I have updated the CHANGELOG.md with a summary of my changes

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:

• update.code.visualstudio.com
  • Triggering command: /usr/local/bin/node node /home/REDACTED/work/prettier-vscode/prettier-vscode/node_modules/.bin/vscode-test (dns 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)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Support for "editor.formatOnSaveMode": "modifications" in vs-code setting</issue_title>
<issue_description>Is your feature request related to a problem? Please describe.
I can't use together

  "editor.defaultFormatter": "esbenp.prettier-vscode",
  "editor.formatOnSaveMode": "modifications",

Describe the solution you'd like
I would like format all modifications by prettier-vscode when i saved a file

Describe alternatives you've considered
I'm using vs-code format default

Context
microsoft/vscode#249960 (comment)
</issue_description>

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

• Fixes Support for "editor.formatOnSaveMode": "modifications" in vs-code setting #3711

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