svelte-check: CLAUDECODE=1 auto-detection broken due to sade default value

[trevormunoz]

Description

The fix in #2870 to auto-detect CLAUDECODE=1 and use machine format doesn't work because the --output option has a default value in the sade CLI definition.

Note: svelte-check --output machine works correctly. The bug is specifically in the auto-detection path when no --output flag is provided.

Minimal Reproduction

// Run: CLAUDECODE=1 node reproduce.js
// Expected output: "machine"
// Actual output: "human-verbose"

const outputFormats = ['human', 'human-verbose', 'machine', 'machine-verbose'];

// sade sets default: .option('--output', '...', 'human-verbose')
const opts = { output: 'human-verbose' };

function getOutputFormat(opts) {
  if (outputFormats.includes(opts.output)) {
    return opts.output;  // ← Always returns here (default is valid)
  } else if (process.env.CLAUDECODE === '1') {
    return 'machine';    // ← Never reached
  }
  return 'human-verbose';
}

console.log('CLAUDECODE:', process.env.CLAUDECODE);
console.log('Result:', getOutputFormat(opts));

Output:

CLAUDECODE: 1
Result: human-verbose

Root Cause

In packages/svelte-check/src/index.ts, the sade option definition provides a default:

.option('--output', '...', 'human-verbose')  // ← Default value

This means opts.output is always 'human-verbose' when user doesn't provide --output, so getOutputFormat() returns early before reaching the CLAUDECODE check.

Suggested Fix

Remove the default from .option():

.option('--output', 'What output format to use...')  // No default

And guard the check in getOutputFormat:

function getOutputFormat(opts) {
    if (opts.output && outputFormats.includes(opts.output)) {
        return opts.output;
    } else if (process.env.CLAUDECODE === '1') {
        return 'machine';
    } else {
        return 'human-verbose';
    }
}

Environment

• svelte-check: 4.3.4
• Node: 20.x