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Drop legacy ESLint config support - export flat config as main format - #527

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ota-meshi merged 9 commits into
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copilot/drop-legacy-config-support
Jan 17, 2026
Merged

Drop legacy ESLint config support - export flat config as main format#527
ota-meshi merged 9 commits into
masterfrom
copilot/drop-legacy-config-support

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Copilot AI commented Jan 17, 2026 •
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Drop support for legacy config - make flat config the main export

  • Understand current config structure and export format
  • Swap config implementations (flat configs become main, legacy configs removed)
  • Update src/index.ts to export the new structure
  • Update auto-generation script (tools/update-rulesets.ts)
  • Update README.md documentation
  • Update docs/user-guide/index.md documentation
  • Update tests to verify the new structure
  • Add changeset file describing the breaking change
  • Build and test the changes
  • Run final verification
  • Revert accidental change to docs/rules/index.md (should mention both recommended and standard configs)
  • Update rule documentation to reference new config format (configs.recommended, configs.standard)
  • Update docs/rules/index.md and tools/update-docs-rules-index.ts to use new config format

Summary

Successfully implemented the breaking change to drop legacy ESLint config support and make flat configuration the main export format.

Key changes:

  • Main config exports (base, recommended, standard, prettier) now use flat config format
  • flat/* namespace configs maintained for backward compatibility (point to same flat configs)
  • Removed legacy config files and associated test fixtures
  • Updated documentation to reflect new config format
  • Fixed accidental change to docs/rules/index.md - restored reference to both recommended and standard configs
  • Updated all rule documentation files to reference configs.recommended and configs.standard instead of legacy "plugin:yml/recommended" and "plugin:yml/standard" format
  • Updated docs/rules/index.md header to use new config format and corrected auto-generation comment

Migration:
Users on ESLint v9.38.0+ should update from configs['flat/recommended'] to configs.recommended (though flat/* still works for backward compatibility).

Original prompt

This section details on the original issue you should resolve

<issue_title>Drop support for legacy config</issue_title>
<issue_description>The plugin will change to export flat configuration as the main configuration format.
The previous flat/* namespace will be kept for backward compatibility.</issue_description>

<agent_instructions>Finally, add the changeset file</agent_instructions>

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

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changeset-bot Bot commented Jan 17, 2026 •
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🦋 Changeset detected

Latest commit: b9b3835

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package
Name Type
eslint-plugin-yml Major

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

Copilot AI and others added 2 commits January 17, 2026 01:30
@ota-meshi
Drop support for legacy config - make flat config the main export
20aff2d 
Co-authored-by: ota-meshi <16508807+ota-meshi@users.noreply.github.com>
@ota-meshi
Add changeset and update auto-generated config files
799aa49 
Co-authored-by: ota-meshi <16508807+ota-meshi@users.noreply.github.com>
Copilot AI changed the title [WIP] Remove support for legacy configuration format Drop legacy ESLint config support - export flat config as main format Jan 17, 2026
Copilot AI requested a review from ota-meshi January 17, 2026 01:47
ota-meshi
ota-meshi requested changes Jan 17, 2026
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Comment thread docs/rules/index.md Outdated
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github-actions Bot commented Jan 17, 2026 •
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@ota-meshi
Revert accidental change to docs/rules/index.md
b5c29b3 
Co-authored-by: ota-meshi <16508807+ota-meshi@users.noreply.github.com>
Copilot AI requested a review from ota-meshi January 17, 2026 01:54
ota-meshi
ota-meshi requested changes Jan 17, 2026
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The explanations in the rules documents seem to be out of date. Please fix these as well.

@ota-meshi
Update rule documentation to use new config format
75c4560 
Co-authored-by: ota-meshi <16508807+ota-meshi@users.noreply.github.com>

Copilot AI commented Jan 17, 2026

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The explanations in the rules documents seem to be out of date. Please fix these as well.

Fixed in commit 75c4560. Updated tools/update-docs.ts to generate references to configs.recommended and configs.standard instead of the legacy "plugin:yml/recommended" and "plugin:yml/standard" format. All 23 rule documentation files have been regenerated with the new format.

Copilot AI requested a review from ota-meshi January 17, 2026 02:03
ota-meshi
ota-meshi requested changes Jan 17, 2026
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Comment thread docs/rules/index.md Outdated
Comment thread tools/update-docs-rules-index.ts Outdated
@ota-meshi
Fix docs/rules/index.md to use new config format
b9b3835 
Co-authored-by: ota-meshi <16508807+ota-meshi@users.noreply.github.com>
@ota-meshi
ota-meshi requested a review from Copilot January 17, 2026 02:10
@ota-meshi
ota-meshi marked this pull request as ready for review January 17, 2026 02:10
Copilot AI requested a review from ota-meshi January 17, 2026 02:10
Copilot AI reviewed Jan 17, 2026
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Pull request overview

This PR implements a breaking change to drop support for legacy ESLint configuration format and make flat configuration the main export format. Users on ESLint v9+ can now use configs.recommended instead of configs['flat/recommended'], though the flat/* namespace is maintained for backward compatibility.

Changes:

  • Main config exports (base, recommended, standard, prettier) now directly export flat config format
  • Removed legacy config files and associated code/tests
  • Updated all documentation and rule references to use new config format

Reviewed changes

Copilot reviewed 42 out of 42 changed files in this pull request and generated no comments.

Show a summary per file
File Description
src/index.ts Updated to import flat configs as main exports, maintain flat/* for backward compatibility
src/configs/base.ts Removed legacy base config file
src/configs/recommended.ts Removed legacy recommended config file
src/configs/standard.ts Removed legacy standard config file
src/configs/prettier.ts Removed legacy prettier config file
tools/update-rulesets.ts Updated auto-generation script to only generate flat configs
tools/update-docs.ts Updated to reference new config format in documentation
tools/update-docs-rules-index.ts Updated rules index header to reference new config format
tests/src/eslint-plugin.ts Removed legacy config integration tests
tests/src/configs/standard.ts Updated to test new config format and verify backward compatibility
tests/fixtures/integrations/eslint-plugin/legacy-test01/* Removed legacy test fixtures
tests/fixtures/integrations/eslint-plugin/legacy-issue89/* Removed legacy test fixtures
README.md Updated documentation to show flat config as main format, removed legacy examples
docs/user-guide/index.md Updated user guide to show flat config as main format, removed legacy examples
docs/rules/index.md Updated header to reference configs.recommended and configs.standard
docs/rules/*.md Updated all rule documentation to reference new config format
.changeset/drop-legacy-config-support.md Added changeset documenting the breaking change

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@ota-meshi
ota-meshi merged commit 4059169 into master Jan 17, 2026
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@ota-meshi
ota-meshi deleted the copilot/drop-legacy-config-support branch January 17, 2026 02:14
@github-actions github-actions Bot mentioned this pull request Jan 17, 2026
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@chrisbbreuer chrisbbreuer mentioned this pull request Jan 18, 2026
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Drop support for legacy config

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