feat(language_server): introduce `ServerFormatter` #13700

Sysix · 2025-09-11T18:26:41Z

First try on formatter integration.
The server will only tell the client, that is supports formatting when fmt.experimental is true.

It will respect the flag in initialize, did_change_configuration (changing configuration), or did_change_workspace_folders.
It will not tell the client, it does not support formatting when the configuration is changed to false.
This can be optimized but has no high priority, because the client needs to send the request and the ServerFormatter needs to be set. The last requirement is then false.

Make WorkspaceWorker.option optional, so we the servers knows when the configuration in initialize or initialized (with request_workspace_configuration). Before the server knew it, by looking at the WorkspaceWorker.server_linter instance.

Sysix · 2025-09-11T18:26:58Z

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codspeed-hq · 2025-09-11T18:33:42Z

CodSpeed Instrumentation Performance Report

Merging #13700 will not alter performance

_{Comparing 09-11-refactor_language_server_introduce_dummy_serverformatter_ (a21ff54) with main (6fcb0d0)}

Summary

✅ 37 untouched

Copilot

Pull Request Overview

This PR introduces experimental formatter support to the OXC language server, adding the ServerFormatter struct and configuring it to be enabled via the fmt.experimental configuration option. The formatter integration uses dynamic LSP capability registration to conditionally advertise formatting support to clients.

Adds ServerFormatter with run_single method for formatting files
Introduces fmt.experimental configuration option for enabling the formatter
Implements dynamic capability registration for textDocument/formatting when formatter is enabled

Reviewed Changes

Copilot reviewed 12 out of 13 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
worker.rs	Adds formatter state management and configuration handling to `WorkspaceWorker`
main.rs	Implements LSP formatting endpoint and dynamic capability registration
formatter/server_formatter.rs	Core formatter implementation with file processing logic
formatter/options.rs	Configuration parsing for formatter experimental flag
capabilities.rs	Enables dynamic formatting capability support
options.rs	Adds test for new `fmt.experimental` configuration option

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crates/oxc_language_server/src/main.rs

crates/oxc_language_server/src/worker.rs

crates/oxc_language_server/src/formatter/options.rs

camc314 · 2025-09-20T18:04:38Z

Merge activity

Sep 20, 6:04 PM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Sep 20, 6:04 PM UTC: camc314 added this pull request to the Graphite merge queue.
Sep 20, 6:10 PM UTC: Merged by the Graphite merge queue.

First try on formatter integration. The server will only tell the client, that is supports `formatting` when `fmt.experimental` is `true`. It will respect the flag in `initialize`, `did_change_configuration` (changing configuration), or `did_change_workspace_folders`. It will not tell the client, it does not support formatting when the configuration is changed to `false`. This can be optimized but has no high priority, because the client needs to send the request and the `ServerFormatter` needs to be set. The last requirement is then false. Make `WorkspaceWorker.option` optional, so we the servers knows when the configuration in `initialize` or `initialized` (with `request_workspace_configuration`). Before the server knew it, by looking at the `WorkspaceWorker.server_linter` instance.

