feat(oxfmt/lsp): support `untitled://` schema by Sysix · Pull Request #19287 · oxc-project/oxc

Sysix · 2026-02-11T22:09:24Z

This PR adds support for formatting unsaved documents using the untitled:// URI scheme in the oxfmt LSP server. This enables VS Code and other LSP clients to format in-memory documents that haven't been saved to disk yet.

Angular is not supported for the moment, could not find a VS Code extension which defines a language ID for it :/

Sysix · 2026-02-11T22:09:37Z

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apps/oxfmt/src/lsp/server_formatter.rs

apps/oxfmt/test/lsp/format/__snapshots__/format.test.ts.snap

leaysgur

Instead of duplicating the strategy/options mapping from LanguageId (the large match blocks in mod.rs)..., you could generate a fake path from the language ID (e.g. "untitled.tsx" for "typescriptreact") and feed it into the existing FormatFileStrategy::try_from(path) + config_resolver.resolve(&strategy) pipeline.

This would eliminate many lines with keeping support.rs as the single source of truth.

And for the fake path, it would be better to use {workspace_root}/untitled.{ext} rather than just untitled.{ext}.

There is a FormatFileStrategy::resolve_relative_path() (which may be needed to tailwind plugin work correctly).
It isn't called in the LSP path, but LSP already using absolute path, so that's not a concern though.

But config_resolver.resolve() and the external formatter's options.filepath both use the path — a workspace-rooted path ensures editorconfig/oxfmtrc overrides and Prettier plugin config resolution work
correctly.

Sysix · 2026-02-13T01:37:55Z

And for the fake path, it would be better to use {workspace_root}/untitled.{ext} rather than just untitled.{ext}.

This will be a problem because there is no real path. We do not know to which config is really should resolve. This why I did go with the "default" way :)
I agree the solution is not the nicest one. Will think about a better solution which could work with oxlint too. See backlog oxc-project/backlog#171

codspeed-hq · 2026-02-14T13:22:41Z

Merging this PR will not alter performance

✅ 47 untouched benchmarks
⏩ 3 skipped benchmarks¹

_{Comparing 02-11-refactor_oxfmt_lsp_split_run_format_to_format_in_memory_and_format_file_ (85e51f8) with 02-11-refacor_oxfmt_lsp_pass_languageid_to_run_format_ (5d5aa58)}

3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

Copilot

Pull request overview

This PR adds support for formatting unsaved documents using the untitled:// URI scheme in the oxfmt LSP server. This enables VS Code and other LSP clients to format in-memory documents that haven't been saved to disk yet.

Changes:

Added inner() method to LanguageId for accessing the underlying string value
Implemented in-memory formatting for untitled:// URIs using language ID to determine format strategy
Refactored test utilities to support both file-based and in-memory formatting tests
Added comprehensive test coverage for unsaved documents across multiple file types

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
`crates/oxc_language_server/src/language_id.rs`	Added `inner()` accessor method to expose the underlying language ID string
`apps/oxfmt/src/lsp/mod.rs`	Added language ID conversion functions to map language IDs to file extensions, parser names, and format strategies
`apps/oxfmt/src/lsp/server_formatter.rs`	Split formatting logic into `format_file()` and `format_in_memory()` methods to handle both file-based and untitled URIs
`apps/oxfmt/test/lsp/utils.ts`	Extracted `formatFixtureContent()` function to support testing with custom URIs
`apps/oxfmt/test/lsp/format/format.test.ts`	Added test suite for unsaved documents covering TypeScript, JSON, Vue, TOML, and plaintext files
`apps/oxfmt/test/lsp/format/__snapshots__/format.test.ts.snap`	Added expected output snapshots for all unsaved document test cases

apps/oxfmt/src/lsp/mod.rs

apps/oxfmt/src/lsp/server_formatter.rs

apps/oxfmt/src/lsp/mod.rs

leaysgur

👀

crates/oxc_language_server/src/language_id.rs

apps/oxfmt/src/lsp/server_formatter.rs

leaysgur

Thanks as always~ 👍🏻

leaysgur · 2026-02-17T01:49:18Z

Merge activity

Feb 17, 1:49 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Feb 17, 1:49 AM UTC: leaysgur added this pull request to the Graphite merge queue.
Feb 17, 2:13 AM UTC: Merged by the Graphite merge queue.

related oxc-project/oxc-vscode#25 > This PR adds support for formatting unsaved documents using the untitled:// URI scheme in the oxfmt LSP server. This enables VS Code and other LSP clients to format in-memory documents that haven't been saved to disk yet. Angular is not supported for the moment, could not find a VS Code extension which defines a language ID for it :/

