feat(staged): allow unmatched rs fmt tasks

packages/rstack/src/fmt/cli.ts

@@ -262,7 +262,9 @@ const runFmtCLI = async (args: string[]): Promise<void> => {
     });
 
     if (files.length === 0) {
-      if (noErrorOnUnmatchedPattern) {
+      // Staged tasks may pass only paths excluded by formatter ignore rules.
+      const allowUnmatched = noErrorOnUnmatchedPattern || process.env.RSTACK_STAGED === '1';
+      if (allowUnmatched) {
         return;
       }
       reportNoSupportedFiles(patterns);

packages/rstack/src/staged.ts

@@ -70,6 +70,9 @@ export async function runStagedCLI(args: string[]): Promise<void> {
     );
   }
 
+  // Let child commands detect that they are running through `rs staged`.
+  process.env.RSTACK_STAGED = '1';
+
   const success = await lintStaged({
     allowEmpty: values.allowEmpty,
     concurrent: values.concurrent === undefined ? undefined : JSON.parse(values.concurrent),

packages/rstack/tests/cli/staged/fmt.test.ts

@@ -81,6 +81,29 @@ test('formats staged files with rs fmt and applies ignore rules', () => {
   expect(git(['show', ':ignored-by-git.ts'])).toBe('const gitIgnored = "git ignored";\n');
 });
 
+test('allows rs fmt when all staged files are ignored', () => {
+  const source = 'const fmtIgnored="fmt ignored"';
+  writeProjectFile('ignored-by-fmt.ts', source);
+  git(['add', '--', 'ignored-by-fmt.ts']);
+
+  const result = runStaged();
+
+  expect(result.status).toBe(0);
+  expect(readProjectFile('ignored-by-fmt.ts')).toBe(source);
+  expect(git(['show', ':ignored-by-fmt.ts'])).toBe(source);
+  expect(`${result.stdout}\n${result.stderr}`).not.toContain('No supported files matched');
+});
+
+test('still rejects staged files unsupported by rs fmt', () => {
+  writeProjectFile('notes.unknown', 'plain text');
+  git(['add', '--', 'notes.unknown']);
+
+  const result = runStaged();
+
+  expect(result.status).toBe(1);
+  expect(`${result.stdout}\n${result.stderr}`).toContain('No supported files matched');
+});
+
 test('propagates rs fmt failures', () => {
   writeProjectFile('invalid.ts', 'const value = ;');
   git(['add', '--', 'invalid.ts']);

packages/rstack/tests/cli/staged/index.test.ts

@@ -1,5 +1,5 @@
 import lintStaged from 'lint-staged';
-import { beforeEach, rs } from 'rstack/test';
+import { afterEach, beforeEach, rs } from 'rstack/test';
 import { test } from '#test-helpers';
 import { loadRstackConfig } from '../../../src/config.ts';
 import { runStagedCLI, type StagedConfig } from '../../../src/staged.ts';
@@ -17,6 +17,7 @@ const stagedConfig: StagedConfig = {
 };
 
 beforeEach(() => {
+  delete process.env.RSTACK_STAGED;
   rs.resetAllMocks();
   mocks.lintStaged.mockResolvedValue(true);
   mocks.loadRstackConfig.mockResolvedValue({
@@ -26,6 +27,10 @@ beforeEach(() => {
   });
 });
 
+afterEach(() => {
+  delete process.env.RSTACK_STAGED;
+});
+
 test('should display the staged help message', ({ execCli, expect }) => {
   const output = execCli('staged --help');
 
@@ -62,6 +67,17 @@ test('should pass default options to lint-staged', async ({ expect }) => {
   });
 });
 
+test('should set the staged environment', async ({ expect }) => {
+  mocks.lintStaged.mockImplementation(async () => {
+    expect(process.env.RSTACK_STAGED).toBe('1');
+    return true;
+  });
+
+  await runStagedCLI([]);
+
+  expect(process.env.RSTACK_STAGED).toBe('1');
+});
+
 test('should pass long options to lint-staged', async ({ expect }) => {
   await runStagedCLI([
     '--allow-empty',

website/docs/en/guide/cli/fmt.mdx

@@ -107,6 +107,8 @@ rs fmt --no-error-on-unmatched-pattern 'src/**/*.ts'
 
 For example, a pre-commit script may always run `rs fmt`, even when the staged changes contain no supported files. This option lets the command exit successfully in that case instead of blocking the commit.
 
+> [`rs staged`](./staged) enables this behavior automatically for its `rs fmt` tasks.
+
 ### `--parallel-workers <count>`
 
 Set the maximum number of formatting workers to a positive integer:

website/docs/zh/guide/cli/fmt.mdx

@@ -107,6 +107,8 @@ rs fmt --no-error-on-unmatched-pattern 'src/**/*.ts'
 
 例如，pre-commit 脚本可能会始终运行 `rs fmt`，即使暂存的改动中没有支持的文件。此选项可让命令在这种情况下成功退出，避免阻止提交。
 
+> [`rs staged`](./staged) 会为其中的 `rs fmt` 任务自动启用此行为。
+
 ### `--parallel-workers <count>`
 
 将格式化 worker 的最大数量设置为正整数：