## [1.17.0] - 2025-09-23 ### 🚀 Features - f47f978 linter/plugins: Add `definePlugin` API (#14008) (overlookmotel) - 3e117c6 linter/plugins: Add `defineRule` API (#13945) (overlookmotel) - 2dc8adb linter/plugins: Add `createOnce` API (#13944) (overlookmotel) - bef8753 linter/plugins: ESTree-compatible AST for JS plugins (#13942) (overlookmotel) - 55c2e11 editor: Add `oxc.fmt.experimental` flag (#13923) (Sysix) - a21ff54 language_server: Introduce `ServerFormatter` (#13700) (Sysix) - a14aa79 npm/oxlint: Convert to ES modules (#13876) (Boshen) - 15eb326 linter: Add `vue/no-required-prop-with-default` rule (#13613) (yefan) - 5d3ba00 linter: Add `vue/require-typed-ref` rule (#13857) (yefan) - b52389a node: Bump `engines` field to require Node.js 20.19.0+ for ESM support (#13879) (Copilot) - 8221a01 linter: Add `eslint/no-misleading-character-class` (#13365) (Sysix) - c75ae8c linter/plugins: Add options to `Context` (#13810) (overlookmotel) - 53d04dd linter: Convert `oxlint` to NAPI app (#13723) (overlookmotel) ### 🐛 Bug Fixes - 1f4be38 napi/parser: Generate `.d.mts` extension for types (#14038) (Daniel Roe) - a018756 linter/plugins: Pin `tsdown` dependency to 0.15.1 (#14005) (overlookmotel) - b8790c2 language_server: Output correct position for parser & semantic errors (#14010) (Sysix) - 4d3c6e1 linter: Support let-chains in codegen node type detection (#14006) (camc314) - a34918a linter/plugins: Avoid lint warnings compiling WASM or big-endian (#13968) (overlookmotel) - 27022ab linter/switch-case-braces: Add support for string including colon on case expression (#13687) (Lukinoh) - dd3843f linter: Set package version in `package.json` (#13890) (overlookmotel) - fa866b3 linter: Sort optimized/unoptimized diagnostics before comparison (#13850) (camc314) - fac7624 linter/plugins: Improve error for no JS plugins (#13858) (overlookmotel) ### 🚜 Refactor - bb040bc parser, linter: Replace `.mjs` files with `.js` (#14045) (overlookmotel) - b353750 linter/plugins: Remove unnecessary `Serialize` derives (#14031) (overlookmotel) - 0d48511 linter/plugins: Improve handling `Context` method calls in `createOnce` (#14032) (overlookmotel) - 36ac0fb language_server: Don't create `mpsc` channel (#14011) (Sysix) - 2e9ae3f linter: Make disable directives own the rule name (#13987) (camc314) - 6bc7664 oxlint: Run oxlint before tsgolint (#13519) (camc314) - 0c93f33 language_server: Use minimal text edit for `ServerFormatter` (#13960) (Sysix) - 823cb57 langauge_server: Move `Backend` into own file (#13955) (Sysix) - dc700f5 language_server: Introduce `LSPFileSystem` (#13731) (Sysix) - 42e2c1d linter: Remove `Rc` from `DisableDirectives` (#13924) (camc314) - ac3e9e9 napi/parser: Move JS code into `src-js` directory (#13899) (overlookmotel) - e90bfe3 linter: Remove double reference in unicorn/error-message (#13916) (camc314) - 83791a0 linter: Remove double reference in vue/jsx-no-undef (#13915) (camc314) - ebd22de linter: Remove double reference in vue/require-typed-ref (#13914) (camc314) - 873e231 language_server: Move `needs_linter_restart` to `ServerLinter` (#13834) (Sysix) - 7e0d736 linter/plugins: Rename `--experimental-js-plugins` to `--js-plugins` (#13860) (overlookmotel) - 6245c8c linter/plugins: Make `Context` properties getters (#13809) (overlookmotel) - a2342a6 linter/plugins: Import named in tests (#13807) (overlookmotel) ### 📚 Documentation - 601c876 linter: Add comment explaining why Mimalloc is feature-gated (#14037) (overlookmotel) ### ⚡ Performance - 4d04c6e linter/plugins: Flatten `LintFileResult` fields (#14033) (overlookmotel) - 06363e0 linter: Add node type codegen support for `match node.kind()` (#13736) (camchenry) - a79af0a linter: Replace `for (... of ...)` loops (#13913) (overlookmotel) - b53292d linter: Use unstable sort where possible (#13818) (sapphi-red) ### 🎨 Styling - 8083740 linter: Import `Serialize` at top level (#14030) (overlookmotel) ### 🧪 Testing - b807b6f language_server: Skip formatter test on windows (#13986) (Sysix) - 2600858 language_server: Add Tester for ServerFormatter (#13969) (Sysix) - 37aadf0 language_server: Add `test_and_snapshot_multiple_file` (#13966) (Sysix) - ad14a41 editor: Fix test setup (#13929) (Sysix) - f51240e linter/plugins: Tests for different import styles (#13859) (overlookmotel) - 407c95e linter/plugins: Check `this` is undefined in visit functions (#13811) (overlookmotel) - f023a22 linter/plugins: Include stack trace in plugin loading errors (#13808) (overlookmotel) ### 💼 Other - 0630d68 linter: Build `oxlint` locally with Mimalloc in release mode (#14034) (overlookmotel) Co-authored-by: camc314 <18101008+camc314@users.noreply.github.com>

github-actions bot added A-editor Area - Editor and Language Server C-cleanup Category - technical debt or refactoring. Solution not expected to change behavior labels Sep 11, 2025

