custom CSV delimiter support

[boneskull]

Depends on #15

Overview

Add support for custom delimiters in CSV output via the --csv-delimiter CLI flag.

Current Behavior

• CSV reporter always uses comma (,) as the delimiter
• Delimiter is hardcoded in the CSVReporter constructor

Desired Behavior

• Users can specify custom delimiters via --csv-delimiter <char> flag
• Common use cases:
  • Semicolon (;) for European locales
  • Tab (\t) for TSV format
  • Pipe (|) for specific processing needs

Implementation Steps

1. Update CLI Command Definition

File: src/cli/commands/run.ts

Add option to yargs configuration:

.option('csv-delimiter', {
  alias: 'csv-delim',
  description: 'Delimiter character for CSV output',
  type: 'string',
  default: ',',
})

2. Update Type Definitions

File: src/types/cli.ts or relevant types file

Add to RunCommandArgs interface:

csvDelimiter?: string;

3. Pass Delimiter to Reporter Registry

File: src/reporters/registry.ts or where reporters are instantiated

When creating CSV reporter, pass delimiter from CLI options:

case 'csv':
  return new CsvReporter({
    delimiter: options.csvDelimiter || ',',
    outputPath: options.output,
    quiet: options.quiet,
  });

4. Update CSV Reporter

File: src/reporters/csv.ts

• Already supports delimiter in constructor options ✅
• Ensure delimiter is used in formatRow() method ✅
• No changes needed (already implemented!)

5. Update Tests

File: test/integration/reporters.test.ts

• Un-skip the test at line 317
• Verify test passes with custom delimiter
• Add additional test cases for common delimiters (tab, pipe)

6. Update Documentation

Files to update:

• README.md - Add --csv-delimiter to CLI options
• ARCHITECTURE.md - Document reporter configuration options
• Examples directory - Add example using custom delimiter

Testing Checklist

• Can specify delimiter via --csv-delimiter flag
• Semicolon delimiter works correctly
• Tab delimiter works correctly
• Pipe delimiter works correctly
• Default comma delimiter still works when flag not specified
• Multi-character delimiters are handled (error or support?)
• Special characters are properly escaped in CSV output
• Works with --output directory option
• Works with stdout output

Edge Cases to Consider

• What if delimiter is the same as the quote character?
• Should we support multi-character delimiters?
• Validate delimiter doesn't contain newlines or invalid characters
• How to specify tab character on command line? (\t vs literal tab)

Estimated Complexity

Low - Most infrastructure already exists, mainly CLI plumbing needed.

Related Files

• src/cli/commands/run.ts
• src/reporters/csv.ts
• src/reporters/registry.ts
• test/integration/reporters.test.ts