feat: add --version and -V flags to CLI

Print the installed version and exit with code 0, consistent with common CLI conventions.

Closes #43

Author: Zhongjin Lu

src/cli.ts

@@ -1,7 +1,7 @@
 import { parseArgs, usage } from './utils/args.ts';
 import { asAppError, AppError } from './utils/errors.ts';
 import { formatSnapshotText, printHumanError, printJson } from './utils/output.ts';
-import { pathToFileURL } from 'node:url';
+import { pathToFileURL, fileURLToPath } from 'node:url';
 import { sendToDaemon } from './daemon-client.ts';
 import fs from 'node:fs';
 import os from 'node:os';
@@ -10,6 +10,14 @@ import path from 'node:path';
 export async function runCli(argv: string[]): Promise<void> {
   const parsed = parseArgs(argv);
 
+  if (parsed.flags.version) {
+    const __dirname = path.dirname(fileURLToPath(import.meta.url));
+    const pkgPath = path.join(__dirname, '..', '..', 'package.json');
+    const pkg = JSON.parse(fs.readFileSync(pkgPath, 'utf8'));
+    process.stdout.write(`${pkg.version}\n`);
+    process.exit(0);
+  }
+
   if (parsed.flags.help || !parsed.command) {
     process.stdout.write(`${usage()}\n`);
     process.exit(parsed.flags.help ? 0 : 1);

src/utils/args.ts

@@ -25,11 +25,12 @@ export type ParsedArgs = {
     noRecord?: boolean;
     replayUpdate?: boolean;
     help: boolean;
+    version: boolean;
   };
 };
 
 export function parseArgs(argv: string[]): ParsedArgs {
-  const flags: ParsedArgs['flags'] = { json: false, help: false };
+  const flags: ParsedArgs['flags'] = { json: false, help: false, version: false };
   const positionals: string[] = [];
 
   for (let i = 0; i < argv.length; i += 1) {
@@ -42,6 +43,10 @@ export function parseArgs(argv: string[]): ParsedArgs {
       flags.help = true;
       continue;
     }
+    if (arg === '--version' || arg === '-V') {
+      flags.version = true;
+      continue;
+    }
     if (arg === '--verbose' || arg === '-v') {
       flags.verbose = true;
       continue;