fix(plugins): normalize relative plugin paths during config loading

[JacquesLeupin]

Summary

Fixes #8488.

In monorepos where nested configurations use extends: "//", relative plugin paths declared in the root configuration could be resolved relative to the child configuration directory, causing plugin loading to fail with "Cannot read file." This is related to the extends: "//" behavior discussed in #8360.

This PR normalizes plugin paths relative to the directory of the configuration file that declares them so that merged configurations keep consistent plugin path semantics.

AI disclosure: I used AI assistance (Cursor / GPT) to explore the codebase and draft the fix and tests.

Test Plan

• Added unit tests for plugin path normalization.
• Added a regression test covering a monorepo where root config plugins are inherited by a child config using extends: "//".

Commands run:

• cargo test -p biome_plugin_loader
• cargo test -p biome_cli --test main -- cases::monorepo
• cargo test -p biome_service
• cargo fmt --check
• cargo clippy -p biome_service -p biome_cli -p biome_plugin_loader -- -D warnings

Docs

No documentation changes are needed (bugfix only).

[changeset-bot]

🦋 Changeset detected

Latest commit: 7d98151

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

This PR includes changesets to release 13 packages

Name	Type
@biomejs/biome	Patch
@biomejs/cli-win32-x64	Patch
@biomejs/cli-win32-arm64	Patch
@biomejs/cli-darwin-x64	Patch
@biomejs/cli-darwin-arm64	Patch
@biomejs/cli-linux-x64	Patch
@biomejs/cli-linux-arm64	Patch
@biomejs/cli-linux-x64-musl	Patch
@biomejs/cli-linux-arm64-musl	Patch
@biomejs/wasm-web	Patch
@biomejs/wasm-bundler	Patch
@biomejs/wasm-nodejs	Patch
@biomejs/backend-jsonrpc	Patch

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

[coderabbitai]

Walkthrough

Normalises plugin paths after configuration extends are applied so relative plugin paths are resolved against the configuration file directory (or the external resolution base if missing). The change adds Plugins::normalize_relative_paths(&mut self, base_dir: &Utf8Path) and invokes it after extends/migration for the main configuration and each override pattern, mutating plugin path entries in-place. Adds unit tests for path normalisation and an integration test verifying plugins from a root config apply when a child config extends it.

Possibly related PRs

• fix: resolve plugin paths relative to config file when using extends #8365: Implements the same plugin-path normalisation fix with matching monorepo test coverage for extended configurations.
• fix(cli): resolve configs from parent paths #8371: Related changes to configuration-path resolution around extends, including fixes for resolving relative extends.

Suggested reviewers

• dyc3

Pre-merge checks and finishing touches

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title directly describes the main change: normalizing relative plugin paths during configuration loading, which is the core fix for issue #8488.
Description check	✅ Passed	The description clearly relates to the changeset by explaining the bug fix, the issue it addresses, test coverage, and verification steps performed.

✨ Finishing touches

• 📝 Generate docstrings

---

📜 Recent review details

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between e127306 and 7d98151.

⛔ Files ignored due to path filters (1)

• crates/biome_cli/tests/snapshots/main_cases_monorepo/plugins_from_root_config_work_in_child_config_extends_root.snap is excluded by !**/*.snap and included by **

📒 Files selected for processing (2)

• .changeset/cruel-clouds-crash.md
• crates/biome_cli/tests/cases/monorepo.rs

🚧 Files skipped from review as they are similar to previous changes (2)

• crates/biome_cli/tests/cases/monorepo.rs
• .changeset/cruel-clouds-crash.md

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (8)

• GitHub Check: Test (depot-ubuntu-24.04-arm-16)
• GitHub Check: Lint project (depot-ubuntu-24.04-arm-16)
• GitHub Check: Check Dependencies
• GitHub Check: Documentation
• GitHub Check: Lint project (depot-windows-2022)
• GitHub Check: Test (depot-windows-2022-16)
• GitHub Check: autofix
• GitHub Check: Test Node.js API

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[deww400]

@dyc3 are you able to review this PR?

[arendjr]

I didn’t look into the code too deeply, but if tests are green and you can confirm the fix works, @deww400 , I think it may be good to go.

[dyc3]

LGTM