NO_COLOR and TTY detection

When mytool list > out.txt writes \x1b[32mOK\x1b[0m into the file, the user opens out.txt and sees escape-code garbage. When CI logs capture ANSI codes as ^[[32m, grep patterns break. When a blind user's screen reader hits color codes, output becomes unintelligible. The NO_COLOR convention (no-color.org) and TTY detection exist for exactly this reason — ignoring them corrupts piped output, log files, and accessibility tooling.

Check process.env.NO_COLOR and process.stdout.isTTY before emitting ANSI codes, or use a library like picocolors that does this automatically. Wire the check once in src/cli/lib/color.ts:

import pc from 'picocolors'
// picocolors honors NO_COLOR and isTTY automatically
console.error(pc.green('Success'))

Test with NO_COLOR=1 mytool list and mytool list | cat.

• ID: cli-quality.io-behavior.no-color-support

• Severity: medium

• What to look for: List all colored output locations in the CLI. For each, check for NO_COLOR environment variable support (see https://no-color.org). Check for TTY detection that disables colors and interactive elements when output is piped. In Node.js, look for chalk/picocolors with NO_COLOR support, or process.stdout.isTTY checks. In Python, look for --no-color flag or NO_COLOR env var handling. In Go, look for isatty checks or --no-color support. Check that --no-color flag or FORCE_COLOR=0 / NO_COLOR=1 disables all ANSI escape codes.

• Pass criteria: The CLI respects the NO_COLOR environment variable by suppressing all ANSI color codes when it is set. When stdout is not a TTY (piped), colors are automatically disabled. A --no-color flag is recommended but not required if NO_COLOR env var is supported — 100% of colored output must be suppressed when NO_COLOR environment variable is set. Report: "X colored output points found, all Y respect NO_COLOR."

• Fail criteria: Colors are output regardless of NO_COLOR env var, or colors are output when stdout is piped to a file/process, or no color control mechanism exists and the CLI outputs ANSI escape codes.

• Skip (N/A) when: The CLI produces no colored output — all output is plain text with no ANSI codes, chalk, picocolors, or equivalent. All checks skip when no CLI entry point is detected.

• Detail on fail: "CLI uses chalk for colored output but does not check NO_COLOR env var or stdout.isTTY — colors will corrupt piped output" or "Colored output sent even when piped: 'mytool list > out.txt' produces ANSI escape codes in the file"

• Remediation: Respect the NO_COLOR convention and detect pipe contexts:

  // Node.js — picocolors respects NO_COLOR automatically
  import pc from 'picocolors'
  // picocolors checks NO_COLOR and stdout.isTTY out of the box
  console.error(pc.green('Success'))  // no color when piped or NO_COLOR set
  
  // Manual check if using raw ANSI codes
  const useColor = process.stdout.isTTY && !process.env.NO_COLOR
  

  # Python — click respects NO_COLOR in recent versions
  import os
  use_color = hasattr(sys.stdout, 'isatty') and sys.stdout.isatty() and not os.environ.get('NO_COLOR')