Feature Description

Currently, external link validation is available through the validate command using the --check-external flag. However, it would be beneficial to have a dedicated command specifically for checking external URLs, similar to how other markdown link checkers work.

Proposed Solution

Add a new standalone command check-links or validate-external that:

1. Focuses exclusively on external URL validation without requiring additional flags
2. Provides a streamlined interface for this common use case
3. Includes smart defaults optimized for external link checking

Example Usage

# Check all external links in the current directory
npx markmv check-links

# Check with custom timeout and specific files
npx markmv check-links docs/**/*.md --timeout 10000

# Check with retry logic for flaky connections
npx markmv check-links --retry 3 --retry-delay 1000

# Output results in different formats
npx markmv check-links --format json
npx markmv check-links --format markdown > broken-links.md

Benefits

1. Improved discoverability - Users looking for external link validation will find it more easily
2. Better defaults - Can optimize timeouts, retries, and output specifically for external URL checking
3. Cleaner CLI interface - No need to remember --check-external flag combination
4. Feature parity - Matches the pattern of dedicated tools like markdown-link-check

Additional Features to Consider

• Parallel checking with configurable concurrency
• Smart retry logic for temporary network failures
• Response code filtering (e.g., ignore 403s from bot detection)
• Cache support to avoid re-checking recently validated URLs
• Progress indicator for large documentation sets
• Ignore patterns via config file or CLI flags
• HTTP method configuration (HEAD vs GET requests)

Alternative Naming Suggestions

• markmv check-external
• markmv validate-urls
• markmv link-check
• markmv external-links

This would make markmv even more powerful as a complete markdown maintenance toolkit while maintaining its focus on intelligent link management.