Sysix mentioned this pull request Sep 11, 2025

refactor(language_server): split options for linting and formatting #13627

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Sysix force-pushed the 09-11-refactor_language_server_introduce_dummy_serverformatter_ branch 2 times, most recently from 80c4f06 to 42a1b9b Compare September 11, 2025 20:51

Sysix force-pushed the 09-09-chore_language_server_split_options_for_linting_and_formatting branch from ce97ea7 to fc596f4 Compare September 12, 2025 11:23

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Sysix force-pushed the 09-09-chore_language_server_split_options_for_linting_and_formatting branch from fc596f4 to 3798dad Compare September 12, 2025 11:34

Sysix changed the base branch from 09-09-chore_language_server_split_options_for_linting_and_formatting to graphite-base/13700 September 12, 2025 17:16

Sysix force-pushed the graphite-base/13700 branch from 3798dad to 3b08bf6 Compare September 12, 2025 17:16

Sysix force-pushed the 09-11-refactor_language_server_introduce_dummy_serverformatter_ branch from df1a8d1 to a2bf52e Compare September 12, 2025 17:16

Sysix changed the base branch from graphite-base/13700 to 09-12-refactor_langauge_server_introdude_lspfilesystem_ September 12, 2025 17:16

Sysix mentioned this pull request Sep 12, 2025

refactor(language_server): introduce LSPFileSystem #13731

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Sysix changed the title ~~refactor(language_server): introduce dummy ServerFormatter~~ feat(language_server): introduce ServerFormatter Sep 12, 2025

github-actions bot added the C-enhancement Category - New feature or request label Sep 12, 2025

Sysix force-pushed the 09-11-refactor_language_server_introduce_dummy_serverformatter_ branch from a2bf52e to 76c2729 Compare September 14, 2025 00:27

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Sysix force-pushed the 09-11-refactor_language_server_introduce_dummy_serverformatter_ branch from 76c2729 to 940f6f4 Compare September 15, 2025 18:54

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Sysix force-pushed the 09-12-refactor_langauge_server_introdude_lspfilesystem_ branch from bdbd19b to 5bf9ca8 Compare September 16, 2025 19:00

Sysix force-pushed the 09-11-refactor_language_server_introduce_dummy_serverformatter_ branch 2 times, most recently from ddf7c62 to 5ad6d97 Compare September 16, 2025 20:07

Sysix force-pushed the 09-11-refactor_language_server_introduce_dummy_serverformatter_ branch from cb54a80 to c1e00fd Compare September 19, 2025 11:41

Sysix force-pushed the 09-12-refactor_langauge_server_introdude_lspfilesystem_ branch from dabd34c to 4649c44 Compare September 19, 2025 11:41

graphite-app bot changed the base branch from 09-12-refactor_langauge_server_introdude_lspfilesystem_ to graphite-base/13700 September 19, 2025 11:47

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Sysix force-pushed the 09-11-refactor_language_server_introduce_dummy_serverformatter_ branch 4 times, most recently from 7854fef to e9ea470 Compare September 19, 2025 17:29

Sysix marked this pull request as ready for review September 20, 2025 11:48

Sysix requested a review from camc314 as a code owner September 20, 2025 11:48

Copilot AI review requested due to automatic review settings September 20, 2025 11:48

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Sysix force-pushed the 09-11-refactor_language_server_introduce_dummy_serverformatter_ branch from e9ea470 to 58926e6 Compare September 20, 2025 11:53

Sysix mentioned this pull request Sep 20, 2025

refactor(langauge_server): move Backend into own file #13955

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Boshen mentioned this pull request Sep 23, 2025

release(oxlint): v1.17.0 #14054

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Sysix mentioned this pull request Oct 19, 2025

Support Oxfmt oxc-project/oxc-intellij-plugin#307

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