# Oxlint ### 💥 BREAKING CHANGES - 4315594 oxlint: [**BREAKING**] Deprecate `"always"` and `"as-needed"` options of the radix rule (#19408) (Sysix) - d4c7af3 linter: [**BREAKING**] Remove `allowRuleToRunWithoutStrictNullChecksIKnowWhatIAmDoing` option (#19451) (camc314) ### 🚀 Features - 82ca5c3 linter: Add typescript/dot-notation rule (#19442) (camc314) - 6db0811 linter: Implement eslint-plugin-vitest/no-importing-vitest-globals (#18694) (Said Atrahouch) - c7fe8ae linter: Implement eslint-plugin-vitest/prefer-import-in-mock (#17966) (Said Atrahouch) - 0abb39a linter: Implement eslint-vitest-jest-plugin/prefer-mock-return-shorthand (#18002) (Said Atrahouch) - 2b95537 linter: Implement `n/no-path-concat` rule (#19502) (Mikhail Baev) - 735d0e4 linter: Implement typescript/no-useless-default-assignment (#19488) (camc314) - 31c3a93 linter: Add typescript/no-unnecessary-type-parameters rule (#19450) (camc314) - c948090 linter: Add typescript/consistent-return rule (#19449) (camc314) - 9f87df0 linter: Add typescript/prefer-string-starts-ends-with rule (#19448) (camc314) - 04536be linter: Add typescript/prefer-regexp-exec rule (#19447) (camc314) - 56a7feb linter: Add typescript/prefer-readonly rule (#19446) (camc314) - a1cea63 linter: Add typescript/no-unnecessary-qualifier rule (#19445) (camc314) - e3144d2 linter: Add typescript/prefer-find rule (#19444) (camc314) - 13c7408 linter: Add typescript/prefer-readonly-parameter-types rule (#19443) (camc314) - 9b17d44 linter: Add typescript/strict-void-return rule (#19441) (camc314) - ed821b4 linter: Add typescript/consistent-type-exports rule (#19440) (camc314) ### 🐛 Bug Fixes - daad7bc linter/array-callback-return: Check `allowVoid` option (#19506) (Said Atrahouch) - 638cf94 linter: Add help text to eslint rule diagnostics (#19508) (Kyle Tse) - 79fc6d7 linter: Move no-use-before-define to eslint plugin (#19438) (camc314) - c832a9f linter: Add `onScrollEnd` and `onScrollEndCapture` to `react/no-unknown-property`. (#19536) (connorshea) - 999a0db linter: Add help text to `symbol-description` diagnostics (#19538) (Anthony Amaro) - f064482 linter: Add help text to eslint rule diagnostics (#19539) (Anthony Amaro) - fd11073 linter/react/no-unknown-property: Add missing `fetchPriority` prop (#19525) (João Pedro Schmitz) - a9bb604 linter/no-shadow: Align initializer shadow handling with typescript-eslint (#19462) (camc314) - 32e6eb9 linter: Handle typed arrays/array buffers in `prefer-spread` rule. (#19478) (connorshea) - e309f84 linter: Handle additional cases in `typescript/consistent-generic-constructors` rule. (#19477) (connorshea) - 71db91a linter/array-callback-return: Check `fromAsync`, update test cases (#19483) (Said Atrahouch) - 2a12d74 linter: Handle optional chaining in `no-array-method-this-argument` rule. (#19476) (connorshea) - f65310b linter: Handle optional chaining in `prefer-object-from-entries` rule. (#19475) (connorshea) - 840acf4 linter: Handle optional chain in `no-unnecessary-array-flat-depth` rule. (#19471) (connorshea) - 85a19e9 linter: Skip string literal imports in `consistent-assert` rule. (#19474) (connorshea) ### ⚡ Performance - 6155ac4 linter/constructor-super: Use node_id over nodes loop (#19489) (camc314) - a02496d linter/consistent-index-object-style: Resolve circular type refs semantically (#19490) (camc314) # Oxfmt ### 🚀 Features - 652c346 oxfmt/lsp: Support `untitled://` schema (#19287) (Sysix) ### 🐛 Bug Fixes - 6c61b70 oxfmt: Fix outdated `sortImports.groups` doc comments (#19513) (leaysgur) Co-authored-by: camc314 <[email protected]>

Sysix mentioned this pull request Feb 11, 2026

chore(lsp): introduce LanguageId struct #19285

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Sysix mentioned this pull request Feb 11, 2026

refactor(oxfmt/lsp): pass LanguageId to run_format #19286

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github-actions bot added A-cli Area - CLI A-formatter Area - Formatter C-cleanup Category - technical debt or refactoring. Solution not expected to change behavior labels Feb 11, 2026

Sysix commented Feb 11, 2026

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Sysix force-pushed the 02-11-refactor_oxfmt_lsp_split_run_format_to_format_in_memory_and_format_file_ branch from f04a325 to 10b4f0b Compare February 12, 2026 22:05

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Sysix mentioned this pull request Feb 12, 2026

feat: support untitled schema for oxfmt oxc-project/oxc-vscode#56

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Sysix changed the title ~~refactor(oxfmt/lsp): split run_format to format_in_memory and format_file~~ feat(oxfmt/lsp): support untitled:// schema Feb 12, 2026

github-actions bot added the C-enhancement Category - New feature or request label Feb 12, 2026

Sysix force-pushed the 02-11-refacor_oxfmt_lsp_pass_languageid_to_run_format_ branch from a9b1aca to 10b8c79 Compare February 12, 2026 22:44

Sysix force-pushed the 02-11-refactor_oxfmt_lsp_split_run_format_to_format_in_memory_and_format_file_ branch from 3e478df to 6d8842d Compare February 12, 2026 22:44

Sysix force-pushed the 02-11-refacor_oxfmt_lsp_pass_languageid_to_run_format_ branch from 10b8c79 to bfe263c Compare February 12, 2026 23:24

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Sysix commented Feb 12, 2026

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Sysix marked this pull request as ready for review February 14, 2026 16:23

Sysix requested a review from camc314 as a code owner February 14, 2026 16:23

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Boshen mentioned this pull request Feb 19, 2026

release(apps): oxlint v1.49.0 && oxfmt v0.34.0 #19553

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Merging this PR will not alter performance

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