refactor: switch from .mts to .ts file extensions (#56)

Since the project uses ESM via "type": "module" in package.json,
the explicit .mts extension is redundant. This simplifies the
developer experience with standard .ts extensions and improves
tooling compatibility.

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: frankieyan

package.json

@@ -3,9 +3,9 @@
   "version": "2.3.1",
   "description": "A React Compiler violation tracker to help migrations and prevent regressions",
   "type": "module",
-  "main": "dist/index.mjs",
+  "main": "dist/index.js",
   "bin": {
-    "react-compiler-tracker": "dist/index.mjs"
+    "react-compiler-tracker": "dist/index.js"
   },
   "scripts": {
     "check": "run-p check:* -c -l",
@@ -44,7 +44,7 @@
     "CHANGELOG.md"
   ],
   "lint-staged": {
-    "*.{js,ts,mjs,mts,json,md}": "biome check --write --no-errors-on-unmatched"
+    "*.{js,ts,json,md}": "biome check --write --no-errors-on-unmatched"
   },
   "devDependencies": {
     "rimraf": "6.1.2",

src/args.test.mts src/args.test.tssrc/args.test.mts renamed to src/args.test.ts

@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest'
-import { parseArgs } from './args.mjs'
+import { parseArgs } from './args.js'
 
 describe('parseArgs', () => {
     it('parses --check-files with files', () => {

src/args.mts src/args.tssrc/args.mts renamed to src/args.ts

@@ -1,6 +1,6 @@
 import { existsSync, readFileSync } from 'node:fs'
 import { afterEach, describe, expect, it, vi } from 'vitest'
-import { DEFAULT_CONFIG, loadConfig } from './config.mjs'
+import { DEFAULT_CONFIG, loadConfig } from './config.js'
 
 vi.mock('node:fs', () => ({
     existsSync: vi.fn(),

src/babel.mts src/babel.tssrc/babel.mts renamed to src/babel.ts

@@ -10,7 +10,7 @@ const recordsPath = join(fixtureDir, '.react-compiler.rec.json')
 const configPath = join(fixtureDir, '.react-compiler-tracker.config.json')
 
 function runCLI(args: string[] = [], cwd = fixtureDir): string {
-    const cliPath = join(__dirname, 'index.mts')
+    const cliPath = join(__dirname, 'index.ts')
     try {
         return execSync(`npx tsx ${cliPath} ${args.join(' ')} 2>&1`, {
             cwd,

src/config.test.mts src/config.test.tssrc/config.test.mts renamed to src/config.test.ts

@@ -2,13 +2,13 @@
 
 import { join, relative } from 'node:path'
 import type { Logger as ReactCompilerLogger } from 'babel-plugin-react-compiler'
-import { parseArgs } from './args.mjs'
-import * as babel from './babel.mjs'
-import { loadConfig } from './config.mjs'
-import type { FileErrors } from './records-file.mjs'
-import * as recordsFile from './records-file.mjs'
-import * as sourceFiles from './source-files.mjs'
-import { pluralize } from './utils.mjs'
+import { parseArgs } from './args.js'
+import * as babel from './babel.js'
+import { loadConfig } from './config.js'
+import type { FileErrors } from './records-file.js'
+import * as recordsFile from './records-file.js'
+import * as sourceFiles from './source-files.js'
+import { pluralize } from './utils.js'
 
 const compilerErrors: Map<string, FileErrors> = new Map()
 

src/config.mts src/config.tssrc/config.mts renamed to src/config.ts

@@ -1,13 +1,13 @@
 import { afterEach, describe, expect, it, vi } from 'vitest'
-import { getErrorChanges, load, save } from './records-file.mjs'
+import { getErrorChanges, load, save } from './records-file.js'
 
 vi.mock('node:fs', () => ({
     existsSync: vi.fn(),
     readFileSync: vi.fn(),
     writeFileSync: vi.fn(),
 }))
 
-vi.mock('./react-compiler.mjs', () => ({
+vi.mock('./react-compiler.js', () => ({
     getVersion: vi.fn(() => '1.0.0'),
 }))