fix(cli): stdin regression

[ematipico]

Summary

Closes #9095

We couldn't catch the bug because in our tests, .read always yields the same input; however, in reality, we can read only once, and then the input is consumed.

For now I kept the changes at a minum, I will follow up with a change to better simulate the real stdin

Test Plan

Manually tested

Docs

[changeset-bot]

🦋 Changeset detected

Latest commit: 09c4da0

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

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[coderabbitai]

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Walkthrough

This patch fixes a regression in stdin formatting that was introduced in a recent refactor. The changes replace stdin-based routing with file path-based routing in the CLI runner's scan kind derivation logic. The derive_best_scan_kind and get_forced_scan_kind functions now accept an optional file path reference instead of a full Stdin object, and the runner passes only the stdin file path to determine the appropriate scan kind.

Possibly related PRs

• refactor(cli): make commands more generic #8485: Introduced the scan kind derivation logic that required refactoring to address the stdin output regression.

Suggested labels

A-CLI, A-Tooling, A-Project

Suggested reviewers

• siketyan

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Merge Conflict Detection	⚠️ Warning	❌ Merge conflicts detected (10 files): ⚔️ Cargo.lock (content) ⚔️ Cargo.toml (content) ⚔️ crates/biome_cli/src/runner/mod.rs (content) ⚔️ crates/biome_cli/src/runner/scan_kind.rs (content) ⚔️ crates/biome_cli/tests/commands/format.rs (content) ⚔️ crates/biome_css_parser/Cargo.toml (content) ⚔️ crates/biome_css_syntax/Cargo.toml (content) ⚔️ crates/biome_css_syntax/src/file_source.rs (content) ⚔️ crates/biome_service/src/workspace/server.rs (content) ⚔️ crates/biome_service/src/workspace/server.tests.rs (content) These conflicts must be resolved before merging into main.	Resolve conflicts locally and push changes to this branch.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'fix(cli): stdin regression' clearly and concisely describes the main change—fixing a regression in stdin handling for the CLI.
Description check	✅ Passed	The description is directly related to the changeset, explaining the stdin regression bug and linking to issue #9095 that this PR closes.
Linked Issues check	✅ Passed	The code changes restore correct stdin handling by switching from stdin-based routing to stdin_file_path-based routing, directly addressing issue #9095 where piped input produced no output.
Out of Scope Changes check	✅ Passed	All changes are focused on fixing stdin handling in the CLI runner and scan kind logic; no unrelated modifications detected.

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• Commit unit tests in branch fix/stdin-regression

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[ematipico]

Going to merge this as it's a huge regression