refactor: Consolidate path normalization into source-files.mts

- Move getGitPrefix() and normalizeFilePaths() from git-utils.mts
- Add absolute path handling to normalizeFilePaths()
- Delete git-utils.mts and git-utils.test.mts

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: frankieyan

src/git-utils.mts

@@ -4,7 +4,6 @@ import { join, relative } from 'node:path'
 import type { Logger as ReactCompilerLogger } from 'babel-plugin-react-compiler'
 import * as babel from './babel.mjs'
 import { loadConfig } from './config.mjs'
-import { normalizeFilePaths } from './git-utils.mjs'
 import type { FileErrors } from './records-file.mjs'
 import * as recordsFile from './records-file.mjs'
 import * as sourceFiles from './source-files.mjs'
@@ -44,7 +43,7 @@ async function main() {
         switch (flag) {
             case STAGE_RECORD_FILE_FLAG: {
                 const filePathParams = process.argv.slice(3)
-                const filePaths = normalizeFilePaths(filePathParams)
+                const filePaths = sourceFiles.normalizeFilePaths(filePathParams)
 
                 return await runStageRecords({
                     filePaths,
@@ -59,7 +58,7 @@ async function main() {
             }
             case CHECK_FILES_FLAG: {
                 const filePathParams = process.argv.slice(3)
-                const filePaths = normalizeFilePaths(filePathParams)
+                const filePaths = sourceFiles.normalizeFilePaths(filePathParams)
 
                 return await runCheckFiles({ filePaths, recordsFilePath: config.recordsFile })
             }

src/git-utils.test.mts

@@ -1,3 +1,5 @@
+import { execSync } from 'node:child_process'
+import { relative } from 'node:path'
 import { glob } from 'glob'
 
 function getAll({ globPattern }: { globPattern: string }) {
@@ -7,4 +9,58 @@ function getAll({ globPattern }: { globPattern: string }) {
     })
 }
 
-export { getAll }
+/**
+ * Gets the current working directory relative to the git repository root.
+ *
+ * @returns The cwd relative to git root (e.g., "apps/frontend/"), empty string if at git root, or null if not in a git repo
+ */
+function getGitPrefix() {
+    try {
+        const result = execSync('git rev-parse --show-prefix', {
+            encoding: 'utf8',
+            stdio: ['pipe', 'pipe', 'pipe'],
+        })
+        return result.trim()
+    } catch {
+        return null
+    }
+}
+
+/**
+ * Normalizes file paths by converting absolute paths to cwd-relative
+ * and stripping the git prefix when present.
+ *
+ * When running from a package subdirectory in a monorepo, file paths from git
+ * (e.g., lint-staged) are relative to the repo root. This function converts
+ * those paths to cwd-relative paths.
+ *
+ * @example
+ * // When cwd is apps/frontend/ (prefix is "apps/frontend/")
+ * normalizeFilePaths(["apps/frontend/src/file.tsx"]) // => ["src/file.tsx"]
+ *
+ * // Absolute paths are converted to cwd-relative
+ * normalizeFilePaths(["/Users/frankie/project/src/file.tsx"]) // => ["src/file.tsx"]
+ *
+ * // Paths that don't start with prefix are unchanged
+ * normalizeFilePaths(["src/file.tsx"]) // => ["src/file.tsx"]
+ */
+function normalizeFilePaths(filePaths: string[]) {
+    const prefix = getGitPrefix()
+    const cwd = process.cwd()
+
+    return filePaths.map((filePath) => {
+        // Handle absolute paths by converting to cwd-relative
+        if (filePath.startsWith('/')) {
+            return relative(cwd, filePath)
+        }
+
+        // Handle monorepo prefix stripping
+        if (prefix && filePath.startsWith(prefix)) {
+            return filePath.slice(prefix.length)
+        }
+
+        return filePath
+    })
+}
+
+export { getAll, normalizeFilePaths }

src/index.mts

@@ -1,6 +1,11 @@
+import { execSync } from 'node:child_process'
 import { glob } from 'glob'
 import { afterEach, describe, expect, it, vi } from 'vitest'
-import { getAll } from './source-files.mjs'
+import { getAll, normalizeFilePaths } from './source-files.mjs'
+
+vi.mock('node:child_process', () => ({
+    execSync: vi.fn(),
+}))
 
 vi.mock('glob', () => ({
     glob: {
@@ -33,3 +38,88 @@ describe('getAll', () => {
         expect(result).toEqual([])
     })
 })
+
+describe('normalizeFilePaths', () => {
+    it('strips prefix from matching paths', () => {
+        vi.mocked(execSync).mockReturnValue('apps/frontend/\n')
+
+        const result = normalizeFilePaths([
+            'apps/frontend/src/App.tsx',
+            'apps/frontend/src/utils/helper.ts',
+        ])
+
+        expect(result).toEqual(['src/App.tsx', 'src/utils/helper.ts'])
+    })
+
+    it('leaves non-matching paths unchanged', () => {
+        vi.mocked(execSync).mockReturnValue('apps/frontend/\n')
+
+        const result = normalizeFilePaths(['src/App.tsx', 'src/utils/helper.ts'])
+
+        expect(result).toEqual(['src/App.tsx', 'src/utils/helper.ts'])
+    })
+
+    it('handles mixed paths (some matching, some not)', () => {
+        vi.mocked(execSync).mockReturnValue('apps/frontend/\n')
+
+        const result = normalizeFilePaths([
+            'apps/frontend/src/App.tsx',
+            'src/local.ts',
+            'apps/frontend/index.ts',
+        ])
+
+        expect(result).toEqual(['src/App.tsx', 'src/local.ts', 'index.ts'])
+    })
+
+    it('returns paths unchanged when at git root', () => {
+        vi.mocked(execSync).mockReturnValue('\n')
+
+        const result = normalizeFilePaths(['src/App.tsx', 'src/utils/helper.ts'])
+
+        expect(result).toEqual(['src/App.tsx', 'src/utils/helper.ts'])
+    })
+
+    it('returns paths unchanged when not in a git repo', () => {
+        vi.mocked(execSync).mockImplementation(() => {
+            throw new Error('fatal: not a git repository')
+        })
+
+        const result = normalizeFilePaths(['src/App.tsx', 'src/utils/helper.ts'])
+
+        expect(result).toEqual(['src/App.tsx', 'src/utils/helper.ts'])
+    })
+
+    it('handles empty file list', () => {
+        vi.mocked(execSync).mockReturnValue('apps/frontend/\n')
+
+        const result = normalizeFilePaths([])
+
+        expect(result).toEqual([])
+    })
+
+    it('converts absolute paths to cwd-relative paths', () => {
+        vi.mocked(execSync).mockReturnValue('\n')
+        const cwd = process.cwd()
+
+        const result = normalizeFilePaths([`${cwd}/src/App.tsx`, `${cwd}/src/utils/helper.ts`])
+
+        expect(result).toEqual(['src/App.tsx', 'src/utils/helper.ts'])
+    })
+
+    it('handles absolute paths outside cwd with ../', () => {
+        vi.mocked(execSync).mockReturnValue('\n')
+
+        const result = normalizeFilePaths(['/other/project/file.tsx'])
+
+        expect(result[0]).toMatch(/^\.\.\//)
+    })
+
+    it('handles mixed absolute and relative paths', () => {
+        vi.mocked(execSync).mockReturnValue('\n')
+        const cwd = process.cwd()
+
+        const result = normalizeFilePaths([`${cwd}/src/App.tsx`, 'src/local.ts'])
+
+        expect(result).toEqual(['src/App.tsx', 'src/local.ts'])
+    })
+})